Table 3

 High sensitivity C reactive protein according to average severity of pain during the last 24 hours in patients with chronic low back pain

Pain severity (VAS)*High sensitivity C reactive protein
Raised values (>2.9 mg/l)
Geometric mean (95% CI)n (%)OR (95% CI)†
*Tertiles of average pain severity during the previous 24 hours from visual analogue scale ranging from 0 (none) to 10 (extreme).
†Odds ratio and 95% confidence interval for high sensitivity C reactive protein >2.90 mg/l (above 75th centile of observed values) from multivariable logistic regression model adjusting for intraindividual dependence of events using generalised estimating equations.
‡For age (continuous), sex, smoking (three categories), alcohol consumption during the previous 24 hours (yes/no), body mass index (continuous), diabetes (yes/no), and use of analgesic drugs during the previous 24 hours.
CI, confidence interval; OR, odds ratio; VAS, visual analogue scale.
⩽2.31.3 (0.8 to 1.9)19 (16.8)1.0 (reference)1.0 (reference)
>2.3 to 4.51.3 (0.9 to 2.0)26 (24.8)1.6 (0.48 to 5.6)1.7 (0.61 to 4.8)
>4.51.4 (0.9 to 2.4)39 (33.3)2.5 (0.70 to 8.8)0.87 (0.25 to 3.0)