An assessment of the minimal clinically important difference for the pain disability quality-of-Life Questionnaire-Spine

Abstract

ObjectiveThe Pain Disability Quality-Of-Life Questionnaire-Spine (PDQQ-S) is a validated six question patient reported outcome measure designed for usage in minimally invasive spine intervention. The purpose of this study was to determine the Minimal Clinically Important Difference (MCID) for the PDQQ-S. DesignRetrospective single arm cohort study involving 411 patients who had undergone lumbar facet and/or sacroiliac joint RFN and had completed pre-and 3-month post RFN PDQQ-S. MethodsThe MCID using both distribution and anchor-based (“Rebook RFN”; “Analgesic Requirements”) methods were calculated. ResultsThe distribution-based approach (using standard error of measurement) estimated the MCID to be −17.3 [PDQQ-S baseline mean (SD): 46.9 (7.9)]. This is supported by the anchor based approach, which calculated the MCID to be: −21.5 for rebook RFN; −11.3, -17.2 and −30.5 for mildly, moderately and dramatically decreased NSAID use respectively; and −11.7, -16.9 and −31.7 for mildly, moderately and dramatically decreased opioid use respectively. A moderate reduction in medication use was deemed to be clinically relevant. ConclusionThe MCID value for the PDQQ-S is a score reduction of 17.