Minimal clinically important difference for change in 6-minute walk test distance of adults with pathology: a systematic review

Rationale, aims, and objectives: The 6-minute walk test (6MWT) is widely used as a test of functional exercise capacity. Several studies have reported the minimal clinically important difference (MCID) for the 6MWT; however, the findings of the studies have not been examined in the context of one another. In this review, we aimed to summarize available information on the MCID for the 6MWT performed by patients with pathology.

Methods: Relevant literature was identified by searches of 3 electronic databases (PubMed, Scopus, and Cumulative Index of Nursing and Allied Health), examination of article reference lists, and consultation with an expert. Inclusion necessitated that articles (1) be original, full length, and peer reviewed, (2) report an MCID for the 6MWT, and (3) focus on adults with medical issues. Articles were excluded if the MCID was determined by a procedure other than receiver operating characteristic curve analysis. Articles were abstracted for information on participants, interventions, 6MWT distance, and the determination of MCID. Quality was assessed using a hybrid 9-item (0- to 18-point) instrument.

Results: Six articles were selected based on the inclusion and exclusion criteria. The populations studied included people with chronic obstructive pulmonary disease, lung cancer, coronary artery disease, diffuse parenchymal lung disease, and non-cystic fibrosis bronchiectasis and adults with fear of falling. Mean baseline 6MWT distances ranged from 295 to 551 m. The MCIDs for which the area under the receiver operating characteristic curve was at least 0.70 ranged from 14.0 to 30.5 m.

Conclusions: Based on our findings, a change of 14.0 to 30.5 m may be clinically important across multiple patient groups.