Uric acid levels and all-cause and cardiovascular mortality in the hemodialysis population

Impact of gout on in-hospital outcomes of acute coronary syndrome-related hospitalizations and revascularizations: Insights from the national inpatient sample

BACKGROUND

Previous studies have established a role of gout in predicting risk and prognosis of cardiovascular diseases. However, large-scale data on the impact of gout on inpatient outcomes of acute coronary syndrome (ACS)-related hospitalizations and post-revascularization is inadequate.

AIM

To evaluate the impact of gout on in-hospital outcomes of ACS hospitalizations, subsequent healthcare burden and predictors of post-revascularization inpatient mortality.

METHODS

We used the national inpatient sample (2010-2014) to identify the ACS and gout-related hospitalizations, relevant comorbidities, revascularization and post-revascularization outcomes using the ICD-9 CM codes. A multivariable analysis was performed to evaluate the predictors of post-revascularization in-hospital mortality.

RESULTS

We identified 3144744 ACS-related hospitalizations, of which 105198 (3.35%) also had gout. The ACS-gout cohort were more often older white males with a higher prevalence of comorbidities. Coronary artery bypass grafting was required more often in the ACS-gout cohort. Post-revascularization complications including cardiac (3.2% vs 2.9%), respiratory (3.5% vs 2.9%), and hemorrhage (3.1% vs 2.7%) were higher whereas all-cause mortality was lower (2.2% vs 3.0%) in the ACS-gout cohort (P < 0.001). An older age (OR 15.63, CI: 5.51-44.39), non-elective admissions (OR 2.00, CI: 1.44-2.79), lower household income (OR 1.44, CI: 1.17-1.78), and comorbid conditions predicted higher mortality in ACS-gout cohort undergoing revascularization (P < 0.001). Odds of post-revascularization in-hospital mortality were lower in Hispanics (OR 0.45, CI: 0.31-0.67) and Asians (OR 0.65, CI: 0.45-0.94) as compared to white (P < 0.001). However, post-operative complications significantly raised mortality odds. Mean length of stay, transfer to other facilities, and hospital charges were higher in the ACS-gout cohort.

CONCLUSION

Although gout was not independently associated with an increased risk of post-revascularization in-hospital mortality in ACS, it did increase post-revascularization complications.

Clinical Studies of Interventions to Mitigate Cardiovascular Risk in Peritoneal Dialysis Patients

Cardiovascular disease (CVD) is highly prevalent in the peritoneal dialysis (PD) population, affecting up to 60% of cohorts. CVD is the primary cause of death in up to 40% of PD patients in Australia, New Zealand, and the United States. Cardiovascular mortality rates are reported to be approximately 14 per 100 patient-years, which are 10- to 20-fold greater than those of age- and sex-matched controls. The excess risk of CVD is related to a combination of traditional risk factors (such as hypertension, dyslipidemia, obesity, smoking, sedentary lifestyle, and insulin resistance), nontraditional (kidney disease-related) risk factors (such as anemia, chronic volume overload, inflammation, malnutrition, hyperuricemia, and mineral and bone disorder), and PD-specific risk factors (such as dialysis solutions, glycation end products, hypokalemia, residual kidney function, and ultrafiltration failure). Interventions targeting these factors may mitigate cardiovascular risk, although high-level clinical evidence is lacking. This review summarizes the evidence relating to cardiovascular interventions targeting modifiable CVD risk factors in PD patients, as well as highlighting the key recommendations of the International Society for Peritoneal Dialysis Cardiovascular and Metabolic Guidelines.

Serum uric acid and cardiovascular mortality in chronic kidney disease: a meta-analysis

Background

Conflicting results have been reported from studies evaluating serum uric acid (SUA) levels as an independent risk factor for cardiovascular mortality in patients with chronic kidney disease (CKD).

Methods

We systematically searched MEDLINE, Web of Science, and bibliographies of retrieved articles to identify studies reporting on the association between SUA levels and cardiovascular mortality in patients with CKD. Random-effects models were used to calculate the pooled hazard ratios (HR) and corresponding 95% confidence intervals (CI).

Results

We included 11 studies with an overall sample of 27,081 patients with CKD in this meta-analysis. By meta-analysis, restricted to 7 studies (n = 11,050), patients with the highest SUA were associated with an increased risk of cardiovascular mortality (HR 1.47, 95% CI 1.11–1.96) compared with patients with the lowest SUA. There was no indication of publication bias or significant heterogeneity (I² = 40.4%; P = 0.109). Meta-analysis of 10 studies (n = 26,660) indicated that every 1 mg/dl increase in SUA levels increased a 12% risk in cardiovascular mortality (HR 1.12, 95% CI 1.02–1.24), with significant heterogeneity (I² = 79.2%, P < 0.001).

Conclusions

Higher SUA levels are associated with significantly increased risk of cardiovascular mortality in patients with CKD. More designed studies, especially randomized controlled trials, should be conducted to determine whether high SUA levels is a potentially modifiable risk factor for cardiovascular mortality in patients with CKD.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1143-7) contains supplementary material, which is available to authorized users.

Hyperuricemia - As a Pathogenetic and Independent Risk Factor in Relation to the Metabolic Syndrome

Introduction: The Metabolic Syndrome is considered at present as one of the most important causes of mortality and morbidity at world level. Even if the uric acid is not part of any definition of the Metabolic Syndrome, the actual studies have shown strong associations between uric acid concentration and the Metabolic Syndrome or its components, the role of Uric Acid within the Metabolic Syndrome (MS) being increasingly investigated.

Aims: We have analyzed recently published data that show the importance of hyperuricemia in MS, Cardiovascular Diseases, Chronic Kidney Disease.

Conclusions: Uric Acid (UA) is a central player in MS progression and in cardiorenal pathology, which is why a multidisciplinary approach and a correct treatment are required, in order to obtain multiple benefits and, possibly, in the future, new therapeutic guidelines in approaching MS.

