The Medication Quantification Scale: measurement of medication usage at a multidisciplinary pain center

Abstract

Program evaluation standards require pain centers to assess medication use as one of an array of outcome criteria. The Medication Quantification Scale (MQS) has been introduced as a continuous method for quantifying medication use in chronic nonmalignant pain patients that overcomes methodological concerns inherent in previous pain medication measures. The reliability and sensitivity to program effects of the MQS was demonstrated by the original authors. The present study reexamined the reliability and sensitivity, and provided evidence for the validity of the MQS in an effort to determine whether use of the MQS can be generalized to other pain centers. Interrater reliability between two nurses on 40 pretreatment and 40 6-month follow-up MQS scores were .958 ( $\mathit{p}\mathrm{<}.0001$ ) and .968 ( $\mathit{p}\mathrm{<}.0001$ ) respectively. Six month follow-up MQS scores were significantly lower than pretreatment MQS scores ( $\mathit{t}=5.40\mathrm{,}\mathit{p}\mathrm{<}.0001$ ) for 106 chronic nonmalignant pain patients treated at a multidisciplinary pain center. Convergent and divergent validity of the MQS were demonstrated by higher correlations between the MQS and conceptually similar rather than dissimilar outcome measures. The reliability, sensitivity, and validity of the MQS was demonstrated suggesting it can be generalized for program evaluation purposes to other pain centers.