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RESULTS

During 1992–1996, there were a total of 68,770 drivers in the medical conditions program excluding drivers in functional ability level 1 (commercial drivers) and level 2 (drivers whose medical condition has resolved). The majority of drivers (54,825, 79.7%) were licensed in a single functional ability category (one medical condition). The remaining drivers (13,832, 20.1%) were licensed in two or more functional ability categories (that is, reported 2 or more medical conditions) during the study period. Most of the drivers reporting multiple conditions were licensed in two functional ability categories; however, the number per licensed driver ranged from one to seven categories during the study period. This is shown in Table 3.

Table 3.
Number of Functional Ability Categories Reported by Drivers with Medical Conditions in Utah, 1992 – 1995

 
Number of Categories Count Percent
1 54,825 79.9%
2 10,595 15.4%
3 2,403 3.5%
4 653 0.9%
5 146 0.2%
6 28 0.0%
7 7 0.0%
Total 68,770 100.0%
Table 4 shows the two way categorical combinations for drivers who were licensed in multiple functional ability categories. Note that drivers may appear more than one time, depending upon the number of functional ability categories reported. The most common 2-way combinations of functional ability categories were "cardiovascular and diabetes," "cardiovascular and vision," and "cardiovascular and pulmonary." As noted, only 2-way combinations were considered.

Table 4.
Two Way Combinations of Drivers Licensed in Multiple Functional Ability Categories, Utah Driver License Division, 1992- 1995

 
  Diabetes Cardiovascular Pulmonary Neurological Epilepsy Learning Psychiatric Alcohol Vision musculoskeletal
Cardiovascular 5,436                  
Pulmonary 717 1,796                
Neurological 614 941 223              
Epilepsy 173 280 89 369            
Learning 102 197 48 380 117          
Psychiatric 497 853 299 243 168 228        
Alcohol 81 98 57 61 52 38 269      
Vision 1,359 1,933 372 315 100 92 176 25    
musculoskeletal 401 574 205 547 80 127 194 53 180  
Functional 
Motor
241 330 94 637 72 150 118 38 140 780
Figure 2 shows the percentages of drivers who were licensed in multiple functional ability categories, by each functional ability category. Over half of these drivers with multiple conditions were in the respective "cardiovascular" and "diabetes and other metabolic conditions" functional ability categories.

Figure 2 -- Drivers Licensed in Multiple Functional Ability Categories, Percentage by Category

Analyses performed for drivers who reported single medical conditions are presented in Tables 5-7. For each functional ability category, rates of citations, crashes, and at-fault crashes are presented, broken out for each functional ability level. Rates are compared to age- and location- matched controls, and odds ratios generated. Analyses are omitted for subgroups that contained too few subjects or events to allow for meaningful analysis.

Table 5.
Relative Risk for Citations, Single Functional Ability Category and Corresponding Comparison Groups, by Functional Ability Level

 
Condition Level Medical Conditions Control Group Rate Ratio
Drivers Citations # Days Rate Drivers Citations # Days Rate Ratio L 95% U 95% Significance
Diabetes 3 5,121 501 3,246,531 1.543 9,956 3,003 16,002,739 1.877 0.822 0.75 0.90 **
  4 6,924 1,959 6,388,418 3.067 13,576 5,941 20,812,910 2.854 1.074 1.02 1.13  
  5 801 140 316,278 4.427 1,588 719 2,400,555 2.995 1.478 1.23 1.77 *
  6 192 12 25,235 4.755 379 174 549,517 3.166 1.502 0.84 2.68  
  7 144 4 11,916 3.357 287 134 434,634 3.083 1.089 0.40 2.94  
  8 11 1 847 11.806 22 14 36,551 3.830 3.082 0.45 21.14  
  9 6 1 455 21.978 12 4 15,397 2.598 8.460 1.36 52.44 *
  10 18 0 6,627 0.000 36 17 50,640 3.357 Zero Rate      
  11 33 6 9,119 6.580 66 32 93,870 3.409 1.930 0.82 4.55  
Cardiovascular 3 16,192 1,175 9,342,197 1.258 29,918 8,212 50,582,274 1.623 0.775 0.73 0.82 **
  4 4,271 217 2,021,556 1.073 8,201 1,963 13,126,357 1.495 0.718 0.62 0.83 **
  5 982 36 255,469 1.409 1,926 445 2,991,355 1.488 0.947 0.67 1.33  
  6 138 0 14,079 0.000 270 81 414,798 1.953 0.000      
  7 10 0 878 0.000 20 15 29,323 5.115 Zero Rate      
  8 6 0 1,253 0.000 12 1 18,385 0.544 Zero Rate      
  9 1 0 128 0.000 2 0 2,997 0.000 Zero Rate      
  10 3 0 1,222 0.000 6 4 8,418 4.752 Zero Rate      
  11 11 8 5,369 14.900 22 11 35,036 3.140 4.746 2.08 10.83 *
Pulmonary 3 2,055 338 1,283,858 2.633 4,058 1,706 6,083,179 2.804 0.939 0.84 1.05  
  4 760 63 363,022 1.735 1,498 488 2,336,598 2.089 0.831 0.64 1.08  
  5 612 37 306,710 1.206 1,212 295 1,883,754 1.566 0.770 0.55 1.08  
  7 217 3 50,490 0.594 428 87 664,096 1.310 0.454 0.15 1.39  
  9 20 0 3,850 0.000 40 10 67,371 1.484 Zero Rate      
  10 14 0 2,691 0.000 28 6 47,373 1.267 Zero Rate      
  11 8 1 733 13.643 16 5 25,487 1.962 6.954 1.10 43.97 *
Neurological 3 510 57 281,984 2.021 1,010 355 1,556,600 2.281 0.886 0.67 1.17  
  4 402 45 206,311 2.181 797 287 1,241,932 2.311 0.944 0.69 1.29  
  5 318 36 165,579 2.174 627 211 963,848 2.189 0.993 0.70 1.41  
  6 136 7 58,892 1.189 270 98 415,232 2.360 0.504 0.24 1.07  
  7 60 3 21,018 1.427 119 26 190,673 1.364 1.047 0.32 3.45  
  9 3 0 374 0.000 6 0 8,375 0.000 Zero Rate      
  10 11 4 5,803 6.893 22 16 33,885 4.722 1.460 0.49 4.34  
  11 9 1 5,595 1.787 18 5 24,214 2.065 0.866 0.10 7.40  
Condition Level Medical Conditions Control Group Rate Ratio
Drivers Citations # Days Rate Drivers Citations # Days Rate Ratio L 95% U 95% Significance
Epilepsy 3 564 138 322,206 4.283 1,111 689 1,677,433 4.107 1.043 0.87 1.25  
  4 2,307 829 2,103,023 3.942 4,562 2,674 6,763,679 3.953 0.997 0.92 1.08  
  5 917 101 202,135 4.997 1,815 1,101 2,606,464 4.224 1.183 0.97 1.45  
  6 281 13 21,759 5.975 557 345 794,758 4.341 1.376 0.79 2.39  
  7 317 11 26,087 4.217 626 388 899,850 4.312 0.978 0.54 1.78  
  8 465 21 51,332 4.091 919 544 1,320,262 4.120 0.993 0.64 1.54  
  10 91 8 23,457 3.411 178 108 255,716 4.223 0.808 0.39 1.65  
  11 98 9 27,345 3.291 193 85 295,129 2.880 1.143 0.58 2.27  
Psychiatric 3 6,219 1,648 4,528,381 3.639 12,205 5,877 18,678,295 3.146 1.157 1.10 1.22 *
  4 1,730 370 668,171 5.538 3,424 1,680 5,080,122 3.307 1.674 1.50 1.87 *
  5 508 63 90,773 6.940 1,004 531 1,511,605 3.513 1.976 1.53 2.55 *
  6 207 14 31,172 4.491 409 241 623,137 3.868 1.161 0.68 1.99  
  9 91 2 14,817 1.350 182 119 277,611 4.287 0.315 0.08 1.18  
  10 17 3 4,507 6.656 34 24 52,107 4.606 1.445 0.44 4.77  
  11 20 0 7,951 0.000 40 15 63,855 2.349 Zero Rate      
Vision 3 6,657 709 2,264,533 3.131 12,814 4,397 19,078,918 2.305 1.359 1.26 1.47 *
  4 2,120 202 742,145 2.722 4,145 1,203 6,215,686 1.935 1.406 1.21 1.63 *
  5 1,854 359 1,286,255 2.791 3,622 1,064 5,495,635 1.936 1.442 1.28 1.62 *
  6 1,240 119 700,795 1.698 2,372 468 3,504,635 1.335 1.272 1.04 1.55 *
  7 146 5 46,826 1.068 289 39 438,558 0.889 1.201 0.47 3.04  
  8 141 20 53,346 3.749 278 59 395,674 1.491 2.514 1.54 4.10 *
  9 32 0 5,704 0.000 63 9 91,639 0.982 Zero Rate      
  10 59 9 39,825 2.260 118 20 170,892 1.170 1.931 0.89 4.18  
  11 44 4 26,004 1.538 87 18 120,303 1.496 1.028 0.35 3.04  
Rates are expressed as citations per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.
** indicates that the medical conditions group has a statistically significant lower rate.
Table 6.
Relative Risk for All Crashes, Single Functional Ability Category and Corresponding Comparison Groups, by Functional Ability Level
 