Prognostic factors for in-hospital mortality of patients hospitalized for acutely decompensated heart failure

Objectives Despite improved treatment during last 20 years, prognosis for patients hospitalized for acutely decompensated heart failure (ADHF) is poor and mortality rates reported for these patients are high. Laboratory results can assist clinicians in evaluation and triaging of patients on hospital admission, and are important for the medical decision-making and prognosis assessments. Recently, new guidelines for the diagnosis and treatment of acute and chronic HF patients were published introducing a new group of patients with mid-range left ventricular ejection fraction (LVEF). Methods In order to explore the prognostic value for the in-hospital mortality of ADHF patients we analyzed laboratory test results for 165 emergency hospitalized patients regarding the survival and LVEF. Results In-hospital mortality was 16%. Patients who died were older than survivals (p = 0.003). There were no differences in LVEF between survivals and non-survivals. Patients who survived had significantly lower N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin T (hs-cTnT), uric acid, urea, creatinine, and red blood cell distribution width (RDW) than patients who died (p < 0.001). All these tests had a good discrimination power between survivals and non-survivals (p < 0.001), but their incremental addition to NT-proBNP didn't improve its overall prognostic value. There was only a very weak correlation between NT-proBNP concentrations and LVEF. Groups with different LVEF status showed significant difference in number of erythrocytes, RDW and hemoglobin concentrations. Conclusions NT-proBNP had the best discriminatory power between survivals and non-survivals. Some routine laboratory test results, like RDW, uric acid, urea, and creatinine, have potentially significant value.

Serum uric acid, protein intake and mortality in hemodialysis patients

Background

The association between serum uric acid (SUA) and mortality has been conflicting among studies using hemodialysis (HD) patients. Given the close link between purine and protein in foods, we hypothesized that normalized protein catabolic rate (nPCR), a dietary protein intake surrogate, modifies the SUA-mortality association in the HD population.

Methods

We identified 4298 patients who initiated HD and had one or more SUA measurement in a contemporary cohort of HD patients over 5 years (1 January 2007-31 December 2011), and examined survival probability according to the first uric acid measurement, adjusting for dialysis vintage, case-mix and malnutrition-inflammation complex-related variables.

Results

Mean SUA concentration was 6.6 ± 1.8 mg/dL. There was a consistent association of higher SUA with better nutritional status and lower all-cause mortality irrespective of adjusted models (Ptrend < 0.001). In the case-mix adjusted model, the highest SUA category (≥8.0 mg/dL) compared with the reference group (>6.0-7.0 mg/dL) showed no significant mortality risk [hazard ratio (HR) 0.90, 95% confidence interval (CI) 0.72-1.13], while the lowest category (<5.0 mg/dL) was associated with higher mortality (HR 1.42, 95% CI 1.16-1.72). The hypouricemia-mortality association was significantly modified by nPCR (Pinteraction = 0.001). Mortality risk of low SUA (<5.0 mg/dL) persisted among patients with low nPCR (<0.9 g/kg/day; HR 1.73, 95% CI 1.42-2.10) but not with high nPCR (≥0.9 g/kg/day; HR 0.99, 95% CI 0.74-1.33).

Conclusions

SUA may be a nutritional marker in HD patients. Contrary to the general population, low but not high SUA is associated with higher all-cause mortality in HD patients, especially in those with low protein intake. Nutritional features of SUA warrant additional studies.

Relationship between serum uric acid and mortality among hemodialysis patients: Retrospective analysis of Korean end-stage renal disease registry data

Background

It is thought that hyperuricemia might lower the risk of mortality among hemodialysis patients, unlike in the general population, but the evidence is controversial. The aim of the current study was to evaluate the impact of serum uric acid level on the long-term clinical outcomes of hemodialysis patients in Korea.

Methods

Retrospective analysis was performed on data from the End-Stage Renal Disease Registry of the Korean Society of Nephrology. This included data for 7,333 patients (mean age, 61 ± 14 years; 61% male) who received hemodialysis from January 2001 through April 2015. Initial laboratory data were used in the analysis.

Results

The mean serum uric acid level in this study was 7.1 ± 1.7 mg/dL. Body mass index, normalized protein catabolic rate, albumin, and cholesterol were positively correlated with serum uric acid level after controlling for age and sex. After controlling for demographic data, comorbidities, and residual renal function, a higher uric acid level was independently associated with a significantly lower all-cause mortality (hazard ratio [HR], 0.90 per 1 mg/dL increase in uric acid level; 95% confidence interval [CI], 0.83-0.97; P = 0.008), but not cardiovascular mortality (HR, 0.90; 95% CI, 0.80-1.01; P = 0.078). Comparing uric acid levels in the highest and lowest quintiles, the HR for all-cause mortality was 0.65 (95% CI, 0.42-0.99; P = 0.046).

Conclusion

Hyperuricemia was strongly associated with a lower risk of all-cause mortality, but there seems to be no significant association between serum uric acid level and cardiovascular mortality among Korean hemodialysis patients with end-stage renal disease.

Uric Acid and the Risks of Kidney Failure and Death in Individuals With CKD

BACKGROUND

Serum uric acid concentrations increase in chronic kidney disease (CKD) and may lead to tubular injury, endothelial dysfunction, oxidative stress, and intrarenal inflammation. Whether uric acid concentrations are associated with kidney failure and death in CKD is unknown.

STUDY DESIGN

Prospective observational cohort study.

SETTINGS & PARTICIPANTS

3,885 individuals with CKD stages 2 to 4 enrolled in the Chronic Renal Insufficiency Cohort (CRIC) between June 2003 and September 2008 and followed up through March 2013.

PREDICTOR

Baseline uric acid concentrations.

OUTCOMES

Kidney failure (initiation of dialysis therapy or transplantation) and all-cause mortality.

RESULTS

During a median follow-up of 7.9 years, 885 participants progressed to kidney failure and 789 participants died. After adjustment for demographic, cardiovascular, and kidney-specific covariates, higher uric acid concentrations were independently associated with risk for kidney failure in participants with estimated glomerular filtration rates (eGFRs) ≥ 45mL/min/1.73m² (adjusted HR per 1-standard deviation greater baseline uric acid, 1.40; 95% CI, 1.12-1.75), but not in those with eGFRs<30mL/min/1.73m². There was a nominally higher HR in participants with eGFRs of 30 to 44mL/min/1.73m² (adjusted HR, 1.13; 95% CI, 0.99-1.29), but this did not reach statistical significance. The relationship between uric acid concentration and all-cause mortality was J-shaped (P=0.007).

LIMITATIONS

Potential residual confounding through unavailable confounders; lack of follow-up measurements to adjust for changes in uric acid concentrations over time.

CONCLUSIONS

Uric acid concentration is an independent risk factor for kidney failure in earlier stages of CKD and has a J-shaped relationship with all-cause mortality in CKD. Adequately powered randomized placebo-controlled trials in CKD are needed to test whether urate lowering may prove to be an effective approach to prevent complications and progression of CKD.

