High prevalence of gouty arthritis among the Hmong population in Minnesota

Gout in Native Hawaiian Patients in Hawai'i: Clinical Characteristics and Disparities

OBJECTIVE

The purpose of this study was to investigate differences in clinical characteristics and health care use of Native Hawaiian and White patients with gout.

METHODS

We performed a retrospective chart review of Native Hawaiian and White patients with gout treated from 2011 to 2017 within a large health care system in Hawai'i. We compared demographic characteristics, clinical outcomes, and risk factors for gout. We used multivariable logistic regression to identify predictive factors of emergency department visits.

RESULTS

We identified 270 Native Hawaiian patients with gout and 239 White patients with gout. The Native Hawaiian patients were younger on average (54.0 vs 64.0 years; P < 0.0001) and had an earlier onset of disease (50.0 vs 57.0 years; P < 0.0001). Native Hawaiian patients with gout had higher mean (7.58 vs 6.87 mg/dL; P < 0.0001) and maximum (10.30 vs 9.50 mg/dL; P < 0.0001) serum urate levels compared to White patients with gout. Native Hawaiian patients with gout also had a greater number of tophi (median 2.00 vs 1.00; P < 0.0001). Native Hawaiians patients with gout were 2.7 times more likely to have frequent (≥1) emergency department visits than White patients with gout. Native Hawaiian patients with gout were less likely to have a therapeutic serum urate ≤6.0 mg/dL and had lower rates of rheumatology specialty care.

CONCLUSION

Native Hawaiian patients have a higher disease burden of gout, with earlier disease onset and more tophi. Native Hawaiian patients with gout are more likely to use emergency services for gout and have lower rates of rheumatology specialty care compared to White patients. Future studies are needed to promote culturally appropriate preventive care and management of gout in Native Hawaiians.

Unsupervised cluster analysis of clinical and ultrasound features reveals unique gout subtypes: Results from the Egyptian College of Rheumatology (ECR)

BACKGROUND

Gout comprises a heterogeneous group of disorders; however, comorbidities have been the focus of most efforts to classify disease subgroups.

OBJECTIVES

We applied cluster analysis using musculoskeletal ultrasound (MSUS) combined with clinical and laboratory findings in patients with gout to identify disease phenotypes, and differences across clusters were investigated.

PATIENTS AND METHODS

Patients with gout who complied with the ACR/EULAR classification criteria were enrolled in the Egyptian College of Rheumatology (ECR)-MSUS Study Group, a multicenter study. Selected variables included demographic, clinical, and laboratory findings. MSUS scans assessed the bilateral knee and first metatarsophalangeal joints. We performed a K-mean cluster analysis and compared the features of each cluster.

RESULTS

425 patients, 267 (62.8 %) males, mean age 54.2 ± 10.3 years were included. Three distinct clusters were identified. Cluster 1 (n = 138, 32.5 %) has the lowest burden of the disease and a lower frequency of MSUS characteristics than the other clusters. Cluster 2 (n = 140, 32.9 %) was mostly women, with a low rate of urate-lowering treatment (ULT). Cluster 3 (n = 147, 34.6 %) has the highest disease burden and the greatest proportion of comorbidities. Significant MSUS variations were found between clusters 2 and 3: joint effusion (p < 0.0001; highest: cluster 3), power Doppler signal (p < 0.0001; highest: clusters 2), and aggregates of crystal deposition (p < 0.0001; highest: cluster 3).

CONCLUSION

Cluster analysis using MSUS findings identified three gout subgroups. People with more MSUS features were more likely to receive ULT. Treatment should be tailored according to the cluster and MSUS features.

Population pharmacokinetics, pharmacodynamics and pharmacogenetics modelling of oxypurinol in Hmong adults with gout and/or hyperuricemia

AIMS

The aim of this study was to quantify identifiable sources of variability, including key pharmacogenetic variants in oxypurinol pharmacokinetics and their pharmacodynamic effect on serum urate (SU).

