SAN DIEGO – Among patients undergoing elective surgical spine procedures, the Short Form–6D derived from the Neck Disability Index was more valid and a better responsive measure of general health and quality of life, compared with the Short Form–6D derived from the Short Form–12 or the EuroQol-5D, results from a single-center study showed.
For such quality of life measures to be useful and meaningful, they “should be reproducible, responsive, economical, easy to use, and sensitive to responder burden,” Dr. John A. Sielatycki said at the annual meeting of the Cervical Spine Research Society.
Dr. John A. Sielatycki
“The EQ-5D is well established and commonly used in many of these studies, as is SF-6D, which in some cases has been shown to be more sensitive in certain disease states,” explained Dr. Sielatycki, a resident in the department of orthopedics at Vanderbilt University, Nashville, Tenn. “The differences between SF-6D and EQ-5D have been studied in a wide variety of disease conditions, but to our knowledge few have looked at this specifically in the setting of cervical spine operations.”
To analyze the validity and responsiveness of the SF-6D (derived from both the SF-12 and the NDI) and the EQ-5D in determining overall health and quality of life following elective cervical spine procedures, Dr. Sielatycki and his associates compared the three tools in 420 consecutive patients who presented over the course of 2 years. Trauma and workers’ compensation cases were excluded from the study, as were patients who had a tumor or an infection.
The researchers collected outcome measures at baseline, 3 months, 6 months, 12 months, and yearly thereafter, and defined meaningful improvement as having a North American Spine Society patient satisfaction score of 1, indicating the procedure “met the patient’s expectations.” Next, they generated receiver operating characteristic curves to discriminate between meaningful and nonmeaningful improvement.
The SF-6D (NDI) was a more valid discriminator of meaningful improvement, compared with the SF-6D (SF-12) or the EQ-5D (area under the curve of .69, .65, and .62, respectively). It was also a more responsive measure, compared with the SF-6D (SF-12) and the EQ-5D (standardized response means difference of .66, .48, and .44, respectively).
“Surgeons, outcomes researchers, and payers should use health metrics that are most responsive to changes in the particular disease in question,” Dr. Sielatycki said. “Based on this analysis, SF-6D derived from NDI may be a more valid and responsive measure of improvement in patients undergoing cervical procedures. We suggest that this metric be used in cost-effectiveness analysis and in calculating quality-adjusted life years for cervical spine patients.”
Dr. Sielatycki acknowledged certain limitations of the study, including the fact that it “should have some external validation done to further corroborate our findings. Our gold standard of meaningful improvement has not been established.”
Dr. Sielatycki reported having no financial disclosures.