Addition of corticosteroids to local anaesthetics for chronic non-cancer pain injections: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND: Despite common use, the benefit of adding steroids to local anaesthetics (SLA) for chronic non-cancer pain (CNCP) injections is uncertain. We performed a systematic review and meta-analysis of English-language RCTs to assess the benefit and safety of adding steroids to local anaesthetics (LA) for CNCP. METHODS: We searched MEDLINE, EMBASE, and CENTRAL databases from inception to May 2019. Trial selection and data extraction were performed in duplicate. Outcomes were guided by the Initiative in Methods, Measurements, and Pain Assessment in Clinical Trials (IMMPACT) statement with pain improvement as the primary outcome and pooled using random effects model and reported as relative risks (RR) or mean differences (MD) with 95% confidence intervals (CIs). RESULTS: Among 5097 abstracts, 73 trials were eligible. Although SLA increased the rate of success (42 trials, 3592 patients; RR=1.14; 95% CI, 1.03-1.25; number needed to treat [NNT], 13), the effect size decreased by nearly 50% (NNT, 22) with the removal of two intrathecal injection studies. The differences in pain scores with SLA were not clinically meaningful (54 trials, 4416 patients, MD=0.44 units; 95% CI, 0.24-0.65). No differences were observed in other outcomes or adverse events. No subgroup effects were detected based on clinical categories. Meta-regression showed no significant association with steroid dose or length of follow-up and pain relief. CONCLUSIONS: Addition of cortico steroids to local anaesthetic has only small benefits and a potential for harm. Injection of local anaesthetic alone could be therapeutic, beyond being diagnostic. A shared decision based on patient preferences should be considered. If used, one must avoid high doses and series of steroid injections. CLINICAL TRIAL REGISTRATION: PROSPERO #: CRD42015020614.