Background:

Selection of appropriate outcome measures is crucial in clinical trials in order to minimize bias and allow for precise comparisons of effects between interventions.

Objectives:

We aimed to assess the frequency and completeness of outcome measures in randomized controlled trials (RCTs) included in Cochrane systematic reviews (SRs), focusing on rehabilitation interventions for mechanical low-back pain.

Methods:

We performed a cross-sectional study of all RCTs included in all Cochrane SRs (full-text) published in the Cochrane Database of Systematic Reviews in February 2013 that focused on evaluations of the efficacy and safety of rehabilitation interventions for mechanical low-back pain. Two authors independently evaluated the type and frequency of each outcome measure reported in the full-text of RCTs, the methods used to measure outcomes, and the proportion of outcomes fully replicable based on the reported information.

Results:

Our literature search identified 11 Cochrane SRs, including 185 RCTs. Across all RCTs, 36 different outcomes were investigated. Those most commonly reported were pain [n=164 RCTs (89%)] and disability [n=119 RCTs (62%)], which were measured by 66 and 44 measurement tools, respectively. Other frequently reported outcomes were range of motion [n=70 RCTs (38%)] and quality of life [n=45 RCTs (24%)]. The procedure of blinding assessment was reported in 52% of the RCTs for pain (n=85) and 44% of RCTs for disability (n=52). Pain, disability, range of motion, and quality of life outcomes were reported as fully replicable in 10% (n=17), 10% (n=12), 6% (n=4), and 7% (n=3) of the RCTs, respectively.

Conclusions:

A large number of outcome measures and a myriad of measurement instruments were used across all RCTs. The reporting was largely incomplete, suggesting better opportunities for the standardization of approaches and reporting.