Keele Research Repository

BACKGROUND: Pregnancy-related low back pain and pelvic girdle pain (LBP/PGP) are common and negatively impact the lives of many pregnant women. Several patient-based outcome instruments measure treatment effect but there is no consensus about which measure to use with women who have these pain presentations. OBJECTIVE: The objective was to compare the responsiveness of 3 outcome measures in LBP/PGP: Oswestry Disability Index-version 2.0 (ODI), Pelvic Girdle Questionnaire (PGQ), and 0-10 numerical rating scale for pain severity (NRS); and to estimate a minimal important change (MIC) for these measures in pregnancy-related LBP/PGP. DESIGN: This was a methodology study using data from a pilot randomised trial (RCT). METHODS: Women (n = 124) with pregnancy-related LBP/PGP were recruited to a pilot RCT evaluating the benefit of adding acupuncture to standard care and 90 completed 8-weeks follow-up. Responsiveness was evaluated by examining correlation between change score and the external anchor (6-point global perceived effect scale) and by using receiver operating characteristic (ROC) curve analysis. MIC was estimated using anchor-based methods. RESULTS: All measures showed good responsiveness, with areas under ROC curve ranging from 0.77 to 0.90. The estimated MICs were 3.1, 11.0, 9.4, 13.3, and 1.3 for ODI, PGQ-total, PGQ-activity, PGQ-symptoms, and NRS, respectively. All the measures, apart from ODI, had MICs larger than the measurement error. LIMITATIONS: Lack of optimal "gold standard" or external criterion for assessing responsiveness and MIC was a limitation of this study. CONCLUSION: All 3 outcome measures demonstrated good responsiveness. MICs were derived for each instrument. The PGQ at 8 weeks post-randomisation was identified as an appropriate outcome measure for pregnancy-related LBP/PGP since it is specific to these pain presentations and assesses both activity limitations and symptoms. The NRS is an efficient, shorter alternative.