title: Prevalence and characteristics of patients with low levels of low-density lipoprotein cholesterol in northern Denmark: a descriptive study.
abstract: BACKGROUND
  With the emergence of new lipid-lowering therapies, more patients are expected to achieve substantial lowering of low-density lipoprotein cholesterol (LDL-C). However, there are limited data examining the clinical experience of patients with low (<1.3 mmol/L) or very low (<0.65 mmol/L) levels of LDL-C. To provide information on patients with low LDL-C, we identified and characterized persons with low LDL-C using data from Danish medical databases.
  
  
  METHODS
  Using a population-based clinical laboratory database, we identified adults with at least one LDL-C measurement in northern Denmark between 1998 and 2011 (population approximately 1.5 million persons). Based on the lowest measurement during the study period, we divided patients into groups with low (<1.3 mmol/L), moderate (1.3-3.3 mmol/L), or high (>3.3 mmol/L) LDL-C. We described their demographic characteristics, entire comorbidity history, and 90-day prescription history prior to the lowest LDL-C value measured. Finally, we further restricted the analysis to individuals with very low LDL-C (<0.65 mmol/L).
  
  
  RESULTS
  Among 765,503 persons with an LDL-C measurement, 23% had high LDL-C, 73% had moderate LDL-C, and 4.8% had low LDL-C. In the latter group, 9.6% (0.46% of total) had very low LDL-C. Compared with the moderate and high LDL-C categories, the low LDL-C group included more males and older persons with a higher prevalence of cardiovascular disease, diabetes, chronic pulmonary disease, ulcer disease, and obesity, as measured by hospital diagnoses or relevant prescription drugs for these diseases. Cancer and use of psychotropic drugs were also more prevalent. These patterns of distribution became even more pronounced when restricting to individuals with very low LDL-C.
  
  
  CONCLUSIONS
  Using Danish medical databases, we identified a cohort of patients with low LDL-C and found that cohort members differed from patients with higher LDL-C levels. These differences may be explained by various factors, including prescribing patterns of lipid-lowering therapies.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Sigrun Alba Johannesdottir
authors.initials: SA
authors.lastname: Schmidt
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Uffe
authors.initials: U
authors.lastname: Heide-Jørgensen
authors.affiliation: Center for Observational Research, Amgen Inc., Thousand Oaks, CA, USA.
authors.forename: Angelika D
authors.initials: AD
authors.lastname: Manthripragada
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Vera
authors.initials: V
authors.lastname: Ehrenstein
keywords: cross-sectional study; hyperlipidemia; registries; statins