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01.12.2015 | Research Article | Ausgabe 1/2015 Open Access

BMC Musculoskeletal Disorders 1/2015

Primary outcome measure use in back pain trials may need radical reassessment

Zeitschrift:
BMC Musculoskeletal Disorders > Ausgabe 1/2015
Autoren:
Robert Froud, David Ellard, Shilpa Patel, Sandra Eldridge, Martin Underwood
Wichtige Hinweise

Electronic supplementary material

The online version of this article (doi:10.​1186/​s12891-015-0534-1) contains supplementary material, which is available to authorized users.

Competing interests

SP, SE, and DE declare that they have no conflicts of interest. RF and MU are also directors and shareholders of a company that provides electronic measurement services to health services researchers; notwithstanding this, they declare that they have no conflicts of interest.

Authors’ contributions

RF, SE, and MU conceived of the study and contributed to the design, RF conducted all of the interviews. DE led on analysis with RF providing independent quality checks. SP and RF led on recruitment. All authors discussed and agreed the framework and charting. RF wrote the first draft of the manuscript and all authors commented in detail on successive drafts. DE produced the figure. All authors read and approved the final manuscript.

Abstract

Background

The answers to patient reported outcome measures and global transition questions for back pain can be discordant. For example, the most commonly used outcome measure in back pain trials, the Roland Morris Disability Questionnaire (RMDQ), can show improvement even though participants say that their back pain is worse. This gives cause for concern as transition questions are used as anchors to estimate minimally important change (MIC) thresholds on patient reported outcome measures such as the RMDQ. We aimed to explore and compare what people with back pain think when they respond to a transition question and when they complete the RMDQ.

Methods

We purposively sampled people enrolled on a back pain randomised controlled trial who completed the RMDQ and two transition questions. One enquired about change in ability to perform tasks, the other about change in back pain. We sampled participants with discordance (in both directions), and participants with concordant scores. We explored participants’ thought processes using in-depth interviews.

Results

We completed 35 in-depth interviews. People with discordant RMDQ change and transition question responses attend to different factors when responding to transition questions compared to people with concordant scores. In particular, those for whom the RMDQ change indicated greater improvement than transition questions, prioritised their pain ahead of functional disability. When completing the RMDQ, participants’ thought processes were comparatively more objective, and specific to each statement.

Conclusion

Approaches to primary outcome assessment in back pain needs re-assessment. The RMDQ may be unsuitable for use as a primary outcome measure since patients may not attend to thinking about their back pain when completing it: patients’ abilities to cope with tasks can be independent of the change in their back pain. Some participants who improve on the RMDQ consider themselves globally worse. As transition questions can be driven by pain and other physical factors, transition questions should not be used to anchor minimally important change thresholds on the RMDQ.
Zusatzmaterial
Additional file 1 Topic Guide. A PDF (.pdf) file showing the original Topic Guide as an indication of the topics covered in our interviews. We note that items 1, 2 and 4 are additional areas that were explored for a linked study. The document provided is the initial topic guide as at the start of the study and is provided as an indication only, as questions prompts and probes evolve with interviews.
12891_2015_534_MOESM1_ESM.pdf
Literatur
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