The minimal clinically important difference for the patient activation measure in a culturally and linguistically diverse cohort with chronic conditions

Purpose: To estimate the Minimally Clinically Important Difference (MCID) for the Patient Activation Measure (PAM) in a culturally diverse sample of people with chronic disease. Methods: This study was embedded in a larger cluster randomised trial exploring chronic disease management interventions in a culturally diverse sample of 254 adults. Patients were consecutively recruited across 16 outpatient clinics in Sydney, Australia and completed a range of outcomes related to the trial, including the Patient Activation Measure at recruitment and 6 months later. For the current study, the MCID for the PAM was estimated using two distribution methods and four anchor-based methods: mean change difference, and from the receiver operating characteristic curve, the Euclidean and Farra methods, and the Youden Index. A modified self-reported global impression of change, aligned to key elements of the PAM, was used as the external criterion and scores were dichotomised into ‘improved’ and ‘not improved.’ Therefore, the results are likely to overestimate the MCID. Results: 228 participants completed pre- and post-assessments; 51% in the improved group and 49% in the not improved group. Anchor-based methods produced MCIDs between 4 and 7.9, with a value of 4.7 from the preferred Youden method. Distribution-based methods produced MCIDs ranging from 0.26 (standardised effect size) to 5.88 PAM points. Conclusion: Different methods of calculating the PAM for MCID provided different results. Using the preferred Youden Index method, an MCID of 4.7 PAM points was identified as clinically meaningful in this culturally diverse chronic disease cohort. Wider estimates from other anchor-based methods (4.0 to 7.9) are reported to illustrate methodological variability. Trial registration: Study data were collected during a two-phase hybrid cluster randomised controlled trial, approved by the South Western Sydney Local Health District Human Research Ethics Committee (2021/ETH12279) and registered prospectively on the Australian and New Zealand Clinical Trials Registry (ACTRN12622000697785).