Associations of Serum Uric Acid Levels With Macrovascular and Renal Microvascular Dysfunction Among Individuals From Sub-Saharan Africa

Disparity of serum uric acid threshold for CKD among hypertensive and non-hypertensive individuals

INTRODUCTION

Hypertension and rising serum uric acid (sUA) played a pivotal role in the development of Chronic Kidney Disease (CKD). This study investigates the interactive effect of sUA and hypertension on CKD and identifies the optimal threshold of sUA among individuals with and without hypertension in the Chinese community population.

MATERIALS AND METHODS

The study included 4180 individuals aged 45-85 years, derived from the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2015. Additionally, a hospital-based study enrolled subjects in the Department of Nephrology at Zhongshan Hospital, China from January 1, 2019, to December 31, 2021. The interaction effect analysis were used to assess the impact of sUA and hypertension on CKD. We also compared the distribution of sUA and the CKD risk in community populations, distinguishing between those with and without hypertension. For the hospital-based population, kidney injury was marked by a KIM-1 positive area.

RESULTS

Our results indicate a higher prevalence of CKD in the community population with hypertension (10.2% vs. 3.9%, p < .001). A significant additive synergistic effects of the sUA and hypertension on the CKD risk were found. When the sUA level was < 4.55 mg/dL in the hypertensive population and < 5.58 mg/dL in the non-hypertensive population, the risk of CKD was comparable (p = .809). In the propensity score matched (PSM) population, the result remained roughly constant.

CONCLUSION

Therefore, even moderate levels of sUA was associated with a higher risk of CKD in middle-aged hypertensive patients, who warrant stricter sUA control.

Kidney function decline mediates the adverse effects of per- and poly-fluoroalkyl substances (PFAS) on uric acid levels and hyperuricemia risk

Previous studies indicated per- and poly-fluoroalkyl substances (PFAS) were related to uric acid and hyperuricemia risk, but evidence for the exposure-response (E-R) curves and combined effect of PFAS mixture is limited. Moreover, the potential mediation effect of kidney function was not assessed. Hence, we conducted a national cross-sectional study involving 13,979 US adults in NHANES 2003-2018 to examine the associations of serum PFAS with uric acid and hyperuricemia risk, and the mediation effects of kidney function. Generalized linear models and E-R curves showed positive associations of individual PFAS with uric acid and hyperuricemia risk, and nearly linear E-R curves indicated no safe threshold for PFAS. Weighted quantile sum regression found positive associations of PFAS mixture with uric acid and hyperuricemia risk, and PFOA was the dominant contributor to the adverse effect of PFAS on uric acid and hyperuricemia risk. Causal mediation analysis indicated significant mediation effects of kidney function decline in the associations of PFAS with uric acid and hyperuricemia risk, with the mediated proportion ranging from 19 % to 57 %. Our findings suggested that PFAS, especially PFOA, may cause increased uric acid and hyperuricemia risk increase even at low levels, and kidney function decline plays a crucial mediation effect.

The Ratio of Serum Uric Acid to Glycosylated Haemoglobin as a Predictor of All-Mortality in Elderly Patients with Diabetic Foot Ulcers: A Longitudinal Cohort Study

Aim

To clarify the relationship between serum uric acid (UA) and glycosylated hemoglobin (UA/HbA1c) ratio and all-cause mortality in patients with diabetic foot ulcers (DFUs).

Methods

A total of 172 inpatients with DFUs (PEDIS grades 2-4) were eligible for inclusion in this study from 2018 to 2023. This was a retrospective, longitudinal cohort study. All subjects were followed up every 6 months for a median of 60 months. According to the cutoff value of the UA/HbA1c ratio of 39.07 obtained from ROC analysis, the participants were divided into two groups: low-level (≤ 39.07, n = 107) and high-level (> 39.07, n = 65) groups. The correlation between UA/HbA1c ratio and all-cause mortality was also evaluated by Cox regression analysis TheKaplan-Meier survival curve analysis and Log rank tests were used to assess the incidence rates of all-cause mortality. The contribution rate of risk factors was estimated by the population-attributable risk percentage (PAR%) analysis.

Results

ROC analysis showed that the optimal cutoff values for UA and the UA/HbA1c ratio were 372 μmol/L and 39.07, respectively. Multivariate Cox regression analysis indicated that a high UA/HbA1c ratio (HR =4.63; 95% CI = 2.004-10.7, P < 0.001) was independently associated with a high risk of all-cause mortality in patients with DFUs. Stratified analysis indicated that subjects aged ≥ 60 years had a greater risk of all-cause mortality associated with a high UA/HbA1c ratio (HR = 4.450; 95% CI = 1.711-11.574, P = 0.002). Kaplan-Meier survival analysis showed that all-cause mortality had a significant positive association with a high UA/HbA1c ratio (log-rank, P < 0.001) and a significant negative correlation with the lowered HbA1c level (< 6.5%) after a follow-up of 32 months (log-rank, P < 0.001). The population attributable risk percentage (PAR%) analysis suggested that the contribution rate of the high-level UA/HbA1c ratio to all-cause mortality was 33.7%, which was much greater than the 19.69% of UA.

