Introduction: We report an internal validation of the Medication Quantification Scale (MQS III) using a chronic pain population. The MQS was designed as a methodology of quantifying different drug regimens in 1992, updated in 1998 (MQS II), and again updated in 2003 (MQS III) using "detriment" weights determined by surveying physician members of the American Pain Society. The MQS has been used as a unitary clinical and research outcome.
Methods: A retrospective chart review was collected from 400 patients in an interdisciplinary outpatient chronic pain clinic. A linear regression equation was developed using the patients' composite MQS III score, and those values were used in a Pearson correlation analysis.
Results: The correlation between the subjects' computed regression detriment weights and the corresponding MQS III detriment weights yielded a significant result (r = 0.962, P < 0.01; two-tailed).
Discussion: Our chronic pain sample-derived detriment weights did differ in some drug classes from that of the physician consensus, most notably the selective serotonin reuptake inhibitor, Opioid Schedule II, and NSAID class detriment. It is necessary to periodically resurvey large groups of physicians in order to control and modify the detriment weights of our categories in light of new information about detrimental effects (eg, COX-2 inhibitors), or to accommodate medical or political changes in prescribing habits (eg, more liberal opioid prescribing in the later years). This work suggests it may also be important to assess patients' perspective on detriment, as well as statistical and empiric use patterns.