Epidemiology of gout and hyperuricemia. A long-term population study

Integrating Experimental and Computational Analyses of Yeast Protein Profiles for Optimizing the Production of High-Quality Microbial Proteins

Microbial proteins represent a promising solution to address the escalating global demand for protein, particularly in regions with limited arable land. Yeasts, such as Saccharomyces cerevisiae, are robust and safe protein-producing strains. However, the utilization of non-conventional yeast strains for microbial protein production has been hindered, partly due to a lack of comprehensive understanding of protein production traits. In this study, we conducted experimental analyses focusing on the growth, protein content, and amino acid composition of nine yeast strains, including one S. cerevisiae strain, three Yarrowia lipolytica strains, and five Pichia spp. strains. We identified that, though Y. lipolytica and Pichia spp. strains consumed glucose at a slower rate compared to S. cerevisiae, Pichia spp. strains showed a higher cellular protein content, and Y. lipolytica strains showed a higher glucose-to-biomass/protein yield and methionine content. We further applied computational approaches to explain that metabolism economy was the main underlying factor for the limited amount of scarce/carbon-inefficient amino acids (such as methionine) within yeast cell proteins. We additionally verified that the specialized metabolism was a key reason for the high methionine content in Y. lipolytica strains, and proposed Y. lipolytica strain as a potential producer of high-quality single-cell protein rich in scarce amino acids. Through experimental evaluation, we identified Pichia jadinii CICC 1258 as a potential strain for high-quality protein production under unfavorable pH/temperature conditions. Our work suggests a promising avenue for optimizing microbial protein production, identifying the factors influencing amino acid composition, and paving the way for the use of unconventional yeast strains to meet the growing protein demands.

The nutritional composition and cell size of microbial biomass for food applications are defined by the growth conditions

BACKGROUND

It is increasingly recognized that conventional food production systems are not able to meet the globally increasing protein needs, resulting in overexploitation and depletion of resources, and environmental degradation. In this context, microbial biomass has emerged as a promising sustainable protein alternative. Nevertheless, often no consideration is given on the fact that the cultivation conditions affect the composition of microbial cells, and hence their quality and nutritional value. Apart from the properties and nutritional quality of the produced microbial food (ingredient), this can also impact its sustainability. To qualitatively assess these aspects, here, we investigated the link between substrate availability, growth rate, cell composition and size of Cupriavidus necator and Komagataella phaffii.

RESULTS

Biomass with decreased nucleic acid and increased protein content was produced at low growth rates. Conversely, high rates resulted in larger cells, which could enable more efficient biomass harvesting. The proteome allocation varied across the different growth rates, with more ribosomal proteins at higher rates, which could potentially affect the techno-functional properties of the biomass. Considering the distinct amino acid profiles established for the different cellular components, variations in their abundance impacts the product quality leading to higher cysteine and phenylalanine content at low growth rates. Therefore, we hint that costly external amino acid supplementations that are often required to meet the nutritional needs could be avoided by carefully applying conditions that enable targeted growth rates.

CONCLUSION

In summary, we demonstrate tradeoffs between nutritional quality and production rate, and we discuss the microbial biomass properties that vary according to the growth conditions.

Delta Neutrophil Index as a New Marker of Purulent Inflammation in Men With Non-odontogenic Abscesses of the Neck

Introduction If non-odontogenic abscesses and phlegmons (all purulent inflammations where the etiology is not a diseased tooth) of the neck are not promptly treated, they can lead to serious complications and even end in the death of the affected patient. Classical markers of inflammation such as plasma concentration of leukocytes (WBC), neutrophils (Neu), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) are elevated in inflammatory neck diseases, but none of them has been proven as a definite marker in the prediction of this type of pathology. This necessitates the search and analysis of new indicators that could be used in the diagnosis, follow-up, and prognosis of patients with purulent neck infections. Potentially, such a marker could be the delta neutrophil index (DNI), which is increasingly entering clinical practice as a prognostic indicator in critically ill patients with life-threatening illnesses, including sepsis and systemic inflammatory response syndrome (SIRS). In the world literature, there are no data that have been studied in patients with purulent diseases of the neck of non-odontogenic origin, which is the aim of this original article. Materials and methods This retrospective study included 40 men with an average age of 46 (18-87) years with non-odontogenic abscesses and phlegmons of the neck who were hospitalized and operated on. In all of them, the concentration of leukocytes, eosinophils (Eo), neutrophils, and mature polymorphonuclear neutrophil leukocytes (PMN) was examined on an automatic 5-Diff hematology analyzer, ADVIA 2120i (Siemens Medical Solutions USA, Malvern, PA). Thus, it was calculated according to the formula for calculating DNI (DNI% = (Neu%+Eo%) - PMN%). Retrospectively, 30 healthy men with an average age of 42 (18-81) years were used as a control group, in which the same indicators were examined during a preventive examination. Results and discussion Comparing the mean values of WBC, Neu, and DNI between the studied patients with non-odontogenic purulent neck infections (n=40) and the healthy male controls (n=30) it was found that all three indicators of inflammation are significantly higher in the ill men, and these differences are statistically significant (p<0.05): 10.19 ±2.68x103/L versus 7.37 ±1.93x103/L for leukocytes, 7.68 ±2, 76x103/L versus 4.13 ±1.48x103/L for neutrophils, and 1.11±0.83% versus -1.07±1.22% for DNI. Therefore, the high mean numbers of measured WBC and Neu in men with non-odontogenic purulent neck infections were associated with an increase in their mean calculated DNI. This gives us reason to think that while WBC and Neu alone are not sufficient for definitive diagnosis, treatment follow-up, and prediction of disease outcome, in combination with DNI they become reliable indicators in purulent neck infections. Conclusions The DNI correlates well with other well-known and established indicators of inflammation, such as the concentration of leukocytes and neutrophils in the peripheral blood of patients. Its calculation is fast as an implementation procedure and is economically beneficial. Its independent use in the diagnosis and treatment of these diseases is about to be investigated and analyzed.

Gene Dose-Dependent and Additive Effects of ABCG2 rs2231142 and SLC2A9 rs3733591 Genetic Polymorphisms on Serum Uric Acid Levels

This study aimed to evaluate whether the single nucleotide polymorphisms of ATP-binding cassette subfamily G member 2 (ABCG2) and solute carrier family 2 member 9 (SLC2A9) affect individual blood uric acid levels using pyrosequencing. ABCG2 (rs2231142, rs72552713, rs2231137), SLC2A9 (rs3734553, rs3733591, rs16890979), and individual uric acid levels were prospectively analyzed in 250 healthy young Korean male participants. Prominent differences in uric acid levels of the alleles were observed in the SLC2A9 rs3733591 polymorphism: wild-type (AA) vs. heterozygote (AG), 0.7 mg/dL (p < 0.0001); AA vs. mutant type (GG), 1.32 mg/dL (p < 0.0001); and AG vs. GG, 0.62 mg/dL (p < 0.01). In ABCG2 single nucleotide polymorphisms (SNPs), the statistically significant differences in uric acid levels were only found in rs2231142 between CC vs. AA (1.06 mg/dL; p < 0.001), and CC vs. CA (0.59 mg/dL; p < 0.01). Serum uric acid levels based on the ABCG2 and SLC2A9 diplotype groups were also compared. The uric acid levels were the lowest in the CC/AA diplotype and highest in the AA/AG diplotype. In addition, the SNP SLC2A9 rs3733591 tended to increase the uric acid levels when the ABCG2 rs2231142 haplotypes were fixed. In conclusion, both the ABCG2 rs2231142 and SLC2A9 rs3733591 polymorphisms may additively elevate blood uric acid levels.