Conclusion

In brief, our study showed that for every 1.0% increase in the UA/HbA1c ratio, the all-cause mortality rate in elderly patients with DFUs aged ≥ 60 years increased by 3.45-fold. For elderly patients with DFUs, a safe and effective strategy to reduce all-cause mortality is to strictly control serum UA levels to < 372 μmol/L and appropriately loosen the control goal of HbA1c to ≥ 6.5%.

Macrovascular and renal microvascular complications in West Africans with intermediate hyperglycemia living in West Africa and Europe: The RODAM study

Background

Metabolic conditions, including intermediate hyperglycemia (IH), affect migrants to a greater extent than the populations of origin. Evidence suggests that IH increases the risk of vascular complications, but it is unclear whether the differences in IH between the non-migrant and migrant populations translate to differences in vascular complications between the two populations. We compared the prevalence of macrovascular and renal microvascular complications among West Africans with IH living in West Africa and their migrant compatriots in Europe.

Methods

Data from the multicenter Research on Obesity and Diabetes among African Migrants(RODAM) study were analyzed. Ghanaians with IH(524 non-migrant and 1439 migrants) were included. Logistic regression analyses were used to determine the associations between migrant status and macrovascular [coronary artery disease(CAD) and peripheral artery disease(PAD)] and renal microvascular[nephropathy] complications with adjustment for age, sex, socioeconomic status, smoking, systolic blood pressure, BMI, total cholesterol, HbA1c, C-reactive protein, and serum uric acid.

Findings

The prevalence of microvascular/macrovascular complications was higher in non-migrants than in migrants(nephropathy 15.3vs.9.7%; PAD 3.1%vs.1.3%; and CAD 15.8% vs. 5.0%). The differences persisted in the fully adjusted model: nephropathy [odds ratio, 2.12; 95% CI(1.46-3.08); PAD, 4.44(1.87-10.51); CAD 2.35(1.64-3.37)]. Non-migrant females had higher odds of nephropathy[2.14(1.34-3.43)], PAD[7.47(2.38-23.40)] and CAD [2.10(1.34-3.27)] compared to migrant females. Non-migrant males had higher odds of nephropathy[2.54(1.30-4.97)] and CAD[2.85(1.48-5.50)], but not PAD[1.81(0.32-10.29)],than their migrant peers.

Interpretation

Macrovascular and renal microvascular complications were more prevalent in non-migrants than in migrant West Africans with IH. Further studies are needed to identify factors that increase the risk to aid preventive/treatment strategies.

Association of Serum Bile Acid and Unsaturated Fatty Acid Profiles with the Risk of Diabetic Retinopathy in Type 2 Diabetic Patients

Aim

We aimed to identify the ability of serum bile acids (BAs) and unsaturated fatty acids (UFAs) profiles to predict the development of diabetic retinopathy (DR) in type 2 diabetes mellitus (T2DM) patients.

Methods

We first used univariate and multivariate analysis to compare 15 serum BA and 11 UFA levels in healthy control (HC) group (n = 82), T2DM patients with DR (n = 58) and T2DM patients without DR (n = 60). Forty T2DM patients were considered for validation. Then, the receiver operating characteristic curve (ROC) and decision curve analysis were used to assess the diagnostic value and clinical benefit of serum biomarkers alone, clinical variables alone or in combination, and the area under the curve (AUC), integrated discrimination improvement (IDI), and net reclassification improvement (NRI) were used to further assess whether the addition of biomarkers significantly improved the predictive ability of the model.

Results

Orthogonal partial least squares-discriminant analysis (OPLS-DA) of serum BAs and UFAs separated the three cohorts including HC, T2DM patients with or without DR. The difference in serum BA and UFA profiles of T2DM patients with or without DR was mainly manifested in the three metabolites of taurolithocholic acid (TLCA), tauroursodeoxycholic acid (TUDCA) and arachidonic acid (AA). Together, they had an AUC of 0.785 (0.918 for validation cohort) for predicting DR in T2DM patients. After adjusting for numerous confounding factors, TLCA, TUDCA, and AA were independent predictors that differentiated T2DM with or without DR. The results of AUC, IDI, and NRI demonstrated that adding these three biomarkers to a model with clinical variables statistically increased their predictive value and were replicated in our independent validation cohort.

Conclusion

These findings highlight the association of three metabolites, TLCA, TUDCA and AA, with DR and may indicate their potential value in the pathogenesis of DR.

