Predictors of treatment adherence in patients with chronic disease using the Multidimensional Adherence Model: unique considerations for patients with haemophilia

Abstract Introduction Adherence to treatment recommendations in patients with chronic disease is complex and is influenced by numerous factors. Haemophilia is a chronic disease with reported levels of adherence ranging from 17–82%. Aim Based on the theoretical foundation of the World Health Organization Multidimensional Adherence Model, the objective of this study was to identify the best combination of the variables infusion frequency, annualised bleed rate, age, distance to haemophilia treatment centre (HTC) and Haemophilia Joint Health Score (HJHS), to predict adherence to treatment recommendations in patients with haemophilia A and B on home infusion prophylaxis in Canada. Methods A one-year retrospective cohort study investigated adherence to treatment recommendations using two measures: 1) subjective report via home infusion diaries, and 2) objective report of inventory ordered from Canadian Blood Services. Stepwise regression was performed for both measures. Results Eighty-seven patients with haemophilia A and B, median age 21 years, were included. Adherence for both measures was 81% and 93% respectively. The sample consisted largely of patients performing an infusion frequency of every other day (34%). Median scores on the HJHS was 10.5; annualised bleed rate was two. Distance to the HTC was 51km. Analysis of the objective measure weakly supported greater infusion frequency as a treatment-related factor for the prediction of lower adherence, however the strength of this relationship was not clinically relevant (R2=0.048). For the subjective measure, none of the explanatory variables were significant. Conclusion Adherence is a multifaceted construct. Despite the use of theory, most of the variance in adherence to treatment recommendations in this sample of patients with haemophilia remains unknown. Further research on other potential predictors of adherence, and possible variables and relationships within factors of the MAM is required.