Sex-related differences for uric acid in the prediction of cardiovascular events in essential hypertension. A population prospective study

Abstract

Background: Uric acid (UA) is an independent prognostic factor for cardiovascular events, but there are no data demonstrating a different risk profile between women and men. Thus, we tested whether UA is associated with a possible sex-related difference in fatal and non-fatal cardiovascular events.

Methods: In this prospective population-based study we enrolled 1,650 never-treated Caucasian hypertensive outpatients referred to Catanzaro University Hospital (Italy). Inclusion criteria were newly diagnosed hypertensive patients, aged 20 years or more. Exclusion criteria were secondary form of hypertension, previous cardiovascular events, rheumatic and non-rheumatic valvular heart disease, prosthetic valves, cardiomyopathies, type-2 diabetes, chronic kidney disease, malignant diseases, gout arthritis and secondary forms of hyperuricemia, liver diseases, peripheral vascular diseases, and heart failure. Anthropometric, clinical, and biochemical parameters were measured. UA prognostic role was investigated by Cox regression analyses. Receiver-operating characteristic curve analyses and area under the curve were used to determine the predictive validity and the optimal cut-off point of UA. We investigated following endpoints: coronary events (fatal and nonfatal myocardial infarction, unstable angina, coronary revascularization procedures, coronary death); fatal and nonfatal stroke; all-cause mortality and major adverse cardiovascular events (MACE).

Results: We enrolled 830 males and 820 females aged 52.2 ± 11.3 years. During 9.5 ± 3.1 years follow-up, there were 424 new clinical events (2.71%): 250 coronary (1.59%), 118 (0.75%) cerebrovascular, and 56 (0.40%) deaths. Comparison between groups demonstrated a higher and significant difference in incidence rate in females for MACE (3.08 vs 2.33%, P = 0.001), coronary (1.82 vs 1.36%, P = 0.014) and cerebrovascular events (0.93 vs 0.57%, P = 0.006). UA at multiple Cox regression analysis resulted a strong and significant predictor of coronary events (HR = 1.493;95% CI 1.375-1.621), cerebrovascular events (HR = 1.256;95% CI 1.109-1.423), MACE (HR = 1.415;95% CI 1.328- 53 1.508), and all-cause mortality (HR = 1.469;95% CI 1.237-1.745) in the whole population and in both groups with a HR higher in females. The best estimated cut-off values of uric acid for males and females predicted these endpoints equally well, but it was always lower in females than males.

Conclusions: We demonstrate, that UA operates with a sex-related impact and best cut-off value in predicting cardiovascular outcomes and all-cause mortality, reflecting a possible sex difference in disease pathophysiology.

Keywords: Cardiovascular risk; Essential hypertension; Gender medicine; Uric acid.