METHODS

Hmong participants (n = 34) received 100 mg allopurinol twice daily for 7 days followed by 150 mg allopurinol twice daily for 7 days. A sequential population pharmacokinetic pharmacodynamics (PKPD) analysis with non-linear mixed effects modelling was performed. Allopurinol maintenance dose to achieve target SU was simulated based on the final PKPD model.

RESULTS

A one-compartment model with first-order absorption and elimination best described the oxypurinol concentration-time data. Inhibition of SU by oxypurinol was described with a direct inhibitory Emax model using steady-state oxypurinol concentrations. Fat-free body mass, estimated creatinine clearance and SLC22A12 rs505802 genotype (0.32 per T allele, 95% CI 0.13, 0.55) were found to predict differences in oxypurinol clearance. Oxypurinol concentration required to inhibit 50% of xanthine dehydrogenase activity was affected by PDZK1 rs12129861 genotype (-0.27 per A allele, 95% CI -0.38, -0.13). Most individuals with both PDZK1 rs12129861 AA and SLC22A12 rs505802 CC genotypes achieve target SU (with at least 75% success rate) with allopurinol below the maximum dose, regardless of renal function and body mass. In contrast, individuals with both PDZK1 rs12129861 GG and SLC22A12 rs505802 TT genotypes would require more than the maximum dose, thus requiring selection of alternative medications.

CONCLUSIONS

The proposed allopurinol dosing guide uses individuals' fat-free mass, renal function and SLC22A12 rs505802 and PDZK1 rs12129861 genotypes to achieve target SU.

Trends in Prevalence of Gout Among US Asian Adults, 2011-2018

Importance

Gout disparities among Black individuals in the US have recently been explained by socioclinical factors; however, no information is available among Asian individuals living in Western countries, despite their disproportionately worsening metabolic health.

Objective

To determine the prevalence of gout and serum urate concentrations according to race and ethnicity and to explore the association of social determinants of health and clinical factors.

Design, Setting, and Participants

This is a population-based, cross-sectional analysis. Data from a nationally representative sample of US adults were obtained from the National Health and Nutrition Examination Survey (NHANES) (2011-2018) in which Asian race data were collected (primary). Data from the UK Biobank (2006-2021) were used for replication of the Asian vs White differences. Data analysis was performed from December 2021 to September 2022.

Main Outcomes and Measures

Race-specific gout prevalence and serum urate levels.

Results

A total of 22 621 participants from NHANES (2011-2018) were included in the analysis (mean [SD] age, 49.8 [17.8] years; 10 948 male participants [48.4%]). In 2017 to 2018, gout affected 12.1 million US individuals, with its crude prevalence increasing from 3.6% (95% CI, 2.8%-4.5%) in 2011 to 2012 to 5.1% (95% CI, 4.2%-5.9%) in 2017 to 2018 (P for trend = .03); this trend was no longer significant after age adjustment (P for trend = .06) or excluding Asian individuals (P for trend = .11). During the same period, age- and sex-adjusted prevalence among Asian Americans doubled from 3.3% (95% CI, 2.1%-4.5%) to 6.6% (95% CI, 4.4%-8.8%) (P for trend = .007) to numerically exceed all other racial and ethnic groups in 2017 to 2018, with age- and sex-adjusted odds ratio (ORs) of 1.61 (95% CI, 1.03-2.51) and a socioclinical factor-adjusted multivariable OR of 2.62 (95% CI, 1.59-4.33) for Asian vs White individuals. The latest age- and sex-adjusted gout prevalence among US individuals aged 65 years and older was 10.0% among White individuals and 14.8% among Asian individuals (including 23.6% of Asian men). Serum urate concentrations also increased between 2011 and 2018 among US Asian individuals (P for trend = .009). The Asian vs White disparity was also present in the UK Biobank.

