All patients who were prescribed statin medications in any VA pharmacy during the study observation period were identified. Statin prescriptions included simvastatin, lovastatin, fluvastatin, pravastatin, atorvastatin and cerivastatin. We collected the dates of prescriptions ordered, the number of days prescribed, number of pills per prescription and number of refills ordered. With this information the statin “defined daily dose” (DDD) was calculated for each subject. The DDD is a validated unit for measuring a prescribed drug amount, and is defined as the average maintenance dose per day of a drug consumed in an adult [33 ]. It is calculated as:
The DDD was re-calculated annually for each year of the study observation period.
The “cumulative defined daily dose” (cDDD) was calculated from the DDD. The cDDD is defined as the total sum of dispensed DDDs of a given medication. Both the DDD and cDDD are recommended by the World Health Organization (WHO) and are widely used for comparison of medications, including statins, along a similar standard [33 ]. Statin use was defined as >28 cDDDs of statin medications prescribed during the study period. Similar information was collected for non-statin lipid lowering agents (cholestyramine, colesevelam, colestipol, ezetimibe, niacin, niacinimide), triglyceride-lowering agents (clofibrate, fenofibrate, gemfibrozil), as well as the antidiabetic agents Metformin, sulfonylureas and thiazolidinedione.
The DDD was re-calculated annually for each year of the study observation period.
The “cumulative defined daily dose” (cDDD) was calculated from the DDD. The cDDD is defined as the total sum of dispensed DDDs of a given medication. Both the DDD and cDDD are recommended by the World Health Organization (WHO) and are widely used for comparison of medications, including statins, along a similar standard [33 ]. Statin use was defined as >28 cDDDs of statin medications prescribed during the study period. Similar information was collected for non-statin lipid lowering agents (cholestyramine, colesevelam, colestipol, ezetimibe, niacin, niacinimide), triglyceride-lowering agents (clofibrate, fenofibrate, gemfibrozil), as well as the antidiabetic agents Metformin, sulfonylureas and thiazolidinedione.
