The reliability of pressure pain threshold in individuals with low back or neck pain: a systematic review

BACKGROUND AND OBJECTIVE: Low-back and neck pain affect a great number of individuals worldwide. The pressure pain threshold has the potential to be a useful quantitative measure of mechanical pain in a clinical setting, if it proves to be reliable in this population. The objectives of this systematic review are to: (1) analyze the literature evaluating the reliability of pressure pain threshold (PPT) measurements in the assessment of neck and low-back pain, (2) summarize the evidence from these studies, and (3) characterize the limitations of PPT measurement. DATABASES AND DATA TREATMENT: Relevant literature from PubMed and the Web of Science electronic databases were screened in a 3-step process according to inclusion/exclusion criteria. Relevant studies were assessed for risk of bias using the Quality Appraisal of Reliability Studies (QAREL) tool, and results of all studies were summarized and tabulated. RESULTS: Of 922 citations identified, 11 studies were deemed relevant for critical appraisal, and 8 studies were deemed to have low risk-of bias. Intra-rater reliability, reported in all studies (n = 637) and inter-rater reliability, reported in 2 studies (n = 200) were consistently reported to be good to excellent (ICC 0.75–0.99 and ICC 0.81–0.90, respectively). Studies were also found to have significant variation in PPT measurement procedures. CONCLUSIONS: Though intra- and inter-rater reliability was found to be high in all studies, the variation in PPT measurement protocols could affect validity and absolute reliability. As such, it is recommended that standard guidelines be developed for clinical use.