Serum uric acid does not predict cardiovascular or all-cause mortality in type 2 diabetes: the Fremantle Diabetes Study

Independent and conjoint associations of gout and hyperuricaemia with total and cardiovascular mortality

BACKGROUND

Gout and serum uric acid are associated with mortality but their simultaneous contributions have not been fully evaluated in the general population.

PURPOSE

To explore the independent and conjoint relationships of gout and uric acid with mortality in the US population.

METHODS

Mortality risks of gout and serum uric acid were determined for 15 773 participants, aged 20 years or older, in the Third National Health and Nutrition Examination Survey by linking baseline information collected during 1988-1994 with mortality data up to 2006. Multivariable Cox proportional hazards regression determined adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each exposure and all analyses were conducted in 2011 and 2012.

RESULTS

Compared with subjects without a history of gout, the multivariable HR for subjects with gout were 1.42 (CI 1.12-1.82) for total and 1.58 (CI 1.13-2.19) for cardiovascular mortality. Adjusted HRs per 59.5 µmol/l (1 mg/dl) increase in uric acid were 1.16 (CI 1.10-1.22) for total and cardiovascular mortality and this pattern was consistent across disease categories. In the conjoint analysis, the adjusted HRs for mortality in the highest two uric acid quartiles were 1.64 (CI 1.08-2.51) and 1.77 (CI 1.23-2.55), respectively, for subjects with gout, and were 1.09 (CI 0.87-1.37) and 1.37 (CI (1.11-1.70), respectively, for subjects without gout, compared with those without gout in the lowest quartile. A similar pattern emerged for cardiovascular mortality.

CONCLUSION

Gout and serum uric acid independently associate with total and cardiovascular mortality. These risks increase with rising uric acid concentrations.

Association of serum uric acid and cardiovascular disease in healthy adults

Studies in different populations with high risk for cardiovascular disease (CVD) have shown an association between serum uric acid (SUA) and CVD. However, only a few studies have demonstrated such an association in healthy populations. The aim of this study was to investigate the association between SUA and CVD in a cohort of men and women without diabetes or CVD. A retrospective study was conducted, with a mean 4.8-year follow-up. The outcome was the occurrence of a cardiovascular event, defined as the diagnosis of ischemic heart disease, acute coronary syndrome, acute myocardial infarction, or ischemic stroke. Mean SUA levels were 6.2 ± 1.1 mg/dl for men (n = 6,580) and 4.4 ± 1.1 mg/dl for women (n = 2,559). For women, the rate of CVD occurrence was 11.6% for the highest quartile of SUA level, compared with 5.0% to 6.5% for the lower 3 quartiles. For men, the rate of CVD occurrence was 14.0% for the highest quartile of SUA level, compared with 10.8% for the lowest quartile. The hazard ratio for CVD, adjusted for age, serum creatinine level, body mass index, systolic blood pressure, low-density lipoprotein cholesterol level, triglyceride level, plasma fasting glucose, physical activity, cardiovascular family history, use of diuretics, and current smoking, was 1.24 (95% confidence interval 1.08 to 1.41) for women and 1.06 (95% confidence interval 1.00 to 1.13) for men (p for interaction = 0.04). In conclusion, the strong association of SUA levels with CVD in women, compared with the much lesser degree in men, highlights the necessity of stratifying by gender in investigations of cardiovascular risk factors and supports exploration of SUA as a marker of CVD risk in healthy populations.

Uric acid as a risk factor for cardiovascular disease and mortality in overweight/obese individuals

Background

The predictive value of serum uric acid (SUA) for adverse cardiovascular events among obese and overweight patients is not known, but potentially important because of the relation between hyperuricaemia and obesity.

Methods

The relationship between SUA and risk of cardiovascular adverse outcomes (nonfatal myocardial infarction, nonfatal stroke, resuscitated cardiac arrest or cardiovascular death) and all-cause mortality, respectively, was evaluated in a post-hoc analysis of the Sibutramine Cardiovascular OUTcomes (SCOUT) trial. Participants enrolled in SCOUT were obese or overweight with pre-existing diabetes and/or cardiovascular disease (CVD). Cox models were used to assess the role of SUA as an independent risk factor.

