Research Results Stress Need for Assessing Outcomes After Spinal Surgery

Research presented in late February at the annual meeting of the American Academy of Orthopaedic Surgeons underscores the increasing importance of functional assessment tools to quantify outcomes after spinal intervention, whether in measuring the effectiveness of a specific procedure or in better understanding the risks faced by patients who undergo spinal surgery in general.Baseline function, as well as functional improvement after spinal surgery, is significantly affected by the number and type of comorbidities seen in patients, according to investigators from the Dartmouth Spine Center in Lebanon, NH.The researchers analyzed SF-36 Physical Component Summary (PCS) and Oswestry Disability Index (ODI) scores for 34,017 patients seen at any of 25 centers in the National Spine Network, along with follow-up scores at 3 months and 1 year for 3482 of those patients.They found that lower scores on both assessment scales were associated with a higher number of comorbidities for a given patient, both at baseline and at follow-up. At baseline, the average PCS score was 33.3 for a patient with no comorbidities, compared with 26 for a patient who has more than 4 comorbidities. Similarly, the average ODI score was 62.2 for those with no comorbidities and 48.7 for those with more than 4 comorbidities. Scores on either scale were more likely to have increased at follow-up in patients with fewer comorbidities (table).Comorbidities had a more significant effect at baseline on patients with lumbar pathologies than on those with cervical or thoracic pathologies. At follow-up, however, changes in score were not affected by pathology site, according to James D. Slover, MD, an orthopedic surgery resident at Dartmouth Hitchcock Medical Center, who presented his group's results at the meeting.The comorbidities most significantly affecting scores on both assessment scales were poor self-reported health and an active workers' compensation case. Depression contributed significantly to ODI scores, and an education level of high school or less contributed significantly to PCS scores. "Clinicians designing studies using PCS or ODI should understand the effect these psychosocial comorbidities have on outcomes," Slover said.Taking a narrower focus in comparing functional outcomes for 2 approaches to single-level spine fusion, researchers from the University of Kentucky found that pain and function scores failed to differentiate patients receiving anterior fusion from those receiving posterior fusion.Clinical outcomes from an ongoing study of posterior interbody fusion for lumbar degenerative disk disease were juxtaposed with those of a study published in the November 1, 2002, issue of Spine; this study involved an anterior approach to patients with similar indications.1 Both protocols used the INFUSE Bone Graft and assessed outcomes using the ODI, SF-36, and back and leg pain questionnaires.Both the anterior and posterior procedures were associated with significant improvement in clinical outcomes at 6 weeks and 1 year, but no difference in improvement was seen between the groups, according to John R. Dimar, MD, associate clinical professor of orthopedic surgery at the university, who presented his group's findings at the meeting. The anterior approach, however, was associated with a shorter operative time, less blood loss, and a shorter hospital stay than was the posterior approach.REFERENCE1. Burkus JK, Transfeldt EE, Kitchel SH, et al. Clinical and radiographic outcomes of anterior lumbar interbody fusion using recombinant human bone morphogenetic protein-2. Spine. 2002;27:2396-2408.