Effects of vitamin C supplementation on gout risk: results from the Physicians' Health Study II trial

BACKGROUND

Short-term randomized trials suggest that a 500 mg/d vitamin C supplement reduces serum urate, whereas observational studies show vitamin E is inversely associated with gout risk.

OBJECTIVES

We evaluated the effect of supplemental vitamin C (prespecified primary exposure) and vitamin E (prespecified secondary exposure) on new diagnoses of gout.

METHODS

We performed a post hoc analysis of data from the Physicians' Health Study II, a randomized, double-blind, placebo-controlled factorial trial of randomized vitamin C (500 mg/d) and vitamin E (400 IU every other day). The primary outcome was new gout diagnoses, self-reported at baseline and throughout the follow-up period of ≤10 y.

RESULTS

Of 14,641 randomly assigned male physicians in our analysis, the mean age was 64 ± 9 y; 1% were Black, and 6.5% had gout prior to randomization. The incidence rate of new gout diagnoses during follow-up was 8.0 per 1000 person-years among those assigned vitamin C compared with 9.1 per 1000 person-years among those assigned placebo. The vitamin C assignment reduced new gout diagnoses by 12% (HR: 0.88; 95% CI: 0.77, 0.99; P = 0.04). These effects were greatest among those with a BMI <25 kg/m 2 (P-interaction = 0.01). Vitamin E was not associated with new gout diagnoses (HR: 1.05; 95% CI: 0.92, 1.19; P = 0.48).

CONCLUSIONS

Vitamin C modestly reduced the risk of new gout diagnoses in middle-aged male physicians. Additional research is needed to determine the effects of higher doses of vitamin C supplementation on serum urate and gout flares in adults with established gout.The Physicians' Health Study II is registered at clinicaltrials.gov (identifier: NCT00270647).

Reference range of serum uric acid and prevalence of hyperuricemia: a cross-sectional study from baseline data of ELSA-Brasil cohort

Background

Most of the few studies that have established reference ranges for serum uric acid (SUA) have not taken into account factors which may interfere with its levels and followed rigorous laboratory quality standards. The aim of this study was to establish reference ranges for SUA and determine the prevalence of hyperuricemia.

Method

Cross-sectional study including 15,100 participants (all sample) aged 35 to 74 years from baseline data of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), a multicentric cohort of volunteer civil servants from five universities and one research institute located in different regions of Brazil. It was established a reference sample excluding participants with factors that directly influence SUA levels: glomerular filtration rate lower than 60 ml/min, excessive alcohol intake, use of diuretics, aspirin, estrogen or urate-lowering therapy. SUA was measured using the uricase method and following rigorous international quality standards. Reference ranges were defined as values between percentiles 2.5 (P2.5) and 97.5 (P97.5) of SUA distribution in the reference sample, stratified by sex. Hyperuricemia was defined as SUA ≥ 7 mg/100 ml in the all sample.

Results

The reference sample was composed of 10,340 individuals (55.3% women, median age 50 years). Reference ranges (P2.5 to P97.5) for SUA were: 4.0 to 9.2 mg/100 ml for men and 2.8 to 6.9 mg/100 ml for women. Sex was a major determinant for SUA levels (median [IQR], mg/100 ml: 6.1 [5.3–7.0] for men versus 4.5 [3.9–5.3] for women, p < 0.001). Higher levels of SUA were found in patients with higher BMI. Higher age had (a modest) influence only for women. The prevalence of hyperuricemia for all sample (N = 15,100) was 31.9% (95% confidence interval [CI] 30.8–33.0%) in men and 4.8% (95% CI 4.3–5.3%) in women.

Conclusion

SUA reference ranges were 4.0 to 9.2 mg/100 ml for men and 2.8 to 6.9 mg/100 ml for women. Prevalence of hyperuricemia was 31.9% in men and 4.8% in women. Updated SUA reference ranges and prevalence of hyperuricemia are higher nowadays and might be used to guide laboratories and the screening for diseases related to SUA.

Towards new carbon-neutral food systems: Combining carbon capture and utilization with microbial protein production

Alternative protein sources such as microbial protein (MP) are currently considered to alleviate the burden that food production exerts on the environment. Even though MP production is highly efficient in land and nutrient utilization, their carbon footprint should be improved. Here we propose the use of CCU as a driver for heterotrophic MP production. By comparing different MP production routes starting from liquid substrates derived from CO2 (i.e., formate, acetate, methanol, and ethanol) and their respective metabolic pathways, the potential of this concept as a carbon-neutral food or feed production process was estimated. Acetate and ethanol appear to be the most beneficial substrates for the integrated CCU-to-MP process in terms of electricity demand (acetate: 25 - 54 kWh/kgproduct, ethanol: 28 - 56 kWh/kgproduct). Moreover, recycling CO2 enables a carbon-negative protein production process by 2030 (considering the projected CO2 emissions from electricity in the EU: 0.096 kgCO2-eq/kWh) for formate, acetate, and ethanol (-1.1 up to 13 kgCO2-eq/kgproduct).

Is repeat serum urate testing superior to a single test to predict incident gout over time?

Elevated serum urate is the most important causal risk factor for developing gout. However, in longitudinal cohort studies, a small proportion of people with normal urate levels develop gout and the majority of those with high urate levels do not. These observations may be due to subsequent variations in serum urate over time. Our analysis examined whether single or repeat testing of serum urate more accurately predicts incident gout over time. Individual participant data from three publicly-available cohorts were included. Data from paired serum urate measures 3-5 years apart, followed by an assessment of gout incidence 5-6 years from the second urate measure were used to calculate the predictive ability of four measures of serum urate on incident gout: the first measure, the second measure, the average of the two measures, and the highest of the two measures. Participants with prevalent gout prior to the second measure were excluded. Receiver operator characteristic (ROC) curves and area under the curve (AUC) statistics were computed to compare the four measures. A total of 16,017 participants were included across the three cohorts, with a mean follow-up from the first serum urate test of 9.3 years (range 8.9-10.1 years). Overall, there was a small increase in the mean serum urate between the first and second measures (322 μmol/L (5.42 mg/dL) vs. 340 μmol/L (5.71 mg/dL), P<0.001) which were a mean of 3.5 years apart, but the first and second measures were highly correlated (r = 0.81, P<0.001). No differences were observed in the predictive ability of incident gout between the four measures of serum urate measurement with ROC curve AUC statistics ranging between 0.81 (95% confidence intervals: 0.78-0.84) and 0.84 (95% confidence intervals: 0.81-0.87). These data show that repeat serum urate testing is not superior to a single measure of serum urate for prediction of incident gout over approximately one decade.

Cut-Off Value of Serum Uric Acid for Development of Gout Disease in Patients with Multiple Co-Morbidities

Objective:

This study aimed to determine the association between hyperuricemia, comorbid diseases and risk of developing gout disease in a Turkish population in a long follow-up period.

Methods:

A total of 2000 Turkish adults were cross-sectionally analysed for serum urate levels in 2009 at the Pamukkale University Faculty of Medicine. All patients on regular follow-up at our tertiary health center (n=1322) were included in this study. Demographic features (age and gender), comorbid clinical conditions, and medication use were noted. The risk of developing gout and the determinant factors were investigated. Multivariate logistic regression analysis was performed to analyse causative effects of factors while receiver operating characteristic (ROC) curve analysis was used to identify optimal cut-off values of uric acid level for predicting the development of gout.

