Psychological correlates of pain behavior in patients withchronic low back pain.

Pain behaviors that are excessive for the degree of knownphysical disease are common in patients with chronic low back pain and arefrequently assumed to arise from a comorbid depressive illness.Although some studies have confirmed an association between depression andexcessive pain behavior, methodologic problems (such as the use ofdepression ratings that also recorded symptoms attributable to physicaldisease) make interpretation of this finding difficult.We recruited 54 consecutive patients with chronic (>6 months) low backpain from a hospital clinic.Subjects completed self-rated assessments of anxiety and depression(Hospital Anxiety and Depression Scale) designed to be minimally affectedby physical symptoms, along with assessments of disability (ODQ), pain(visual analogue scale), pain behavior (Waddell checklist), and physicalimpairment.Seventeen subjects (31%) exhibited excessive pain behavior.Overall, they were no more depressed or anxious than the remainder,although men with excessive pain behavior showed a trend toward being moredepressed.Patients with excessive pain behavior were more disabled (self-rated andobserver-rated), reported greater pain, and were more likely to be femaleand to have pain of shorter duration.Pain behavior did not correlate with anxiety or depression, but correlatedwith measures of disability and pain intensity.Factor analysis revealed that physical disability, pain intensity, andpain behavior loaded heavily on the first factor.Anxiety and depression loaded together on a separate factor.We conclude that pain behaviors were not related to anxiety or depressionin our group, although gender differences between groups could havecontributed to our negative findings.Pain behaviors may influence other physical measures.Further studies are required to investigate the relation betweendepression and pain behavior while controlling for genderdifferences.