Conclusions and Relevance

The findings of this study suggest that the prevalence of gout among Asian individuals numerically surpassed that for all other racial and ethnic groups in 2017 to 2018. This Asian vs White disparity did not appear to be associated with socioclinical factors.

Hmong microbiome ANd Gout, Obesity, Vitamin C (HMANGO-C): A phase II clinical study protocol

BACKGROUND

Hmong men in Minnesota exhibit a high prevalence of gout and hyperuricemia. Although evidence of vitamin C's effectiveness as a treatment for gout is mixed, analysis of therapeutic benefit based on an individual's multiomic signature may identify predictive markers of treatment success.

OBJECTIVES

The primary objective of the Hmong Microbiome ANd Gout, Obesity, Vitamin C (HMANGO-C) study was to assess the effectiveness of vitamin C on serum urate in Hmong adults with and without gout/hyperuricemia. The secondary objectives were to assess if 1) vitamin C impacts the taxonomic and functional patterns of microbiota; 2) taxonomic and functional patterns of microbiota impact vitamin C's urate-lowering effects; 3) genetic variations impact vitamin C's urate-lowering effects; 4) differential microbial biomarkers exist for patients with or without gout; and 5) there is an association between obesity, gut microbiota and gout/hyperuricemia.

METHODS

This prospective open-labelled clinical trial was guided by community-based participatory research principles and conducted under research safety restrictions for SARS-CoV-2. We aimed to enroll a convenient sample of 180 Hmong adults (120 with gout/hyperuricemia and 60 without gout/hyperuricemia) who provided medical, demographic, dietary and anthropometric information. Participants took vitamin C 500mg twice daily for 8 weeks and provided pre-and post- samples of blood and urine for urate measurements as well as stool samples for gut microbiome. Salivary DNA was also collected for genetic markers relevant to uric acid disposition.

EXPECTED RESULTS

We expected to quantify the impact of vitamin C on serum urate in Hmong adults with and without gout/hyperuricemia. The outcome will enhance our understanding of how gut microbiome and genomic variants impact the urate-lowering of vitamin C and associations between obesity, gut microbiota and gout/hyperuricemia. Ultimately, findings may improve our understanding of the causes and potential interventions that could be used to address health disparities in the prevalence and management of gout in this underserved population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04938024 (first posted: 06/24/2021).

Health Disparities of Cardiometabolic Disorders Among Filipino Americans: Implications for Health Equity and Community-Based Genetic Research

Health disparities are well-documented among different racial and ethnic minority groups in the United States. Filipino Americans (FAs) are the third-largest Asian-American group in the USA and are commonly grouped under the Asian categorization. FAs have a higher prevalence of cardiometabolic disorders than non-Hispanic Whites and other Asian subgroups with rates comparable to African Americans. Although no major epidemiological studies have ascertained the prevalence of cardiometabolic diseases in FAs, limited reports suggest that FAs have a higher prevalence of dyslipidemia, hypertension, diabetes, metabolic syndrome, hyperuricemia, and gout than non-FAs. A recent genetic study has shown that FAs could have the highest prevalence of a genetic polymorphism strongly associated with the development of gout and gout-related comorbidities. While developing cardiometabolic disorders is a heterogeneous and multifaceted process, the overall prevalence of certain cardiometabolic disorders parallel the prevalence of population-level risk factors, including genetics, dietary lifestyles, health beliefs, and social determinants of health. Therefore, assessment of the Filipino cuisine, health behaviors among Filipinos, socio-cultural factors, and acculturation to living in the USA are equally critical. Ascertaining the contribution of the biological causes to disease onset and the different psychosocial factors that could modulate disease risk or disease management are needed. Ultimately, a multilevel research approach is critical to assess the role of biological and non-biological risk factors of cardiometabolic disorders in FAs to inform culturally appropriate health promotion, disease prevention strategies, and a personalized approach to health.

