Association of serum uric acid and carotid intima media thickness among hypertensive population in primary care clinic / Mohd Zulhilmie Mohd Nasir

Introduction: Early atherosclerosis can be measured through carotid intima-media thickness (CIMT). Elevated CIMT confirms the presence of subclinical atherosclerosis and is directly associated with an increased risk of cardiovascular disease. Serum uric acids (SUA) is commonly associated with hypertension and may compound the risk for atherosclerosis. The association of SUA on CIMT among the hypertensive population remains unclear and need to be investigated further.
Objectives: This study sought to investigate the association of SUA on CIMT in uncomplicated essential hypertensive population attending primary care clinic.
Method: A cross-sectional study was conducted between September 2018 to September 2019 in three primary care clinics in Gombak, Selangor. Using convenient sampling, 140 patients who were ≥ 30 years old and was diagnosed with hypertension were recruited. Information on socio-demographic characteristics, anthropometry measurements, clinical, biochemical investigations, and electrocardiogram (ECG) were recorded in a proforma. Two trained radiologists performed the ultrasonography to assess the left and right CIMT on a different date. Elevated CIMT was defined by CIMT of ≥ 75th percentile. The trend of mean CIMT (right and left) across the SUA was analysed using Analysis of Variance (ANOVA) for trends. The odds of an elevated CIMT according to the SUA quartiles was analysed using unadjusted (Model 1) and adjusted logistic regression (hierarchical model). The adjusted variable included Model 2 (age and smoking status based on Model 1). Model 3 (menopause, hypertension medication, antilipidemic medication based on Model 2) and Model 4 (waist circumference, systolic blood pressure, high density lipoprotein, low density lipoprotein, triglyceride, fasting blood sugar based on Model 3).
Results: Participants’ mean age was 53.4 ±SD 9.99 years. The mean systolic blood pressure was 137.09 ±SD 13.22 mmHg for systolic and 81.89 ±SD 8.95 mmHg for diastolic. Left ventricular hypertrophy and microalbuminuria was present in 1.7% and 6.4% of the participants. The prevalence of hyperuricaemia and metabolic syndrome was 25.7% and 54.3% respectively. With elevated CIMT defined by ≥ 75th percentile, the cut-off definition value for elevated CIMT was 0.633 mm for the right and 0.666 mm for the left. In a logistic regression model, compared with the first quartile of the SUA level, participants’ right common carotid artery in quartile 4 showed a higher odd (OR=2.00; 95% CI= 0.64 - 6.27, p=0.576) of an elevated CIMT, while participants’ left common carotid artery in quartile 4 showed a lower odd (OR=0.62; 95% CI= 0.20-2.00, p=0.594) of having an elevated CIMT. However, the changes in the odd on both sides were not statistically significant. These findings remained non-significant after controlling for potential confounders in the hierarchical logistic regression model.
Conclusions: Our findings did not observe SUA as a significant factor for subclinical atherosclerosis. This suggests that SUA may not play a role in the development of subclinical atherosclerosis as measured by CIMT among our study population who have optimally controlled, uncomplicated hypertension and high prevalence of metabolic syndrome.