Evaluation of the Effectiveness of Xanthine Oxidoreductase Inhibitors on Haemodialysis Patients using a Marginal Structural Model

A lower serum uric acid (UA) level has been associated with a higher mortality rate in haemodialysis patients. We investigated the long-term confounding factors of UA and mortality, and fitted a marginal structural model (MSM) based on the causal effect of xanthine oxidoreductase inhibitors (XORi). In total, 2429 patients on regular dialysis from April 2013 to March 2016 were included, and divided into quintiles by serum UA with Kaplan Meier (KM) curves and log rank analysis. Baseline characteristics were evaluated for relationships with all-cause mortality and cardiovascular disease (CVD) using the Cox hazard model. The MSM was used to control for time-dependent confounders of the XORi treatment effect. KM curves indicated that patients in the highest UA quintile had better outcomes than those in the lowest UA quintile. UA was not correlated with all-cause mortality or CVD events in the Cox model; however, the hazard ratio (HR) for mortality was 0.96 for the baseline administration of XORi. The MSM analysis for the effect of XORi treatment on all-cause mortality revealed a HR of 0.24 (95% confidence interval: 0.15-0.38) in all cohorts. These results suggest that XORi improved all-cause mortality in end-stage renal disease, irrespective of the serum UA level.

Association of serum uric acid level with coronary artery stenosis severity in Korean end-stage renal disease patients

Background

Hyperuricemia is common in end-stage renal disease (ESRD) patients, and many previous studies have reported the associations between hyperuricemia and adverse cardiovascular outcomes, which are the major cause of death in such patients. We investigated the relationship between serum uric acid level and the severity of coronary stenosis in ESRD patients on maintenance hemodialysis (MHD).

Methods

Among 721 patients who started MHD treatment, 102 underwent coronary angiographic tests complaining of chest discomfort that was new at initiation of MHD. We collected data on uric acid level and coronary artery luminal diameter, defining luminal diameter narrowing of more than 50% in any major coronary artery as critical-stenosis.

Results

We detected critical coronary artery stenosis in 52 (57.8%) patients. The mean uric acid level was 6.6 ± 2.2 mg/dL, and that was significantly higher in the critical-stenosis group (4.9 ± 1.4 mg/dL vs. 7.8 ± 2.0 mg/dL, P < 0.001). The only independent predictor of critical-stenosis in multivariate analysis was serum uric acid level (P < 0.001).

Conclusion

High serum uric acid was associated with severe coronary artery stenosis in Korean ESRD patients. Hyperuricemia is a readily modifiable factor, and appropriately preventing it could provide significant benefits in ESRD patients.

High Uric Acid Ameliorates Indoxyl Sulfate-Induced Endothelial Dysfunction and Is Associated with Lower Mortality among Hemodialysis Patients

High uric acid (UA) can act as a pro-oxidant in normal physiological conditions; however, emerging evidence is still debatable with regard to the association between high UA and poor outcomes among chronic hemodialysis (HD) patients. In the present study, 27,229 stable prevalent HD patients were enrolled and divided into four groups according to the quartiles of baseline UA concentration, and 5737 died during a median follow-up of 38 months. Multivariate Cox regression analysis showed that a UA level of <6.1 mg/dL was associated with a higher risk of all-cause mortality compared with a UA level of >8.1 mg/dL [HR, 1.20, 95% CI (1.10–1.31)] adjusting for baseline demographic and biochemical parameters. Moreover, a UA level of <6.1 mg/dL was associated with greater risks of cardiovascular mortality [HR, 1.26, 95% CI (1.13–1.41)] and stroke-related mortality [HR, 1.59, 95% CI (1.12–2.25)], respectively. In vitro experiments further showed an increase in oxidative stress and an inhibition nitric oxide synthesis by indoxyl sulfate (IS) in human aortic endothelial cells, which were significantly attenuated by UA in a dose-dependent manner. We concluded that higher UA in serum was associated with lower risk of all-cause and cardiovascular mortality among HD patients probably through its antioxidant property in ameliorating the IS-related vascular toxicity.

Management of secondary hyperparathyroidism: how and why?

Secondary hyperparathyroidism (SHPT) is a common complication in chronic kidney disease. Currently, various treatment options are available, including vitamin D receptor activators, cinacalcet hydrochloride, and parathyroidectomy. These treatment options have contributed to the successful control of SHPT, and recent clinical studies have provided evidence suggesting that effective treatment of SHPT leads to improved survival. Although bone disease is the most widely recognized consequence of SHPT and remains a major target for treatment of SHPT, there is increasing evidence that parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23), both of which are markedly elevated in SHPT, have multiple adverse effects on extraskeletal tissues. These actions may lead to the pathological development of left ventricular hypertrophy, renal anemia, immune dysfunction, inflammation, wasting, muscle atrophy, and urate accumulation. Given that treatment of SHPT leads to decreases in both PTH and FGF23, these data provide an additional rationale for treating SHPT. However, definitive evidence is still lacking, and future research should focus on whether treatment of SHPT prevents the adverse effects of PTH and FGF23.

A Comparative Study of Lipid Profile and Cardiovascular Risk Biomarkers Among Chronic Haemodialysis Patients and Healthy Individuals

INTRODUCTION

Lipid abnormalities and increase in inflammatory markers are common among patients with End Stage Renal Disease (ESRD) and it tends to persist/worsen even after initiating Intermittent Haemodialysis (IHD). The cardiovascular mortality and morbidity remains significantly high in this population.

AIM

The present study was carried out to assess the pattern of lipid abnormality in our population and to find its association with inflammatory markers.

MATERIALS AND METHODS

It was a cross-sectional, observational study on ESRD patients undergoing Haemodialysis (HD) in comparison with age and sex matched healthy individuals in a tertiary care hospital. About 40 adult male and female patients aged >18 years, undergoing chronic HD for more than 6 months were enrolled in Group A. Patients who were alcoholics, tobacco consumers and those on steroids and hypolipidemic drugs were excluded. Group B consisted of healthy, age and sex matched controls. Serum lipid profile, lipoprotein A, apolipoprotein A1, apolipoprotein B and apo B/A1 ratio, serum uric acid, homocysteine, hs-CRP and testosterone levels were estimated among patients undergoing intermittent HD and healthy individuals. Chi-square/Fisher's-exact test was used for comparing ratios. A p-value of <0.05 was considered statistically significant.

RESULTS

The mean Total Cholesterol (TC), Low Density Lipoprotein (LDL) and Non-HDL High Density Lipoprotein cholesterol was significantly lower in HD patients as compared to control group with all the three parameters attaining statistical significance (p<0.005). The mean lipoprotein A level was significantly higher (p=0.037), while Apo A1 was found to be significantly lower (p=0.001) in patients receiving HD. Inflammatory markers like uric acid was high (p<0.005) and serum testotsterone level in male HD patient was significantly low (p<0.005).

