The Million Visual Analogue Scale: its utility for predicting outcomes after tertiary rehabilitation

Abstract

Tom Mayer, MD, Timothy Proctor, PhD, Robert J. Gatchel, PhD, Dallas, TX, USAIntroduction: The Million Visual Analogue Scale (MVAS) [1] is a 15-item visual analog measure of spinal pain disability. This instrument produces a total functional disability score ranging from 0 to 150. Like other “disability inventories,” such as the Oswestry and the Roland-Morris, 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 be the strongest functional rating scale, because all questions relate to the patient's ability to perform activities of daily living. In addition, this instrument has the advantage of a visual analog format, which is typically considered more effective than other commonly used self-report formats. The purpose of the present study was to determine if pretreatment MVAS disability rating severity predicts the ability to complete functional restoration rehabilitation and to determine if pre- or posttreatment MVAS disability perception predicts 1-year posttreatment socioeconomic outcomes (work status, health utilization, postrehabilitation surgery, recurrent injury, case resolution). We also evaluated the relationship of the scale to pre- and posttreatment psychosocial measures and pre- and posttreatment physical performance levels.Subjects: A large cohort of 1,750 chronically disabled spinal disorder (CDSD) patients who underwent tertiary rehabilitation was divided into groups by the severity of disability rated on the MVAS at pre- and posttreatment assessment. The six groups were as follows: no reported disability (0); mild disability (1 to 40); moderate disability (41 to 70); severe disability (71 to 100); very severe disability (101 to 130); and extreme disability (131 to 150). The demographics for these groups when divided by pretreatment scores were as follows: no reported disability (n=0), mild (n=54; age 40 + 10; 74% male), moderate (n=240; age 41+10; 60% male) severe (n=786; age 41 + 10; 63% male), very severe (n=626; age 41 + 10; 60% male) and extreme (n=44; age 41 + 9; 48% male). The distribution of posttreatment MVAS scores (n=1,334) was no reported disability (n=17), mild (n=297), moderate (n=446), severe (n=412), very severe (n=146) and extreme (n=16). There were no age- or gender-related trends.Methods: All patients underwent a 3-week tertiary functional restoration program combining quantitatively directed exercise progression with a multimodal disability management approach, using psychological and case management techniques. Before the start of the program, and again upon completion, all patients received a standard psychosocial assessment battery that, in addition to the MVAS, included the Beck Depression Inventory (BDI). Also at pre- and posttreatment, patients were assessed on a variety of physical motion, strength, aerobic and functional factors, and a Cumulative Score (CS), summarizing the relationship to population-based norms, was calculated. A structured clinical interview examining socioeconomic outcomes was conducted at 1-year after program completion.Results: More severe posttreatment MVAS scores were linearly associated (p<.001; chi-squared linear by linear analysis) with work return decreasing from 93% to 64%, work retention decreasing from 86% to 43% and financial settlement decreasing from 94% to 75%. A linear trend was also found with respect to the rate of postrehabilitation surgeries, with the percentages increasing from 0% in the no reported disability group to 13% in the extreme group (p<.001). More severe pretreatment MVAS scores were predictive of a lower program completion rate (94% to 87%; p<.001) and a higher rate of postrehabilitation health-care utilization from a new provider (14% to 41%; p<.001). More severe pretreatment MVAS scores were also linearly related to lower levels of pretreatment physical performance (CS from 53 to 23; p<.001). More severe pretreatment MVAS ratings were linearly related to higher rates of pretreatment depression, with BDI scores increasing from 9 (no/mild depression) in the mild group to 24 (moderate depression) in the extreme group (p<.001).Conclusion: The present study represents the first large-scale examination of the relationship between MVAS ratings and treatment outcomes in a CDSD population. In this study, higher pretreatment MVAS scores correlated with more prerehabilitation depression and physical inhibition, and were predictive of a lesser ability to complete tertiary rehabilitation, and a higher rate of postrehabilitation health utilization. More severe posttreatment MVAS ratings were predictive of poorer work, surgery and case closure outcomes at 1 year. The results of this large cohort study demonstrate the importance of a simple disability rating scale such as the MVAS for systematic disability assessment in predicting treatment outcomes in CDSD patients. The MVAS is the first disability inventory to be shown effective for this purpose in a CDSD population.