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Evaluating the Quality of Subgroup Analyses in Randomized Controlled Trials of Therapist-Delivered Interventions for Nonspecific Low Back Pain: A Systematic Review

Mistry, Dipesh MSc; Patel, Shilpa MSc, BSc Hons, C.Psychol; Hee, Siew Wan PhD; Stallard, Nigel PhD; Underwood, Martin MD

Spine:
doi: 10.1097/BRS.0000000000000231
Literature Review
Abstract

Study Design. Systematic review.

Objective. To evaluate the quality, conduct, and reporting of subgroup analyses performed in randomized controlled trials of therapist-delivered interventions for nonspecific low back pain (NSLBP).

Summary of Background Data. Randomized controlled trials of therapist-delivered interventions for NSLBP to date have, at best, shown small to moderate positive effects. Identifying subgroups is an important research priority. This review evaluates the quality, conduct, and reporting of subgroup analyses performed in the NSLBP literature.

Methods. Multiple electronic databases were searched for randomized controlled trials of therapist-delivered interventions for NSLBP. Of the identified articles, only articles reporting subgroup analyses (confirmatory or exploratory) were included in the final review. Methodological criteria were used to evaluate the quality of subgroup analyses. The quality of conduct and reporting was also evaluated.

Results. Thirty-nine articles were included in the final review. Of these, only 3 (8%) tested hypotheses about moderators (confirmatory findings), 18 (46%) generated hypotheses about moderators to inform future research (exploratory findings), and 18 (46%) provided insufficient findings. The appropriate statistical test for interaction was performed in 27 of the articles, of which 10 reported results from interaction tests, 4 incorrectly reported results within individual subgroups, and the remaining articles reported either P values or nothing at all.

Conclusion. Subgroup analyses performed in NSLBP trials have been severely underpowered, are only able to provide exploratory or insufficient findings, and have rather poor quality of reporting. Using current approaches, few definitive trials of subgrouping in back pain are very likely to be performed. There is a need to develop new approaches to subgroup identification in back pain research.

Level of Evidence: 1

In Brief

A systematic review evaluating the quality of subgroup analyses in nonspecific low back pain trials. Review found that subgroup analyses are of a poor quality. There is a need to develop new approaches to subgroup identification in back pain research.

Author Information

From the Division of Health Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom.

Address correspondence and reprint requests to Dipesh Mistry, MSc, Warwick Clinical Trials Unit, Warwick Medical School, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL; E-mail: D.Mistry@Warwick.ac.uk

Acknowledgment date: July 12, 2013. Revision date: August 2, 2013. Acceptance date: January 13, 2014.

The manuscript submitted does not contain information about medical device(s)/drug(s).

The National Institute for Health Research, under its Programme Grants for Applied Research (RP-PG-0608-10076), funds were received in support of this work. This project benefited from facilities funded through Birmingham Science City Translational Medicine Clinical Research and infrastructure Trials platform, with support from Advantage West Midlands.

Relevant financial activities outside the submitted work: board membership, expert testimony, grants, payment for lecture, stocks.

© 2014 by Lippincott Williams & Wilkins