Condition Level Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Diabetes 3 5,121 422 3,246,531 1.300 9,956 1,770 16,002,739 1.106 1.175 1.06 1.31 *
  4 6,924 1,263 6,388,418 1.977 13,576 2,837 20,812,910 1.363 1.450 1.36 1.55 *
  5 801 58 316,278 1.834 1,588 335 2,400,555 1.396 1.314 1.00 1.73  
  6 192 6 25,235 2.378 379 76 549,517 1.383 1.719 0.76 3.91  
  7 144 3 11,916 2.518 287 69 434,634 1.588 1.586 0.50 4.99  
  8 11 0 847 0.000 22 4 36,551 1.094 Zero Rate      
  9 6 0 455 0.000 12 0 15,397 0.000 Zero Rate      
  10 18 0 6,627 0.000 36 8 50,640 1.580 Zero Rate      
  11 33 2 9,119 2.193 66 17 93,870 1.811 1.211 0.28 5.23  
Cardiovascular 3 16,192 983 9,342,197 1.052 29,918 5,142 50,582,274 1.017 1.035 0.97 1.11  
  4 4,271 183 2,021,556 0.905 8,201 1,297 13,126,357 0.988 0.916 0.78 1.07  
  5 982 43 255,469 1.683 1,926 308 2,991,355 1.030 1.635 1.19 2.24 *
  6 138 0 14,079 0.000 270 39 414,798 0.940 Zero Rate      
  7 10 0 878 0.000 20 5 29,323 1.705 Zero Rate      
  8 6 0 1,253 0.000 12 3 18,385 1.632 Zero Rate      
  9 1 0 128 0.000 2 0 2,997 0.000 Zero Rate      
  10 3 0 1,222 0.000 6 1 8,418 1.188 Zero Rate      
  11 11 3 5,369 5.588 22 2 35,036 0.571 9.788 2.29 41.86 *
Pulmonary 3 2,055 213 1,283,858 1.659 4,058 798 6,083,179 1.312 1.265 1.09 1.47 *
  4 760 51 363,022 1.405 1,498 283 2,336,598 1.211 1.160 0.86 1.56  
  5 612 33 306,710 1.076 1,212 205 1,883,754 1.088 0.989 0.68 1.43  
  7 217 5 50,490 0.990 428 73 664,096 1.099 0.901 0.36 2.23  
  9 20 0 3,850 0.000 40 5 67,371 0.742 Zero Rate      
  10 14 0 2,691 0.000 28 6 47,373 1.267 Zero Rate      
  11 8 1 733 13.643 16 4 25,487 1.569 8.693 1.41 53.45 *
Neuralgic 3 510 50 281,984 1.773 1,010 169 1,556,600 1.086 1.633 1.20 2.23 *
  4 402 42 206,311 2.036 797 133 1,241,932 1.071 1.901 1.35 2.67 *
  5 318 32 165,579 1.933 627 110 963,848 1.141 1.693 1.15 2.50 *
  6 136 9 58,892 1.528 270 57 415,232 1.373 1.113 0.55 2.25  
  7 60 4 21,018 1.903 119 23 190,673 1.206 1.578 0.55 4.52  
  9 3 0 374 0.000 6 0 8,375 0.000 Zero Rate      
  10 11 2 5,803 3.447 22 6 33,885 1.771 1.946 0.40 9.37  
  11 9 1 5,595 1.787 18 2 24,214 0.826 2.164 0.21 22.51  
Condition Level Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Epilepsy 3 564 86 322,206 2.669 1,111 262 1,677,433 1.562 1.709 1.34 2.17 *
  4 2,307 563 2,103,023 2.677 4,562 1,047 6,763,679 1.548 1.729 1.56 1.91 *
  5 917 59 202,135 2.919 1,815 451 2,606,464 1.730 1.687 1.29 2.21 *
  6 281 8 21,759 3.677 557 141 794,758 1.774 2.072 1.03 4.16 *
  7 317 5 26,087 1.917 626 184 899,850 2.045 0.937 0.39 2.28  
  8 465 15 51,332 2.922 919 240 1,320,262 1.818 1.608 0.96 2.70  
  10 91 8 23,457 3.411 178 45 255,716 1.760 1.938 0.93 4.06  
  11 98 4 27,345 1.463 193 50 295,129 1.694 0.863 0.31 2.39  
Psychiatric 3 6,219 985 4,528,381 2.175 12,205 2,631 18,678,295 1.409 1.544 1.44 1.66 *
  4 1,730 167 668,171 2.499 3,424 752 5,080,122 1.480 1.688 1.43 1.99 *
  5 508 32 90,773 3.525 1,004 235 1,511,605 1.555 2.268 1.58 3.25 *
  6 207 12 31,172 3.850 409 93 623,137 1.492 2.579 1.45 4.60 *
  9 91 2 14,817 1.350 182 26 277,611 0.937 1.441 0.34 6.02  
  10 17 1 4,507 2.219 34 8 52,107 1.535 1.445 0.18 11.42  
  11 20 0 7,951 0.000 40 14 63,855 2.192 Zero Rate      
Vision 3 6,657 416 2,264,533 1.837 12,814 2,491 19,078,918 1.306 1.407 1.27 1.56 *
  4 2,120 132 742,145 1.779 4,145 733 6,215,686 1.179 1.508 1.25 1.81 *
  5 1,854 205 1,286,255 1.594 3,622 655 5,495,635 1.192 1.337 1.14 1.56 *
  6 1,240 92 700,795 1.313 2,372 357 3,504,635 1.019 1.289 1.03 1.62 *
  7 146 6 46,826 1.281 289 47 438,558 1.072 1.196 0.51 2.79  
  8 141 17 53,346 3.187 278 44 395,674 1.112 2.866 1.68 4.89 *
  9 32 0 5,704 0.000 63 13 91,639 1.419 Zero Rate      
  10 59 6 39,825 1.507 118 15 170,892 0.878 1.716 0.67 4.37  
  11 44 1 26,004 0.385 87 21 120,303 1.746 0.220 0.04 1.37  
Rates are expressed as crashes per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.
Table 7.
Relative Risk for At-Fault Crashes, Single Functional Ability Category and Corresponding Comparison Groups, by Functional Ability Level
 
