Association Between a Composite Score of Pain Sensitivity and Clinical Parameters in Low-back Pain

Abstract

A limited number of quantitative sensory pain tests (QST) were selected on the basis of ease of application and interpretation in a clinical setting. QST results were summarized as a composite score on a scale of 0 to 4 that was deemed to facilitate clinical interpretation. The QST set was used to investigate differences in pain sensitivity between low-back pain (LBP) subgroups and was correlated with important clinical parameters. A total of 198 LBP patients and 44 controls were recruited and data were collected on: LBP intensity and duration, improvement in LBP, functional status, psychological profile, quality of life, and current work situation. QST consisted of pressure-pain threshold of the infraspinatus muscle, pain intensity with sustained mechanical pressure on the thumb nailbed, conditioned pain modulation, and pain tolerance assessed by cold-pressor test. Chronic, but not acute LBP patients scored significantly higher on the composite score of pain sensitivity than controls. A weak linear correlation between the composite score of pain sensitivity and intensity of clinical LBP and disability was found. A contingency was found between a high pain sensitivity (dichotomized composite score of pain sensitivity) and the lack of improvement in LBP. Pain sensitivity did not correlate with LBP duration, psychological profile, or sick leave. Pain sensitivity may be important for the prognosis of LBP, but QST is not currently part of routine clinical examination of LBP patients. The selected set of pain tests and the composite score of pain sensitivity could serve as a clinically applicable QST procedure in the examination of LBP.