Effects of serum uric acid on blood-pressure lowering treatment

Uric Acid, Hypertensive Phenotypes, and Organ Damage: Data from the Pamela Study

PURPOSE OF REVIEW

To examine published and unpublished data collected in the context of the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study on the relationships between serum uric acid (SUA), office and out-of-office blood pressure (BP), and organ damage.

RECENT FINDINGS

SUA values were directly and significantly related to a large number of covariates that participate at cardiovascular risk determination, such as blood glucose, total serum cholesterol, serum triglycerides, body mass index, and serum creatinine. Additional variables included echocardiographically-determined left ventricular mass index and BP values, the latter not just when measured in the office but also when evaluated at home or over the 24-h period. White-coat hypertension and masked hypertension were characterized, as sustained hypertension, by a significant increase in SUA levels, which were also directly related to different indices of 24-h BP variability. No substantial difference in SUA levels was found when data were analyzed according to the dipping or non-dipping nocturnal BP profile. Data collected in the frame of the PAMELA study document the presence of a close relationship between SUA levels and BP values independently on the hypertensive phenotype patterns of BP increase (office, 24 h, or both) and nighttime BP profile. They also document the increase in SUA as a potential factor favoring the occurrence of new hypertension and new left ventricular hypertrophy.

Population Attributable Risk of Hyperuricemia in Hypertension Incidence in 20-74-Year-Old Population during a 10-Year Longitudinal Cohort: Yazd Healthy Heart Cohort

Background

The population attributable risk (PAR) percent has used widely in public health policy. We aimed to calculate the attribute risk of hypertension due to hyperuricemia by Levin's formulas compare to direct PAR calculation method.

Methods

This was a sub-study of Yazd Healthy Heart Cohort (YHHC). Overall, 1256 normotensive individuals were enrolled through multistage randomized cluster sampling and followed up for mean 9.8 years, from 2005-2015. The threshold cutoff point of the hyperuricemia was considered equal and more than 75^th percentile that equal to 5.5 mg/dl for men and 4.3mg/dl for women. To calculate the attributable risk of hyperuricemia in developing hypertension, two methods were applied. Levin's formulas and direct PAR estimation by population risk calculation via exposure prevalence weighted formula. Multiple logistic regression was used for estimate of odds ratio (OR) of hyperuricemia in developing hypertension. We calculated Relative Risk (RR) from OR. The data were analyzed using SPSS software version 16. A significant level of 0.05 was considered.

Results

Hypertension developed in 44.7% of individuals with uric acid level ≥ 75^th percentile vs. 35.6% of other individuals (P=0.024). Attributable risk (AR) of hyperuricemia in hypertension incidence was 9.1%. PAR of hyperuricemia for hypertension incidence by using two methods mentioned before was 6%, 5.8% respectively.

Conclusion

The results of the study confirmed the noticeable contribution of hyperuricemia as an independent other risk factor for the occurrence of hypertension. PAR of hyperuricemia for hypertension incidence by using two methods almost near was 6%, 5.8% respectively.

Serum metabolites are associated with all-cause mortality in chronic kidney disease

Chronic kidney disease (CKD) involves significant metabolic abnormalities and has a high mortality rate. Because the levels of serum metabolites in patients with CKD might provide insight into subclinical disease states and risk for future mortality, we determined which serum metabolites reproducibly associate with mortality in CKD using a discovery and replication design. Metabolite levels were quantified via untargeted liquid chromatography and mass spectroscopy from serum samples of 299 patients with CKD in the Modification of Diet in Renal Disease (MDRD) study as a discovery cohort. Six among 622 metabolites were significantly associated with mortality over a median follow-up of 17 years after adjustment for demographic and clinical covariates, including urine protein and measured glomerular filtration rate. We then replicated associations with mortality in 963 patients with CKD from the African American Study of Kidney Disease and Hypertension (AASK) cohort over a median follow-up of ten years. Three of the six metabolites identified in the MDRD cohort replicated in the AASK cohort: fumarate, allantoin, and ribonate, belonging to energy, nucleotide, and carbohydrate pathways, respectively. Point estimates were similar in both studies and in meta-analysis (adjusted hazard ratios 1.63, 1.59, and 1.61, respectively, per doubling of the metabolite). Thus, selected serum metabolites were reproducibly associated with long-term mortality in CKD beyond markers of kidney function in two well characterized cohorts, providing targets for investigation.