Abstract
PURPOSE: Chronic musculoskeletal pain is often associated with psychological distress and maladaptive beliefs and these are sometimes reported to have a negative impact on surgical outcome. The influence of a surgical intervention, and in particular its outcome, on the course of change in psychological status is poorly documented. In this prospective study, we sought to examine the dynamic interplay between psychological factors and outcome in patients undergoing decompression surgery for spinal stenosis/herniated disc. METHODS: Before and 12 months after surgery, 159 patients (100 men, 59 women; 65 ± 11 years) completed a questionnaire booklet containing questions on socio-demographics, medical history, pain characteristics (intensity, frequency, use of medication), psychological disturbance [ZUNG Depression Scale and Modified Somatic Perception Questionnaire (MSPQ)], catastrophising (sub-scale of the Coping Strategies Questionnaire) and disability (Roland and Morris questionnaire) and the Fear Avoidance Beliefs Questionnaire about physical activity (FABQ-PA). The global outcome of surgery was assessed at 12 months using a five-point Likert scale and dichotomised as "good" (operation helped/helped a lot; coded 1) and "poor" (operation helped only little/did not help/made things worse; coded 0). RESULTS: Valid questionnaire data were available for 148 patients at 12 months' follow-up: 113 (76.4 %) reported a good outcome and 35 (23.6 %) a poor outcome. In univariate analyses, the following baseline variables each significantly (p < 0.05) predicted a good 12-month global outcome: no involvement in a disability claim, and lower LBP frequency, average LBP in the last week, average score on all pain scales, FABQ-PA and catastrophising. In multiple logistic regression, only lower FABQ-PA scores [OR 0.877 (95 %CI 0.809-0.949), p = 0.001] and lower LBP frequency at baseline [OR 0.340 (1.249-1.783), p < 0.0001] significantly predicted a good outcome at 12 months. A second "explanatory" logistic regression model revealed that a good outcome at 12 months was significantly associated with improvements (from baseline to 12 months) in average score on all the pain intensity scales [OR 1.6879 (1.187-2.398)], general health [OR 1.246 (1.004-1.545)], psychological disturbance [OR 1.073 (1.006-1.144)] and Roland Morris Disability [OR 1.243 (1.074-1.439)]. CONCLUSION: In a multivariable prospective (predictive) model, FABQ-PA was the only baseline psychological factor that significantly predicted outcome. Future studies should assess whether pre-operative cognitive-behavioural therapy in patients with maladaptive beliefs improves treatment outcome. Psychological disturbance did not significantly predict outcome, but it improved post-operatively in patients with a good outcome and worsened in those with a poor outcome. Rather than being a risk factor for poor outcome, in this group it appeared to be more a consequence of long-standing, unremitting pain that improved when symptoms resolved after successful surgery.