Which instruments can detect submaximal physical and functional capacity in patients with chronic nonspecific back pain? A systematic review.

Study Design: Systematic review.

Objective: To evaluate the validity of instruments that claim to detect submaximal capacity when maximal capacity is requested in patients with chronic nonspecific musculoskeletal pain.

Summary Of Background Data: Several instruments have been developed to measure capacity in patients with chronic pain. The detection of submaximal capacity can have major implications for patients. The validity of these instruments has never been systematically reviewed.

Methods: A systematic literature search was performed including the following databases: Web of Knowledge (including PubMed and Cinahl), Scopus, and Cochrane. Two reviewers independently selected the articles based on the title and abstract according to the study selection criteria. Studies were included when they contained original data and when they objectified submaximal physical or functional capacity when maximal physical or functional capacity was requested. Two authors independently extracted data and rated the quality of the articles. The included studies were scored according to the subscales "Criterion Validity" and "Hypothesis Testing" of the COSMIN checklist. A Best Evidence Synthesis was performed.

Results: Seven studies were included, 5 of which used a reference standard for submaximal capacity. Three studies were of good methodological quality and validly detected submaximal capacity with specificity rates between 75% and 100%.

Conclusion: There is strong evidence that submaximal capacity can be detected in patients with chronic low back pain with a lumbar motion monitor or visual observations accompanying a functional capacity evaluation lifting test.