Background: Occupational injuries are responsible for more lost time from work, productivity, and working years of life than any other health condition in either civilian or noncombat military sectors. Injuries, not illnesses, are the leading cause of morbidity and mortality among U.S. Army personnel. We examined the separate and joint roles of gender, race/ethnicity, and age in the odds of discharge from the Army for disabling knee injury.
Methods: A total of 860 women and 7868 men were discharged from the Army between 1980 and 1995 for knee-related disability and met all inclusion criteria for this study. All women and a subsample of 1005 men were included in these analyses, along with a simple random sample of three controls per case, stratified by gender, drawn from the population of all active-duty enlisted soldiers in each year from 1980 to 1995. We identified predictors of the occurrence or nonoccurrence of discharge from the Army for disabling knee injury using unconditional multiple logistic regression analyses.
Results: We found relations between the risk of knee-related disability and age and race, with marked effect modification by gender. Non-Caucasian men and women were at lower risk than Caucasians at all ages. At most ages, Caucasian women were at higher risk than Caucasian men, and non-Caucasian women were at lower risk than non-Caucasian men. Within race/ethnicity and gender, the risks for men showed an inverted "U" shape with increasing age, and the risks for women showed a "J" shape with increasing age.
Conclusions: Age, race/ethnicity, and gender interactions are important in occupational injury. Differences in risk may be related to differences in work assignments, leisure activities, physical or physiological differences, or the ways in which disability compensation is granted.