Condition Level Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Diabetes 3 5,121 229 3,246,531 0.705 9,956 894 16,002,739 0.559 1.263 1.09 1.46 *
  4 6,924 746 6,388,418 1.168 13,576 1,538 20,812,910 0.739 1.580 1.45 1.72 *
  5 801 38 316,278 1.202 1,588 185 2,400,555 0.771 1.559 1.10 2.20 *
  6 192 4 25,235 1.585 379 42 549,517 0.764 2.074 0.76 5.66  
  7 144 3 11,916 2.518 287 37 434,634 0.851 2.957 0.96 9.07  
  8 11 0 847 0.000 22 2 36,551 0.547 Zero Rate      
  9 6 0 455 0.000 12 0 15,397 0.000 Zero Rate      
  10 18 0 6,627 0.000 36 5 50,640 0.987 Zero Rate      
  11 33 1 9,119 1.097 66 10 93,870 1.065 1.029 0.13 8.04  
Cardiovascular 3 16,192 517 9,342,197 0.553 29,918 2,640 50,582,274 0.522 1.060 0.96 1.17  
  4 4,271 101 2,021,556 0.500 8,201 727 13,126,357 0.554 0.902 0.73 1.11  
  5 982 19 255,469 0.744 1,926 172 2,991,355 0.575 1.293 0.81 2.07  
  6 138 0 14,079 0.000 270 22 414,798 0.530 Zero Rate      
  7 10 0 878 0.000 20 3 29,323 1.023 Zero Rate      
  8 6 0 1,253 0.000 12 2 18,385 1.088 Zero Rate      
  9 1 0 128 0.000 2 0 2,997 0.000 Zero Rate      
  10 3 0 1,222 0.000 6 1 8,418 1.188 Zero Rate      
  11 11 2 5,369 3.725 22 1 35,036 0.285 13.051 2.06 82.89 *
Pulmonary 3 2,055 113 1,283,858 0.880 4,058 421 6,083,179 0.692 1.272 1.03 1.56 *
  4 760 28 363,022 0.771 1,498 145 2,336,598 0.621 1.243 0.83 1.86  
  5 612 26 306,710 0.848 1,212 110 1,883,754 0.584 1.452 0.95 2.22  
  7 217 5 50,490 0.990 428 41 664,096 0.617 1.604 0.64 4.02  
  9 20 0 3,850 0.000 40 3 67,371 0.445 Zero Rate      
  10 14 0 2,691 0.000 28 3 47,373 0.633 Zero Rate      
  11 8 1 733 13.643 16 4 25,487 1.569 8.693 1.41 53.45 *
Neuralgic 3 510 36 281,984 1.277 1,010 96 1,556,600 0.617 2.070 1.42 3.01 *
  4 402 28 206,311 1.357 797 64 1,241,932 0.515 2.634 1.72 4.04 *
  5 318 22 165,579 1.329 627 54 963,848 0.560 2.372 1.47 3.84 *
  6 136 5 58,892 0.849 270 33 415,232 0.795 1.068 0.42 2.74  
  7 60 2 21,018 0.952 119 14 190,673 0.734 1.296 0.30 5.68  
  9 3 0 374 0.000 6 0 8,375 0.000 Zero Rate      
  10 11 2 5,803 3.447 22 4 33,885 1.180 2.920 0.58 14.74  
  11 9 1 5,595 1.787 18 1 24,214 0.413 4.328 0.34 54.80  
Condition Level Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Epilepsy 3 564 53 322,206 1.645 1,111 155 1,677,433 0.924 1.780 1.31 2.42 *
  4 2,307 372 2,103,023 1.769 4,562 588 6,763,679 0.869 2.035 1.79 2.31 *
  5 917 38 202,135 1.880 1,815 258 2,606,464 0.990 1.899 1.36 2.65 *
  6 281 8 21,759 3.677 557 73 794,758 0.919 4.003 2.04 7.86 *
  7 317 4 26,087 1.533 626 95 899,850 1.056 1.452 0.54 3.93  
  8 465 13 51,332 2.533 919 136 1,320,262 1.030 2.458 1.42 4.26 *
  10 91 8 23,457 3.411 178 23 255,716 0.899 3.792 1.79 8.01 *
  11 98 3 27,345 1.097 193 28 295,129 0.949 1.156 0.35 3.80  
Psychiatric 3 6,219 586 4,528,381 1.294 12,205 1,360 18,678,295 0.728 1.777 1.62 1.96 *
  4 1,730 117 668,171 1.751 3,424 400 5,080,122 0.787 2.224 1.82 2.72 *
  5 508 24 90,773 2.644 1,004 125 1,511,605 0.827 3.197 2.12 4.83 *
  6 207 11 31,172 3.529 409 54 623,137 0.867 4.072 2.24 7.41 *
  9 91 2 14,817 1.350 182 15 277,611 0.540 2.498 0.60 10.39  
  10 17 0 4,507 0.000 34 6 52,107 1.151 Zero Rate      
  11 20 0 7,951 0.000 40 5 63,855 0.783 Zero Rate      
Vision 3 6,657 272 2,264,533 1.201 12,814 1,473 19,078,918 0.772 1.556 1.37 1.77 *
  4 2,120 90 742,145 1.213 4,145 416 6,215,686 0.669 1.812 1.45 2.27 *
  5 1,854 131 1,286,255 1.019 3,622 372 5,495,635 0.677 1.505 1.23 1.83 *
  6 1,240 75 700,795 1.070 2,372 242 3,504,635 0.691 1.550 1.20 2.00 *
  7 146 5 46,826 1.068 289 31 438,558 0.707 1.511 0.59 3.86  
  8 141 15 53,346 2.812 278 29 395,674 0.733 3.836 2.15 6.84 *
  9 32 0 5,704 0.000 63 13 91,639 1.419 Zero Rate      
  10 59 6 39,825 1.507 118 10 170,892 0.585 2.575 0.97 6.83  
  11 44 1 26,004 0.385 87 15 120,303 1.247 0.308 0.05 2.09  
Rates are expressed as at–fault crashes per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.

