Study design and participants
The data we analyzed came from the Chinese Hypertension Registry Study (http://www.chictr.org.cn/, No: ChiCTR1800017274), and details about the purpose, protocol, and outcome of the study have been described. The inclusion and exclusion criteria for the study are described in detail in Table S1. In short, this study is a large observational cohort study of patients with hypertension. The aim of the study was to explore the prevalence of hypertension in China and the risk factors that influence its treatment and prognosis. Hypertension was defined as Systolic blood pressure (SBP) values ≥140 mmHg and/or diastolic BP (DBP) values ≥90 mmHg, self-report history of hypertension, or the use of antihypertensive drug(s) at baseline. From March to August 2018, a total of 14,268 patients with hypertension were recruited into our study in Wuyuan, Jiangxi Province, China, and all study participants signed informed consent before being recruited into the study. In our study, we excluded participants who were not treated with lipid-lowering drugs and finally analyzed data from 13,721 hypertensive patients. The study was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of the Anhui Medical University Biomedical Institute (No. CH1059).
In the current study, staffs with physician qualifications collected venous fasting blood for each study participant. The collected blood samples were frozen and transported to the Biaojia Biotechnology Laboratory in Shenzhen, China. Laboratory staff tested the biochemical indicators in the blood samples by an automatic clinical analyzer (Beckman Coulter, USA). Laboratory indicators include lipids, liver function, renal function, Hcy, blood glucose. Details of biochemical indicators were shown in Table 1. Body mass index (BMI) was calculated by dividing weight by the square of height (kg/m2). After a 10-minute rest, each participant's blood pressure and heart rate were measured by an electronic sphygmomanometer. Other covariates were obtained through questionnaires, including age, sex, smoking and drinking status, disease and medication history. The specific contents of the questionnaire were presented in Table 1.
Definition of nontraditional lipid profiles and HUA
The nontraditional lipid profiles represented TC/HDL-C ratio, TG/HDL-C ratio, LDL-C/HDL-C ratio and non-HDL-C[13, 14, 21, 22]. The TC/HDL-C, TG/HDL-C and LDL-C/HDL-C ratios were calculated as TC, TG, LDL-C divided by HDL-C, respectively. Non-HDL-C was calculated as HDL-C subtracted from TC. To date, eight guideline documents recommended that serum uric acid level >420 μmol/L (7 mg/dL) was diagnosed as HUA, regardless of sex[23-25]. According to the updated Chinese guidelines, HUA in our study was defined as serum uric acid level >420 μmol/L (7 mg/dL), regardless of gender.
Baseline characteristics of the study population were displayed according to with or without HUA. Continuous variables are presented as the mean ± SD and categorical variables are presented as percentage (%). Logistic regression analyses models were performed to assess the association of nontraditional lipid profiles (TC/HDL-C ratio, TG/HDL-C ratio, LDL-C/HDL-C ratio, and non-HDL-C) with HUA by presenting the odds ratio (OR) and 95% confidence interval (CI) after adjusting for confounding factors. The trend test was used to evaluate the linear relationship between nontraditional lipid profiles and HUA, when nontraditional lipid profiles used as tertiles. Fully adjusted smoothing curve fitting (penalized spline method) visually demonstrated the relationship between nontraditional lipid profiles and HUA.
All statistical analyses were performed using the statistical package R (http://www.R-project.org, The R Foundation) and Empower (R) (http://www.empowerstats.com, X&Y Solutions, Inc., Boston, MA). Statistical significance was defined as two-tailed P < 0.05.