Postoperative Hyperuricemia-A Risk Factor in Elective Cardiosurgical Patients

Hyperuricemia is a well-known cardiovascular risk factor. The aim of our study was to investigate the connection between postoperative hyperuricemia and poor outcomes after elective cardiac surgery compared to patients without postoperative hyperuricemia. In this retrospective study, a total of 227 patients after elective cardiac surgery were divided into two groups: 42 patients with postoperative hyperuricemia (mean age 65.14 ± 8.9 years) and a second group of 185 patients without it (mean age 62.67 ± 7.45 years). The time spent on mechanical ventilation (hours) and in the intensive care unit (days) were taken as the primary outcome measures while the secondary measure comprised postoperative complications. The preoperative patient characteristics were similar. Most of the patients were men. The EuroSCORE value of assessing the risk was not different between the groups nor the comorbidities. Among the most common comorbidities was hypertension, seen in 66% of all patients (69% in patients with postoperative hyperuricemia and 63.7% in those without it). A group of patients with postoperative hyperuricemia had a prolonged time of treatment in the intensive care unit (p = 0.03), as well as a prolonged duration of mechanical ventilation (p < 0.01) and a significantly higher incidence of the following postoperative complications: circulatory instability and/or low cardiac output syndrome (LCOS) (χ2 = 4486, p < 0.01), renal failure and/or continuous venovenous hemodiafiltration (CVVHDF's) (χ2 = 10,241, p < 0.001), and mortality (χ2 = 5.22, p < 0.01). Compared to patients without postoperative hyperuricemia, elective cardiac patients with postoperative hyperuricemia have prolonged postoperative treatment in intensive care units, extended durations of mechanically assisted ventilation, and a higher incidence of postoperative circulatory instability, renal failure, and death.

Detection and Quantification of the Relationship between the Ratio of Triglycerides over High-Density Lipoprotein Cholesterol and the Level of Serum Uric Acid: One Cross-Sectional Study

Background

Hyperuricemia acts as an independently known risk factor for diabetes, cardiovascular disease, and gout. It was previously reported that the ratio of triglycerides to high-density lipoprotein cholesterol (TG/HDL-C) is not only an important marker of cardiovascular disease, stroke, atherosclerosis, and insulin resistance but is also associated with an elevated level of serum uric acid. However, it is still poorly understood what the association is between TG/HDL-C and serum uric acid levels. Hence, the aim of this research was to determine this association.

Methods

A total of 5,402 participants who underwent physical examinations in 2021 were analyzed during our cross-sectional research. In order to verify this correlation between TG/HDL-C and uric acid, we performed both a generalized additive model (GAM) and a smoothing curve fit. We also performed receiver operating characteristic (ROC) curves for evaluation of differences in clinical risk factor models in identifying hyperuricemia risk before and after the introduction of TG/HDL-C.

Results

Upon adjustment for confounders, we found that there was a nonlinear positive correlation between TG/HDL-C and the level of uric acid, and the inflection point was 1.41. When TG/HDL-C was less than 1.41, the effect size was 40.56 (19.08-62.04, P = 0.0002), whereas when TG/HDL-C was more than 1.41 the effect size was 17.18 (3.70-30.65, P=0.0125). As shown by the ROC curve, a significant increase in the area under the curve (AUC) was observed upon the introduction of TG/HDL-C into the established risk factor model which elevated from 0.7206(0.7053-0.7359, P < 0.05) to 0.8291 (0.8175-0.8407, P < 0.05).

Conclusion

Therefore, TG/HDL-C is positively and nonlinearly correlated to the level of uric acid, and the inflection point is 1.41. Furthermore, TG/HDL-C leads to an improvement in hyperuricemia risk stratification.

Association of Serum Uric Acid With Retinal Capillary Plexus

BACKGROUND

To determine the association between serum uric acid (SUA) and the retinal capillary plexus (RCP) using optical coherence tomography angiography (OCTA).

METHODS

This cross-sectional study evaluated data from August 2019 to January 2020 from participants recruited from the Jidong community (Tangshan, Hebei, China). All participants completed detailed anthropometrical measurements, laboratory tests and comprehensive ophthalmic examinations. We assessed the vessel density in RCP using OCTA. We used multivariable analysis to evaluate the sex-specific association between SUA and RCP after adjusting for confounders.

RESULTS

A total of 2730 participants were included in this study. The mean age of the participants was 44.0 ± 11.6 years, and 1463 (53.6%) were women. The multivariable βs and 95% confidence intervals (CIs) of superficial RCP vessel density in the second through fourth SUA quartiles compared with the lowest SUA quartiles were -0.27 (-0.56 - 0.03), -0.30 (-0.60 - 0.01), and -0.46 (-0.78 - -0.14) (P for trend = 0.007) in men.

CONCLUSIONS

Higher SUA levels were significantly associated with lower RCP vessel density in men. Our findings provide evidence for the detrimental effect of high SUA levels on the retinal microvasculature and imply the importance of modulating SUA to prevent the microvascular alternation especially for men.