Minimal clinically important differences in randomised clinical trials on pain management after total hip and knee arthroplasty: a systematic review

Abstract

Background: Sample size determination is essential for reliable hypothesis testing in clinical trials and should rely on adequate sample size calculations with alpha, beta, variance, and an effect size being the minimal clinically important difference (MCID). This facilitates interpretation of the clinical relevance of statistically significant results. No gold standard for MCIDs exists in postoperative pain research. Methods: We searched Cochrane Central Register of Controlled Trials, MEDLINE, and Embase for English language articles on randomised trials investigating analgesic interventions after total hip or knee arthroplasty. Primary outcomes were the reported MCIDs for pain score and cumulated rescue opioid consumption. Secondary outcomes included reported sample size calculations and propensity to report statistical significance without reaching MCID. Trend analyses were conducted using statistical process control. Results: We included 570 trials. Median MCID for 0-24 h opioid consumption was 10 mg i.v. morphine equivalents for absolute reductions (interquartile range [IQR]: 6.8-14.5) and relative 40% (IQR: 30e50%). Median MCIDs for pain scores were absolute 15 mm at rest (IQR: 10e20) and 18 mm during movement (IQR: 10e20) on a 0e100 mm VAS and relative 30% (IQR: 20e30%). No trends were demonstrated for MCIDs. Adequate sample size calculations were reported in 34% of trials. In 46% of trials with statistically significant primary outcomes, the differences did not reach the predetermined MCID. Conclusions: We provide clinician-perceived MCID estimates for rescue opioid consumption and pain scores that can be used for sample size calculations until reliable evidence-based patient-rated MCIDs emerge. Nearly half of the trials with significant findings did not reach the predetermined MCID.

Effect of Neuromuscular Electrical Stimulation After Total Knee Arthroplasty: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

“…We included five RCTs and found that NMES improved postoperative pain at mid-term (1–2 months and 3–6 months) following TKA. However, the improved differences did not reach the minimal clinically important difference (MCID) in pain ( 50 ).…”

“…As far as we knew, this was the first systematic review and meta-analysis to comprehensively explore the effect of NMES on quadriceps muscle strength, pain, and function following TKA. However, the differences did not reach the MCID in pain (50). Given the included studies adopt different scales in many essential outcomes, the SMD was used to calculate the total effect of quadriceps muscle strength and WOMAC, which may generate issues with heterogeneity.…”

Efficacy of intra-articular ketorolac for pain control in arthroscopic surgeries: a systematic review and meta-analysis

“…In our meta-analysis, the MD in pain scores ranged from 0.58 at 2–4 h to 1.28 at 24 h. Indeed, the difference is not large and the clinical relevance of reduced pain with ketorolac can be questionable. In a recent study, Laigaard et al [ 31 ] have shown that MCID for pain after hip/knee arthroplasty is 1.5 on VAS. Olsen et al [ 30 ] in their systematic review have suggested that MCID can range from 0.8 to 4 for acute pain and can vary with baseline pain, definitions of improved patients, and study design.…”

Assessing Postoperative Benefits of a Nerve Block: Study Design is Critical [Letter]

“… 5 Thus, it was unclear whether absolute decrease in 24-h intravenous milligram morphine consumption in the TPVB group exceeded the recommended minimal clinically important difference in the literature, ie, an absolute reduction of 10 mg intravenous morphine. 6 …”