Case-control study of discharge from the U.S, army for disabling occupational knee injury - The role of gender, race/ethnicity, and age

Background: Occupational injuries are responsible for more lost time from w ork, productivity, and working years of life than any other health conditio n in either civilian or noncombat military sectors. Injuries, not illnesses , are the leading cause of morbidity and mortality among U.S. A-my personne l. 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 be tween 1980 and 1995 for knee-related disability and met all inclusion crite ria 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 cas e, stratified by gender, drawn from the population of all active-duty enlis ted soldiers in each year from 1980 to 1995. Mie identified predictors of t he occurrence or nonoccurrence of discharge from the Army for disabling kne e 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, Ca ucasian women were at higher risk than Caucasian men, and non-Caucasian wom en were at lower risk than non-Caucasian men. Within race/ethnicity and gen der, the risks for men showed an inverted "U" shape with increasing age, an d 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 w ork assignments, leisure activities, physical or physiological differences, or the ways in which disability compensation is granted.