Diabetes mellitus and other metabolic conditions

This was the second largest category, and included 10,069 licensed drivers with diabetes mellitus and thyroid, parathyroid, pituitary or other metabolic conditions. These results exclude the 7,245 drivers licensed in this category along with other medical conditions. The rate of citations was significantly lower than the comparison group for functional ability level 3 [odds ratio (OR) 0.82], and higher than the comparison group for levels 5 and 9 (OR 1.48 and 8.46 respectively). The absolute number of events was small in the latter category, only 1 for level 9. The rate of crashes was significantly higher than the comparison group for levels 3 and 4 (OR 1.18 and 1.45 respectively). The rate of at-fault crashes was significantly higher than the comparison group for levels 3 (OR 1.24), 4 (OR 1.58) and 5 (OR 1.56).

To summarize, drivers with diabetes mellitus and other metabolic conditions at the numerically lowest functional ability levels (least restricted drivers) had higher rates of crashes and at-fault crashes than comparison drivers, and the effect was of fairly modest magnitude (OR 1.2-1.6). This effect disappeared at numerically higher levels (more restricted drivers) and was not seen at all for citations.

Cardiovascular conditions

This was the largest category, and included 18,990 licensed drivers with cardiovascular conditions including heart disease, rhythm disturbances, or history of myocardial infarctions, heart surgery or hypertension. This excludes the 9,504 drivers who were licensed in the cardiovascular conditions category along with other functional ability categories. The rate of citations was significantly lower than the comparison group for functional ability levels 3 and 4 (OR 0.78 and 0.72 respectively) and higher than the comparison group for level 11 (OR 4.75). The absolute number of events was small, only 8, in category 11. The rate of crashes was significantly higher than the comparison group for level 5 (OR 1.64). The rate of at-fault crashes was significantly higher than the comparison group for level 11 (OR 13.05), where the absolute number of events was small at 2.

To summarize, drivers with cardiovascular conditions at a single functional ability level, level 5 (unrestricted drivers), had higher rates of crashes, but not at-fault crashes, than comparison drivers, and the effect was of fairly modest magnitude (OR 1.64). This effect was not seen at other levels or for at-fault crashes, or for citations, where the rate was actually lower than comparison drivers for the numerically lowest functional ability levels.

Pulmonary conditions

This category includes 2,615 drivers licensed with pulmonary conditions including pulmonary disease or symptoms, impaired function or severe respiratory difficulties. This excludes the 2,552 drivers who were licensed in the pulmonary conditions category along with other functional ability categories. The rate of citations was not significantly different than the comparison group for any functional ability level. The rate of crashes was significantly higher than the comparison group for levels 3 (OR 1.27) and 11 (OR 8.70): the absolute number of crashes for the latter level was small at 1. The rate of at-fault crashes was significantly higher than the comparison group for levels 3 (OR 1.27) and 11 (OR 8.70): the absolute number of at-fault crashes for the latter level was small at 1.

To summarize, drivers with pulmonary conditions at functional ability level 3, (the least restricted drivers) had higher rates of crashes and at-fault crashes than comparison drivers, and the effect was of fairly modest magnitude, OR roughly 1.3). This effect was not seen at other levels or for citations.

Neurological conditions

This category includes 887 drivers with neurological conditions including strokes, head injuries, cerebral palsy, multiple sclerosis, Parkinson disease, progressive conditions such as muscular atrophies and dystrophy, myasthenia gravis and other spinal cord and brain diseases. Note that epilepsy is considered a separate functional ability category. Alzheimer disease is not included in this category. (Alzheimer disease is included in the “learning, memory and communication” category, which contains a total of 107 individuals and therefore did no undergo analysis by functional ability level in this report). This excludes the 2,352 drivers who were licensed with neurological conditions along with other functional ability categories. Approximately 12.3% (119) of the drivers in this category fluctuated amongst the various functional ability levels over time. The rate of citations was not significantly different than the comparison group for any functional ability level. The rate of crashes was significantly higher than the comparison group for levels 3 (OR 1.63), 4 (OR 1.90) and 5 (OR 1.69). The rate of at-fault crashes was significantly higher than the comparison group for levels 3 (OR 2.07), 4 (OR 2.63) and 5 (OR 2.37).

To summarize, drivers with neurological conditions at functional ability level 3, 4 and 5, (the least restricted drivers) had higher rates of crashes and at-fault crashes than comparison drivers, at an OR of roughly 2. This effect was not seen at other levels or for citations.