Association of alpha-1-adrenergic antagonist use with the risk of gout development in benign prostatic hyperplasia patients: a population-based cohort study

BACKGROUND

Men are more likely to develop benign prostatic hyperplasia (BPH) and gout as they age. However, the role of alpha-1-adrenergic antagonists, the medication for BPH, in the development of gout is uncertain.

OBJECTIVE

To investigate the effect of alpha-1-adrenergic antagonist use on the risk of developing gout in BPH patients.

METHODS

Data of patients with newly diagnosed BPH were retrieved from Taiwan's 2000-2013 National Health Insurance Research Database (total number: 15,390 patients; 7,695 patients in each cohort). Propensity score matching was conducted according to age, comorbidities, medication history for cohorts that received or did not receive alpha-1-adrenergic antagonists. Hazard ratios (HRs) were assessed for gout development using Cox proportional hazards regression models.

RESULTS

Use of alpha-1-adrenergic antagonists was not associated with gout development in BPH patients (HR = 0.92; 95% confidence interval [CI], 0.78-1.10; P = 0.35). However, after stratification according to the average number of days of alpha-1-adrenergic antagonist use per year, patients with an average of >300 days had a significantly higher risk of gout development than patients who did not receive alpha-1-adrenergic antagonists (adjusted HR = 1.57; 95% CI, 1.25-1.97; P < 0.001). Patients with more days of medication use per year had a higher risk of gout development than those with fewer days of medication use (P < 0.001).

CONCLUSION

Patients who received more doses of alpha-1-adrenergic antagonists per year had a higher risk of developing gout. A causal proof of the role of alpha-1-adrenergic antagonists use in gout development should be analysed in future studies designed as double blind randomized controlled trials.

Gout prevalence in the Hmong: a prime example of health disparity and the role of community-based genetic research

Individuals of distinct Asian backgrounds are commonly aggregated as Asian, which could mask the differences in the etiology and prevalence of health conditions in the different Asian subgroups. The Hmong are a growing Asian subgroup in the United States with a higher prevalence of gout and gout-related comorbidities than non-Hmong. Genetic explorations in the Hmong suggest a higher prevalence of genetic polymorphisms associated with an increased risk of hyperuricemia and gout. History of immigration, acculturation, lifestyle factors, including dietary and social behavioral patterns, and the use of traditional medicines in the Hmong community may also increase the risk of developing gout and lead to poor gout management outcomes. Engaging minorities such as the Hmong population in biomedical research is a needed step to reduce the burden of health disparities within their respective communities, increase diversity in genomic studies, and accelerate the adoption of precision medicine to clinical practice.

The Epidemiology and Genetics of Hyperuricemia and Gout across Major Racial Groups: A Literature Review and Population Genetics Secondary Database Analysis

Gout is an inflammatory condition caused by elevated serum urate (SU), a condition known as hyperuricemia (HU). Genetic variations, including single nucleotide polymorphisms (SNPs), can alter the function of urate transporters, leading to differential HU and gout prevalence across different populations. In the United States (U.S.), gout prevalence differentially affects certain racial groups. The objective of this proposed analysis is to compare the frequency of urate-related genetic risk alleles between Europeans (EUR) and the following major racial groups: Africans in Southwest U.S. (ASW), Han-Chinese (CHS), Japanese (JPT), and Mexican (MXL) from the 1000 Genomes Project. The Ensembl genome browser of the 1000 Genomes Project was used to conduct cross-population allele frequency comparisons of 11 SNPs across 11 genes, physiologically involved and significantly associated with SU levels and gout risk. Gene/SNP pairs included: ABCG2 (rs2231142), SLC2A9 (rs734553), SLC17A1 (rs1183201), SLC16A9 (rs1171614), GCKR (rs1260326), SLC22A11 (rs2078267), SLC22A12 (rs505802), INHBC (rs3741414), RREB1 (rs675209), PDZK1 (rs12129861), and NRXN2 (rs478607). Allele frequencies were compared to EUR using Chi-Square or Fisher’s Exact test, when appropriate. Bonferroni correction for multiple comparisons was used, with p < 0.0045 for statistical significance. Risk alleles were defined as the allele that is associated with baseline or higher HU and gout risks. The cumulative HU or gout risk allele index of the 11 SNPs was estimated for each population. The prevalence of HU and gout in U.S. and non-US populations was evaluated using published epidemiological data and literature review. Compared with EUR, the SNP frequencies of 7/11 in ASW, 9/11 in MXL, 9/11 JPT, and 11/11 CHS were significantly different. HU or gout risk allele indices were 5, 6, 9, and 11 in ASW, MXL, CHS, and JPT, respectively. Out of the 11 SNPs, the percentage of risk alleles in CHS and JPT was 100%. Compared to non-US populations, the prevalence of HU and gout appear to be higher in western world countries. Compared with EUR, CHS and JPT populations had the highest HU or gout risk allele frequencies, followed by MXL and ASW. These results suggest that individuals of Asian descent are at higher HU and gout risk, which may partly explain the nearly three-fold higher gout prevalence among Asians versus Caucasians in ambulatory care settings. Furthermore, gout remains a disease of developed countries with a marked global rising.

