Follow-up study on hypolipidemic drug use (only available in French)

Background 

Based on statistics gathered by the Régie de l’assurance maladie du Québec (RAMQ) in 2008, 21.9% of individuals insured by the public portion of the Basic Prescription Drug Insurance Plan received at least one prescription for a hypolipidemic drug over the course of the year. Numerous studies report problems with hypolipidemic drug use. With limited recent Canadian and Québec findings available, a study of hypolipidemic drug use was necessary. 

Objective

The objective of this study was to provide an overview of hypolipidemic drug use by adults who were covered by the Public Prescription Drug Insurance Plan over the course of five years, between January 1, 2004 and December 31, 2008.

Methods

A retrospective longitudinal cohort study was conducted with adults aged 18 and over who were insured under the Public Prescription Drug Insurance Plan. Individuals having a history of atherosclerotic vascular disease (AVD) or type 1 or 2 diabetes, based on the medical and pharmaceutical services information provided, were considered to be at high risk for cardiovascular disease (CVD). Pharmaceutical services were also consulted to characterize the use of hypolipidemic drugs among these individuals between 2004 and 2008. Annual prevalences of hypolipidemic drug use were calculated for the general population based on age, gender, coverage category, and cardiovascular risk. New users and their treatments were also described. Certain prescription determinants were established by logistic regression among the individuals identified as being at high risk for cardiovascular disease. 

Results

Between 2004 and 2008, the prevalence of hypolipidemic drug use among Québec adults insured by the Public Prescription Drug Insurance Plan increased by 21.4%, climbing from 23.4% to 28.4%. While only 52.5% of adults considered to be at high risk for cardiovascular disease were prescribed hypolipidemic drugs in 2004, that prevalence jumped to 62.9% in 2008, which represents a relative increase of 19.8%. The relative increase in hypolipidemic use was similar among individuals with low or moderate risk (18.5%). Among those individuals considered to be at high risk for cardiovascular disease, the main determinant for hypolipidemic prescription was age, with adjusted odds ratios (OR) varying between 4.1 and 16.7 depending on age category.  Among new hypolipidemic drug users, 46.1% were considered to be at high risk for cardiovascular disease in 2004 compared to 40.8% in 2008, while the proportion of individuals at high risk among the general population has remained relatively stable. The study reveals that 47.4% of individuals at high risk for cardiovascular disease who were treated with statins received high doses after two years, and this proportion was relatively the same at the beginning of treatment (44.3%). The proportion of new hypolipidemic drug users who remained on treatment dropped significantly at the 180-day mark (73.6%) and stabilized thereafter. 

Conclusion

It seems that many more people at high risk for cardiovascular disease can benefit from hypolipidemic therapy, but that for various reasons, they are not being treated. The use of hypolipidemic drugs among individuals considered at low or moderate risk for cardiovascular disease seems more prevalent than expected, particularly among seniors. This use may be justified, however, considering that the data used did not include clinical information such as lipid values. Further studies investigating the use of hypolipidemic drug use among the Québec population are required in order to determine if the use of hypolipidemic drugs by individuals considered at low or moderate risk for cardiovascular disease remains justified, and to identify the factors that are hindering hypolipidemic drug use by individuals at high risk, so that targeted solutions can be developed.