The association between multimorbidity and out-of-pocket expenditure for prescription medicines among adults in Denmark: a population-based register study

Background: Multimorbidity, defined as two or more chronic conditions in an individual, is increasing in prevalence and is associated with polypharmacy. Polypharmacy can lead to increased out-of-pocket payments for prescription medicines. This, in turn, can be associated with cost-related non-adherence and impoverishment. Healthcare in Denmark is mostly free at the point-of-use; prescription medicines are one of the only exceptions.

Objective: To examine the association between multimorbidity and annual out-of-pocket prescription medicine expenditure for adults in Denmark.

Methods: A population-based register study was conducted. The study population included all adults residing in Denmark in 2020. Frequencies and descriptive statistics were used and regression analyses were conducted to assess the association between multimorbidity and annual out-of-pocket prescription medicine expenditure, while controlling for demographic and socioeconomic covariates.

Results: Overall, 1,212,033 (24.2 %) individuals had multimorbidity. Individuals with five or more conditions spent, on average, €320 in out-of-pocket prescription medicines expenditure compared to €187 for those with two conditions and €44 for those with no conditions. Amongst those with any out-of-pocket prescription medicine expenditure, having multimorbidity was associated with 2-4 times greater out-of-pocket prescription medicine expenditure than those with zero conditions. Amongst those in the quantile with the highest expenditure, those with five or more conditions spent €408 more than those with no conditions, and those with two conditions spent €185 more than those with no conditions.

Conclusions: For adults in Denmark, multimorbidity was associated with significantly higher out-of-pocket prescription medicine expenditure, even after controlling for demographic and socioeconomic covariates. This is similar to patterns in other countries and likely affects those with lowest income the most, given the known socioeconomic patterning of multimorbidity, and raises concerns about cost related non-adherence. Potential protective mechanisms could include subsidies for certain vulnerable patient groups (e.g. those with severe mental illness) and low-income groups.