Results:

Among 1322 patients, the mean age was 56.9 (SD:14.68) years. 57.3% (n=758) of the patients were female. The most common co-morbid disease was chronic kidney disease (581, 43%), followed by hypertension (522, 39.4%). Gout developed in 25 patients (1.8%). Gout development risk and presence of all the above comorbidities were significantly higher in patients with serum urate ≥7mg/dl compared with <7mg/dl. Male gender and not using urate lowering drugs were the main risk factors for developing gout disease. ROC analysis of serum uric acid levels identified a cut-off value of >7 (AUC: 0.776, sensitivity 86.96%, specificity 66.74%).

Conclusion:

There is still a dilemma concerning the culprit effects of both comorbidities and hyperuricemia on the risk of developing gout disease.

Mini Review: Reappraisal of Uric Acid in Chronic Kidney Disease

Hyperuricemia predicts the development of chronic kidney disease (CKD) and metabolic complications, but whether it has a causal role has been controversial. This is especially true given the 2 recently conducted randomized controlled trials that failed to show a benefit of lowering uric acid in type 1 diabetes-associated CKD and subjects with stage 3-4 CKD. While these studies suggest that use of urate-lowering drugs in unselected patients is unlikely to slow the progression of CKD, there are subsets of subjects with CKD where reducing uric acid synthesis may be beneficial. This may be the case in patients with gout, hyperuricemia (especially associated with increased production), and urate crystalluria. Here, we discuss the evidence and propose that future clinical trials targeting these specific subgroups should be performed.

The Effect of Size of Materials Formed or Implanted In Vivo on the Macrophage Response and the Resultant Influence on Clinical Outcome

Both the chemistry and size of a material formed in vivo, or an implanted biomaterial, can alter the in vivo host response. Within the size range covered within this review, over 1 μm, chemistry is only important if the solid material is unstable and leeching small molecules. The macrophage activity and the resultant inflammatory response, however, are related to the size of the solid material. The premise of this review is that differences in size of the solid material, in different cases, can be the reason why there is some individual-to-individual variation in response. Specifically, the inflammatory response is enhanced when the size is between 1-50 μm. This will be looked at for three configurations: spherical particulate (silicone oil or gel from breast implants), elongated particulate (monosodium urate [MSU] crystals in gout or in kidney stones), and fibers (e.g., polyester used in fabric implants). These specific examples were selected because many still believe that the clinical outcome for each is controlled by the surface chemistry, when in fact it is the size. In each case, specific studies will be highlighted to either show a mechanism for creating different sizes and therefore a differential biological response (first three) or how changing the size and shape (diameter and spacing of fibers, in this example) can affect the response and can help explain the different responses to fabric implants found in vivo within the 1-50 μm size range. It was found that polyester fibers under 70 μm had a significant increase in macrophage response. Further, it was found that compounds found in synovial fluid could limit MSU crystal size. In addition, it was shown that plasma with low triglyceride levels emulsifies silicone oils to a greater extent than plasma with higher triglyceride levels. Therefore, in three cases it appears that differences in the inflammatory response between individuals and between different implants could be explained just by the size of the material formed or implanted.

Chronic tophaceous gout mimicking widespread metastasis

Gout is a common crystal-induced arthropathy affecting mainly the joints of the appendicular skeleton; however, rarely this condition affects the axial skeleton as well. Spinal gout can cause radiculopathy, cord compression, canal stenosis and discitis. We describe a case of a 71-year-old woman where the initial presentation of destructive arthropathy and spinal masses secondary to axial gout was mistaken for a metastatic malignancy. Despite chronic polyarthropathy and bilateral subcutaneous gouty tophi, spinal gout was not considered a differential diagnosis during initial assessment.The patient was managed conservatively with pharmacological treatment resulting in improvement of her upper limb radiculopathy and systemic joint pain, although little improvement in mobility. Such extensive involvement is rare and the masses can mimic an underlying metastatic disease. Careful history and clinical examination recognising polyarthropathy and subcutaneous tophi can aid the clinician to make the right diagnosis and institute correct treatment. Delay in recognising gout as a differential diagnosis can lead to marked morbidity as illustrated in our case.

Wastewater-based estimation of the prevalence of gout in Australia

Allopurinol, a first-line gout treatment drug in Australia, was assessed as a wastewater-based epidemiology biomarker of gout via quantification of the urinary metabolite, oxypurinol in wastewater. The in-sewer stability of oxypurinol was examined using laboratory-scale sewer reactors. Wastewater from 75 wastewater treatment plants across Australia, covering approximately 52% (12.2 million) of the country's population, was collected on the 2016 census day. Oxypurinol was quantified in the wastewater samples and population-weighted mass loads calculated. Pearson and Spearman rank-order correlations were applied to investigate any link between allopurinol, other selected wastewater biomarkers, and socio-economic indicators. Oxypurinol was shown to be stable in sewer conditions and suitable as a WBE biomarker. Oxypurinol was detected in all wastewater samples. The estimated consumption of allopurinol ranged from 1.9 to 32 g/day/1000 people equating to 4.8 to 80 DDD/day/1000 people. The prevalence of gout across all tested sewer catchments was between 0.5% to 8%, with a median of 2.9% nationally. No significant positive correlation was observed between allopurinol consumption and alcohol consumption, mean age of catchment population, remoteness or higher socioeconomic status. There was a significant positive correlation with selective analgesic drug use. Wastewater analysis can be used to study gout prevalence and can provide additional insights on population level risk factors when triangulated with other biomarkers.

The Paradoxical Role of Uric Acid in Osteoporosis

Because of its high prevalence worldwide, osteoporosis is considered a serious public health concern. Many known risk factors for developing osteoporosis have been identified and are crucial if planning health care needs. Recently, an association between uric acid (UA) and bone fractures had been explored. Extracellular UA exhibits antioxidant properties by effectively scavenging free radicals in human plasma, but this benefit might be disturbed by the hydrophobic lipid layer of the cell membrane. In contrast, intracellular free oxygen radicals are produced during UA degradation, and superoxide is further enhanced by interacting with NADPH oxidase. This intracellular oxidative stress, together with inflammatory cytokines induced by UA, stimulates osteoclast bone resorption and inhibits osteoblast bone formation. UA also inhibits vitamin D production and thereby results in hyper-parathyroidism, which causes less UA excretion in the intestines and renal proximal tubules by inhibiting the urate transporter ATP-binding cassette subfamily G member 2 (ABCG2). At normal or high levels, UA is associated with a reduction in bone mineral density and protects against bone fracture. However, in hyperuricemia or gout arthritis, UA increases bone fracture risk because oxidative stress and inflammatory cytokines can increase bone resorption and decrease bone formation. Vitamin D deficiency, and consequent secondary hyperparathyroidism, can further increase bone resorption and aggravated bone loss in UA-induced osteoporosis.

Effect of Inositol Hexaphosphate (IP6) on Serum Uric Acid in Hyperuricemic Subjects: a Randomized, Double-Blind, Placebo-Controlled, Crossover Study

Inositol hexaphosphate (IP₆), a food constituent with various health benefits, has been shown to suppress postprandial elevations of serum uric acid (SUA) levels in healthy adults by inhibiting purine nucleoside and base absorption. Here, we investigated the effect of repeated intake of IP₆ on fasting SUA levels in hyperuricemic subjects. This randomized double-blind placebo-controlled crossover design study included 31 asymptomatic hyperuricemic subjects (fasting SUA level > 7.0 but <9.0 mg/dL). Subjects ingested placebo or IP₆ drinks (600 mg twice daily) during two 2-week intervention periods with a 2-week washout period. The primary outcome was fasting SUA level; the secondary outcome was the urinary uric acid to creatinine ratio. Fasting SUA levels in the IP₆ group were lower than those in the placebo group (p < 0.05). The urinary uric acid to creatinine ratio did not change between the placebo and IP₆ groups (p > 0.05). This study showed that a 2-weeks supplementation period of 600 mg IP₆ twice daily can improve fasting SUA levels in hyperuricemic subjects.

