Minimal clinically important change of knee flexion in people with knee osteoarthritis after non-surgical interventions using a meta-analytical approach

BackgroundMinimal clinically important change (MCIC) represents the minimum patient-perceived improvement in an outcome after treatment, in an individual or within a group over time. This study aimed to determine MCIC of knee flexion in people with knee OA after non-surgical interventions using a meta-analytical approach.MethodsFour databases (MEDLINE, Cochrane, Web of Science and CINAHL) were searched for studies of randomised clinical trials of non-surgical interventions with intervention duration of <= 3 months that reported change in (Delta) (mean change between baseline and immediately after the intervention) knee flexion with Delta pain or Delta function measured using tools that have established MCIC values. The risk of bias in the included studies was assessed using version 2 of the Cochrane risk-of-bias tool for randomised trials (RoB 2). Bayesian meta-analytic models were used to determine relationships between Delta flexion with Delta pain and Delta function after non-surgical interventions and MCIC of knee flexion.ResultsSeventy-two studies (k = 72, n = 5174) were eligible. Meta-analyses included 140 intervention arms (k = 61, n = 4516) that reported Delta flexion with Delta pain using the visual analog scale (pain-VAS) and Delta function using the Western Ontario and McMaster Universities Osteoarthritis Index function subscale (function-WOMAC). Linear relationships between Delta pain at rest-VAS (0-100 mm) with Delta flexion were - 0.29 (- 0.44; - 0.15) (beta: posterior median (CrI: credible interval)). Relationships between Delta pain during activity VAS and Delta flexion were - 0.29 (- 0.41, - 0.18), and Delta pain-general VAS and Delta flexion were - 0.33 (- 0.42, - 0.23). The relationship between Delta function-WOMAC (out of 100) and Delta flexion was - 0.15 (- 0.25, - 0.07). Increased Delta flexion was associated with decreased Delta pain-VAS and increased Delta function-WOMAC. The point estimates for MCIC of knee flexion ranged from 3.8 to 6.4 degrees.ConclusionsThe estimated knee flexion MCIC values from this study are the first to be reported using a novel meta-analytical method. The novel meta-analytical method may be useful to estimate MCIC for other measures where anchor questions are problematic.Systematic review registrationPROSPERO CRD42022323927.