CONCLUSION

The mean values of traditional serum lipid profile remained lower in HD patients than the control group. The abnormalities in lipoprotein A and apolipoproteins were more pronounced in patients undergoing HD. The mean level of testosterone also was found to be lower in male patients receiving HD. Hence, estimation of lipoprotein A, apolipoproteins and inflammatory markers may serve as a potential tool in cardiovascular risk stratification.

Serum uric acid and mortality in chronic kidney disease: A systematic review and meta-analysis

BACKGROUND

Studies have shown inconsistent results about the association between serum uric acid levels and mortality in patients with chronic kidney disease (CKD).

METHODS

A systematic literature search in MEDLINE, Web of Science and bibliographies of retrieved articles was performed to identify studies investigating the association between serum uric acid and mortality in patients with CKD. Pooled hazard ratios (HR) and corresponding 95% confidence intervals (CIs) were calculated using random-effects models.

RESULTS

A total of 24 studies with 25,453 patients with CKD were included. By meta-analysis, patients with the highest serum uric acid level were associated with a significantly higher risk for mortality (14 studies; HR, 1.52; 95% CI, 1.33-1.73) compared with patients with the lowest serum uric acid level. For dose-response analysis, a linear relationship (8 studies; Pfor non-linearity=0.14) between serum uric acid levels and risk of mortality was found. Overall, an increase of 1mg/dl in serum uric acid level was associated with an 8% increased risk of mortality (21 studies; HR, 1.08; 95% CI, 1.04-1.11).

CONCLUSIONS

Elevated serum uric acid levels are significantly associated with risk of mortality in patients with CKD. Further randomized controlled trials should attempt to determine whether it improves survival to target serum uric acid in patients with CKD.

Longitudinal Study of Serum Uric Acid, Nutritional Status, and Mortality in Maintenance Hemodialysis Patients

BACKGROUND AND OBJECTIVES

We hypothesized that longitudinal changes in uric acid (UA) may have independent associations with changes in nutritional parameters over time and consequently, long-term survival of patients on maintenance hemodialysis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a retrospective, longitudinal cohort study of a clinical database containing the medical records of patients on maintenance hemodialysis receiving dialysis between June of 1999 and December of 2012 in a single center; 200 patients (130 men and 70 women) with a median age of 69.0 (interquartile range, 59.3-77.0) years old were included in the study. Dietary intake, biochemical markers of nutrition, anthropometric measurements, and UA levels were recorded at 0, 6, 12, 18, 24, 30, and 36 months followed by 15 additional months of clinical observations. The patients were followed until January 31, 2015 (median follow-up was 38.0 [interquartile range, 30.0-46.8] months).

RESULTS

In a linear mixed effects model adjusted for baseline demographics and clinical parameters, each 1.0-mg/dl longitudinal increase in UA was associated with a 13.4% slower rate of decline in geriatric nutritional risk index (GNRI) levels over 3 years of observation (95% confidence interval [95% CI], 0.11 to 0.39; P<0.001 for UA × time interaction). UA remained associated with the rate of change in GNRI, even after controlling for C-reactive protein. During the follow-up, 87 (43.5%) all-cause and 38 (19.0%) cardiovascular deaths were reported. For each 1.0-mg/dl increase in serum UA over time, the multivariate adjusted all-cause mortality hazard ratio using Cox models with the effect of time-varying risk was 0.83 (95% CI, 0.74 to 0.95; P<0.01), which continued to be significant, even after including the baseline GNRI levels in this model: 0.89 (95% CI, 0.79 to 0.98; P=0.02).

CONCLUSIONS

Longitudinal changes in serum UA seem to track with changes in nutritional status over time, and these changes are associated with survival of patients on maintenance hemodialysis. An increase in serum UA levels over time is accompanied by improvement of nutritional status and lower mortality rate.

Lower serum uric acid level predicts mortality in dialysis patients

We evaluated the impact of serum uric acid (SUA) on mortality in patients with chronic dialysis. A total of 4132 adult patients on dialysis were enrolled prospectively between August 2008 and September 2014. Among them, we included 1738 patients who maintained dialysis for at least 3 months and had available SUA in the database. We categorized the time averaged-SUA (TA-SUA) into 5 groups: <5.5, 5.5-6.4, 6.5-7.4, 7.5-8.4, and ≥8.5 mg/dL. Cox regression analysis was used to calculate the hazard ratio (HR) of all-cause mortality according to SUA group. The mean TA-SUA level was slightly higher in men than in women. Patients with lower TA-SUA level tended to have lower body mass index (BMI), phosphorus, serum albumin level, higher proportion of diabetes mellitus (DM), and higher proportion of malnourishment on the subjective global assessment (SGA). During a median follow-up of 43.9 months, 206 patients died. Patients with the highest SUA had a similar risk to the middle 3 TA-SUA groups, but the lowest TA-SUA group had a significantly elevated HR for mortality. The lowest TA-SUA group was significantly associated with increased all-cause mortality (adjusted HR, 1.720; 95% confidence interval, 1.007-2.937; P = 0.047) even after adjusting for demographic, comorbid, nutritional covariables, and medication use that could affect SUA levels. This association was prominent in patients with well nourishment on the SGA, a preserved serum albumin level, a higher BMI, and concomitant DM although these parameters had no significant interaction in the TA-SUA-mortality relationship except DM. In conclusion, a lower TA-SUA level <5.5 mg/dL predicted all-cause mortality in patients with chronic dialysis.

Febuxostat and Increased Dialysis as a Treatment for Severe Tophaceous Gout in a Hemodialysis Patient

Uric acid accumulates in renal failure and is thought to be a uremic toxin—that is, higher levels of uric acid are more damaging to the kidneys. Urate crystals can precipitate in the kidney tubules, cause urate stones, and promote inflammatory changes in the renal interstitium and vascular endothelium. Uric acid is also a small non-protein-bound molecule and therefore easily dialyzable. Here, we present the case of an anuric hemodialysis patient with severe tophaceous gout who regained some renal function and whose gout burden significantly decreased resulting in marked improvement in functional status using a new gout medication, febuxostat, and increased frequency of dialysis.

Serum uric acid and the risk of cardiovascular and renal disease

Substantial evidence suggests that chronic hyperuricemia is an independent risk factor for hypertension, metabolic syndrome, chronic kidney disease (CKD) and cardiovascular diseases. This highlights the need for greater attention to serum uric acid levels when profiling patients, and suggests that the threshold above which uricemia is considered abnormal is 6  mg/dl, in light of the available evidence. Another important question is whether lowering serum uric acid can improve cardiovascular and renal outcomes, and what therapeutic mechanism of action could provide more clinical benefits to patients; the available literature shows a trend toward improvement associated with administration of urate-lowering drugs, in particular for the xanthine oxidase inhibitors. The demonstrated efficacy of urate-lowering therapy on outcomes other than gout flares leads to the consideration that treatment may be beneficial even in the absence of overt gout when hyperuricemia accompanies other clinical conditions, such as urate deposition, advanced CKD or cardiovascular risk factors.