Painless gouty tophus in the nasal bridge: A case report and literature review

RATIONALE

A gouty tophus, arising from the deposition of monosodium urate crystals (MSU), rarely occurs in the nasal bridge. There have been only 7 documented cases of a gouty tophus in the nasal bridge from 1978 to 2018 in English-language literature.

PATIENT CONCERNS

A 65-year-old male had a chief complaint of a lump in the nasal bridge that was slowly growing for over 1 year.

DIAGNOSIS

MSU crystals were confirmed through ultrasonography (US) and pathological examinations.

INTERVENTIONS

A cosmetically less destructive method, ultrasound-guided fine needle aspiration cytology (FNAC) was used to approach the mass lesion of nasal bridge.

OUTCOMES

The diagnosis was confirmed as a gouty tophus without performing a nasal subdermal exploration.

LESSONS

This case report is the first use of US with FNAC to approach and diagnosed a gouty tophus in the nasal bridge.

Joint Clinical Consensus Statement of the American College of Foot and Ankle Surgeons® and the American Association of Nurse Practitioners®: Etiology, Diagnosis, and Treatment Consensus for Gouty Arthritis of the Foot and Ankle

Gout is a condition that commonly affects the foot and ankle, and practitioners who treat these structures should be aware of the methods to diagnose and treat this form of arthritis. Practitioners also need to recognize extra-articular manifestations of the disease. Although the acutely red, hot, swollen joint is a common presentation, chronic tophaceous gout can be associated with pain, nodule formation, and cutaneous compromise. Since the underlying causes that lead to excessive monosodium urate deposition may be treatable, early and accurate diagnosis can be very beneficial and may even prevent articular degeneration.

Effects of a Dietary Approach to Stop Hypertension (DASH) Diet Intervention on Serum Uric Acid in African Americans With Hypertension

OBJECTIVE

To examine whether partial replacement of a diet typical of the average American diet with Dietary Approaches to Stop Hypertension (DASH)-related foods in the home environment lowers the serum uric acid (UA) level in individuals with hypertension.

METHODS

We conducted an ancillary study of a randomized trial of African American adults with controlled hypertension from an urban clinic. Participants were assigned to either a control group or an intervention (DASH-Plus) group. DASH-Plus participants received coach-directed dietary advice, assistance with purchasing DASH-related foods ($30/week), and home delivery of food via a community supermarket. Participants in the control group received a DASH diet brochure and a debit card account ($30/week) to purchase foods. Serum UA levels were measured at baseline and after 8 weeks.

RESULTS

Of the original 123 randomized participants, 117 had available serum UA measurements. Seventy percent of the participants were women, the mean ± SD age was 59 ± 9.5 years, and the mean ± SD serum UA level was 6.4 ± 1.7 mg/dl. The DASH-Plus diet did not reduce serum UA levels compared with the control diet (difference in difference -0.01 mg/dl [95% confidence interval -0.39, 0.38]). However, there was a significant trend toward a greater reduction in the serum UA level in participants with higher baseline serum UA levels (P for trend = 0.008). Baseline changes in the serum UA level were inversely associated with changes in systolic blood pressure (P = 0.002), diastolic blood pressure (P = 0.001), and urinary sodium excretion (P = 0.05).

CONCLUSION

Overall, in African American individuals, partial replacement of a typical diet with DASH foods did not lower serum UA levels compared with a control diet. However, there was a significant trend toward a greater reduction in serum UA levels in subjects with higher baseline serum UA levels. Furthermore, changes in serum UA levels were associated with known correlates, suggesting heterogeneity of effects in the treatment and control arms. Future pragmatic studies of consumption of the DASH diet to lower serum UA levels should optimize replacement strategies and enroll individuals with hyperuricemia or gout.

Minimally Invasive Excision of Lumbar Tophaceous Gout: Case Report

Background

Symptomatic spinal gout is relatively rare. Open laminectomy, with or without fusion, has been so far the standard treatment for symptomatic spinal gout. We describe here the first case of spinal tophaceus gout treated with minimally invasive surgery.

Methods

A 60-year-old patient, morbidly obese, with no previous history of gout, presented with neurogenic claudication due to severe lumbar canal stenosis at L3/4. Surgery was performed through a minimally invasive approach, using tubular retractors. During surgery, an extradural mass with a thin capsule and containing white "chalky" partially calcified material, slightly adherent to and compressing the theca, was removed.

Results

There were no intra- or perioperative complications. Surgery successfully improved the functional status, with a significant increase in walking distance and no residual leg pain or neurogenic claudication. Histopathology confirmed the diagnosis of spinal tophaceous gout.

Conclusions/Level of evidence

Although spinal gout is usually responsive to medical treatment, surgery is often the first line treatment, particularly in patients with neurological deficits. Would surgery be indicated, we believe that minimally invasive surgery can be effective in treating symptomatic spinal tophaceous gout. Level of Evidence: Class IV.

Uric acid lowering therapies for preventing or delaying the progression of chronic kidney disease

BACKGROUND

Non-randomised data have shown a link between hyperuricaemia and the progression or development of chronic kidney disease (CKD). If this is correct, urate lowering therapy might form an important part of chronic kidney disease care, reducing risks for cardiovascular outcomes and end-stage kidney disease.

OBJECTIVES

This review aims to study the benefits and harms of uric acid lowering therapy on the progression of CKD and other cardiovascular endpoints.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 20 July 2017 through contact with the Information Specialist using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE, and EMBASE; handsearching conference proceedings; and searching the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials testing primary urate lowering therapy in patients with or without CKD.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. Statistical analyses were performed using a random effects model and results expressed as risk ratio (RR) with 95% confidence intervals (CI) for dichotomous outcomes or mean difference (MD) for continuous outcomes, or standardised mean difference (SMD) if different scales were used.

MAIN RESULTS

Twelve studies (1187 participants) were included in the review. Risk of bias was unclear for the majority of domains in each study.Uric acid lowering therapy may make little or no difference in death at six months (2 studies, 498 participants: RR 1.66, 95% CI 0.61 to 4.48) or two years (2 studies, 220 participants): RR 0.13, 95% CI 0.02 to 1.06) (low certainty evidence). Uric acid lowering therapy may make little of no difference (low certainty evidence) in the incidence of ESKD at one or two years. Kidney function may be improved by uric acid lowering therapy at one year with a reduction in serum creatinine (2 studies, 83 participants: MD -73.35 µmol/L, 95% CI -107.28 to -39.41) and a rise in eGFR (1 study, 113 participants: MD 5.50 mL/min/1.73 m², 95% CI 0.59 to 10.41). However it probably makes little or no difference to eGFR at two years (2 studies, 164 participants: MD 4.00 mL/min, 95% CI -3.28 to 11.28). Uric acid lowering therapy reduced uric acid levels at all time points (3, 4, 6, 12 and 24 months) (high certainty evidence).There is insufficient evidence to support an effect on blood pressure, proteinuria or other cardiovascular markers by uric acid lowering therapy. It should be noted that the apparent benefits of treatment were not apparent at all time points, introducing the potential for bias.