Epilepsy and other episodic conditions

This category includes 2,620 drivers with epilepsy or related episodic conditions including syncope, cataplexy, narcolepsy, hypoglycemia, and episodic vertigo. This excludes the 934 drivers who were licensed with epilepsy along with other functional ability categories. Approximately 27.5% (745) of the drivers in this category fluctuated amongst the various functional ability levels over time. The rate of citations was not significantly different than the comparison group for any functional ability level. The rate of crashes was significantly higher than the comparison group for levels 3 (OR 1.71), 4 (OR 1.73) 5 (OR 1.69), and 6 (OR 2.07). The rate of at-fault crashes was significantly higher than the comparison group for levels 3 (OR 1.78), 4 (OR 2.04), 5 (OR 1.90), 6 (OR 4.0), 8 (OR 2.49), and 10 (OR 1.78).

To summarize, drivers with epilepsy and other episodic conditions at functional ability level 3-6 (the least restricted drivers) had higher rates of crashes than comparison drivers, while rates of at-fault crashes were higher for most levels; the OR was roughly 2. No effect was seen for citations.

Psychiatric or emotional conditions

This category includes 6,703 drivers with history of psychiatric or emotional conditions, psychotic illness, including suicidal tendencies, perceptual distortions, psychomotor retardation, schizophrenia, major depressive disorders, bipolar disorders and/or organic brain syndromes. This does not include the 2,065 drivers who were licensed in this category along with other functional ability categories. The rate of citations was significantly higher than the comparison group for levels 3 (OR 1.16), 4 (OR 1.67) and 5 (OR 1.98). The rate of crashes was significantly higher than the comparison group for levels 3 (OR 1.54), 4 (OR 1.73) 5 (OR 2.27), and 6 (OR 2.58). The rate of at-fault crashes was significantly higher than the comparison group for levels 3 (OR 1.78), 4 (OR 2.22) 5 (OR 3.20), and 6 (OR 4.0).

To summarize, drivers with psychiatric or emotional conditions at functional ability level 3-6 had higher rates of citations, crashes and at-fault crashes than comparison drivers. The increase in rate was modest for citations (OR about 1.5) but was moderately high for crashes (OR 1.5-2.5) and particularly for at-fault crashes in numerically higher functional ability levels (OR up to 3-4).

Visual acuity

This category includes 11,363 drivers with history of eye conditions that may affect vision. The rate of citations was significantly higher than the comparison group for levels 3 (OR 1.36), 4 (OR 1.41), 5 (OR 1.44), 6 (OR 1.27), and 8 (OR 2.51). The rate of crashes was significantly higher than the comparison group for levels 3 (OR 1.41), 4 (OR 1.51), 5 (OR 1.44), 6 (OR 1.29), and 8 (OR 2.87). The rate of at-fault crashes was significantly higher than the comparison group for levels 3 (OR 1.56), 4 (OR 1.81), 5 (OR 1.51), 6 (OR 1.55), and 8 (OR 3.84). The number of drivers and events in level 8 was small.

To summarize, drivers with visual conditions at functional ability level 3-6 and 8 had higher rates of citations, crashes and at-fault crashes than comparison drivers. The increase in rate was generally modest (OR about 1.5).

MULTIPLE MEDICAL CONDITIONS

Analyses performed for drivers who reported multiple medical conditions are presented in Tables 8-14. Individuals with three- and four-way combinations of medical conditions existed, but in small numbers for each, therefore only two-way combinations that included adequate numbers for analysis were considered (see Tables 3 and 4). Similarly, small numbers at each functional ability level for each medical condition precluded meaningful analysis by individual functional ability level. Therefore, functional ability levels were collapsed into unrestricted (levels 3-5) and unrestricted (levels 6-11) groups for analysis. Table 8 presents the relative risk for all adverse driving events (citations, crashes, and at-fault crashes) combined, by restriction status. Tables 9-14 present the relative risk for citations, crashes, and at-fault crashes for specific combinations of medical conditions.

Table 8.
Relative Risk for All Adverse Driving Events+, Drivers with Multiple Medical Conditions and Corresponding Comparison Groups by Combined Restriction Status, Utah 1992 – 1996

 
  Restriction¦
Status
Medical Conditions Comparison Group Rate Ratio
Drivers # Events # Days Rate Comparison # Events # Days Rate Ratio L 95% U 95% Significance
Citation Not Restricted 13,408 2,122 12,430,892 1.71 25,496 7,2247 41,429,463 1.74 0.98 0.93 1.03  
  Restricted 2,414 100 662,027 1.51 4,774 1,380 7,322,259 1.88 0.80 0.65 0.98 **
Crash Not Restricted 13,408 1,965 12,430,892 1.58 25,496 4,659 41,429,463 1.12 1.41 1.33 1.45 *
  Restricted 2,414 97 662,027 1.47 4,774 840 7,322,259 1.15 1.28 1.04 1.58 *
At Fault Crash Not Restricted 13,408 1,229 12,430,892 0.99 25,496 2,567 41,429,463 .62 1.60 1.49 1.71 *
  Restricted 2,414 73 662,027 1.10 4,774 483 7,322,259 .66 1.67 1.31 2.13 *
*The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.
** indicates that the medical conditions group has a statistically significant lower rate.
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
+ Adverse driving events: Citations, crashes, and at-fault crashes.
Table 9.
Relative Risk for Citations, Unrestricted Drivers in Two Functional Ability Categories and Corresponding Comparison Groups
 
