Low-density lipoprotein-cholesterol (LDL-C) greater than 100mg/dL as a quality indicator: locating risk in person, place and time

Rationale, aims and objectivesAchieving control over elevated lipid parameters, particularly low-density lipoprotein (LDL)-cholesterol, is an acknowledged quality indicator in primary care. The Centers for Disease Control and Prevention (CDC)'s model for investigation of outbreaks (person-place-time) can be applied to the analysis of quality indicators. MethodsA sample of 322 family medicine patients for whom lipid levels were ordered was extracted. LDL>100mg/dL was cross-tabulated by personal characteristics [age group, gender, body mass index (BMI), diagnoses], month (time) and ordering department (place). ResultsAge (except one age category), gender, time and location were not related to LDL>100mg/dL after adjustment for covariates. All levels of BMI above normal elevated the risk of LDL>100mg/dL [BMI 25-29.9: odds ratio (OR)=3.41, confidence interval (CI)=1.61-7.23, P=0.0014; BMI 30-34.9: OR=2.93, CI=1.28-6.70, P=0.0109; BMI35: OR=2.75, CI=1.19-6.37, P=0.0181]. Patients with coronary artery disease (CAD) and diabetes mellitus (DM) were at reduced risk for LDL>100mg/dL (CAD: OR=0.47, CI=0.24-0.91, P=0.0254; DM: OR=0.28, CI=0.14-0.55, P=0.0002). ConclusionAn outbreak investigation model is useful for analysing variations in this quality indicator. Patients with higher BMI and those not diagnosed with CAD or DM type I/II may be considered for intensified lipid lowering using quality improvement efforts. These might include counselling for lifestyle changes or medication therapy depending upon their calculated cardiac risk.