Determinants of undertreatment of hypercholesterolaemia in a population-based study in The netherlands: Proceedings of the Dutch Society for Clinical Pharmacology and Biopharmacy, 8 October 2001

Prevalence of undertreatment of patients with hypercholesterolaemia is high and it remains uncertain which patients receive treatment. The aim was to identify determinants of non‐use of lipid lowering drugs among those eligible for pharmacological treatment. Data were obtained from two population‐based surveys ( n =65,428) on cardiovascular disease risk factors conducted from 1987–1997 in The Netherlands. All respondents (age 20–59 years) completed a questionnaire which contained questions on demographic variables, cardiovascular disease (CVD) risk factors and medication use. Blood pressure, total‐cholesterol and HDL‐cholesterol levels were measured. Treatment eligibility was established for all respondents according to the Dutch Consensus Cholesterol 1998. This standard indicates pharmacological treatment in secondary prevention (unless Tc<5 mmol l −1 ) and for primary prevention when the absolute level of risk exceeds an age‐ and gender‐specific cut‐off point (based on the Framingham risk function). Secondary prevention was defined as a history of myocardial infarction (MI), cerebrovascular accident (CVA), coronary artery bypass grafts (CABG) or percutaneous transluminal coronary angioplasty (PTCA). Multivariate logistic regression models were used to assess the association between demographic variables, CVD risk factors, medication use and treatment with lipid lowering drugs and to estimate odds ratios (OR) and their 95% confidence intervals. Of all respondents, 2719 were eligible for lipid lowering treatment (4.2%). In secondary prevention, 137 of the 1225 eligible respondents were treated (11.2%). Age (OR=0.96 per year; 0.93–1.00), calendar year (OR= 0.69 per year; 0.59–0.82), a history of MI (OR=0.34; 0.20–0.57), CABG (OR=0.28; 0.16–0.47) or PTCA (OR=0.44; 0.24–0.79) and antihypertensive drug use (OR=0.56; 0.34–0.90) were inversely related to non‐use of lipid lowering drugs. Non‐use in secondary prevention increased with untreated hypertension (OR=1.37), diabetes mellitus (OR=2.21) and male gender (OR=1.20), although not statistically significant. In primary prevention, 294 of the 1494 respondents eligible for treatment were treated (19.7%). Male gender (OR=12.2; 4.6–32.9), diabetes mellitus (OR=13.1; 6.6–25.8), untreated hypertension (systolic blood pressure >160 mmHg or diastolic blood pressure >95 mmHg) (OR=13.4; 7.0–25.8) current smoking (OR=11.7; 6.4–21.2) were most strongly associated with non‐use of lipid lowering drugs, while non‐use decreased with concomitant anticoagulant drug use (OR=0.05; 0.01–0.19). For age, we found an increase in risk of 1.26 (1.21–1.32) per year of age. This study indicates that many subpopulations of respondents eligible for treatment with lipid lowering drugs but not receiving medication can be identified. Attention should be focused on the elderly, men (especially in primary prevention), patients with diabetes mellitus and untreated hypertensives.