Unique Considerations for the Management of Gout in the Hmong Population: Examining Tertiary Encounters at a Large Regional Health Care System

OBJECTIVE

To evaluate demographic characteristics, care encounters, comorbidities, and clinical differences in Hmong and non-Hmong patients with gout.

METHODS

Using retrospective chart review, all inpatient encounters (Hmong versus non-Hmong) were reviewed from 2014 to 2017. Acute or chronic gout was the primary or secondary diagnosis for the encounter.

RESULTS

Hmong gout patients were on average 11 years younger than non-Hmong patients, but after adjustment for age, sex, and type of encounter, they had similar rates of hypertension, diabetes mellitus, and heart disease. Hmong patients had significantly decreased renal function at the time of presentation; the odds ratio of chronic kidney disease for Hmong patients was 2.33 versus 1.48 for non-Hmong patients (P < 0.05), the mean creatinine level was 3.3 mg/dl versus 2.0 mg/dl (β = 1.35, P < 0.001), and the glomerular filtration rate was 44.8 ml/minute versus 49.3 ml/minute (β = -6.95, P < 0.001). Hmong gout patients were more likely to use emergency care versus elective or urgent care, they were less likely to be using medications for the treatment of gout prior to admission (32.3% versus 58.2%), and the length of hospital stay was increased (8.8 versus 5.2 days; P < 0.05).

CONCLUSION

Hmong gout patients who had a tertiary care encounter were 11 years younger than non-Hmong patients with similar rates of comorbidities but had worse renal function despite the age differences. They were more likely to use emergency services, to be insured through Medicaid, and not to use preventive medications for gout prior to their encounter. Intensive efforts are needed in the Hmong population for culturally appropriate preventive care management of gout along with diabetes mellitus, hypertension, heart disease, and kidney disease.

Review of Hmong-Related Health Problems: A Quick Guide for Healthcare Providers

The people of Hmong descent are one of the largest resettled communities in the United States (US). The Central Valley of California is well known to be the home to the largest Hmong population in the US. However, despite the presence of such a large Hmong community in the Central Valley, our knowledge of their cultural perceptions of medicine is limited. Based on local Central Valley health providers’ experiences and observations, the Hmong people have a number of health-related challenges that differ from those of the general population, and this should be considered when dealing with their healthcare needs. In this report, we present a quick guide about the Hmong community and their health-related issues. We hope this will help clinicians and researchers better understand the Hmong community, which in turn would help provide a better quality of healthcare to the Hmong people and stimulate intellectual curiosity among healthcare providers towards this unique Asian ethnicity.

The Rising Incidence of Gout and the Increasing Burden of Comorbidities: A Population-based Study over 20 Years

OBJECTIVE

To examine the incidence of gout over the last 20 years and to evaluate possible changes in associated comorbid conditions.

