Danish validation of the Multimorbidity Treatment Burden Questionnaire (MTBQ) and findings from a population health survey: a mixed-methods study

OBJECTIVE: To validate the Danish Multimorbidity Treatment Burden Questionnaire (MTBQ) and obtain a population-based evaluation of treatment burden. DESIGN: Mixed-methods. SETTING: Danish population-based survey. PARTICIPANTS: Translation by professional translators and an expert group. The scale was tested by 13 407 participants (aged ≥25 years) in treatment. MEASURES: The 10-item MTBQ was translated into Danish using forward-backward translation and used in a large population health survey. A global MTBQ score was calculated and factor analysis and Cronbach’s alpha assessed dimensional structure and internal consistency reliability, respectively. Spearman’s rank correlations between global MTBQ scores and scores of self-rated health, health-related quality of life and the number of long-term conditions, respectively, assessed construct validity. MTBQ scores were grouped into four categories (no, low, medium, high burden) to assess interpretability and population-based evaluation of treatment burden. RESULTS: The scale showed high internal consistency (α=0.87), positive skewness and large floor effects. Factor analysis supported a one-dimensional structure of the scale with a three-dimensional structure as a less parsimonious alternative. The MTBQ score was negatively associated with self-rated health (r(S)−0.45, p<0.0001) and health-related quality of life (r(S)−0.46/−0.51, p<0.0001), and positively associated with the number of long-term conditions (r(S) 0.26, p<0.0001) and perceived stress (r(S) 0.44, p<0.0001). Higher treatment burden was associated with young age, male sex, high educational level, unemployment, being permanently out of work, not living with a spouse/cohabitant, living with child(ren) and long-term conditions (eg, heart attack, stroke, diabetes and mental illness). CONCLUSION: The Danish MTBQ is a valid measure of treatment burden with good construct validity and high internal reliability. This is the first study to explore treatment burden at a population level and provides important evidence to policy makers and clinicians about sociodemographic groups at risk of higher treatment burden.