Condition Restriction¦
Status
Medical Conditions Control Group Rate Ratio
Drivers Citations # Days Rate Drivers Citations # Days Rate Ratio L 95% U 95% Significance
Diabetes and 
Cardiovascular
Not Restricted 5,149 421 3,715,559 1.133 9,878 2,256 16,149,087 1.397 0.811 0.731 0.900 **
Diabetes and 
Pulmonary
Not Restricted 653 48 409,290 1.173 1,289 290 2,031,244 1.428 0.821 0.606 1.114  
Diabetes and 
Neurological 
Not Restricted 521 49 313,089 1.565 1,029 259 1,630,494 1.588 0.985 0.726 1.337  
Diabetes and 
Psychiatric
Not Restricted 434 61 287,196 2.124 861 288 1,363,088 2.113 1.005 0.763 1.325  
Diabetes and 
Visual Acuity
Not Restricted 456 19 151,781 1.252 898 214 1,370,701 1.561 0.802 0.502 1.281  
Cardiovascular and 
Pulmonary
Not Restricted 1,611 110 974,995 1.128 3,151 703 5,040,618 1.395 0.809 0.662 0.989 **
Cardiovascular and 
Neurological
Not Restricted 759 51 437,952 1.165 1,490 342 2,348,393 1.456 0.800 0.596 1.072  
Cardiovascular and 
Psychiatric
Not Restricted 758 64 438,084 1.461 1,500 425 2,391,625 1.777 0.822 0.632 1.069  
Cardiovascular and 
Visual Acuity
Not Restricted 437 13 139,103 0.935 858 148 1,288,721 1.148 0.814 0.462 1.433  
Cardiovascular and 
Musculoskeletal
Not Restricted 478 20 226,092 0.885 946 180 1,464,925 1.229 0.720 0.455 1.140  
Neurological and 
Musculoskeletal
Not Restricted 419 61 220,366 2.768 830 353 1,313,067 2.688 1.030 0.785 1.351  
Neurological and 
Functional Motor
Not Restricted 499 90 284,244 3.166 986 406 1,556,055 2.609 1.214 0.966 1.524  
Musculoskeletal and 
Functional Motor
Not Restricted 639 87 365,992 2.377 1,264 482 1,983,002 2.431 0.978 0.778 1.229  
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
Rates are expressed as citations per 10,000 license days.
Medical conditions groups did not have a statistically significant higher rate in any of the combination categories.
** indicates that the medical conditions group has a statistically significant lower rate.
Table 10.
Relative Risk for Crashes, Unrestricted Drivers in Two Functional Ability Categories and Corresponding Comparison Groups
 
Condition Restriction¦
Status
Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Diabetes and 
Cardiovascular
Not Restricted 5,149 447 3,715,559 1.203 9,878 1,660 16,149,087 1.028 1.170 1.054 1.299 *
Diabetes and 
Pulmonary
Not Restricted 653 51 409,290 1.246 1,289 218 2,031,244 1.073 1.161 0.856 1.574  
Diabetes and 
Neurological 
Not Restricted 521 54 313,089 1.725 1,029 189 1,630,494 1.159 1.488 1.102 2.009 *
Diabetes and 
Psychiatric
Not Restricted 434 52 287,196 1.811 861 163 1,363,088 1.196 1.514 1.111 2.064 *
Diabetes and 
Visual Acuity
Not Restricted 456 36 151,781 2.372 898 143 1,370,701 1.043 2.273 1.593 3.244 *
Cardiovascular and 
Pulmonary
Not Restricted 1,611 106 974,995 1.087 3,151 519 5,040,618 1.030 1.056 0.857 1.301  
Cardiovascular and 
Neurological
Not Restricted 759 45 437,952 1.028 1,490 275 2,348,393 1.171 0.877 0.640 1.202  
Cardiovascular and 
Psychiatric
Not Restricted 758 58 438,084 1.324 1,500 249 2,391,625 1.041 1.272 0.956 1.691  
Cardiovascular and 
Visual Acuity
Not Restricted 437 18 139,103 1.294 858 131 1,288,721 1.017 1.273 0.779 2.081  
Cardiovascular and 
Musculoskeletal
Not Restricted 478 17 226,092 0.752 946 129 1,464,925 0.881 0.854 0.515 1.415  
Neurological and 
Musculoskeletal
Not Restricted 419 45 220,366 2.042 830 164 1,313,067 1.249 1.635 1.179 2.266 *
Neurological and 
Functional Motor
Not Restricted 499 73 284,244 2.568 986 174 1,556,055 1.118 2.297 1.761 2.995 *
Musculoskeletal and 
Functional Motor
Not Restricted 639 67 365,992 1.831 1,264 230 1,983,002 1.160 1.578 1.205 2.067 *
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
Rates are expressed as crashes per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.
Table 11.
Relative Risk for At-Fault Crashes, Unrestricted Drivers in Two Functional Ability Categories and Corresponding Comparison Groups
 
Condition Restriction¦
Status
Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Diabetes and 
Cardiovascular
Not Restricted 5,149 283 3,715,559 0.762 9,878 872 16,149,087 0.540 1.411 1.234 1.612 *
Diabetes and 
Pulmonary
Not Restricted 653 30 409,290 0.733 1,289 115 2,031,244 0.566 1.295 0.867 1.933  
Diabetes and 
Neurological 
Not Restricted 521 33 313,089 1.054 1,029 104 1,630,494 0.638 1.652 1.122 2.435 *
Diabetes and 
Psychiatric
Not Restricted 434 32 287,196 1.114 861 79 1,363,088 0.580 1.922 1.284 2.878 *
Diabetes and 
Visual Acuity
Not Restricted 456 22 151,781 1.449 898 85 1,370,701 0.620 2.337 1.483 3.684 *
Cardiovascular and 
Pulmonary
Not Restricted 1,611 56 974,995 0.574 3,151 278 5,040,618 0.552 1.041 0.782 1.388  
Cardiovascular and 
Neurological
Not Restricted 759 33 437,952 0.754 1,490 152 2,348,393 0.647 1.164 0.799 1.696  
Cardiovascular and 
Psychiatric
Not Restricted 758 31 438,084 0.708 861 79 1,363,088 0.580 1.221 0.806 1.848  
Cardiovascular and 
Visual Acuity
Not Restricted 437 11 139,103 0.791 858 80 1,288,721 0.621 1.274 0.679 2.389  
Cardiovascular and 
Musculoskeletal
Not Restricted 478 13 226,092 0.575 946 77 1,464,925 0.526 1.094 0.608 1.969  
Neurological and 
Musculoskeletal
Not Restricted 419 31 220,366 1.407 830 84 1,313,067 0.640 2.199 1.472 3.285 *
Neurological and 
Functional Motor
Not Restricted 499 49 284,244 1.724 986 90 1,556,055 0.578 2.980 2.140 4.151 *
Musculoskeletal and 
Functional Motor
Not Restricted 639 46 365,992 1.257 1,264 127 1,983,002 0.640 1.962 1.409 2.732 *
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
Rates are expressed as at-fault crashes per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.
Table 12.
Relative Risk for Citations, Restricted Drivers in Two Functional Ability Categories, and Corresponding Comparison Groups
 