Serum uric acid predicts cardiovascular mortality in male peritoneal dialysis patients with diabetes

BACKGROUND AND AIMS

Serum uric acid may predict mortality in diabetic patients and dialysis patients. However, the relationship between serum uric acid and prognosis in diabetic peritoneal dialysis (PD) patients is unclear.

METHODS AND RESULTS

We conducted a cohort study of 1278 incident PD patients, (mean age 47.6 years), of which 328 (25.7%) had diabetes and 289 (22.6%) had diabetic nephropathy. During a median follow-up period of 30.7 months, 231 deaths occurred, of which 126 were ascribed to cardiovascular events. Mean serum uric acid was lower for diabetic patients than non-diabetic patients (6.8 ± 1.3 vs. 7.4 ± 1.4 mg/dL, respectively; P < 0.001). Cox regression models were adjusted for glycated hemoglobin, dialysis-related factors, traditional risk factors, and treatments. After adjustments, the highest sex-specific tertile of uric acid was associated with an increased risk of cardiovascular mortality (HR, 2.26; 95% CI, 1.14-4.48) compared to the lowest tertile in diabetic patients. Adjusted HRs per 1 mg/dL higher uric acid for all-cause and cardiovascular mortality were 1.09 (95% CI, 0.91-1.32) and 1.42 (95% CI, 1.13-1.79) for diabetic men and 1.06 (95% CI, 0.83-1.35) and 1.12 (95% CI, 0.78-1.61) for diabetic women, respectively. Elevated serum uric acid predicted a higher risk of all-cause and cardiovascular mortality in non-diabetic men but not in non-diabetic women.

CONCLUSIONS

Elevated serum uric acid is an independent predictor of cardiovascular mortality in diabetic male PD patients.

Switching from allopurinol to febuxostat: efficacy and tolerability in hemodialysis patients

Background

Febuxostat is a novel xanthine oxidase inhibitor. However, few studies have examined the long-term efficacy and tolerability of febuxostat after switching from allopurinol in hemodialysis (HD) patients. Therefore, the present study evaluated the long-term efficacy and tolerability of febuxostat in HD patients after switching from allopurinol.

Findings

We monitored the levels of hemoglobin, hematocrit, platelet count, blood urea nitrogen, serum creatinine, serum sodium, serum potassium, serum chloride, serum calcium, serum inorganic phosphorus, aspartate transaminase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, and total protein that were considered overall as a tolerability index, while the serum uric acid (UA) level was considered an index of efficacy. All values were measured at baseline and at 1, 6, 12, and 16 months after the switch to febuxostat therapy. All subjects switched from allopurinol (100 mg/day) to febuxostat (10 mg/day) in August 2013. Clinical laboratory data were collected at baseline in July 2013 until December 2014. Nine patients were included in the study analysis. Results showed that clinical laboratory data at baseline versus those at 16 months were not significantly different. Serum UA levels, which represented the efficacy index, were significantly different between the baseline level (6.8 ± 1.4) and those at 1, 6, 12, and 16 months (5.2 ± 1.1, 5.1 ± 1.1, 4.6 ± 0.9, and 5.4 ± 1.8 mg/dL, respectively; all p < 0.05).

Conclusion

Switching from allopurinol to febuxostat in HD patients reduced serum UA levels, with no changes in other clinical laboratory data in the long term.

Plasma Xanthine Oxidase Activity Is Predictive of Cardiovascular Disease in Patients with Chronic Kidney Disease, Independently of Uric Acid Levels

BACKGROUND

Chronic kidney disease (CKD) is associated with increased cardiovascular morbidity and mortality. Oxidative stress seems to play a pivotal role in this process, and purine metabolism may be involved in CKD-related oxidative stress. Xanthine oxidase (XO) is an enzyme involved in purine metabolism and is also responsible for the production of reactive oxygen species.

METHODS

This prospective study aimed to analyze the relation between plasma dosages of molecules involved in redox balance, purine metabolism and cardiovascular events in patients with non-diabetic CKD stages 3-5 or on chronic hemodialysis (HD). CKD (n = 51) and HD (n = 50) patients were compared to matched healthy controls (n = 38) and followed-up for 3 years.

RESULTS

Both CKD and HD patients had decreased plasma levels of antioxidants (selenium, zinc, vitamin C). HD patients had decreased levels of the antioxidant enzyme superoxide dismutase and increased levels of oxidation products (ischemia-modified albumin, malondialdehyde [MDA]). The following substrates and enzymes involved in purine metabolism were increased in the HD cohort: adenosine, adenosine deaminase and the pro-oxidant XO. XO activity was negatively correlated with super oxide dismutase and positively with MDA. Interestingly, XO activity was an independent predictor of cardiovascular events in CKD and HD patients, regardless of uric acid levels. Uric acid was not predictive of events.

CONCLUSION

This highlights a possible role of XO itself in CKD-related cardiovascular disease (CVD) and raises the hypothesis that beneficial effects observed with XO inhibitors on CVD in CKD may also be due to the reduction of oxidative stress.

Clinical implications and outcome prediction in chronic hemodialysis patients with lower serum potassium×uric acid product

BACKGROUND

The aims of this study were to evaluate correlations between serum potassium (S[K]) and uric acid (S[UA]) in hemodialysis patients and to determine whether lower levels of both S[K] and S[UA] were associated with poor long-term prognoses in these patients.

METHODS

A cohort of 424 maintenance hemodialysis patients (58±13 years of age; 47% male; 39% with diabetes) from a single center were divided into tertiles based on the product of S[K]×S[UA] (K×UA): Group 1: low K×UA: n=141; Group 2: median K×UA: n=141; and Group 3: high K×UA: n=142. The longest observation period was 60 months.

RESULTS

S[K] showed a positive linear correlation with S[UA] (r=0.33; p<0.001). In multivariate logistic regression analysis, Group 1 was characterized by hypoalbuminemia (odds ratio [OR]=0.20, 95% confidence interval (CI)=0.11-0.35) and lower levels of normalized protein catabolism [nPCR] (OR=0.10, 95%CI=0.05-0.22) and phosphate levels (OR=0.41, 95%CI=0.33-0.51). In contrast, Group 3 was associated with higher nPCR (OR=6.07, 95%CI=2.93-12.50) and albumin levels (OR=2.12, 95% CI=2.12-7.00). Compared to the reference (Group 1), the hazard ratio (HR) for long-term mortality was significantly lower in Groups 2 (HR=0.65, 95%CI=0.43-0.99) and 3 (HR=0.56, 95%CI=0.36-0.89). In multivariate Cox proportional analysis, the risk of mortality decreased by 2% (HR=0.98; 95%CI=0.96-0.99) per 1 unit increase in K×UA product.