Results

9742 subjects were included in the study; 83.6% had diabetes, and 75.1% had CVD. During an average follow-up time of 4.2 years, 1043 subjects had a primary outcome (myocardial infarction, resuscitated cardiac arrest, stroke, or cardiovascular death), and 816 died. In a univariate Cox model, the highest SUA quartile was associated with an increased risk of cardiovascular adverse outcomes compared with the lowest SUA quartile in women (hazard ratio [HR]: 1.59; 95% confidence interval [CI]: 1.20–2.10). In multivariate analyses, adjusting for known cardiovascular risk factors the increased risk for the highest SUA quartile was no longer statistically significant among women (HR: 0.99; 95% CI: 0.72–1.36) nor was it among men. Analyses of all-cause mortality found an interaction between sex and SUA. In a multivariate Cox model including women only, the highest SUA quartile was associated with an increased risk in all-cause mortality compared to the lowest SUA quartile (HR: 1.51; 95% CI: 1.08–2.12). No relationship was observed in men (HR: 1.06; 95% CI: 0.82–1.36).

Conclusion

SUA was not an independent predictor of cardiovascular disease and death in these high-risk overweight/obese people. However, our results suggested that SUA was an independent predictor of all-cause mortality in women.

Uric acid levels, even in the normal range, are associated with increased cardiovascular risk: the Guangzhou Biobank Cohort Study

OBJECTIVE

To examine the association between serum uric acid (UA) levels and cardiovascular risk factors in subjects without diabetes or hyperuricemia.

METHODS

6172 women and 2662 men aged 50+ years without diabetes from Phase 1 of the Guangzhou Biobank Cohort Study were included. Data on personal history, physical examination and biochemical parameters were collected. Subjects were categorized by serum UA concentration, and the association between UA levels and cardiovascular risk factors was examined using generalized linear models.

RESULTS

In both men and women with normouricemia (UA<420 μmol/l in men and <360 μmol/l in women), tertiles of UA levels were adversely associated with body mass index, waist circumference, waist-to-hip ratio, total- and HDL-cholesterol, apolipoprotein A1, systolic and diastolic blood pressures, pulse pressure, fasting plasma glucose and white blood cell count (P value for trend ranged from 0.04 to <0.001), and also consistently associated with metabolic disorders including obesity, hypertension, hypertension treatment, dyslipidemia, waist circumference increased since the age of 18 years and the metabolic syndrome (P value for trend ranged from 0.02 to <0.001).

CONCLUSION

Increasing UA levels, even in subjects with normouricemia and without diabetes, were associated with increasing prevalence of cardiovascular risk factors, suggesting that clinically dichotomous definition of hyperuricemia may be inadequate and high-normal value of UA may warn of metabolic disorders.

Prognostic value of uric acid in patients with Type 2 diabetes mellitus and coronary artery disease

Studies investigating the prognostic role of UA (uric acid) in patients with Type 2 diabetes mellitus have given conflicting findings. We undertook the present study to assess the association between UA and outcome in patients with Type 2 diabetes mellitus and CAD (coronary artery disease). The study included 3705 patients with diabetes mellitus and angiography-proven CAD. UA was measured before coronary angiography. The primary outcome was 1-year all-cause mortality. The UA concentration [median (25th–75th quartiles)] was 6.44 mg/dl (5.40–7.70 mg/dl). There were 264 deaths (7.1%) during follow-up: 45 deaths in patients of the first UA quartile, 43 deaths in patients of the second UA quartile, 51 deaths in patients of the third UA quartile and 125 deaths in patients of the fourth UA quartile {Kaplan–Meier estimates of mortality, 5.1, 4.8, 5.6 and 14.0% respectively; unadjusted HR (hazard ratio), 2.81 [95% CI (confidence interval), 2.21–3.58]; P<0.001 for fourth quartile compared with first–third quartiles combined}. In the multivariable analysis, UA predicted all-cause mortality with an adjusted HR of 1.29 (95% CI, 1.12–1.48; P<0.001), for each S.D. increase in the logarithmic scale of UA level. The inclusion of UA in the multivariable model alongside known cardiovascular risk factors and other relevant variables increased the discriminatory power of the model regarding prediction of all-cause mortality [absolute and relative IDI (integrated discrimination improvement) 0.034 and 20.5% respectively; P<0.001]. In conclusion, in patients with Type 2 diabetes mellitus and confirmed CAD, elevated levels of UA predict mortality independently of known cardiovascular risk factors.

An initial reduction in serum uric acid during angiotensin receptor blocker treatment is associated with cardiovascular protection: a post-hoc analysis of the RENAAL and IDNT trials

OBJECTIVE

Increased levels of serum uric acid (SUA) are thought to be an independent risk marker for cardiovascular complications. Treatment with the angiotensin receptor blocker (ARB) losartan lowers SUA in contrast to other ARBs. Whether reductions in SUA during ARB therapy are associated with cardiovascular protection is unclear. We aimed to investigate this.