AUTHORS' CONCLUSIONS

There is limited data which suggests uric acid lowering therapy may prevent progression of chronic kidney disease but the conclusion is very uncertain. Benefits were not observed at all time points and study quality was generally low. Larger studies are required to study the effect of uric acid lowering therapy on CKD progression. Three ongoing studies will hopefully provide much needed high quality data.

Uric acid in the pathogenesis of metabolic, renal, and cardiovascular diseases: A review

The association between uric acid (UA) on one side and systemic hypertension (Htn), dyslipidemia, glucose intolerance, overweight, fatty liver, renal disease and cardiovascular disease (CVD) on the other side is well recognized. However, the causal relationship between UA and these different clinical problems is still debatable. The recent years have witnessed hundreds of experimental and clinical trials that favored the opinion that UA is a probable player in the pathogenesis of these disease entities. These studies disclosed the strong association between hyperuricemia and metabolic syndrome (MS), obesity, Htn, type 2 diabetes mellitus (DM), non-alcoholic fatty liver disease, hypertriglyceridemia, acute kidney injury, chronic kidney disease (CKD), coronary heart disease (CHD), heart failure and increased mortality among cardiac and CKD patients. The association between UA and nephrolithiasis or preeclampsia is a non-debatable association. Recent experimental trials have disclosed different changes in enzyme activities induced by UA. Nitric oxide (NO) synthase, adenosine monophosphate kinase (AMPK), adenosine monophosphate dehydrogenase (AMPD), and nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase are affected by UA. These changes in enzymatic activities can lead to the observed biochemical and pathological changes associated with UA. The recent experimental, clinical, interventional, and epidemiologic trials favor the concept of a causative role of UA in the pathogenesis of MS, renal, and CVDs.

Single nucleotide polymorphisms associated with P2X7R function regulate the onset of gouty arthritis

BACKGROUND

Gout is an inflammatory disease that is caused by the increased production of Interleukin-1β (IL-1β) stimulated by monosodium urate (MSU) crystals. However, some hyperuricemia patients, even gouty patients with tophi in the joints, never experience gout attack, which indicates that pathogenic pathways other than MSU participate in the secretion of IL-1β in the pathogenesis of acute gouty arthritis. The ATP-P2X7R-IL-1β axis may be one of these pathways.

OBJECTIVE

This study examines the role of Adenosine triphosphate (ATP) in the pathogenesis of gout and the association of ATP receptor (P2X7R) function with single nucleotide polymorphisms and gout arthritis.

METHODS

Non-synonymous single nucleotide polymorphisms (SNP) loci of P2X7R in Chinese people were screened to compare the frequencies of different alleles and genotype distribution of selective SNPs in 117 gouty patients and 95 hyperuricemia patients. Peripheral white blood cells were purified from the peripheral blood of 43 randomly selected gout patients and 36 hyperuricemia patients from the total group. Cells were cultured with MSU or MSU + ATP, and supernatants were collected for the detection of IL-1β concentrations using enzyme-linked immunosorbent assay (ELISA).

RESULTS

1. Eight SNP loci, including rs1653624, rs10160951, rs1718119, rs7958316, rs16950860, rs208294, rs17525809 and rs2230912, were screened and detected, and rs1653624, rs7958316 and rs17525809 were associated with gout arthritis. 2. IL-1β concentrations in supernatants after MSU + ATP stimulation were significantly higher in gouty patients than in the hyperuricemia group [(131.08 ± 176.11) pg/ml vs. (50.84 ± 86.10) pg/ml]; Patients (including gout and hyperuricemia) carrying the susceptibility genotype AA or AT of rs1653624 exhibited significantly higher concentrations of IL-1β than patients carrying the non-susceptibility genotype TT [(104.20 ± 164.25) pg/ml vs. (21.90 ± 12.14) pg/ml]; However, no differences were found with MSU stimulation alone.

CONCLUSIONS

ATP promotes the pathogenesis of gouty arthritis via increasing the secretion of IL-1 β, and its receptor (P2X7R) function associated single nucleotide polymorphisms may be related to gouty arthritis, which indicates that ATP-P2X7R signaling pathway plays a significant regulatory role in the pathogenesis of gout.

Clinical significance of delta neutrophil index in the differential diagnosis between septic arthritis and acute gout attack within 24 hours after hospitalization

The most important differential diagnoses of acute monoarticular arthritis are septic arthritis and acute gout attack. Identifying infection is crucial in preventing the devastating outcome of septic arthritis. The delta neutrophil index (DNI) is a value that corresponds to the fraction of circulating immature granulocytes. As DNI reflects the burden of infection, we evaluated this index as a differentiating marker between septic arthritis and acute gout attack.The medical records of 149 patients with septic arthritis and 194 patients with acute gout attack were reviewed. A specific cell analyzer, ADVIA 2120, was used to measure DNI. Clinical and laboratory markers associated with predicting septic arthritis were assessed by using logistic regression.Patients with septic arthritis showed higher levels of DNI than those with acute gout attack (3.3 vs 0.6%, P < .001). Similar results were observed in patients without monosodium urate (MSU) crystal confirmation or those with normouricemia (3.3 vs 0.5 and 3.1 vs 0.7%, respectively; P < .001 for both). A DNI level of 1.9% was determined as the cutoff value for predicting septic arthritis. In the multivariate analysis, DNI was the most powerful independent value for predicting septic arthritis (odds ratio 14.003).This study showed the possibility of using DNI as a differentiating marker between septic arthritis and acute gout attack at the crucial early phase. DNI showed its relevance regardless of confirmation of MSU crystal deposition or serum level of uric acid.

Potassium oxonate induces acute hyperuricemia in the tree shrew (tupaia belangeri chinensis)

Potassium oxonate, a selectively competitive uricase inhibitor, produced hyperuricemia (HUA) in rodents in a previous study. In this study, we employed the tree shrew as an animal model to study potassium oxonate-induced HUA. The effect of allopurinol (ALLO), a uric acid reducer, was also examined in this model. Potassium oxonate at doses of 5, 20, 40, 60, 80, 100, and 1,000 mg/kg was given intraperitoneally to tree shrews. The results showed that potassium oxonate can effectively increase the levels of uric acid in tree shrews at doses ranging from 40 to 100 mg/kg. Semiquantitative RT-PCR showed that the xanthine dehydrogenase/oxidase (XDH/XO) mRNA expression level was significantly higher in the liver tissue of tree shrews with high levels of uric acid. There were no changes in serum urea nitrogen, or serum creatinine values. ALLO can significantly decrease serum uric acid levels (P<0.01) and raise XDH/XO mRNA expression levels in the liver tissue of tree shrews with HUA. XDH/XO mRNA expression levels did not change in untreated tree shrews. Studies on acute toxicity in the tree shrew did not show any significantly abnormal signs. There were no adverse effects at the macroscopic level up to doses ≤100 mg/kg. Potassium oxonate induced acute HUA in tree shrews at lower doses compared with other animal models. Potassium oxonate-treated tree shrews may be a potential animal model for studying pathogenic mechanism and evaluating a new therapeutic agent for treatment of HUA in humans.

Benchmark dose of alcohol consumption for development of hyperuricemia in Japanese male workers: An 8-year cohort study

BACKGROUND

To estimate the benchmark dose (BMD) and their 95% lower confidence limits (BMDL) of alcohol consumption as the reference level for the development of hyperuricemia based on the dose-response relationship.

