Primary non-adherence in general practice: a Danish register study

Abstract

Purpose: The aim of this study was to describe primary non-adherence (PNA) in a Danish general practitioner (GP) setting, i.e. the extent to which patients fail to fill the first prescription for a new drug. We also assessed the length of time between the issuing of a prescription by the GP and the dispensing of the drug by the pharmacist. Lastly, we sought to identify associations between PNA and the characteristics of the patient, the drug and the GP.

Methods: By linking data on issued prescriptions compiled in the Danish General Practice Database with data on redeemed prescriptions contained in the Danish National Prescription Registry, we calculated the rate of PNA among Danish patients from January 2011 through to August 2012. Characteristics associated with PNA were analysed using a mixed effects logistic regression model.

Results: A total of 146,959 unique patients were started on 307,678 new treatments during the study period. The overall rate of PNA was 9.3 %, but it varied according to the major groups of the Anatomical Therapeutic Chemical (ATC) Classification System, ranging from 16.9 % for "Blood and bloodforming organs" (ATC group B) to 4.7 % for "Cardiovascular system" (ATC group C). Most of the patients redeemed their prescriptions within the first week. Older age, high income and a diagnosis of chronic obstructive pulmonary disease were found to be significantly associated with lower rates of PNA, while polypharmacy and a diagnosis of ischaemic heart disease were associated with higher rates of PNA.

Conclusions: The overall rate of PNA among Danish residents in a GP setting was 9.3 %. Certain drug classes and patient characteristics were associated with PNA.