Assessing the causal relationships between gout and hypertension: a bidirectional Mendelian randomisation study with coarsened exposures

Quality of life improvements and clinical assessments in kidney transplant recipients undergoing pegloticase treatment for uncontrolled gout: findings of the phase 4 PROTECT clinical trial

Introduction

Gout is 12-times more prevalent in kidney transplant (KT) recipients than in non-transplanted population. We report quality-of-life (QOL) and clinical assessment findings from the PROTECT trial examining pegloticase efficacy and safety in KT recipients with uncontrolled gout.

Methods

Patients with serum urate (SU) ≥7 mg/dL, oral urate-lowering therapy refractory/intolerant, and with one of the following were enrolled: ≥2 flares/year, unresolving tophi, or chronic gouty arthritis. Patients were ≥1 year post-transplant, with a graft eGFR ≥15 ml/min/1.73m2 and received stable immunosuppression. Pegloticase was administered for 24 weeks. QOL endpoints included the Health Assessment Questionnaire (HAQ; Disability Index [DI], Health, Pain) and Physician Global Assessment (PhGA) of Gout. Key clinical assessments included proportion of patients with resolution of ≥1 tophus and change from baseline in blood pressure (BP) at Week 24.

Results

Twenty KT recipients (85.0% male, age: 53.9±10.9 years, BMI: 30.6±7.2 kg/m2, eGFR: 45.8±11.9 ml/min/1.73 m2, time since kidney transplant: 14.6±6.9 years) were included. The primary endpoint was achieved with 89% of patients reaching and maintaining a SU of <6 mg/dL during Month 6. Meaningful improvements occurred over 24 weeks of treatment in all QOL measures (mean [95% CI] change from baseline: HAQ-DI: -0.3 [-0.6, 0.1], HAQ-Pain: -35.5 [-54.5, -16.5], HAQ-Health: -22.4 [-39.5, -5.2], PhGA: -2.4 [-3.7, -1.1]) and clinical assessments (≥1 tophus resolved: 3 of 7 with tophi at baseline [42.9%]; change from baseline in mean arterial BP: -6.8 [-12.5, -1.0] mmHg).

Conclusions

Given the high prevalence of uncontrolled gout in KT recipients, proper SU management is of particular importance. Additionally, intensive urate-lowering with pegloticase may have clinical and QOL benefits.

Association of Metabolic Score for Visceral Fat (METS-VF) with Gout Risk in Patients with Hypertension and Hyperuricemia: A Multicenter Study Based on the Chinese Population

Background

Gout, a rheumatic disease precipitated by hyperuricemia, has become a global health concern due to its increasing prevalence, especially in China. Hyperuricemia and hypertension are significant risk factors for gout, and their coexistence amplifies this risk. Visceral adipose tissue (VAT) plays a crucial role in cardiometabolic diseases, and the metabolic score for visceral fat (METS-VF) is a non-invasive tool for estimating VAT and predicting cardiometabolic risk.

Methods

We conducted a multicenter cross-sectional study involving 8877 patients with hypertension and hyperuricemia from three Chinese medical centers between March 2021 and September 2024. We calculated the METS-VF and other obesity indices and analyzed their associations with gout risk using logistic regression models. The predictive performance of these indices was evaluated using receiver operating characteristic (ROC) curve analysis and clinical decision curve analysis (DCA).

Results

The METS-VF demonstrated a significant positive association with gout risk, independent of traditional risk factors. Each 1-standard deviation increase in the METS-VF was associated with an 82% higher odds of gout (OR=1.82, 95% CI: 1.62 to 2.03). The METS-VF outperformed other obesity indices in predicting gout risk, with a higher area under the ROC curve (AUC) value. DCA indicated that the METS-VF provided a significant net benefit across a wide range of threshold probabilities for predicting gout risk in both genders.

Conclusion

The METS-VF's robust association with gout risk in our multicenter study, independent of conventional risk factors, positions it as a potent predictor for gout. Further investigation is warranted to clarify the underlying mechanisms and the long-term predictive validity of the METS-VF across diverse populations.