METHODS

An 8-year prospective cohort study was conducted in 8097 male workers at a Japanese steel company who received annual health check-ups between 2002 and 2009. The endpoints for development of hyperuricemia were defined as a uric acid ≥7 mg/dL or taking any anti-hyperuricemic medication. The dose-response relationship of alcohol consumption was investigated using multivariate-pooled logistic regression analyses adjusted for other potential covariates. We estimated the BMD and BMDL of alcohol consumption for the development of hyperuricemia, using the parameters obtained by pooled logistic regression with a benchmark response (BMR) of 5% or 10%.

RESULTS

Mean observed years per person was 3.86 years. The incidence rate per 1000 person-years was 61.1. The odds ratio calculated for the development of hyperuricemia was 1.29 [95% confidence interval, (1.22-1.36)] with an increase in alcohol consumption per 1 gou/day (1 gou/day = alcohol 22 g/day). The estimated BMDL/BMD with a BMR of 5% was 2.5/2.8 gou/day (54.5/61.8 g/day) and with a BMR of 10% was 4.0/4.6 gou/day (88.9/100.9 g/day).

CONCLUSIONS

The present study showed that alcohol consumption of 2.5 gou/day (=ethanol 55 g/day) caused a distinct increase in the risk of hyperuricemia. Valuable information for preventing alcohol-induced hyperuricemia was obtained by a long-term follow-up study of a large cohort.

Study for Updated Gout Classification Criteria: Identification of Features to Classify Gout

OBJECTIVE

To determine which clinical, laboratory, and imaging features most accurately distinguished gout from non-gout.

METHODS

We performed a cross-sectional study of consecutive rheumatology clinic patients with ≥1 swollen joint or subcutaneous tophus. Gout was defined by synovial fluid or tophus aspirate microscopy by certified examiners in all patients. The sample was randomly divided into a model development (two-thirds) and test sample (one-third). Univariate and multivariate association between clinical features and monosodium urate-defined gout was determined using logistic regression modeling. Shrinkage of regression weights was performed to prevent overfitting of the final model. Latent class analysis was conducted to identify patterns of joint involvement.

RESULTS

In total, 983 patients were included. Gout was present in 509 (52%). In the development sample (n = 653), the following features were selected for the final model: joint erythema (multivariate odds ratio [OR] 2.13), difficulty walking (multivariate OR 7.34), time to maximal pain <24 hours (multivariate OR 1.32), resolution by 2 weeks (multivariate OR 3.58), tophus (multivariate OR 7.29), first metatarsophalangeal (MTP1) joint ever involved (multivariate OR 2.30), location of currently tender joints in other foot/ankle (multivariate OR 2.28) or MTP1 joint (multivariate OR 2.82), serum urate level >6 mg/dl (0.36 mmoles/liter; multivariate OR 3.35), ultrasound double contour sign (multivariate OR 7.23), and radiograph erosion or cyst (multivariate OR 2.49). The final model performed adequately in the test set, with no evidence of misfit, high discrimination, and predictive ability. MTP1 joint involvement was the most common joint pattern (39.4%) in gout cases.

CONCLUSION

Ten key discriminating features have been identified for further evaluation for new gout classification criteria. Ultrasound findings and degree of uricemia add discriminating value, and will significantly contribute to more accurate classification criteria.

Clinical efficacy and safety of topiroxostat in Japanese male hyperuricemic patients with or without gout: an exploratory, phase 2a, multicentre, randomized, double-blind, placebo-controlled study

WHAT IS KNOWN AND OBJECTIVE

In Japan, although topiroxostat, a selective xanthine oxidoreductase inhibitor, has been used for the treatment of patients with hyperuricemia including gout, no published randomized controlled studies evaluating the dose-dependent relationship with respect to the serum urate-lowering efficacy have been reported. The aim of this study was to evaluate the dose-dependent relationship with serum urate-lowering efficacy and safety of topiroxostat in Japanese hyperuricemic patients including gout.

METHODS

We conducted an exploratory, phase 2a, multicentre, randomized, double-blind, 8-week, placebo-controlled study in Japanese hyperuricemic patients with or without gout. The study arms were placebo and topiroxostat 40, 60, 80 or 120 mg/day. The primary efficacy endpoint was the per cent change in serum urate level from baseline to the final visit.

RESULTS AND DISCUSSION

One hundred and eighty-seven eligible patients were randomized and 186 received at least one dose of the study drug. The study results demonstrated a dose-dependent serum urate reduction effect ranging from 40 to 120 mg/day (P < 0·001, Jonckheere-Terpstra test). The mean per cent change in serum urate level from baseline at the final visit was -30·8% in the 120-mg group and 1·6% with placebo, with a between-group difference of -32·4% ([95% confidence interval, -38·9% to -25·9%]; P < 0·001). Incidences of overall adverse events (AEs) in the topiroxostat groups were comparable to those in the placebo group; however, the incidence of AEs in the 120-mg group was statistically lower than that in the placebo group. The incidences of gouty arthritis were not statistically but numerically higher in the topiroxostat 80- and 120-mg groups.

WHAT IS NEW AND CONCLUSIONS

A dose-dependent serum urate-lowering efficacy of topiroxostat was observed in Japanese hyperuricemic male patients with or without gout. Further clinical studies aimed at evaluating the long-term safety and clinical efficacy are warranted.

The first metatarsophalangeal joint in gout: a systematic review and meta-analysis

Background

The aim of this review was to qualitatively synthesise studies that have investigated characteristics of the first metatarsophalangeal joint (1^st MTP) in gout and to undertake a meta-analysis to estimate the average prevalence of acute 1^st MTP arthritis across studies in people with gout.

Methods

Studies published in English were included if they involved participants who had a diagnosis of gout and presented original findings relating to the following outcome measures associated with the 1^st MTP: epidemiology; clinical features; structural and functional characteristics; and microscopic and imaging features.

Results

Forty-five studies were included in the qualitative synthesis. 1^st MTP pain was a prominent feature in people with gout. People with 1^st MTP gout reported walking- and general-disability. Structural and functional characteristics of 1^st MTP gout included hallux valgus, osteoarthritis, and restricted joint motion. Successful crystal aspiration ranged from 81 to 91 % and positive crystal identification via microscopy ranged from 83 to 93 % in patients with a history of 1^st MTP gout. Imaging features were common at the 1^st MTP including the double contour sign, tophi and erosions. Eleven studies involving 2,325 participants were included in the meta-analysis, providing an estimate of the average prevalence of acute 1^st MTP arthritis across studies of 73 % (95 % prediction interval 40–92 %; range 48–97 %; I² = 93 %).

Conclusions

1^st MTP acute arthritis is highly prevalent in people with gout and has a substantial impact on patient-reported pain and disability. Gout affects the structure and function of the 1^st MTP. Microscopic and imaging studies have demonstrated crystal deposition and joint damage at the 1^st MTP in people with gout.

Gouty arthropathy: Review of clinico-pathologic and imaging features

Gout is a common inflammatory arthropathy in adults, with the prevalence increasing in males of older age. It occurs when monosodium urate (MSU) crystals are deposited in joints and connective tissue causing inflammation. The gold standard for the diagnosis of gout is the demonstration of negatively birefringent, needle-shaped MSU crystals through synovial fluid aspiration. However, this is an invasive technique and may not always be conclusive or feasible. Imaging techniques have been developed to aid in diagnosis of gout non-invasively. Radiography has a low utility in the early diagnosis of gout and demonstrates erosions in late stages. Ultrasound (US) has a high overall sensitivity in diagnosing gout with the 'double contour' sign having a high specificity. Magnetic resonance imaging is good at detecting tophi, bone marrow oedema and erosions, but has a limited role in diagnosis because of its high cost and limited availability. Conventional computed tomography (CT) has no role in the routine diagnosis of gout before development of erosions and tophi. A newer technology, dual-energy CT (DECT) has been shown to be able to detect MSU crystals burden with high accuracy. It has a higher specificity and lower sensitivity that US in gout diagnosis. However, because of radiation exposure and cost, it has a better utility in diagnosing clinically suspected gout complicated by other concurrent rheumatologic conditions or if radiography, US and synovial aspiration are inconclusive or not feasible. This paper will review the clinico-pathologic and imaging features of gouty arthropathy.