Condition Restriction¦
Status
Medical Conditions Control Group Rate Ratio
Drivers Citations # Days Rate Drivers Citations # Days Rate Ratio L 95% U 95% Significance
Diabetes and 
Cardiovascular
Restricted 369 5 63,087 0.793 732 145 1,169,976 1.239 0.640 0.264 1.548  
Diabetes and 
Visual Acuity
Restricted 136 5 37,775 1.324 268 41 411,682 0.996 1.329 0.527 3.353  
Cardiovascular and 
Pulmonary
Restricted 257 4 59,324 0.674 504 104 795,688 1.307 0.516 0.193 1.375  
Cardiovascular and 
Neurological
Restricted 186 1 49,253 0.203 369 75 567,701 1.321 0.154 0.028 0.851 **
Cardiovascular and 
Visual Acuity
Restricted 145 7 41,661 1.680 287 38 444,009 0.856 1.963 0.890 4.330  
Neurological and 
Musculoskeletal
Restricted 176 14 68,648 2.039 349 141 538,049 2.621 0.778 0.450 1.346  
Neurological and 
Functional Motor
Restricted 176 12 62,282 1.927 350 162 528,730 3.064 0.629 0.352 1.124  
Musculoskeletal and 
Functional Motor
Restricted 149 9 53,274 1.689 297 131 457,298 2.865 0.590 0.302 1.150  
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
Rates are expressed as citations per 10,000 license days.
Medical conditions groups did not have a statistically significant higher rate in any of the combination categories.
** indicates that the medical conditions group has a statistically significant lower rate.
Table 13.
Relative Risk for All Crashes, Restricted Drivers in Two Functional Ability Categories, and Corresponding Comparison Groups
 
Condition Restriction¦ Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Diabetes and 
Cardiovascular
Restricted 369 11 63,087 1.744 732 110 1,169,976 0.940 1.855 1.008 3.413 *
Diabetes and 
Visual Acuity
Restricted 136 7 37,775 1.853 268 43 411,682 1.045 1.774 0.807 3.901  
Cardiovascular and 
Pulmonary
Restricted 257 2 59,324 0.337 504 79 795,688 0.993 0.340 0.089 1.293  
Cardiovascular and 
Neurological
Restricted 186 2 49,253 0.406 369 73 567,701 1.286 0.316 0.084 1.194  
Cardiovascular and 
Visual Acuity
Restricted 145 7 41,661 1.680 287 44 444,009 0.991 1.696 0.771 3.730  
Neurological and 
Musculoskeletal
Restricted 176 17 68,648 2.476 349 55 538,049 1.022 2.423 1.431 4.102 *
Neurological and 
Functional Motor
Restricted 176 15 62,282 2.408 350 57 528,730 1.078 2.234 1.284 3.887 *
Musculoskeletal and 
Functional Motor
Restricted 149 11 53,274 2.065 297 48 457,298 1.050 1.967 1.034 3.741 *
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
Rates are expressed as crashes per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.
Table 14.
Relative Risk for At-Fault Crashes, Restricted Drivers in Two Functional Ability Categories, and Corresponding Comparison Groups
 
Condition Restriction¦ Medical Conditions Control Group Rate Ratio
Drivers Crashes # Days Rate Drivers Crashes # Days Rate Ratio L 95% U 95% Significance
Diabetes and 
Cardiovascular
Restricted 369 10 63,087 1.585 732 60 1,169,976 0.513 3.091 1.638 5.834 *
Diabetes and 
Visual Acuity
Restricted 136 7 37,775 1.853 268 30 411,682 0.729 2.543 1.150 5.623 *
Cardiovascular and 
Pulmonary
Restricted 257 2 59,324 0.337 504 44 795,688 0.553 0.610 0.150 2.479  
Cardiovascular and 
Neurological
Restricted 186 2 49,253 0.406 369 40 567,701 0.705 0.576 0.142 2.343  
Cardiovascular and 
Visual Acuity
Restricted 145 7 41,661 1.680 287 29 444,009 0.653 2.573 1.161 5.699 *
Neurological and 
Musculoskeletal
Restricted 176 10 68,648 1.457 349 24 538,049 0.446 3.266 1.628 6.552 *
Neurological and 
Functional Motor
Restricted 176 12 62,282 1.927 350 31 528,730 0.586 3.286 1.753 6.162 *
Musculoskeletal and 
Functional Motor
Restricted 149 8 53,274 1.502 297 22 457,298 0.481 3.121 1.449 6.722 *
¦ Not restricted: Functional ability levels 3-5. Restricted: Functional ability levels 6-11.
Rates are expressed as at-fault crashes per 10,000 license days.
* The confidence interval does not include 1.0. Therefore, the higher rate of the medical conditions group is statistically significant.

All Drivers licensed in multiple functional ability categories

This category includes 13,408 drivers licensed during the study period. Rates for unrestricted drivers (functional ability levels 3-5) in this category were 1.71, 1.58 and 0.99 per 10,000 license days for citation, all crash and at fault crashes respectively compared to 1.74, 1.12 and 0.62 respectively for their corresponding comparison group. The rates for the restricted drivers (functional ability levels 6-11) in this category were all 1.51, 1.47 and 1.10 per 10,000 licensed days for citation, crash and at fault crash compared to 1.88, 1.15 and 0.66 for their corresponding comparison group.

The relative risks (odds ratios) for citation, crash and at-fault crashes were 0.98, 1.41 and 1.60 for unrestricted drivers, and 0.80, 1.28 and 1.67 for restricted drivers for citation, crash and at-fault crash during the study period. The confidence levels for all crash and at-fault crash in both groups were higher than those of their respective comparison groups at a statistical significance level of 5%. However, the rate of citation for restricted drivers was significantly lower than that of their corresponding comparison group, while the rate of citation for unrestricted drivers was similar to the rate of the comparison drivers.

Diabetes Mellitus and other Metabolic Conditions plus Cardiovascular Conditions

This was the largest group of individuals with multiple medical conditions, and included 5149 unrestricted and 369 restricted drivers licensed during the study period. Rates for unrestricted drivers were 1.133, 1.203, and 0.762 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.397, 1.028, and 0.540 for the corresponding comparison groups. Rates were significantly lower than comparison drivers for citations (OR 0.81). Rates were significantly higher than comparison drivers for crashes and at-fault crashes (OR 1.03 and 1.41 respectively).

Rates for restricted drivers were 0.793, 1.744 and 1.585 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.239, 0.940, and 0.513 for the corresponding control groups. Rates were significantly higher than comparison drivers for crashes and at-fault crashes (OR 1.86 and 3.09 respectively). Absolute numbers of these latter two events were small.

