Effect of non-steroidal anti-inflammatory medications on the risk of amyotrophic lateral sclerosis

Inflammatory processes may be involved in the pathogenesis of amyotrophic lateral sclerosis ( ALS). We examined the association of non-steroidal anti-inflammatory drugs (NSAIDs) with the risk of ALS in case-control study of incident cases ( n=111) conducted within the Kaiser Permanente Medical Care Program of Northern California during the years 1996-2000. Controls (n5258) randomly selected from the same population were frequency matched by age and gender to the ALS cases. Information regarding use of NSAIDs (non-aspirin and aspirin) and three classes of control' medications was collected by in-person structured interview. Subjects who used medication at least twice a week for at least a month were classified as 'ever users'. Multivariable logistic regression models were adjusted for age, gender, history of osteoarthritis/ rheumatoid arthritis and pain, and other medication use. Overall, there was no association between NSAID use and ALS; however, some sex differences were noted for non-aspirin NSAID use. Among men, non-aspirin NSAID use was associated with a two-fold increased risk of ALS (adjusted odds ratio (OR) 2.0, 95% confidence interval (CI) 1.0-3.9), whereas among women, non-aspirin NSAID use was not associated with increased ALS risk ( adjusted OR 0.5, 95% CI 0.2-1.2). ALS risk was not associated with aspirin use or with 'control' medications. This study did not find any evidence to suggest that NSAID use reduces the risk of ALS. The observed sex differences with non- aspirin NSAID use could be due to chance or an unmeasured confounder.