Objective To investigate the efficacy, acceptability, and safety of muscle relaxants for low back pain. Design Systematic review and meta-analysis of randomised controlled trials. Data sources Medline, Embase, CINAHL, CENTRAL, ClinicalTrials.gov, clinicialtrialsregister.eu, and WHO ICTRP from inception to 23 February 2021. Eligibility criteria for study selection Randomised controlled trials of muscle relaxants compared with placebo, usual care, waiting list, or no treatment in adults (≥18 years) reporting non-specific low back pain. Data extraction and synthesis Two reviewers independently identified studies, extracted data, and assessed the risk of bias and certainty of the evidence using the Cochrane risk-of-bias tool and Grading of Recommendations, Assessment, Development and Evaluations, respectively. Random effects meta-analytical models through restricted maximum likelihood estimation were used to estimate pooled effects and corresponding 95% confidence intervals. Outcomes included pain intensity (measured on a 0-100 point scale), disability (0-100 point scale), acceptability (discontinuation of the drug for any reason during treatment), and safety (adverse events, serious adverse events, and number of participants who withdrew from the trial because of an adverse event). Results 49 trials were included in the review, of which 31, sampling 6505 participants, were quantitatively analysed. For acute low back pain, very low certainty evidence showed that at two weeks or less non-benzodiazepine antispasmodics were associated with a reduction in pain intensity compared with control (mean difference −7.7, 95% confidence interval−12.1 to−3.3) but not a reduction in disability (−3.3, −7.3 to 0.7). Low and very low certainty evidence showed that non-benzodiazepine antispasmodics might increase the risk of an adverse event (relative risk 1.6, 1.2 to 2.0) and might have little to no effect on acceptability (0.8, 0.6 to 1.1) compared with control for acute low back pain, respectively. The number of trials investigating other muscle relaxants and different durations of low back pain were small and the certainty of evidence was reduced because most trials were at high risk of bias. Conclusions Considerable uncertainty exists about the clinical efficacy and safety of muscle relaxants. Very low and low certainty evidence shows that non-benzodiazepine antispasmodics might provide small but not clinically important reductions in pain intensity at or before two weeks and might increase the risk of an adverse event in acute low back pain, respectively. Large, high quality, placebo controlled trials are urgently needed to resolve uncertainty. Systematic review registration PROSPERO CRD42019126820 and Open Science Framework . Data sharing: The dataset used and analysed during this study and the accompanying code are available from the corresponding author on reasonable request.

中文翻译：

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肌肉松弛剂对成人非特异性腰痛的有效性、可接受性和安全性：系统评价和荟萃分析

目的探讨肌松药治疗腰痛的疗效、可接受性和安全性。设计 随机对照试验的系统评价和荟萃分析。数据来源 Medline、Embase、CINAHL、CENTRAL、ClinicalTrials.gov、clinicaltrialsregister.eu 和 WHO ICTRP 从开始到 2021 年 2 月 23 日。 研究选择的资格标准 肌肉松弛剂与安慰剂、常规护理、等候名单或报告非特异性腰痛的成人（≥18 岁）未接受治疗。数据提取和综合 两名评价员分别使用 Cochrane 偏倚风险工具和推荐分级、评估、开发和评价独立识别研究、提取数据并评估偏倚风险和证据的确定性。通过受限最大似然估计的随机效应元分析模型用于估计合并效应和相应的 95% 置信区间。结果包括疼痛强度（以 0-100 分制衡量）、残疾（0-100 分制）、可接受性（治疗期间因任何原因停药）和安全性（不良事件、严重不良事件和因不良事件退出试验的参与者）。结果 评价纳入 49 项试验，其中 31 项，6505 名参与者，进行了定量分析。对于急性腰痛，非常低确定性的证据表明，与对照组相比，在两周或更短的时间内，非苯二氮卓类解痉药与疼痛强度降低相关（平均差为 -7.7，95% 置信区间为 -12.1 至 -3。3) 但没有减少残疾（-3.3，-7.3 到 0.7）。低和极低确定性证据表明，与急性期的对照组相比，非苯二氮卓类解痉药可能会增加不良事件的风险（相对风险 1.6、1.2 至 2.0），并且对可接受性几乎没有影响（0.8、0.6 至 1.1）。分别是腰痛。研究其他肌肉松弛剂和不同持续时间的腰痛的试验数量很少，证据的确定性降低，因为大多数试验存在高偏倚风险。结论 肌松药的临床疗效和安全性存在相当大的不确定性。非常低和低确定性的证据表明，非苯二氮卓类解痉药可能会在两周内或两周前提供较小但无临床意义的疼痛强度降低，并可能分别增加急性腰痛不良事件的风险。迫切需要大型、高质量、安慰剂对照试验来解决不确定性。系统审查注册 PROSPERO CRD42019126820 和开放科学框架. 数据共享：本研究中使用和分析的数据集以及随附的代码可根据合理要求从相应作者处获得。