Psychological and functional profiles in select subjects with low back pain

Background context: Some researchers have found a correlation of poor treatment outcomes in patients with low back pain and abnormal psychological profiles, whereas others have failed to confirm this correlation. A critical feature of this debate has been whether abnormal psychological profiles seen in patients with back pain are the result of the ongoing back pain or whether pre-existing psychological features predispose to a poor clinical outcome. Purpose: To determine the relationship of psychometric testing scores to the presence and duration of back pain of differing causes. Study design/setting: This was a prospective observational study of the psychological profiles of groups of patients with low back pain and controls. Patient sample: Subjects having a variety of painful back conditions (n=310) were compared with a control group of subjects without low back complaints who had undergone cervical spine surgery (n=73). Outcomes measures: Psychometric testing (Modified Zung and Modified Somatic Pain Questionnaire) was performed along with pain scores (visual analog scale [VAS]), a standardized Low Back Pain Questionnaire, and the Oswestry Low Back Pain Disability Questionnaire in the evaluation of back pain and control subjects. Methods: The subjects with painful back conditions included patients with presumed discogenic pain undergoing discography (n=95); patients with symptomatic isthmic spondylolisthesis coming to fusion (n=61); patients with chronic vertebral osteomyelitis before diagnosis and treatment (n=39). There was also a nonpatient group of soldiers with chronic low back pain not seeking medical care (n=115). The control subjects without low back pain consisted of a group who had undergone cervical spine surgery (n=73). Psychometric testing was performed and compared in the evaluation of subjects having these different painful back conditions. Analysis was done comparing pain scores, function scores, and psychological testing scores between the symptomatic and asymptomatic groups. Results: The VAS maximum in last week score for the entire group was 7.1, and scores were not significantly different in all low back pain groups. The Oswestry scores were poorest in the discography group compared to spondylolisthesis and osteomyelitis. Functional scores were similar in the soldiers with low back pain and controls without low back pain. Both Depression and Somatic Pain scores were most abnormal in the discogenic low back pain group. Only 21% of this group had normal scores, compared with 71% of the spondylolisthesis group, 79% of osteomyelitis group, and 88% of the group with chronic low back pain not seeking treatment ( p<.001 in all groups). The asymptomatic control group had 85% normal scores. Conclusions: Despite similar pain levels and pain duration, patients with the discographic diagnosis of discogenic back pain have poorer functional scores and very abnormal psychological scores compared with other subjects with chronic low back pain resulting from spondylolisthesis requiring surgery or chronic pyogenic osteomyelitis. Chronic moderately severe mechanical low back pain in healthy subjects was not associated with abnormal psychological scores or functional disability.