RT Journal Article SR Electronic T1 Nortriptyline for pain in knee osteoarthritis: a double-blind randomised controlled trial in New Zealand general practice JF British Journal of General Practice JO Br J Gen Pract FD British Journal of General Practice SP e538 OP e546 DO 10.3399/BJGP.2020.0797 VO 71 IS 708 A1 Ben Hudson A1 Jonathan A Williman A1 Lisa K Stamp A1 John S Alchin A1 Gary J Hooper A1 Dee Mangin A1 Bronwyn F Lenox Thompson A1 Les Toop YR 2021 UL http://bjgp.org/content/71/708/e538.abstract AB Background Osteoarthritis (OA) of the knee is a common cause of chronic pain. Analgesics that are currently available have limited efficacy and may be poorly tolerated. Tricyclic antidepressants are used as analgesics for other chronic conditions, but they have not been evaluated as analgesics in OA.Aim To investigate the analgesic efficacy of nortriptyline in people with knee OA.Design and setting A two-arm, parallel-group, 1:1, double-blind, randomised, placebo-controlled trial in Christchurch, New Zealand.Method Participants were recruited from orthopaedic outpatient clinics, primary care, and through public advertising. Adults with knee OA and a pain score of ≥20 points on the 50-point Western Ontario and McMaster University Osteoarthritis Index (WOMAC) pain subscale were randomised to receive either nortriptyline or identical placebo for 14 weeks. The primary outcome was knee pain at 14 weeks measured using the WOMAC pain subscale. Secondary outcomes included: function; stiffness; non-steroidal anti-inflammatory drug, opioid, and/or paracetamol use; each participant’s global assessment; and adverse effects at 14 weeks.Results Of the 205 randomised participants, 201 (98.0%) completed follow-up at 14 weeks. The baseline-adjusted mean WOMAC pain subscale score at week 14 was 6.2 points lower (95% confidence interval = −0.26 to 12.6, P = 0.06) in the nortriptyline arm versus the placebo arm. Differences in secondary outcomes generally favoured the nortriptyline arm, but were small and unlikely to be clinically relevant. However, the following were all more commonly reported by participants taking nortriptyline than those taking a placebo: dry mouth (86.9% versus 51.0%, respectively, P<0.001), constipation (58.6% versus 30.4%, respectively, P<0.001), and sweating (31.3% versus 20.6%, respectively, P = 0.033).Conclusion This study suggests nortriptyline does not significantly reduce pain in people with knee OA. The adverse effect profile was as expected.