Gout and Hyperuricemia: A Narrative Review of Their Comorbidities and Clinical Implications

Gout is the most common form of inflammatory arthritis, caused by the deposition of monosodium urate crystals in the joints due to elevated serum uric acid levels. Its prevalence and associated healthcare burden have been rising in recent decades, a trend expected to continue. It is crucial to recognize that gout and hyperuricemia are not merely causes of painful joint flares, but systemic metabolic disorders linked to a broad spectrum of comorbidities such as cardiovascular diseases, chronic kidney disease, diabetes, insulin resistance, steatotic liver disease, osteoarthritis, and respiratory and eye diseases. Numerous risk factors for gout and hyperuricemia have been identified, with recent research uncovering further associations with other conditions. To optimize patient outcomes, gout and hyperuricemia must be addressed through a holistic approach that accounts for these risk factors while providing comprehensive management of related comorbidities affecting various organ systems. This review summarizes the current knowledge on the risk factors, comorbidities, and clinical implications of gout and hyperuricemia. Future research should focus on improving patient outcomes by tailoring treatments individually and addressing the underlying metabolic comorbidities of gout with multimodal treatment.

Exploring genetic links between blood metabolites and gout susceptibility

BACKGROUND

Gout, a prevalent form of inflammatory arthritis, has a complex etiology where the causal relationship between metabolites and the disease remains underexplored. This study aims to elucidate the impact of genetically determined blood metabolites on gout.

METHODS

Employing a two-sample bidirectional Mendelian randomization analysis, we examined the association between 1400 blood metabolites and gout. Causal associations were determined using the inverse variance weighted (IVW) method with false discovery rate (FDR) correction. Sensitivity analyses encompassed weighted models, MR-Egger, weighted median, and MR-PRESSO approaches. MR-pleiotropy and Cochran's Q statistic were utilized to evaluate potential heterogeneity and pleiotropy. Additionally, metabolic pathway analyses were conducted to pinpoint relevant pathways.

RESULTS

Of the initial 4 serum metabolites identified, 3 known metabolites-hexanoylglutamine levels, mannose content, and the phosphate to mannose ratio-were found to be causally associated with gout, along with 55 serum metabolites identified as potential predictors of gout (PIVW < 0.05). Furthermore, we discovered 3 metabolic pathways implicated in gouty attacks.

CONCLUSION

Our findings, derived from Mendelian randomization, indicate that the identified metabolites and pathways may serve as biomarkers for clinical screening and prevention of gout. Additionally, they offer novel insights into the mechanisms of the disease and potential drug targets. Key points • Conducted a comprehensive Mendelian randomization study involving 1400 blood metabolites to explore their genetic impact on gout development and progression • Identified three key metabolites-hexanoylglutamine, mannose, and the phosphate-to-mannose ratio-with causal associations to gout, highlighting their potential use as biomarkers for early detection and risk stratification • Discovered 55 additional serum metabolites as potential predictors of gout, offering new insights into the pathophysiology of the disease and identifying high-risk individuals • Revealed three novel metabolic pathways involved in gout attacks, providing new therapeutic targets for precision medicine in gout treatment.

Is cardiac function associated with the clinical course of disease in patients with gout? A prospective study

OBJECTIVE

To analyze the function of the left heart in patients with different courses of gout, the independent influencing factors for left heart functional changes, and interactions between left atrial and left ventricular functions.

METHODS

Patients with gout (n = 171) were selected; 87 patients with a disease course <10 years were included in Group I, and 84 patients with a disease course ≥10 years were included in Group II. Ninety-four healthy volunteers comprised the control group.

RESULTS

The intergroup differences in cardiac strain parameters were statistically significant (p < .05). Moreover, the differences gradually declined with disease progression. Multivariate logistic regression analysis showed that uric acid was an independent predictor of decreased left ventricular global longitudinal strain (LVGLS). Moreover, LVGLS had a positive effect on the left atrial systolic rate (LASr) and the left atrial systolic contraction time (LASct) but no interaction with the left atrial systolic contraction duration (LAScd).

CONCLUSION

The course of the disease significantly affected the function of the left heart in gout patients, and uric acid was observed to be an independent predictor of decreased LVGLS in gout patients.

Association between triglyceride glycemic index and gout in US adults

BACKGROUND

Insulin resistance (IR) has been linked to the development of gout. The triglyceride glycemic (TyG) index is a useful biomarker of IR, and the evidences between TyG and gout are limited. Therefore, this study aimed to examine the association between the TyG index and gout in the United States (U.S).

