The Million Visual Analog Scale: Its utility for predicting tertiary rehabilitation outcomes

Study Design. A longitudinal cohort study involving 1749 patients with chronically disabling spine disorder (CDSD) who underwent tertiary rehabilitation investigated the relation between the Million Visual Analog Scale (MVAS) score and treatment outcome. Objectives. To determine whether the pretreatment MVAS rating of disability severity is associated with the ability to complete functional restoration rehabilitation, and to determine whether pre- or posttreatment MVAS disability perception is associated with 1-year posttreatment socioeconomic outcomes. The relation of the MVAS to pre- and posttreatment psychosocial measures and physical performance levels also was evaluated. Summary of Background Data. The MVAS yields a total functional disability score ranging from 0 to 150. Like other "disability inventories," the MVAS differs from a "pain inventory" in that the focus is on disability and function, as opposed to self-reported pain. The MVAS may currently be the most powerful functional rating scale because all its questions relate to the patient's ability to perform activities of daily living. It also has the advantage of a visual analog format, which typically is considered more effective than other commonly used self-report formats. Methods. A large cohort of 1749 patients with CDSD who underwent tertiary rehabilitation was divided into groups by their severity of disability, rated on the MVAS, both at pre- and posttreatment assessment. The patients were divided into groups ranging from "no reported disability" (MVAS = 0) to "extreme disability" (MVAS = 131-150). The distribution into the six groups was assessed on both pre- and posttreatment MVAS ratings. The patients underwent a 3-week functional restoration program consisting of daily quantitatively directed exercise progression and multimodal disability management. Physical capacity and psychosocial assessments, performed before and after treatment, were correlated with the MVAS scores. A 1-year posttreatment clinical interview obtained information on socioeconomic outcomes, which also were correlated with the MVAS ratings. Results. Mantel-Haenszel linear analyses showed a number of relations between demographic variables and both pre- and posttreatment MVAS scores. Most importantly, the findings showed that severe pretreatment MVAS scores were associated with a lower program completion rate (94% vs 89%; P < 0.001) and a higher rate of postrehabilitation health care use from a new provider (12% vs 41%; P < 0.001). Prerehabilitation scores also were linearly related to lower levels of pretreatment physical performance and higher rates of pretreatment depression. More severe posttreatment MVAS scores were associated linearly with a drop in the work return rate from 93% to 63%, a drop in the work retention rate 1 year after rehabilitation from 86% to 44%, and a drop in the financial settlement rate from 94% to 79% (P < 0.001). A linear trend also was found in the rate of postrehabilitation surgeries, with the percentages rising from 0% in the group with no reported disabilities to 12% in the group with extreme disabilities (P < 0.001). Conclusions. The current study represents the first large-scale examination of the relation between MVAS ratings and treatment outcomes in a CDSD population. These results demonstrate the effectiveness of a simple disability rating scale, such as the MVAS, for systematic disability assessment in potentially predicting treatment outcomes in patients with CDSD. Despite the popularity of other questionnaires, the MVAS is the first disability inventory with demonstrated effectiveness for this purpose in a large CDSD population.