Pain Mechanisms in Low Back Pain

STUDY DESIGN: Systematic review and meta-analysis. BACKGROUND: Quantitative mechanical sensory testing (QST) assesses sensory functioning and detects functional changes in (central) nociceptive processing. In the current low back pain literature it has been hypothesized that these functional changes might be apparent in people with non-specific low back pain (NSLBP), although the results are mixed. OBJECTIVE: The aim of this systematic review/meta-analysis was to appraise and summarize the literature about QST outcomes in people with subacute and chronic NSLBP and healthy controls (HC). METHODS: This systematic review and meta-analysis was reported using PRISMA guidelines. Five databases were searched for relevant literature. Studies comparing mechanical QST-measures involving people with subacute and chronic low back pain and HC were included if 1) pressure pain thresholds (PPTs), 2) temporal summation (TS) and/or 3) conditioned pain modulation (CPM) were reported. Risk of bias was assessed using the Newcastle-Ottawa quality assessment scale (NOS). If possible, the results from different studies were pooled. RESULTS: Twenty-four studies were included. NOS scores varied between one and six points. Meta-analysis showed that people with NSLBP, compared to HC have significantly lower PPTs at remote sites and increased TS at the lower back. For example, PPTs measured at the scapula, were significantly lower in patients with NSLBP than in HC (pooled mean difference (MD): 119.2, 95% confidence interval (CI): (91.8, 146.6), P