Drug violations and aviation accidents: findings from the US mandatory drug testing programs.

AIMS To assess the role of drug violations in aviation accidents. DESIGN Case-control analysis. SETTING Commercial aviation in the United States. PARTICIPANTS Aviation employees who were tested for drugs during 1995-2005 under the post-accident testing program (cases, n = 4977) or under the random testing program (controls, n = 1 129 922). MEASUREMENTS Point prevalence of drug violations, odds ratio of accident involvement and attributable risk in the population. A drug violation was defined as a confirmed positive test for marijuana (≥50 ng/ml), cocaine (≥300 ng/ml), amphetamines (≥1000 ng/ml), opiates (≥2000 ng/ml) or phencyclidine (≥25 ng/ml). FINDINGS The prevalence of drug violations was 0.64% [95% confidence interval (CI): 0.62-0.65%] in random drug tests and 1.82% (95% CI: 1.47-2.24%) in post-accident tests. The odds of accident involvement for employees who tested positive for drugs was almost three times the odds for those who tested negative (odds ratio 2.90, 95% CI: 2.35-3.57), with an estimated attributable risk of 1.2%. Marijuana accounted for 67.3% of the illicit drugs detected. The proportion of illicit drugs represented by amphetamines increased progressively during the study period, from 3.4% in 1995 to 10.3% in 2005 (P < 0.0001). CONCLUSIONS Use of illicit drugs by aviation employees is associated with a significantly increased risk of accident involvement. Due to the very low prevalence, drug violations contribute to only a small fraction of aviation accidents.