Abstract
BackgroundResearchers in clinical trials in rheumatoid arthritis (RA) and osteoarthritis (OA) often measure pain levels with a visual analogue scale (VAS). Of interest to clinical practice and future clinical trial design are associations of change from baseline (CFB) between time points with predictive ability of earlier response for long-term treatment benefit. We assessed the association and predictive ability of CFB in VAS pain between 2, 6 and 12 weeks in randomised controlled trials (RCTs) of non-steroidal anti-inflammatory drugs (NSAIDs).MethodsAggregated VAS pain data at baseline and CFB at 2, 6 and 12 weeks were collected from a systematic literature review of 176 RCTs in OA and RA. The predictive ability of earlier assessments for longer-term pain reduction was estimated using correlation and regression analyses. Analysis was performed using the R software package for statistical programming, version 3.1.1.ResultsAppropriate data were available from 50 RCTs (22,854 patients). Correlations between time points were high (weighted correlation coefficients between 2 and 6 weeks, 0.84; between 2 and 12 weeks, 0.79; and between 6 and 12 weeks, 0.96). CFB at 6 weeks was highly predictive and close to CFB at 12 weeks (regression coefficient 0.9, 95 % confidence interval 0.9–1.0). CFB at 2 weeks was significantly associated with CFB at 12 (0.8, 0.7–0.8) and 6 weeks (0.9, 0.8–1.0).ConclusionsThe results showed that early analgesic response measured by VAS for pain beyond 2 weeks of treatment with a particular NSAID is likely to be predictive of response at 12 weeks. Failure to achieve desired pain relief in OA and RA after 2 weeks should trigger reassessment of dosage and/or analgesic.Electronic supplementary materialThe online version of this article (doi:10.1186/s13075-016-0972-7) contains supplementary material, which is available to authorized users.
Highlights
Researchers in clinical trials in rheumatoid arthritis (RA) and osteoarthritis (OA) often measure pain levels with a visual analogue scale (VAS)
For patients with OA and RA, early analgesic response measured by VAS for pain beyond 2 weeks of treatment with a particular non-steroidal anti-inflammatory drug (NSAID) is likely to be predictive of response at 12 weeks
N-weighted random intercept model: change from baseline (CFB) 2 weeks vs. CFB 6 weeks observed vs. predicted values
Summary
Researchers in clinical trials in rheumatoid arthritis (RA) and osteoarthritis (OA) often measure pain levels with a visual analogue scale (VAS). We assessed the association and predictive ability of CFB in VAS pain between 2, 6 and 12 weeks in randomised controlled trials (RCTs) of non-steroidal anti-inflammatory drugs (NSAIDs). Osteoarthritis (OA) and rheumatoid arthritis (RA) are the most common arthritic conditions in adults [1] They lead to joint degeneration and chronic pain [2, 3]. Non-steroidal anti-inflammatory drugs (NSAIDs), both traditional and cyclooxygenase 2 inhibitors (COXIBs), are commonly prescribed to relieve pain and inflammation [2, 3] and are the cornerstones for treating pain in arthritis [8, 9]. Knowledge of their effectiveness derives from randomised trials and meta-analyses of randomised trials. While clearly not the only outcome of interest, pain is an important efficacy outcome in OA and RA trials and perhaps the one most important to patients [10–13]
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