Assessment of health-related quality of life in spine treatment: conversion from SF-36 to VR-12

Publication date: Available online 28 February 2018
Source:The Spine Journal
Author(s): Matthew F. Gornet, Anne G. Copay, Katrine M. Sorensen, Francine W. Schranck
Background Context.Health-related quality-of-life outcomes have been collected with the Medical Outcomes Study (MOS) Short Form 36 (SF-36) survey. Boston University School of Public Health has developed algorithms for the conversion of SF-36 to VR-12 physical component summary (PCS) and mental component summary (MCS).Purpose.The purpose of this study is to investigate the conversion of the SF-36 to VR-12 PCS and MCS scores.Study Design.Preoperative and postoperative SF-36 were collected from patients who underwent lumbar and/or cervical surgery from a single surgeon between August 1998 and January 2013.Methods.SF-36 PCS and MCS scores were calculated following their original instructions. The SF-36 answers were then converted to VR-12 PCS and MCS scores following the algorithm provided by the Boston University School of Public Health. The mean score, preoperative to postoperative change, and proportions of patients who reach the minimum detectable change were compared between SF-36 and VR-12.Results.A total of 1968 patients (1559 lumbar and 409 cervical) had completed preoperative and postoperative SF-36. The values of the SF-36 and VR-12 mean scores were extremely similar with score differences ranging from 0.77 to 1.82. The preoperative to postoperative improvement was highly significant (p<0.001) for both SF-36 and VR-12 scores. The mean change score were similar with a difference of up to 0.93 for PCS and up to 0.37 for MCS. Minimum Detectable Change (MDC) values were almost identical for SF-36 and VR-12 with a 0.12 difference for PCS and up to 0.41 for MCS. The proportions of patients whose change in score reached MDC were also nearly identical for SF-36 and VR-12. About 90% of the patients above SF-36 MDC were also above VR-12 MDC.Conclusions.The converted VR-12 scores, similarly to the SF-36 scores, detect a significant postoperative improvement in PCS and MCS score. The calculated MDC values and the proportions of patients whose score improvement reach MDC are similar for both SF-36 and VR-12.



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