Drug utilization according to reason for prescribing: a pharmacoepidemiologic method based on an indication hierarchy

Abstract

Purpose To develop a pharmacoepidemiologic method for drug utilization analysis according to indication, gender, and age by means of register‐based information. Statin utilization in 2005 was applied as an example. Methods Following the recommendations for statin therapy, we constructed an indication hierarchy with eight mutually exclusive levels of register markers of cardiovascular disease and diabetes. Danish residents, as of January 1, 1996, were followed at the individual level in nationwide registers with respect to dispensed prescriptions of cardiovascular drugs and antidiabetics (1996–2005) along with discharge diagnoses and surgical procedures (1977–2005). The highest current possible indication level was assigned to all cohort members. Stratified by indication, gender, and age, statin treatment prevalence and incidence were calculated. Results Statin treatment prevalence was highest among individuals with myocardial infarction and tended to be higher among men with indications in the upper part of the hierarchy, but it was higher among women (especially the elderly) in the lower part of the hierarchy. Treatment incidence rates followed roughly the same pattern. Women with no register marker or primary hypertension accounted for almost 50% of all incident female users; among men, the figure was 35%. The proportion of incident users with ischemic heart disease or myocardial infarction increased with age. Conclusion The proposed indication hierarchy provided new insight into prescription patterns of statins. The method can be implemented for other drug categories and could be useful for studying trends in drug utilization, differential drug adherence, and cross‐national comparisons. Copyright © 2011 John Wiley & Sons, Ltd.

Statin utilization according to indication and age: A Danish cohort study on changing prescribing and purchasing behaviour

“…We performed a nationwide cohort study applying data from Danish individual-level registries [34], and retrieved information on dispensed cardiovascular drugs (1995-2009), discharge diagnoses and surgical procedures (in-patient/out-patient 1977-2009), and demographics (for details see [35]). …”

“…We required all individuals to be observable for at least 10 years before the study period to avoid misclassification of register markers [35]. The cohort can, thus, be considered as unselected and representative of the Danish population.…”

“…By means of a previously developed indication hierarchy [35], we followed a cohort of Danish citizens in the nationwide registries during 1996-2009, exploring the increasing statin utilization in individuals aged ≥ 40.…”

“…To explore trends in statin utilization by indication and age, we applied the above-mentioned indication hierarchy based on register markers (hospital and/or prescription information) for eight mutually exclusive medical conditions for statin prescribing [35]. The indication hierarchy follows statin recommendations described in Danish and European guidelines for CVD prevention [11,40] and includes MI, IHD without MI, stroke, PAD in the lower limbs, other potential atherosclerotic conditions (PAC), diabetes, and primary hypertension (i.e.…”

“…By means of the Danish individual-level registries, covering information on a range of healthcare and socio-demographic factors [34], we recently developed a pharmacoepidemiological method for analyzing drug utilization, applying a hierarchy of register-based markers for the indication of statin prescribing [35]. The indication hierarchy includes cardiovascular events: myocardial infarction (MI), ischemic heart disease (IHD), stroke, peripheral artery disease (PAD), other potentially atherosclerotic conditions (PAC) as well as diabetes and primary hypertension.…”