Background To compare the 4-week effectiveness and tolerability of an add-on treatment with oral high dose methocarbamol (MET) vs long-acting oral opioid analgesics (LAO) in patients with non-specific low back pain (nsLBP) poorly responsive to recommended 1st line treatments. Methods Analysis of anonymized, propensity score-matched real-world data from the German Pain e-Registry, using a sequential non-inferiority superiority approach, for adult outpatients with nsLBP who had initiated treatment with MET or LAO between 1st January 2018 and 31st December 2019 (EUPAS identifier: 38484). The primary effectiveness variable was the absolute change of the average 24-h. pain intensity index (PIX). Safety was assessed by incidence of physician-confirmed drug-related adverse events (DRAEs), and DRAEs leading to discontinuation. Results Propensity score-matched data were analyzed for 374 patients treated with MET and 374 patients treated with LAO. Mean +/- SD (median) MET dose over the 4-week evaluation period was 2390.4 +/- 1980 (3000) mg and 69.6 +/- 25.9 (60) mg morphine equivalent for LAO. With 25.8 +/- 11.4 (median 26, 95%CI: 24.5-27.1) vs. 11.4 +/- 6.8 (median 11; 95%CI: 10.6-12.2) mm VAS, absolute 4-week improvement vs. baseline was superior for MET vs. LAO [p < .001; effect size 1.6; least square mean difference 14.4 (95%CI: 13.4-15.3)]. Percentages of patients with a PIX improvement >= MCID was 81.8 vs. 24.6% [p < .001; OR: 13.8 (9.7-19.6), RR: 4.0 (3.2-5.0), NNT: 1.7]. A significantly lower number of patients treated with MET vs. LAO reported DRAEs in response to study medication: 36 (9.6%) vs. 139 (37.2%; p < .001; NNT 4), and 9 patients treated with MET (2.4%) vs. 86 (23.0%) treated with LAO discontinued treatment in response to these DRAEs (p < .001; NNT: 5). Conclusion 4-week add-on treatment with MET in patients with nsLBP who showed an inadequate response to recommended 1(st) line treatments is superior effective to LAO and significantly better tolerated.KEY MESSAGES Low back pain is the most common musculoskeletal problem worldwide. In the majority of patients, LBP does not have a specific cause and the most prevalently coded form is mechanical, non-specific (ns) LBP associated with muscular tension, restrictions in mobility, and static malposition. Current treatment recommendations for nsLBP are largely "non-specific" as well, limited to symptomatic pain-relieving measures. In our propensity score-matched two cohort analyses of depersonalized real-world data from the German Pain e-Registry, a 4-week treatment with the muscle relaxant methocarbamol proved superior effective and significantly better tolerated than treatment with oral long-acting opioid analgesics in patients who poorly responded to recommended 1st line treatments.
