Increased risk for new-onset psychiatric adverse events in patients with newly diagnosed primary restless legs syndrome who initiate treatment with dopamine agonists: A large-scale retrospective claims matched-cohort analysis

Abstract

Study Objectives: Published literature documents increased risk for psychiatric adverse events (P-AEs) following dopamine agonist (DA) initiation for treatment of primary restless legs syndrome (RLS). We examined the association between DA initiation and subsequent new-onset P-AEs among patients with a new diagnosis of RLS who had no history of psychiatric disorder or DA use. Methods: Selected were adults (age 18 years or older) enrolled through United States employer-sponsored plans and Medicare Advantage from 7/1/2008–12/ 31/2014, with ≥ 2 years of claims data preceding their first RLS diagnosis (“preindex period”). Excluded were those with psychiatric diagnoses (International Classification of Diseases, Ninth Revision [ICD-9] 290-319) or DA use during the preindex period, and those with possible secondary RLS. Patients who initiated (DA+) versus did not initiate (DA−) DAs were matched 1:1 on age at index RLS diagnosis, sex, geographic region, and employment status, and preindex period comorbid illness burden and number of non-DA drug fills. Using a validated ICD-9-based severity-of-illness psychiatric disorder classification system, we compared likelihoods of new-onset P-AEs between matched pairs during parallel follow-up periods. Results: Identified were 889 matched pairs. Compared with their DA− counterparts, DA+ patients were nearly two times more likely to experience development of any P-AE (odds ratio [OR] 1.71, 95% confidence interval [CI] 1.31–2.24, P