Diabetes Mellitus and other Metabolic Conditions plus Pulmonary Conditions

This group included 653 unrestricted drivers licensed during the study period; the number of restricted drivers with this combination of conditions was too small for meaningful analysis. Rates for unrestricted drivers were 1.173, 1.246 and 0.733 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.428, 1.073 and 0.566 for the corresponding comparison groups. These rates did not differ significantly.

Diabetes Mellitus and other Metabolic Conditions plus Neurological Conditions

This group included 521 unrestricted drivers licensed during the study period; the number of restricted drivers with this combination of conditions was too small for meaningful analysis. Rates for unrestricted drivers were 1.565, 1.725, and 1.054 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.588, 1.159, and 0.638 for the corresponding comparison groups. Rates were significantly higher than the comparison groups for crashes and at-fault crashes (OR 1.49 and 1.65 respectively).

Diabetes Mellitus and other Metabolic Conditions plus Psychiatric Conditions

This group included 434 unrestricted drivers licensed during the study period; the number of restricted drivers with this combination of conditions was too small for meaningful analysis. Rates for unrestricted drivers were 2.124, 1.811, and 1.114 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 2.113, 1.196, and 0.580 for the corresponding comparison groups. Rates were significantly higher than the comparison groups for crashes and at-fault crashes (OR 1.514 and 1.1.922 respectively).

Diabetes Mellitus and other Metabolic Conditions plus Visual Acuity

This group included 456 unrestricted and 136 restricted drivers licensed during the study period. Rates for unrestricted drivers were 1.252, 2.372 and 1.449 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.561, 1.043 and 0.620 for the corresponding comparison groups. Rates were significantly higher than the comparison groups for crashes and at-fault crashes (OR 2.27 and 2.34 respectively).

Rates for restricted drivers were 1.324, 1.853 and 1.853 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 0.996, 1.045, and 0.729 for the corresponding control groups. Rates were significantly higher than comparison drivers for at-fault crashes (OR 2.54). Absolute numbers of at-fault crashes were small.

Cardiovascular plus Pulmonary

This group included 1611 unrestricted and 257 restricted drivers licensed during the study period. Rates for unrestricted drivers were 1.128, 1.087 and 0.574 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.395, 1.030 and 0.552 for the corresponding comparison groups. The rate for citations was significantly lower than the comparison groups (OR 0.81), while rates for crashes and at-fault crashes did not differ significantly from the comparison groups.

Rates for restricted drivers were 0.674, 0.337 and 0.337 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.307, 0.993 and 0.553 for the corresponding comparison groups. These rates did not differ significantly from the comparison groups.

Cardiovascular plus Neurological

This group included 759 unrestricted and 186 restricted drivers licensed during the study period. Rates for unrestricted drivers were 1.165, 1.028 and 0.754 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.456, 1.171 and 0.647 for the corresponding comparison groups. These rates did not differ significantly from the comparison groups.

Rates for restricted drivers were 0.203, 0.406 and 0.406 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.321, 1.286 and 0.705 for the corresponding comparison groups. The rate for citations was significantly lower than the comparison groups (OR 0.15), while rates for crashes and at-fault crashes did not differ significantly from the comparison groups.

Cardiovascular plus Psychiatric Conditions

This group included 758 unrestricted drivers licensed during the study period; the number of restricted drivers with this combination of conditions was too small for meaningful analysis. Rates for unrestricted drivers were 1.461, 1.32 and 0.708 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.777, 1.041 and 0.580 for the corresponding comparison groups. These rates did not differ significantly from the comparison groups.

Cardiovascular plus Visual Acuity

This group included 437 unrestricted and 145 restricted drivers licensed during the study period. Rates for unrestricted drivers were 0.935, 1.294 and 0.791 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.148, 1.017 and 0.621 for the corresponding comparison groups. These rates did not differ significantly from the comparison groups.

Rates for restricted drivers were 1.680, 1.680 and 1.680 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 0.856, 0.991 and 0.653 for the corresponding comparison groups. The rates for citations and crashes did not differ significantly from the comparison groups, while the rate for at-fault crashes was significantly higher (OR 2.57).

Cardiovascular plus Musculoskeletal

This group included 478 unrestricted drivers licensed during the study period; the number of restricted drivers with this combination of conditions was too small for meaningful analysis. Rates for unrestricted drivers were 0.885, 0.752, and 0.575 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 1.229, 0.881 and 0.526for the corresponding comparison groups. These rates did not differ significantly from the comparison groups.

Neurological plus Musculoskeletal

This group included 419 unrestricted and 176 restricted drivers licensed during the study period. Rates for unrestricted drivers were 2.768, 2.042, and 1.407 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 2.688, 1.249 and 0.640 for the corresponding comparison groups. The rates for citations did not differ significantly from the comparison group, while the rate for crashes and at-fault crashes were significantly higher (OR 1.64 and 2.20 respectively).

Rates for restricted drivers were 2.039, 2.476 and 1.457 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 2.621, 1.022 and 0.446 for the corresponding comparison groups. The rates for citations did not differ significantly from the comparison group, while the rate for crashes and at-fault crashes were significantly higher (OR 2.42 and 3.27 respectively).

Neurological plus Functional Motor

This group included 499 unrestricted and 176 restricted drivers licensed during the study period. Rates for unrestricted drivers were 3.166, 2.568 and 1.724 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 2.609, 1.118 and 0.578 for the corresponding comparison groups. The rates for citations did not differ significantly from the comparison group, while the rates for crashes and at-fault crashes were significantly higher (OR 2.30 and 2.98 respectively).

Rates for restricted drivers were 1.927, 2.408 and 1.927 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 3.064, 1.078 and 0.586 for the corresponding comparison groups. The rates for citations did not differ significantly from the comparison group, while the rate for crashes and at-fault crashes were significantly higher (OR 2.23 and 3.29 respectively).

Musculoskeletal plus Functional Motor

This group included 639 unrestricted and 149 restricted drivers licensed during the study period. Rates for unrestricted drivers were 2.377, 1.831 and 1.257 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 2.431, 1.160 and 0.640 for the corresponding comparison groups. The rates for citations did not differ significantly from the comparison group, while the rates for crashes and at-fault crashes were significantly higher (OR 1.58 and 1.96 respectively).

Rates for restricted drivers were 1.689, 2.065 and 1.502 per 10,000 license days for citations, crashes, and at-fault crashes respectively, compared with 2.865, 1.050 and 0.481 for the corresponding comparison groups. The rates for citations did not differ significantly from the comparison group, while the rate for crashes and at-fault crashes were significantly higher (OR 1.967 and 3.121 respectively).

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