Predicting health-utility scores from the Cervical Spine Outcomes Questionnaire in a multicenter nationwide study of anterior cervical spine surgery.

STUDY

DESIGN

Cross-sectional analysis of the Cervical Spine Research Society Outcomes Study, a longitudinal multicenter cohort study.

OBJECTIVE

To provide a statistical model for estimating health utility from the Cervical Spine Outcomes Questionnaire (CSOQ) domain scores.

SUMMARY OF BACKGROUND DATA: There is consensus among health-policy researchers that the results of economic evaluations of health can be reported in quality-adjusted life-years (QALY). The CSOQ is a condition-specific instrument that assesses individuals across several domains, including neck and arm/shoulder pain and psychological distress.

METHODS

The CSOQ and 36-Item Short Form Health Survey (SF-36) were prospectively administered before surgery (within 4 weeks) and after surgery (at 3, 6, and 24 months) to individuals undergoing anterior cervical decompression and fusion for degenerative disc disease of the cervical spine. Using methods reported by Brazier et al, health utility (SF-6D) was estimated using the SF-36. Regression analyses were used on a training dataset (n = 164) to compute the SF-6D from the domain scores of the CSOQ. A validation dataset (n = 328) was used to estimate the SF-6D for comparison to the calculated health utility from the SF-36. RESULTS.: Domain scores were moderately correlated with health utility (SF-6D) (P < 0.001) with correlation coefficients ranging from 0.48 to 0.70. The regression equation to predict SF-6D on the basis of CSOQ domain scores and patient age using the training dataset accounted for 65% of the variation in health utility. In the validation dataset, predicted SF-6D was positively correlated with observed SF-6D (r = 0.680, P < 0.001).

CONCLUSION

Our findings show that the CSOQ's domain scores can be used to estimate health-utility scores among those undergoing elective anterior cervical decompression and fusion for cervical degenerative disc disease. The ability to assess health utility, coupled with the psychometric properties of the CSOQ, should increase the clinical utility of this patient-reported outcomes instrument.