METHODS

The medical records were reviewed of all adults with a diagnosis of incident gout in Olmsted County, Minnesota, USA, during 2 time periods (January 1, 1989-December 31, 1992, and January 1, 2009-December 31, 2010). Incident cases had to fulfill at least 1 of 3 criteria: the American Rheumatism Association 1977 preliminary criteria for gout, the Rome criteria, or the New York criteria.

RESULTS

A total of 158 patients with new-onset gout were identified during 1989-1992 and 271 patients during 2009-2010, yielding age- and sex-adjusted incidence rates of 66.6/100,000 (95% CI 55.9-77.4) in 1989-1992 and 136.7/100,000 (95% CI 120.4-153.1) in 2009-2010. The incidence rate ratio was 2.62 (95% CI 1.80-3.83). At the time of their first gout flare, patients diagnosed with gout in 2009-2010 had higher prevalence of comorbid conditions compared with 1989-1992, including hypertension (69% vs 54%), diabetes mellitus (25% vs 6%), renal disease (28% vs 11%), hyperlipidemia (61% vs 21%), and morbid obesity (body mass index ≥ 35 kg/m²; 29% vs 10%).

CONCLUSION

The incidence of gout has more than doubled over the recent 20 years. This increase together with the more frequent occurrence of comorbid conditions and cardiovascular risk factors represents a significant public health challenge.

Health Literacy and Associated Factors Among Hmong American Immigrants: Addressing the Health Disparities

Hmong Americans face a disproportionate health burden ranging from the high prevalence of diabetes to depressive disorders. Little research attention has been paid toward exploring contributing factors to this disparity. As such, the present study seeks to fill the gap in the literature by examining the health literacy levels in Hmong Americans and its associated factors. The present study employed Andersen's behavioral model of health service as the theoretical framework. A cross-sectional survey research design was used and information was gathered from 168 Hmong American immigrants. Participants were recruited using a purposive sampling strategy. A multiple regression analysis was conducted to identify the factors linked to health literacy. Approximately half of the participants had low health literacy and reported that they did not understand health information well. Health literacy levels were found to differ significantly based on the number of years participants have lived in the U.S., their social or religious group attendance, health status, and whether they had difficulties with activities of daily living. Our exploratory findings could be used prompt more research to help inform the development of interventions aiming to improve health literacy levels and address the health disparities in Hmong American Population.

Assessment of genetic polymorphisms associated with hyperuricemia or gout in the Hmong

AIM

Hyperuricemia commonly causes gout. Minnesota Hmong exhibit a two- to fivefold higher prevalence of gout versus non-Hmong. To elucidate a possible genomic contribution to this disparity, prevalence of risk alleles for hyperuricemia in Hmong was compared with European (CEU) and Han-Chinese (CHB).

METHODS

In total, 235 Hmong were genotyped for eight SNPs representing five candidate genes (SLC22A12, SLC2A9, ABCG2, SLC17A1 and PDZK1).

RESULTS

The frequency of seven out of eight risk alleles in the Hmong was significantly different than CEU; six higher and one with lower prevalence. The frequency of three out of eight risk alleles in the Hmong was significantly different than CHB; two higher and one with lower prevalence.

CONCLUSION

Hyperuricemia risk alleles are more prevalent in the Hmong than CEU and HB.

Gout: a review of nonmodifiable and modifiable risk factors

Gout is a common inflammatory arthritis triggered by the crystallization of uric acid within the joints. Gout affects millions worldwide and has an increasing prevalence. Recent research has been carried out to better qualify and quantify the risk factors predisposing individuals to gout. These can largely be broken into nonmodifiable risk factors, such as gender, age, race, and genetics, and modifiable risk factors, such as diet and lifestyle. Increasing knowledge of factors predisposing certain individuals to gout could potentially lead to improved preventive practices. This review summarizes the nonmodifiable and modifiable risk factors associated with development of gout.

