Details
International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) diagnosis codes are thought to have better accuracy for capturing suicide intent compared to International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. As an update to a previous Sentinel study that used ICD-9-CM codes to identify intentional self-harm, this study assessed the risk of intentional self-harm events in patients aged 10 and older with asthma following use of either montelukast or inhaled corticosteroids (ICS) as monotherapy. Intentional self-harm in this study was defined using ICD-10-CM diagnosis codes, and the analysis used inverse probability of treatment weighting to balance baseline covariates. Among 752,230 and 724,855 patients in the montelukast and ICS exposure groups respectively, no association was found between montelukast use and intentional self-harm compared to ICS use [Hazard Ratio (95% Confidence Interval): 0.96 (0.85, 1.08)]. This finding was consistent across age, sex, psychiatric history and pre/post Boxed Warning period subgroups, and sensitivity analyses showed similar null findings. These results cannot exclude other neuropsychiatric idiosyncratic reactions to montelukast. Compared to the previous Sentinel study, this study identified about double the rate of intentional self-harm events, suggesting a greater sensitivity of ICD-10-CM codes for measuring intentional self-harm than ICD-9-CM codes. This study provided more information to FDA on the use of diagnosis codes for capturing intentional self-harm, an important health outcome in drug safety studies.