Clinical characteristics of cardiovascular patients with extremely low levels of high-density lipoprotein cholesterol

Background Extremely low levels of high-density lipoprotein cholesterol (HDL-C) are related to high cardiovascular mortality. The underlying mechanism is not well known. This research aims to study the clinical characteristics of cardiovascular patients with extremely low levels of HDL-C. Methods All cardiovascular patients in a single Chinese cardiology center that were admitted from January to December 2019 were reviewed. The clinical characteristics of those with HDL-C<20 mg/dL were investigated. Results A total of 20,655 individuals were enrolled. Of these, 52.17 % were males, and the average age was 58.20 ± 12.98 years old. The prevalence of HDL-C<20 mg/dL was 0.47 % for all patients (N=98) and 1.05 % for inpatients. Of those with HDL-C<20 mg/dL, 88.8 % were inpatients, and 77.6 % were males. Their average age was 60.7 ± 15.1 years. Compared with matched patients with normal HDL-C, systemic inflammation (OR= 5.556, 95% CI 2.798–11.030), hypoalbuminemia (OR=5.714, 95% CI 2.702–12.085), hyperuricemia (OR=5.156, 95% CI 2.560–10.386), low T3 syndrome (OR=4.278, 95% CI 1.627–11.245), anemia (OR=3.577, 95% CI 1.680–7.617), diabetes (OR=3.534, 95% CI 1.693–7.376) and hypertriglyceridemia (OR=2.493, 95% CI 1.264–4.918) were identified as adverse concomitant factors of extremely low HDL-C. HDL-C levels were inversely correlated with the total risk scores in patients with HDL-C<20 mg/dL (r=-0.381, P<0.001) and more significantly correlated in patients with HDL-C<15 mg/dL (r=-0.511, P=0.004). Conclusions Extremely low levels of HDL-C tend to occur more frequently in males, older individuals and inpatients. For cardiovascular patients, extremely low levels of HDL-C are usually due to the presence of multiple adverse factors with relatively severe conditions. This could explain the high cardiovascular mortality of individuals with extremely low levels of HDL-C.