The impact of comorbidities on the change in short-form 36 and oswestry scores following lumbar spine surgery

STUDY DESIGN. This is an observational study of 3482 patients undergoing lumbar spine surgery from the National Spine Network. OBJECTIVES. To explore the influence of medical and psychosocial comorbidities on the change in Short-form 36 (SF-36) general health survey and condition-specific Oswestry Disability Index (ODI) scores in patients undergoing lumbar spine surgery. SUMMARY OF BACKGROUND DATA. It remains unclear as to which type of health instrument is more appropriate for monitoring improvement in patients who undergo lumbar spine surgery. Most clinicians would suspect that comorbidities (medical and psychosocial) play a significant role in the outcome of spine patients. Yet, it has been difficult to quantify specifically the impact of comorbidities on the responsiveness of traditional health status instruments for spine patients. METHODS. Analysis of variance was performed to assess the difference in the change in survey scores across comorbidity groups for the population of National Spine Network patients who had undergone lumbar spine surgical intervention and completed 3-month and 1-year follow-up surveys. Multiple linear regressions were used to identify the most influential individual comorbidities on the change scores. RESULTS. Comorbidities had a significant impact on the change in scores at 3 months and 1 year. The average change in bodily pain, physical function, physical component summary scores of the SF-36, as well as ODI scores decreased in response to surgery as the number of comorbidities increased. Psychosocial comorbidities such as an active compensation case, self-rated poor health, and smoking exerted large effects on the change in survey scores after surgery (P < 0.003). Medical disorders such as headaches, depression, and nervous system disorders were also highly influential (P < 0.05). CONCLUSIONS. The negative impact of medical and psychosocial comorbidities on the change in SF-36 general health survey and condition-specific ODI scores, despite spine surgery, highlights the need for researchers and clinicians to consider these comorbidities when using these, and perhaps all, health survey instruments and interpreting these scores after surgery. Contrary to current assumptions regarding condition-specific health surveys, medical and psychosocial comorbidities similarly affect the generic SF-36 and condition-specific ODI. Further studiesare needed to determine if spine surgery outcomes can be improved by specifically addressing potentially modifiable comorbidities, which negatively impact survey scores, or whether comorbidity burden should play a role in the selection process for surgical intervention. Failure to incorporate consideration of medical and psychosocial comorbidities into preoperative discussions can be a failure to allow our patients (and ourselves) to have realistic expectations and, consequently, the best possible outcome from their treatment choice.