Study design: Prospective cohort study.
Objective: To examine the relationship between improvement in pain intensity and subsequent improvement in physical function and disability during the first 12 months after lumbar spine surgery.
Summary of background data: Little is known about how reduction of pain intensity after surgery may predict improvements in physical function and disability.
Methods: We prospectively enrolled 260 individuals undergoing elective surgery for degenerative lumbar spine conditions from August 2005 through August 2011. Preoperative and postoperative (3, 6, and 12 mo) assessment tools were numeric pain rating scale, Short Form 12 version 2 physical component score (physical function), and Oswestry Disability Index (disability). Changes were defined using minimum clinically important differences. The association between improvement in pain intensity and subsequent improvement in physical function and disability during the first 12 postoperative months was assessed using standard regression methods. Significance was set at a P value less than 0.05.
Results: Preoperatively, mean pain intensity was 5.2 (standard deviation, 2.4), physical function was 27.9 (standard deviation, 9.2), and disability was 40.1% (standard deviation, 16.8%). Pain intensity had improved in 164 (63.1%) patients by 3 and 6 months and in 184 (70.8%) by 12 months. Patients with improvement in pain postoperatively were more likely to have subsequent improvement in physical function (odds ratio, 2.11; 95% confidence interval, 1.10-3.16) during the course of 12 postoperative months. The association between postoperative pain reduction and reduced disability was similar (odds ratio, 1.61; confidence interval, 1.12-2.33).
Conclusion: Most patients experienced clinically important postsurgical reductions in pain intensity by 3 months after surgery. Those patients were more likely to have clinically important improvement in physical function and reduction in disability during the first postoperative year.
Level of evidence: 1.