METHODS

The cross-sectional study was conducted among adults with complete TyG index and gout data in the 2007-2017 National Health and Nutrition Examination Survey (NHANES). The TyG index was calculated as fasting triglycerides (mg/dl) * fasting glucose (mg/dl)/2. Gout was assessed by self-report questionnaire (MCQ160n). Weighted chi-squared and weighted Student's t-test were used to assess group differences. Weighted multivariable logistic regression analysis, subgroup analysis, and interaction tests were used to examine the TyG index and gout association.

RESULTS

The final participants were 11,768; 5910 (50.32%) were female, 7784 (73.26%) were 18-60 years old, 5232 (69.63%) were white, and 573 (5.12%) had gout. After adjusting for all covariates, the TyG index was positively associated with gout; each unit increase in TyG index was associated with 40% higher odds of gout (odds ratio (OR), 1.40; 95% CI: 1.82-2.66; p < 0.0001). Participants in the highest TyG index tertile group were at high risk of gout (odds ratio (OR), 1.64; 95% CI: 1.06-2.54, p = 0.03) versus those in the lowest tertile group. Interaction tests showed no significant effect of age, race, marital status, PIR level, education, BMI, smoking status, drinking status, hypertension, and DM on this association between TyG index and gout (p for interaction > 0.05).

CONCLUSIONS

In this large cross-sectional study, our results suggested that a higher TyG index was associated with an increased likelihood of gout in U.S. adults. Our findings highlight that the TyG index is a reliable biomarker of IR; management of IR among adults may prevent or alleviate the development of gout; meanwhile, the TyG index may be a simple and cost-effective method to detect gout.

Hyperuricemia and gout enhanced the risk of long-term mortality in hypertension: insights from the National Health and Nutrition Examination Survey 2007-2018

BACKGROUND

Asymptomatic hyperuricemia (HUA) and normouricemic gout are common in clinic but recommendations for them in hypertension management are absent. The present study aims to simultaneously evaluate the effect of HUA and gout on long-term mortality in hypertension.

METHODS

Individuals from 2007-2018 National Health and Nutrition Examination Survey were enrolled. Hazard ratios and 95% confidence intervals (CIs) were calculated with the aid of the Cox proportional-hazards model. The restricted cubic spline (RCS) analysis was made to show the dose-response relationship between uric acid and mortality. All-cause mortality and cardiovascular mortality were compared using the Kaplan-Meier curve with a log-rank test.

RESULTS

Thirty thousand eight hundred and nineteen eligible individuals were included, of which 5841 suffered from HUA and 1476 suffered from gout. During a median follow-up of 7.25 (95% CI 7.18-7.32) years, 2924 (6.8%) patients died, including 722 (1.6%) cases of cardiovascular death. Hypertensive patients with HUA and gout showed 1.34 and 1.29 times higher all-cause mortality compared with those without HUA or gout. For hypertensive patients without gout, HUA was significantly associated with higher risk of all-cause [1.27 (1.13, 1.43)] and cardiovascular [1.80 (1.44, 2.24)] mortality compared with normouricemia. However, for hypertensive patients without HUA, gout was associated with a higher mortality but not statistically significant. A J-shaped relationship was found between serum uric acid and mortality.

CONCLUSION

HUA and gout are additive risk factors for all-cause and cardiovascular mortality in hypertension. Furthermore, asymptomatic HUA is significantly associated with poor long-term prognosis but normouricemic gout is not.

Large-scale cross-ancestry genome-wide meta-analysis of serum urate

Hyperuricemia is an essential causal risk factor for gout and is associated with cardiometabolic diseases. Given the limited contribution of East Asian ancestry to genome-wide association studies of serum urate, the genetic architecture of serum urate requires exploration. A large-scale cross-ancestry genome-wide association meta-analysis of 1,029,323 individuals and ancestry-specific meta-analysis identifies a total of 351 loci, including 17 previously unreported loci. The genetic architecture of serum urate control is similar between European and East Asian populations. A transcriptome-wide association study, enrichment analysis, and colocalization analysis in relevant tissues identify candidate serum urate-associated genes, including CTBP1, SKIV2L, and WWP2. A phenome-wide association study using polygenic risk scores identifies serum urate-correlated diseases including heart failure and hypertension. Mendelian randomization and mediation analyses show that serum urate-associated genes might have a causal relationship with serum urate-correlated diseases via mediation effects. This study elucidates our understanding of the genetic architecture of serum urate control.