Characteristics of the first metatarsophalangeal joint in gout and asymptomatic hyperuricaemia: a cross-sectional observational study

Background

This study aimed to identify patient-reported outcomes and clinician-assessed characteristics of the first metatarsophalangeal joint (1MTPJ) in people with gout and with asymptomatic hyperuricaemia by comparing them to normouricaemic controls.

Methods

Twenty four people with gout (without current symptoms of acute arthritis), 29 with asymptomatic hyperuricaemia and 34 age- and sex-matched controls participated in this cross-sectional observational study. Patient-reported outcomes included 1MTPJ pain, foot pain and disability, body pain, lower limb function, activity limitation and overall wellbeing. Clinician-assessed characteristics of the 1MTPJ included range of motion (ROM), plantar- and dorsi-flexion force, foot posture, temperature and hallux valgus severity.

Results

Compared to controls, participants with gout reported greater 1MTPJ pain (p = 0.014), greater foot pain and disability (p < 0.001), increased odds of having disabling foot pain (odds ratio (OR) 13.4, p < 0.001), decreased lower limb function for daily living (p = 0.002) and recreational (p < 0.001) activities, increased activity limitation (p = 0.002), reduced overall wellbeing (p = 0.034), reduced ROM (p < 0.001), reduced plantarflexion force (p = 0.012), increased 1MTPJ plantar (p = 0.004), dorsal (p = 0.003) and medial (p = 0.004) temperature and had increased odds of having more severe hallux valgus (OR 0.3 p = 0.041). Compared to controls, participants with asymptomatic hyperuricaemia had increased odds of having disabling foot pain (OR 4.2, p = 0.013), increased activity limitation (p = 0.033), decreased lower limb function for daily living (p = 0.026) and recreational (p = 0.010) activities, increased 1MTPJ plantarflexion force (p = 0.004) and a more pronated foot type (p = 0.036).

Conclusions

People with gout demonstrate 1MTPJ-specific changes indicative of subclinical inflammation, even in the absence of acute arthritis. People with asymptomatic hyperuricaemia, who exhibit no features or symptoms of gout, also report high levels of foot- and lower limb-related pain and disability.

Global epidemiology of gout: prevalence, incidence and risk factors

Gout is a crystal-deposition disease that results from chronic elevation of uric acid levels above the saturation point for monosodium urate (MSU) crystal formation. Initial presentation is mainly severely painful episodes of peripheral joint synovitis (acute self-limiting 'attacks') but joint damage and deformity, chronic usage-related pain and subcutaneous tophus deposition can eventually develop. The global burden of gout is substantial and seems to be increasing in many parts of the world over the past 50 years. However, methodological differences impair the comparison of gout epidemiology between countries. In this comprehensive Review, data from epidemiological studies from diverse regions of the world are synthesized to depict the geographic variation in gout prevalence and incidence. Key advances in the understanding of factors associated with increased risk of gout are also summarized. The collected data indicate that the distribution of gout is uneven across the globe, with prevalence being highest in Pacific countries. Developed countries tend to have a higher burden of gout than developing countries, and seem to have increasing prevalence and incidence of the disease. Some ethnic groups are particularly susceptible to gout, supporting the importance of genetic predisposition. Socioeconomic and dietary factors, as well as comorbidities and medications that can influence uric acid levels and/or facilitate MSU crystal formation, are also important in determining the risk of developing clinically evident gout.

Thoracic cord compression due to ligamentum flavum gouty tophus: a case report and literature review

Study design:

Here we describe a patient who developed myelopathy due to gouty tophi of the ligamentum flavum in the thoracic spine. We also review similar cases previously reported in the literature.

Objective:

Our aim was to present a case of myelopathy due to thoracic spinal gouty tophus.

Methods:

We report the case of a 56-year-old male with history of peripheral gout and renal insufficiency. The patient complained of back pain and paraparesis of the left lower limb. Multiple tophi were noted over several interphalangeal and metatarsophalangeal joints. Neurological examination showed decreased left lower limb strength and a positive Babinski sign. Magnetic resonance imaging of the thoracic spine revealed hypertrophy of the ligamentum flavum at the level of T3/T4, T5/T6, T9/T10, T10/T11 and T11/T12.

Results:

A thoracic laminectomy at T1-T5 was performed. Chalky white granular material was found in the ligamentum flavum during surgery. Histological analysis of the specimen demonstrated a gouty tophus. The patient's back pain and paraparesis of the lower left limb improved.

Conclusion:

The clinician should include spinal gout in the differential diagnosis when dealing with patients with gout and axial pain with or without neurologic deficits. If this diagnosis is seriously entertained, then a CT scan or magnetic resonance imaging as well as tissue biopsy may be needed to establish the diagnosis.

Uric acid levels within the normal range predict increased risk of hypertension: a cohort study

There are data describing that cardiovascular risks related to serum uric acid (SUA) levels may begin below the current diagnostic level for hyperuricemia. Values from 5.2 to 6.0 mg/dL were positively associated with higher cardiovascular risk. The risk associated with lower SUA levels has not been fully assessed in healthy adults. The purpose of this study was to evaluate whether normal SUA levels, even below 5-6 mg/dL, might be related to an increased risk of hypertension, compared with low-normal SUA. This cohort study was conducted in an outpatient setting: all clinics of the largest Health Maintenance Organization in Israel, in a national distribution. A total of 118,920 healthy adults (40-70 years old), who had SUA levels screened during 2002, were eligible for the study. They were stratified according to baseline SUA, and were followed for 10 years. The study endpoint was any new diagnosis of hypertension during the study period (until December 31, 2011). During 10 years of follow-up (2002-2011), 28,436 examinees developed hypertension (23.9%). Compared with the pre-defined SUA reference values (2-3 mg/dL), women with SUA within the normal range had a gradual, increased risk of developing new-onset hypertension, starting at values as low as 3-4 mg/dL (adjusted odds ratio, 1.15; 95% confidence interval, 1.01-1.30). Women with SUA 5-6 mg/dL, still accepted as normouricemia, had a 66% increased risk of developing hypertension. Younger women (ages 40-50 years at baseline) in a similar SUA subgroup (5-6 mg/dL) had an even higher risk (odds ratio, 2.25; 95% confidence interval, 1.96-2.60). Similar results were seen among men. The possibility of subtle confounders exists, despite extensive adjustment. SUA within the normal range is associated with new-onset hypertension among healthy adults, compared with once very common low-normal range values. Further study is warranted to determine new cutoffs of hypo-, normo-, and hyperuricemia, which might be far lower than current scales.

Epidemiology and management of gout in Taiwan: a nationwide population study

INTRODUCTION

Gout is the most common inflammatory arthritis worldwide and is the only type of chronic arthritis that potentially can be 'cured'. However, data on gout incidence, prevalence and management, assessed at multiple time points in the same population, are sparse, particularly in Asian populations. The aim of this study was to describe trends in the epidemiology of gout in the general population of Taiwan.