Determinants of the prevalence of gout in the general population: a systematic review and meta-regression

Studies on the occurrence of gout show a large range in estimates. However, a clear insight into the factors responsible for this variation in estimates is lacking. Therefore, our aim was to review the literature on the prevalence and incidence of gout systematically and to obtain insight into the degree of and factors contributing to the heterogeneity. We searched MEDLINE, EMBASE, and Web of Science (January 1962 to July 2012) to identify primary studies on the prevalence and incidence of gout in the general population. Data were extracted by two persons on sources of clinical heterogeneity, methodological heterogeneity, and variation in outcome reporting. Meta-analysis and meta-regression analysis were performed for the prevalence of gout. Of 1,466 articles screened, 77 articles were included, of which 71 reported the prevalence and 12 the incidence of gout. The pooled prevalence (67 studies; N = 12,226,425) based on a random effects model was 0.6% (95% CI 0.4; 0.7), however there was a high level of heterogeneity (I(2) = 99.9%). Results from a mixed-effects meta-regression model indicated that age (p = 0.019), sex (p < 0.001), continent (p < 0.001), response rate (p = 0.016), consistency in data collection (p = 0.002), and case definition (p < 0.001) were significantly associated with gout prevalence and jointly accounted for 88.7% of the heterogeneity. The incidence in the total population ranged from 0.06 to 2.68 per 1,000 person-years. In conclusion, gout is a common disease and the large variation in the prevalence data on gout is explained by sex, continent on which the study was performed, and the case definition of gout.

Epidemiology and clinical pathophysiology of uric acid kidney stones

There is global diversity in the prevalence of uric acid (UA) nephrolithiasis. UA nephrolithiasis comprises 8-10 % of all kidney stones in the United States. However, its prevalence is higher in patients with type 2 diabetes mellitus and those with obesity. Three significant urinary abnormalities have been described as the main etiologic factors for the development of UA nephrolithiasis; low urinary pH, hyperuricosuria and low urinary volume. However, an unduly acidic urine below the ionization constant of uric acid (pKa < 5.5) increases the urinary content of undissociated uric acid and thereby uric acid precipitation. Previous studies have shown the two major pathogenic mechanisms for unduly urinary pH are increased net acid excretion (NAE) and reduced renal ammonium (NH4 (+)), with a combination resulting in overly acidic urine. The impaired ammonium excretion has been demonstrated in a steady state in 24-hour urine and also following an oral ammonium chloride (NH4Cl) challenge to amplify ammoniogenic defects in this population. Similar abnormalities have been disclosed in normal populations and also in T2DM populations without kidney stones. To date, the underlying mechanism of increased acid production, source and nature of putative organic acid anions have not been fully elucidated. One plausible mechanism is the production of organic acid by intestinal and aerobic metabolism. This may occur in obese, diabetic and uric acid stone formers due to the differences in gut microflora.

Racial and gender disparities among patients with gout

Gout affects 8.3 million Americans according to NHANES 2007-2008, approximately 3.9 % of the US population. Gout has substantial effect on physical function, productivity, health-related quality of life (HRQOL), and health care costs. Uncontrolled gout is also associated with significant use of emergency care services. Women are less likely to have gout than men, but in the postmenopausal years the gender difference in disease incidence decreases. Compared with whites, racial and/or ethnic minorities, especially blacks, have higher prevalence of gout. Blacks are also less likely to receive quality gout care, leading to disproportionate morbidity. Women are less likely than men to receive allopurinol, and less likely to undergo joint aspirations for crystal analysis to establish diagnosis, but those on urate-lowering therapy are as likely as, or more likely than, men to undergo serum urate check within six months of initiation. Although a few studies provide the knowledge related to gender and race and/or ethnicity disparities for gout, several knowledge gaps exist in gout epidemiology and outcomes differences by gender and race and/or ethnicity. These should be investigated in future studies.