Off-label low dose amitriptyline for insomnia disorder: Patient-reported outcomes.

Purpose: Low dose amitriptyline is prescribed off-label to improve sleep maintenance in patients with insomnia disorder. Data on treatment outcomes are limited. We aimed to assess patient-reported treatment effect and side effects of low dose amitriptyline for insomnia in routine care data.

Methods: Cross-sectional study: Seven hundred fifty-two consecutive patients with insomnia disorder having sleep maintenance problems were treated in an outpatient sleep clinic with low dose amitriptyline (10-20 mg based on self-titration). Treatment was intended to improve sleep maintenance. Before the planned follow-up consultation (approximately 6 weeks after start treatment) patients completed an online treatment evaluation questionnaire. Treatment (dose, adherence), sleep, fatigue, satisfaction and side effects were assessed by multiple-choice questions with room for free-text elaboration.

Results: 53.7% of the patients reported to use amitriptyline up to 10 mg/day, 42.9% used a self-increased dose of mostly 20 mg/day, while 3.5% had discontinued treatment. 73.9% of the total study population reported improvement of sleep maintenance, 31.3% improved sleep onset, 35.2% improved daytime fatigue, and 45.8% reported to be (very) satisfied with treatment results. 66.1% reported at least one side effect. The reported side effects were generally the already known side effects of amitriptyline.

Conclusion: These patient-reported outcomes support the clinical observations that low dose amitriptyline improves sleep maintenance on the short term and that it is generally well tolerated. This further justifies randomized controlled trials in patients with insomnia disorder and sleep maintenance problems to assess the effectiveness and safety of low dose amitriptyline on the short and long term.