METHODS

The National Health Insurance Research Database was used to identify patients with gout and to estimate the prevalence and incidence of gout for each calendar year from 2005 to 2010. The pattern of gout management was also examined.

RESULTS

Of 23,371,362 beneficiaries in 2010, there were 1,458,569 prevalent and 56,595 incident cases of gout, giving a prevalence of 6.24% (95% confidence interval (CI), 6.23% to 6.25%) and an incidence of 2.74 (95% CI, 2.72 to 2.76) per 1,000 person-years. The annual percentage change (APC) of the standardised prevalence was -0.7% (95% CI, -1.7% to 0.3%; P=0.14), suggesting that the prevalence of gout was essentially the same throughout the study period. However, The APC of incidence was -13.4 (95% CI, -16.1 to -10.6) between 2005 and 2007 and -2.1 (95% CI, -10.4 to 7.1) between 2007 and 2010. Regions with the highest prevalence and incidence were eastern coastal counties and offshore islets, where indigenous people are clustered. Among prevalent gout cases in 2010, only 22.93% (95% CI, 22.87% to 23.00%) were prescribed urate-lowering treatment (ULT), which remained unchanged between 2005 and 2010 at an APC of 0.0 (95% CI, -3.8 to 4.0). Uricosuric agents were more commonly prescribed than xanthine oxidase inhibitors in Taiwan.

CONCLUSIONS

In Taiwan, 1 in 16 people have gout. Whereas the incidence has decreased recently, the prevalence remains unchanged. Management of gout in Taiwan is poor, with only one in five affected people being treated with ULT.

HOMA-IR and the risk of hyperuricemia: a prospective study in non-diabetic Japanese men

AIMS

To examine the relation of insulin resistant status determined by homeostasis model assessment of insulin resistance (HOMA-IR) with the risk of incident hyperuricemia.

METHODS

The study participants included 2071 Japanese men without hyperuricemia and diabetes, aged 35-54 years. The participants had undergone annual heath examinations for 6 years to compare incident hyperuricemia (serum uric acid >416.4μmol/L (7.0mg/dL) and/or taking medication for hyperuricemia) in four groups based on quartiles of baseline HOMA-IR.

RESULTS

During follow-up there were 331 incident cases of hyperuricemia. The hazard ratios for hyperuricemia, compared with HOMA-IR ≤0.66, were 1.42 (95% confidence interval 1.02-1.98) for HOMA-IR 0.67-0.98, 1.20 (0.86-1.68) for HOMA-IR 0.99-1.49 and 1.44 (1.04-1.98) for HOMA-IR ≥1.50 after adjustment for baseline serum uric acid, creatinine, hypercholesterolemia and hypertension status, age, alcohol intake, and smoking and exercise habits. The hazard ratio associated with an increase of one standard deviation in lnHOMA-IR (1.85 as one geometric standard deviation of HOMA-IR) was 1.14 (1.03-1.28) (p for trend=0.02).

CONCLUSIONS

Increased HOMA-IR independently predicted the subsequent development of hyperuricemia. Insulin resistance itself or compensatory hyperinsulinemia may contribute to the development of hyperuricemia.

The crystallization of monosodium urate

Gout is a common crystal-induced arthritis, in which monosodium urate (MSU) crystals precipitate within joints and soft tissues and elicit an inflammatory response. The causes of elevated serum urate and the inflammatory pathways activated by MSU crystals have been well studied, but less is known about the processes leading to crystal formation and growth. Uric acid, the final product of purine metabolism, is a weak acid that circulates as the deprotonated urate anion under physiologic conditions, and combines with sodium ions to form MSU. MSU crystals are known to have a triclinic structure, in which stacked sheets of purine rings form the needle-shaped crystals that are observed microscopically. Exposed, charged crystal surfaces are thought to allow for interaction with phospholipid membranes and serum factors, playing a role in the crystal-mediated inflammatory response. While hyperuricemia is a clear risk factor for gout, local factors have been hypothesized to play a role in crystal formation, such as temperature, pH, mechanical stress, cartilage components, and other synovial and serum factors. Interestingly, several studies suggest that MSU crystals may drive the generation of crystal-specific antibodies that facilitate future MSU crystallization. Here, we review MSU crystal biology, including a discussion of crystal structure, effector function, and factors thought to play a role in crystal formation. We also briefly compare MSU biology to that of uric acid stones causing nephrolithasis, and consider the potential treatment implications of MSU crystal biology.

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.

Psoriasis, psoriatic arthritis and risk of gout in US men and women

BACKGROUND AND OBJECTIVE

Individuals with psoriasis have increased blood levels of uric acid. However, there is no prospective data on the association between psoriasis and uric acid levels and subsequent development of gout. In this study, we examined the risk of gout among individuals with psoriasis and psoriatic arthritis (PsA) in two cohorts of men and women, the Health Professionals Follow-up Study (HPFS) (1986-2010) and Nurses' Health Study (NHS) (1998-2010).

METHODS

27 751 men and 71 059 women were included in the analysis. Lifetime history of physician-diagnosed incident psoriasis and PsA was confirmed by validated supplementary questionnaires. Incident gout diagnoses were confirmed based on the American College of Rheumatology survey criteria. We used Cox proportional hazards models controlling for potential risk factors to calculate the HRs with 95% CIs of incident gout while simultaneously adjusting for several common risk factors.

RESULTS

We documented 2217 incident cases of gout during follow-up. Psoriasis was associated with an increased risk of subsequent gout with a multivariate HR of 1.71 (95% CI 1.36 to 2.15) in the pooled analysis. Risk of gout was substantially augmented among those with psoriasis and concomitant PsA (pooled multivariate HR: 4.95, 95% CI 2.72 to 9.01) when compared to participants without psoriasis.

CONCLUSIONS

In this prospective study of US women and men, psoriasis and PsA were associated with an increased risk of gout.

The degree of asymptomatic hyperuricemia and the risk of gout. A retrospective analysis of a large cohort

This study was conducted to examine the relationship between the degree of asymptomatic hyperuricemia and the development of gout, in men and women. The database of a screening center was searched for all subjects with asymptomatic hyperuricemia (>7.0 mg/dl men, >5.6 mg/dl women) during 2000-2012. We included men and women without previous diagnosis of gout, and a follow-up of at least 5 years. The risk of gout was analyzed in relation to the degree of hyperuricemia at the first visit. Of the 5,234 subjects who matched the inclusion criteria, 4,241 were normouricemic at their first visit and 993 were hyperuricemic. The mean follow up period was 7.5 years. Gout was diagnosed at the last visit in 34 subjects; four in the normouricemia group and 30 in the hyperuricemia group (0.1 % vs. 3.0 %, p < 0.001). Only one woman developed gout. The odds ratio (OR) for developing gout was 32 times higher in the hyperuricemic group than in the normouricemic group. The OR to develop gout was 11.2 (confidence interval [CI] 3.6-35.2) in men with mild hyperuricemia compared to 107.1 (CI 34.2-334.9) in men with moderate hyperuricemia, and 624.8 (CI 134.0-2,913.1) in men with severe hyperuricemia. Multivariate analysis of uric acid levels, thiazide use, regular alcohol consumption and estimated glomerular filtration rate (eGFR) showed that only the level of uric acid retained statistically significant for increasing the risk of gout. There is a strong association between the absolute level of uric acid and the risk to develop gout, strikingly so for men with severe hyperuricemia. Monitoring is recommended for that group, which poses the greatest risk to develop gout.