CONCLUSION

Hemodialysis patients with lower S[K] and [UA] levels were characterized by hypoalbuminemia and lower nPCR, and they were associated with a long-term mortality risk.

The association between blood pressure level and serum uric acid concentration in hemodialysis patients

Background: High blood pressure is a common condition in hemodialysis patients. Uric acid, which is high in these patients due to decreased clearance, had been shown to positively correlate with blood pressure in animal studies.

Objectives: The goal of this investigation was to evaluate the impact of high uric acid level on blood pressure in these patients.

Patients and Methods: Ninety-one patients, on three times weekly hemodialysis, were studied. Uric acid levels were measured just before and after hemodialysis along with blood pressures before, during and after each session. Data were analyzed by SPSS 15. A P value less than 0.05 was considered significant.

Results: 40 (44%) of patients had serum uric acid ≥6 mg/dl. Before dialysis 51 (61%) and 19 (21%) had high systolic blood and diastolic blood pressures respectively. Also, 50 (55%) were with wide pulse pressure and 63 (69%) had high mean arterial pressure (MAP). Additionally 62 (68%) developed inter-dialysis hypotension. After measuring odds ratio for hyperuricemia in each group, we observed low risk of hypruricemia in the group with high systolic pressure (OR = 0.352; 95% CI: 0.147-0.844; P = 0.01), the high MAP group (OR = 0.382; 95% CI: 0.153-0.955; P = 0.03) and wide pulse pressure group (OR = 0.416; 95% CI: 0.177-0.975; P = 0.04). There was no association between high uric acid level and diastolic pressure (P = 0.11) and inter-dialysis hypotension (P = 0.33). No relationship was found between serum uric acid and KT/V (P = 0.2), normalized protein catabolic rate (nPCR) (P = 0.07) and body mass index (BMI) (P = 0.4).

Conclusions: This study showed paradoxical association between high uric acid level and high systolic pressure, high MAP and wide pulse pressure and these effects were independent of dialysis duration, dialysis efficacy and nutrition, assuming that these relationships could be due to reverse epidemiology in dialysis patients.

Colestilan for the treatment of hyperphosphatemia in chronic kidney disease patients on dialysis

Chronic kidney disease in the later stages poses many treatment challenges. Hyperphosphatemia is one that is well-known and is often linked to increased cardiovascular morbidity/mortality. Currently, a number of phosphate binders are available that act to conserve serum phosphate at normal or near normal levels. However, it is the overall profile of all binders that needs to be taken into account and the risks and the potential benefits associated with each agent must be balanced when selecting a particular phosphate binder. It is known that calcium-based binders, although effective phosphate binders, may lead to hypercalcemia and/or positive calcium balance and cardiovascular calcification. One, new non-calcium phosphate binder, recently approved in Europe, is colestilan. Colestilan possesses a range of properties that may afford further advantages over simply reducing serum phosphate. This review assesses the pharmacology and clinical data of colestilan used to treat hyperphosphatemia in chronic kidney disease stage 5 patients on dialysis. The article was written based on literature searches using PubMed to find articles published on phosphate binders or colestilan over the last 10 years.

Risk score to predict mortality in continuous ambulatory peritoneal dialysis patients

BACKGROUND

Patients with continuous ambulatory peritoneal dialysis (CAPD) have high all-cause mortality risk that varies extensively among different conditions. The objective of this study was to develop and validate risk models to predict the 2-year all-cause mortality risks of CAPD patients.

MATERIAL AND METHODS

A total of 1354 patients who received CAPD treatment > 3 months from a single dialysis centre were enrolled into the study from January 1, 2006 to December 31, 2011 and followed up until June 30, 2013. The dataset was randomly divided into the derivation dataset (2/3, n = 903) and the validation dataset (1/3, n = 451). Baseline information, including demographic characteristics, comorbid conditions and laboratory data, was recorded and included in the models. Risk models were developed using Cox proportional hazards regression. C-statistic, Akaike Information Criterion, Hosmer-Lemeshow χ(2) test and net reclassification improvement (NRI) were performed to evaluate model prediction and validation.

RESULTS

During the entire follow-up period, 175 (19·38%) and 85 (18·85%) patients died in the derivation and validation datasets respectively. A model that included age, diabetes mellitus, hypertension, cardiovascular disease, diastolic blood pressure, serum albumin, serum creatinine, phosphate, haemoglobin and fasting blood glucose demonstrated good discrimination in the derivation and validation datasets to predict 2-year all-cause mortality (C-statistic, 0·790 and 0·759, respectively). In the validation dataset, the above model performed good calibration (χ(2) = 2·08, P = 0·98) and NRI (7·37% compared with model 2, P = 0·05).

CONCLUSIONS

The risk model can accurately predict 2-year all-cause mortality in Chinese CAPD patients and external validation is needed in future.

Hyperuricemia and chronic kidney disease: an enigma yet to be solved

The role of uric acid (UA) on the pathogenesis and progression of chronic kidney disease (CKD) remains controversial. Experimental and clinical studies indicate that UA is associated with several risk factors of CKD including diabetes, hypertension, oxidative stress, and inflammation and hyperuricemia could be considered as a common dominator linking CKD and cardiovascular disease. Notably, the impact of serum UA levels on the survival of CKD, dialysis patients, and renal transplant recipients is also a matter of debate, as there are conflicting results from clinical studies. At present, there is no definite data whether UA is causal, compensatory, coincidental or it is only an epiphenomenon in these patients. In this article, we attempt to review and elucidate the dark side of this old molecule in CKD and renal transplantation.

Febuxostat for hyperuricemia in patients with advanced chronic kidney disease

Febuxostat is a nonpurine xanthine oxidase (XO) inhibitor, which recently received marketing approval. However, information regarding the experience with this agent among advanced chronic kidney disease (CKD) patients is limited. In the current study, we investigated the effects of oral febuxostat in patients with advanced CKD with asymptomatic hyperuricemia. We demonstrated, for the first time, that not only the serum levels of uric acid (UA) but also those of 8-hydroxydeoxyguanosine, an oxidative stress marker, were significantly reduced after six months of febuxostat treatment, with no adverse events. These results encouraged us to pursue further investigations regarding the clinical impact of lowering the serum UA levels with febuxostat in advanced CKD patients in terms of concomitantly reducing oxidative stress via the blockade of XO. More detailed studies with a larger number of subjects and assessments of the effects of multiple factors affecting hyperuricemia, such as age, sex, and dietary habits, would shed light on the therapeutic challenges of treating asymptomatic hyperuricemia in patients with various stages of CKD.