Exploring the causal associations of micronutrients on urate levels and the risk of gout: A Mendelian randomization study

BACKGROUND & AIMS

Growing evidence has indicated a potential association between micronutrient levels, urate levels, and the risk of gout. However, the causal association underlying these associations still remains uncertain. Previous observational studies and randomized controlled trials investigating the association between micronutrients, urate levels, and the risk of gout have been limited in their scope and depth. The aim of this study was to utilize Mendelian randomization (MR) to investigate the causal associations between genetically predicted micronutrient levels, urate levels, and the risk of gout.

METHODS

In this study, we conducted a comprehensive examination of 10 specific micronutrients (vitamin B6, vitamin B12, vitamin C, vitamin D, folate, calcium, iron, copper, zinc, and selenium) as potential exposures. Two-sample MR analyses were performed to explore their causal associations with urate levels and the risk of gout. In these analyses, gout data were collected from the Global Biobank Meta-Analysis Initiative (N = 1,069,839, N cases = 30,549) and urate levels data from CKDGen Consortium (N = 288,649) by utilizing publicly available summary statistics from independent cohorts of European ancestry. We performed inverse-variance weighted MR analyses as main analyses, along with a range of sensitivity analyses, such as MR-Egger, weighted median, simple mode, weighted mode, Steiger filtering, MR-PRESSO, and Radial MR analysis, to ensure the robustness of our findings.

RESULTS

The results of our study indicate that there were negative associations between serum vitamin B12 and urate levels, as well as serum folate and the risk of gout. Specifically, we found a negative association between vitamin B12 levels and urate levels, with a β coefficient of -0.324 (95% CI -0.0581 to -0.0066, P = 0.0137) per one standard deviation (SD) increase. Similarly, a negative association was observed between folate levels and gout risk, with an odds ratio of 0.8044 (95% CI 0.6637 to 0.9750, P = 0.0265) per one SD increase. On the other hand, we identified positive associations between serum calcium levels and both urate levels and the risk of gout. Specifically, there was a positive association between serum calcium levels and urate levels (β coefficient: 0.0994, 95% CI 0.0519 to 0.1468, P = 4.11E-05) per one SD increase. Furthermore, a positive association was found between serum calcium levels and the risk of gout, with an odds ratio of 1.1479 (95% CI 1.0460 to 1.2598, P = 0.0036) per one SD increase. These findings were robust in extensive sensitivity analyses. By employing MR-PRESSO and Radial MR to eliminate outliers, the observed associations have been reinforced. No clear associations were found between the other micronutrients and the urate levels, as well as the risk of gout.

CONCLUSION

Our findings provided evidence that there were negative associations between serum vitamin B12 and urate levels, as well as serum folate and the risk of gout, while positive associations existed between the serum calcium levels and urate levels, as well as the risk of gout.

The Application of Genetic Risk Scores in Rheumatic Diseases: A Perspective

Modest effect sizes have limited the clinical applicability of genetic associations with rheumatic diseases. Genetic risk scores (GRSs) have emerged as a promising solution to translate genetics into useful tools. In this review, we provide an overview of the recent literature on GRSs in rheumatic diseases. We describe six categories for which GRSs are used: (a) disease (outcome) prediction, (b) genetic commonalities between diseases, (c) disease differentiation, (d) interplay between genetics and environmental factors, (e) heritability and transferability, and (f) detecting causal relationships between traits. In our review of the literature, we identified current lacunas and opportunities for future work. First, the shortage of non-European genetic data restricts the application of many GRSs to European populations. Next, many GRSs are tested in settings enriched for cases that limit the transferability to real life. If intended for clinical application, GRSs are ideally tested in the relevant setting. Finally, there is much to elucidate regarding the co-occurrence of clinical traits to identify shared causal paths and elucidate relationships between the diseases. GRSs are useful instruments for this. Overall, the ever-continuing research on GRSs gives a hopeful outlook into the future of GRSs and indicates significant progress in their potential applications.