Abstract
Study design
A prospective study on predictive factors for the outcome of 164 patients with adult isthmic spondylolisthesis operated on with fusion between 1990 and 2003.
Purpose
In view of the need to better select patients for fusion we investigated the use of the pain drawing (PD) and other potential factors for predicting the outcome of fusion.
Background
Results on predictive factors of outcome after spinal fusion have been contradictory and large, well defined, patient samples with adequate observation times are lacking
Methods
QuestionnairesF including possible predictive factors as well as PDs were obtained preoperatively. Degree and level of slip were documented. Outcome was quantified by measurement of pain (VAS), Disability Rating Index (DRI), the Oswestry Disability Index and global assessment by the patient into “much better”, “better”, “unchanged” or “worse”. The 2-year follow up rate was 160/164 (98%).
Results
In the total sample 49% of patients were much better, 25% better, 14% unchanged and 12% worse. Most factors investigated did not correlate with the outcome including; degree of slip, level of slip, fusion technique, age, smoking, drinking habits, weight, BMI, sciatica, laminectomy, marital status, level of education, type of domicile, possible immigrant status, dominant hand, births and number of children. The following preoperative factors correlated to a worse outcome in the univariate analysis: Not working, no regular exercise, female gender, shortness in stature and a non-organic PD. The multivariate regression analysis showed that work status was the main determinant of outcome. Gender and exercise had less but significant impact (p=0.004 and 0.02, respectively), whereas the PD was of borderline significance (p=0.06). These factors, however, explained only 22% of the variability of outcome.
Conclusion
Prediction of outcome after fusion is difficult. Only a limited number of predictive factors were identified, with working preoperatively being the strongest predictor. Also male gender and regular exercise are indicators of a better outcome. Female patients not working, not exercising, or with a non-organic pain drawing, should be informed about their suboptimal chances of an excellent outcome after fusion.