Serum uric acid as a clinically useful nutritional marker and predictor of outcome in maintenance hemodialysis patients

OBJECTIVE

The importance of serum uric acid (SUA) for the maintenance of a hemodialysis (MHD) population has not been well established. The aim of this study was to determine if SUA levels are associated with nutritional risk and consequently with adverse clinical outcomes in MHD patients.

METHODS

This was a 2-y prospective observational study, performed on 261 MHD outpatients (38.7% women) with a mean age of 68.6 ± 13.6 y. We measured prospective all-cause and cardiovascular (CV) hospitalization and mortality, nutritional scores (malnutrition-inflammation score [MIS) and geriatric nutritional risk index (GNRI), handgrip strength (HGS), and short-form 36 (SF36) quality-of-life (QoL) scores.

RESULTS

SUA positively correlated with laboratory nutritional markers (albumin, creatinine), body composition parameters, HGS (r = 0.26; P < 0.001) and GNRI (r = 0.34; P < 0.001). SUA negatively correlated with MIS (r = -0.33; P < 0.001) and interleukin-6 (r = -0.13; P = 0.04). Patients in the highest SUA tertile had higher total SF-36 scores (P = 0.04), higher physical functioning (P = 0.003), and role-physical (P = 0.006) SF-36 scales. For each 1 mg/dL increase in baseline SUA levels, the first hospitalization hazard ratio (HR) was 0.79 (95% confidence interval [CI], 0.68-0.91) and first CV event HR was 0.60 (95% CI, 0.44-0.82); all-cause death HR was 0.55 (95% CI, 0.43-0.72) and CV death HR was 0.55 (95% CI, 0.35-0.80). Associations between SUA and mortality risk continued to be significant after adjustments for various confounders including MIS and interleukin-6. Cubic spline survival models confirmed the linear trends.

CONCLUSIONS

In MHD patients, SUA is a good nutritional marker and associates with body composition, muscle function, inflammation, and health-related QoL, upcoming hospitalizations, as well as independently predicting all-cause and CV death risk.

Association between allopurinol and mortality among Japanese hemodialysis patients: results from the DOPPS

Purpose

Allopurinol, for treating hyperuricemia, is associated with lower mortality among hyperuricemic patients without chronic kidney disease (CKD). Greater allopurinol utilization in hemodialysis (HD) in Japan versus other countries provides an opportunity for understanding allopurinol-related HD outcomes.

Methods

Data from 6,252 Japanese HD patients from phases 1–3 of the Dialysis Outcomes and Practice Patterns Study (1999–2008) at ~60 facilities per phase were analyzed. Mortality was compared for patients prescribed (25 %) versus not-prescribed allopurinol using Cox regression, overall, and in patient subgroups.

Results

Patients prescribed allopurinol were more likely to be younger, male, and non-diabetic, and had higher serum creatinine and lower (treated) serum uric acid levels (mean = 7.0 vs. 8.0 mg/dL, p < 0.001). The inverse association between allopurinol prescription and mortality in unadjusted analyses (HR 0.65, 95 % CI 0.52–0.81) was attenuated by covariate adjustment (HR 0.84, 0.66–1.06). In subgroup analyses, allopurinol was associated with lower mortality among patients with no history of cardiovascular disease (CVD) (HR 0.48, 0.28–0.83), but not among patients with CVD (HR 1.00, 0.76–1.32). A similar pattern was seen outside Japan and for cardiovascular (CV)-related mortality.

Conclusions

Allopurinol prescription was not significantly associated with case-mix-adjusted mortality in Japanese HD patients overall, but was associated with lower all-cause and CV-related mortality in the subgroup of patients with no prior CVD history. These findings in HD patients may be related to findings in non-dialysis CKD patients showing lower CV event rates and mortality, and improved endothelial function with allopurinol prescription. These results are useful for designing future trials of allopurinol use in HD patients.

Serum uric acid level and cardiovascular risks in hemodialysis patients: an Algerian cohort study

Elevated Serum Uric Acid (SUA) was usually associated with an increased risk of cardiovascular events and mortality in general population. However, there are few reports concerning the clinical impact and the pathogenic role of Uric Acid (UA) in Hemodialysis (HD) patients. The aim of the study was to investigate the relationship between SUA and various Cardiovascular (CV) risk factors in HD patients. This retrospective; observational cohort study includes 45 HD patients with a mean age of 51.26+/-15.21 years. The differences of the CV risk factors between the patients according to their SUA levels were investigated. Age, Cardiovascular Diseases (CVD), increased creatinine, Fasting Blood Glucose (FBG), Corrected Calcium (cCa), Phosphate (P), cCa x P product and LDL cholesterol levels were associated with lower SUA levels, whereas higher SUA level was associated with Diabetes Mellitus (DM), hypertension and increased triglycerides level (p<0.01). In multiple regression analysis, history of diabetes (beta= 0.360, p<0.05), reduced corrected serum calcium (cCa) (beta = -1.456, p<0.01) and Phosphate (P) levels (beta= -1.752, p<0.01) were predictive of an increased SUA concentration. Despite from what has been demonstrated in the general population and DM patients, a lower SUA level in HD patients was associated with higher cardiovascular risk factors and high co-morbidity burden. Moreover, higher SUA concentrations may be cardioprotective in dialysis patients.

The associations of uric acid, cardiovascular and all-cause mortality in peritoneal dialysis patients

AIMS

To investigate whether uric acid (UA) is an independent predictor of cardiovascular (CV) and all-cause mortality in peritoneal dialysis (PD) patients after controlling for recognized CV risk factors.

METHODS

A total of 2264 patients on chronic PD were collected from seven centers affiliated with the Socioeconomic Status on the Outcome of Peritoneal Dialysis (SSOP) Study. All demographic and laboratory data were recorded at baseline. Multivariate Cox regression was used to calculate the hazard ratio (HR) of CV and all-cause mortality with adjustments for recognized traditional and uremia-related CV factors.

RESULTS

There were no significant differences in baseline characteristics between patients with (n = 2193) and without (n = 71) UA measured. Each 1 mg/dL of increase in UA was associated with higher all-cause mortality with 1.05(1.00∼1.10) of HR and higher CV mortality with 1.12 (1.05∼1.20) of HR after adjusting for age, gender and center size. The highest gender-specific tertile of UA predicted higher all-cause mortality with 1.23(1.00∼1.52) of HR and higher CV mortality with 1.69 (1.21∼2.38) of HR after adjusting for age, gender and center size. The predictive value of UA was stronger in patients younger than 65 years without CV disease or diabetes at baseline. The prognostic value of UA as both continuous and categorical variable weakened or disappeared after further adjusted for uremia-related and traditional CV risk factors.

