Abstract
BACKGROUND: The severity of pain from musculoskeletal disorders might be associated with high sensitivity C reactive protein (hsCRP), a sensitive marker of low grade systemic inflammation. OBJECTIVE: To study the association between pain as assessed by a visual analogue scale (VAS) and hsCRP in patients with chronic low back pain and acute sciatic pain. METHODS: Information on pain severity, determinants of hsCRP, and hsCRP values were obtained prospectively at up to 10 time points during six months in 72 consecutive patients (mean age 43.3 years; 59.7% female): 41 with chronic low back pain and 31 with acute sciatic pain. The association between severity of pain and raised (highest quartile) hsCRP values at any time point was estimated by multivariable logistic regression using generalised estimating equations to adjust odds ratios (OR) and their confidence intervals (CI) for intraindividual dependence of measurements. RESULTS: Mean intensity of pain (VAS 0-10) at baseline was 4.9 and 5.5 in patients with chronic low back and acute sciatic pain, respectively. Highest v lowest tertile of average intensity of pain during the last 24 hours was associated with increased hsCRP levels among patients with acute sciatic pain (adjusted OR = 3.4 (95% CI, 1.1 to 10), but not in patients with chronic low back pain (adjusted OR = 0.87 (0.25 to 3.0)). CONCLUSIONS: Mean intensity of pain during the previous 24 hours as assessed by VAS was independently associated with high levels of hsCRP in patients with acute sciatic pain but not in those with chronic low back pain.