Background: In many Western countries cardiovascular treatment intensity (DDD/1000 inhabitants/day, DDD/TID) has grown substantially during the last decades. Changed drug utilization pattern - rather than population ageing - was hypothesized to be the main driving force behind the growth. Objectives: To investigate the driving forces behind the increasing treatment prevalence of cardiovascular drugs, in particular statins, by means of a dynamic epidemiologic drug utilization model. Methods: Material: All Danish residents older than 20 years by January 1, 1996 (4.0 million inhabitants), were followed with respect to out-of-hospital redemptions of cardiovascular prescription drugs in the period 1996-2005. The impact of population ageing on cardiovascular treatment intensity was investigated by comparing crude and age/gender standardised intensities. Epidemiologic model: We developed a three-state (untreated, treated, dead) semi-Markov model to analyse the dynamics of drug use. Transitions were from untreated to treated (incidence), the reverse (discontinuation), and from either untreated or treated to dead. Stratified by sex and age categories, prevalence trends of "growth driving" drug categories were analysed, exploring trends in incidence- mortality- and discontinuation rates. Trends in prevalence proportions were estimated from logistic regression. Incidence-, discontinuation and mortality rates from Poisson regression. Results: The total cardiovascular treatment intensity increased from 285 to 619 DDD/TID from 1996 to 2005 (117%). Population ageing accounted for 22 percentage points. Treatment intensity with statins increased from 5 to 121 DDD/TID. Population ageing accounted for one eighth of this increase. Increasing incidence rates was the main driving force behind the growing statin prevalence. Conclusions: Increasing cardiovascular treatment intensity was driven by increases in age/gender specific drug use - rather than by population ageing. Although the increased prevalence of use in all age groups reflects an increasing incidence, recruitment of long-term users is expected to add considerably to the future growth in treatment intensity.
population ageing, increasig cardiovascular drug utilisation, model analysis, utilization patterns
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International Conference on Pharmacoepidemiology & Therapeutic Risk Management, 2009