Purpose
To estimate non-adherence in relation to the therapeutic intensity (TI) and the number of dispensed drugs per individual and studywhether the TI can be used as an estimator of non-adherence with an increasing number of drugs.
Methods
The study comprised an individual-based register of all dispensed outpatient prescriptions in Sweden in 2006, including6.2 million individuals. The applied definition of drug was the chemical entity or substance comprising the fifth level in the World HealthOrganisation’s Anatomic, Therapeutic, Chemical classification. The defined daily dosage per individual during 12 months was applied asan indicator of the TI.
Results
We found a positive linear relation between the TI and the increasing number of dispensed drugs per individual, both for men andwomen. We found a slightly diminishing TI with an increasing number of drugs only for the age groups above 70 years, at a level above 13drugs per individual.
Conclusions
The linear relationship between the TI and the increasing number of dispensed drugs per individual provides poor support forusing decreasing TI as an estimator of non-adherence. The low rate of cost-related non-adherence in Sweden might contribute to explainingthe linear relationship.