The impact of ageing and changing utilization patterns on future cardiovascular drug expenditure: a pharmacoepidemiological projection approach

Abstract

Purpose: To develop a method for projecting the impact of ageing and changing drug utilization patterns on future drug expenditure.

Methods: Applying nationwide registries, prescriptions of three categories of cardiovascular drugs were followed for all Danish residents from 1 January 1996 until 2006. The official Danish population forecast 2006-2015 was applied for projecting the population composition. A previously developed pharmacoepidemiological semi-Markov model was extended to apply for projection of future drug utilization. We either assumed that past trends in model parameters (incidence, discontinuation and drug user mortality) would continue during 2006-2015, or that all model parameters would remain unchanged at their values in 2005. Yearly drug expenditure per user of a particular drug was assumed to remain unchanged. Scenarios of future treatment prevalence with different drug categories were modelled by extrapolating future age- and gender-specific parameter values (treatment incidence, discontinuation and drug user mortality) from historic point estimates and their historic trend.

Results: Provided a continuance of past trends, increasing utilization of ACE inhibitors, angiotensin II antagonists and statins translates into a rise in annual expenditure of 176%, mainly explained by increases in treatment incidence. Due to pharmacoepidemiological disequilibrium, unchanged model parameters would imply an increase of 64%, ageing alone 14%.

Conclusion: Increasing cardiovascular drug utilization may pose a substantial burden on future health care resources. However, prescribing behaviour is likely to depend on changing clinical guidelines. Despite the limited impact as cost driver, population ageing remains a challenge for future health care services.