CONCLUSIONS

The prognostic value of UA in CV and all-cause mortality was weak in PD patients generally, which was confounded by uremia-related and traditional CV risk factors.

Relationship between serum uric acid and all-cause and cardiovascular mortality in patients treated with peritoneal dialysis

BACKGROUND

Although serum uric acid level appears to be associated with mortality in individuals treated with hemodialysis, the relationship between serum uric acid level and death is uncertain in patients treated with peritoneal dialysis (PD).

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

985 patients from a single PD center in South China followed up for a median of 25.3 months.

PREDICTOR

Serum uric acid level.

OUTCOMES & MEASUREMENTS

The association of baseline sex-specific uric acid level with all-cause and cardiovascular mortality was evaluated. Models were adjusted for age, body mass index, comorbidity score, residual kidney function, total Kt/V, allopurinol and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use, and laboratory test results, including hemoglobin, serum albumin, creatinine, calcium, phosphorus, triglycerides, low-density lipoprotein cholesterol, and high-sensitivity C-reactive protein.

RESULTS

Mean age was 48.3±15.4 (SD) years, and 23% had diabetes. Mean uric acid level was 7.0±1.3 (range, 3.8-19.8) mg/dL. During follow-up, 144 deaths were recorded, of which 64 were due to cardiovascular events. In multivariable models, the highest sex-specific tertile of uric acid level was associated with increased risk of all-cause mortality (HR, 1.93; 95% CI, 1.27-2.93; P=0.004) and cardiovascular mortality (HR, 3.31; 95% CI, 1.70-6.41; P<0.001) compared to the lowest tertile. Adjusted Cox regression models showed that the HRs per 1-mg/dL higher uric acid level for all-cause and cardiovascular mortality were 1.33 (95% CI, 1.14-1.56; P<0.001) and 1.44 (95% CI, 1.17-1.77; P=0.001) for men and 1.03 (95% CI, 0.86-1.24; P=0.8) and 1.16 (95% CI, 0.97-1.38; P=0.1) for women, respectively. A formal test for interaction indicated that the association of uric acid level with all-cause and cardiovascular mortality differed by sex (β = -0.06 [P=0.02] and β = -0.10 [P=0.02], respectively).

LIMITATIONS

Single measurement of uric acid at baseline. Cause of death determined by death certificates and expert consensus.

CONCLUSIONS

Elevated serum uric acid level is an independent risk factor for all-cause and cardiovascular mortality in men treated with PD.

The kidney in hyperuricemia and gout

PURPOSE OF REVIEW

Gout is a painful inflammatory arthritis associated with hyperuricemia, with a prevalence of almost 10 million in the USA. Reduced renal excretion of urate is the underlying hyperuricemic mechanism in the vast majority of gout patients; most of the genes that affect serum urate level (SUA) encode urate transporters or associated regulatory proteins. Acquired influences can also modulate SUA and renal urate excretion, sometimes precipitating acute gout. Coincidentally, the prevalence of renal comorbidities in gout - hypertension, chronic kidney disease (CKD), and nephrolithiasis - is very high.

RECENT FINDINGS

Recent advances in genetics and molecular physiology have greatly enhanced the understanding of renal reabsorption and secretion of filtered urate. Moreover, baseline SUA appears to be set by the net balance of absorption and secretion across epithelial cells in the kidney and intestine. There have also been substantial advances in the management of gout in patients with CKD.

SUMMARY

The stage is set for an increasingly molecular understanding of baseline and regulated urate transport by the kidney and intestine. The increasing prevalence of gout with CKD will be balanced by an expanding spectrum of therapeutic options for this important disease.

Advanced kidney failure and hyperuricemia

Metabolic end products accumulate in kidney failure, including uric acid (UA), a terminal product of purine catabolism. Hyperuricemia (HUA) can cause gout and has been increasingly linked with cardiovascular (CV) morbidity and mortality, outcomes that are highly prevalent in patients with kidney disease. Serum UA levels rise as glomerular filtration declines, whereas the frequency of gouty attacks declines and the incidence of CV death rises precipitously. Herein, we review the kinetics of UA metabolism in CKD and dialysis and discuss the possible mechanisms of gout mitigation in kidney failure and the potential contribution of hyperuricemic milieu to CV outcomes in patients with kidney disease.

The rheumatology of gout

Gout is a metabolic disorder of purine metabolism with primary manifestations of acute and chronic arthritis and tophus formation. The prevalence of gout appears to be increasing and may affect up to 8 million people in the United States. The development of novel therapies for gout after a 40-year hiatus has opened new understanding of this disease. In addition to causing severe musculoskeletal pain, gout is associated with impaired quality of life, reduced functional status, and injury to joints. The quality of care for many patients with gout is unfortunately not in keeping with current guidelines. The approval of new therapies to treat hyperuricemia, such as febuxostat and pegloticase, has increased our knowledge of the challenges of adequately controlling the disease. Rather than providing a comprehensive overview of gout, this review focuses on new developments in the clinical aspects of gout and highlights advances in the drug therapy of gout.

The effects of mammalian target of rapamycin inhibitors on serum uric acid levels in renal transplant patients

BACKGROUNDS/AIMS

Elevated uric acid (UA) levels are frequently observed after renal transplantation. We investigated the consequences of shifting from calcineurin inhibitors (CNI) to mammalian target of rapamycin inhibitors (mTORi) on UA levels and graft functions.

METHODS

Ninety-six patients were enrolled. Main points of interest were changes in UA and glomerular filtration rate (GFR).

RESULTS

Mean age of the whole population was 39 ± 11 years (18-73), and 64.2 % were male. Patients were stratified into two groups according to their CNI type prior to the switch as cyclosporin A (CsA) or tacrolimus (Tac). Patients that were switched from CsA had a mean GFR of 49 ± 18 ml/min and serum UA level of 7.4 ± 1.8 mg/dl at the pre-switch period. Mean GFR increased to 53 ± 22 ml/min (p = 0.03), and UA levels decreased to 6.2 ± 1.6 mg/dl at the final visit (p < 0.001). In the Tac group, pre-switch mean GFR was 59 ± 28 ml/min and serum UA level 6.6 ± 2.6 mg/dl. In this group, mean GFR increased to 63 ± 28 ml/min (p = 0.03) and UA levels decreased to 6.2 ± 2.1 at the last visit (p < 0.001).

CONCLUSION

Switch from CNI to mTORi-based regimen provides better control of UA levels and improves renal functions.