METHOD

In a post-hoc analysis of the Reduction of Endpoints in Non insulin dependent diabetes mellitus with the Angiotensin II Antagonist Losartan (RENAAL) and Irbesartan Diabetic Nephropathy (IDNT) trials we determined whether the short-term effect of losartan and of irbesartan on SUA is related with long-term cardiovascular outcome by means of Cox regression.

RESULTS

Compared to placebo, losartan significantly changed SUA [-0.16  mg/dl; 95% confidence interval (CI) -0.01 to -0.30; P = 0.031], whereas irbesartan did not (-0.09  mg/dl; (95% CI 0.09 to -0.28; P = 0.30). Each 0.5  mg/dl decrement in SUA during losartan treatment in the first 6 months resulted in a reduction in the risk of cardiovascular outcomes by 5.3% (95% CI 0.9 to 9.9; P = 0.017). Losartan reduced the risk of cardiovascular outcomes by 9.2% (95% CI -7.9 to 23.6). Adjustment for the 6-month change in SUA attenuated the treatment effect to 4.6% (95% CI -16.2 to 22.0), suggesting that part of the cardiovascular protective effect of losartan is attributable to its short-term effect on SUA.

CONCLUSION

Losartan but not irbesartan significantly lowers SUA compared to placebo in patients with type 2 diabetes and nephropathy. The degree of reduction in SUA explains part of the cardiovascular effect of losartan. This supports the hypothesis that SUA is a modifiable risk factor for cardiovascular disease, at least in type 2 diabetics with nephropathy.

The role of serum uric acid in cardiovascular disease in type 2 diabetic and non-diabetic subjects: a narrative review

The role of serum uric acid (UA) as a marker or risk factor of cardiovascular disease (CVD) is still controversial. The strong association of serum UA with established risk factors such as hypertension, Type 2 diabetes, dyslipidemia, and chronic kidney disease makes it difficult to establish a direct causal role of serum UA in the development and progression of CVD. The main aims of this review are: 1) to briefly summarize the most relevant studies concerning the association of serum UA with hypertension, chronic kidney disease, CVD events, and death both in patients without diabetes and in those with Type 2 diabetes; and 2) to briefly discuss the putative underlying mechanisms that link serum UA to adverse CVD outcomes. A search was conducted to identify relevant studies in the major electronic databases (MEDLINE and EMBASE, from January 1990 to December 2010) using Medical Subjects Headings and keywords. Collectively, by reviewing the published data in the literature, it emerges that serum UA may exert a number of potentially adverse cardiovascular effects. Nevertheless, the prognostic role of elevated serum UA level as a causal risk factor of adverse CVD outcomes remains still controversial, especially in patients with Type 2 diabetes. At this time, the treatment of asymptomatic hyperuricemia for the primary prevention of CVD is not recommended.

Hyperuricemia is independently associated with coronary heart disease and renal dysfunction in patients with type 2 diabetes mellitus

AIMS

To investigate the relationship between hyperuricemia (HUA) and the clinical backgrounds in Japanese patients with type 2 diabetes mellitus.

METHODS

After a cross-sectional study evaluating the association of HUA with the clinical characteristics in 1,213 patients with type 2 diabetes mellitus, the estimated glomerular filtration rate (eGFR) and the incidence of diabetic macroangiopathies was investigated in a prospective observational study in 1,073 patients during a 3.5 year period. HUA was defined by serum uric acid levels >327 μmol/L or as patients using allopurinol.

RESULTS

The frequency of HUA was significantly higher in the diabetic patients (32% in men and 15% in women) than in the normal controls (14% in men and 1% in women). In total, HUA was found in 299 (25%) of the patients during the cross-sectional study. Even after adjusting for sex, drinking status, treatment for diabetes mellitus, body mass index, hypertension, use of diuretics, hyperlipidemia, HbA1c and/or the eGFR, the HUA was independently associated with some diabetic complications. The eGFR was significantly reduced in HUA patients compared to those with normouricemia in the 12 months after observation was started. HUA was also an independent risk factor for coronary heart disease even after adjustment in the Cox proportional hazard model.

CONCLUSIONS

HUA is a associated with diabetic micro- and macroangiopathies. HUA is a predictor of coronary heart disease and renal dysfunction in patients with type 2 diabetes mellitus. However, the influence of HUA is considered to be limited.

Uric acid and mortality from all-causes and cardiovascular disease among adults with and without diagnosed diabetes: findings from the National Health and Nutrition Examination Survey III Linked Mortality Study

Using data from the National Health and Nutrition Examination Survey III Linked Mortality Study, uric acid concentration was significantly related to mortality from all-causes (978 diabetic participants: hazard ratio per mg/dl, 1.14; 95% confidence interval, 1.01-1.28; 12,824 nondiabetic participants: hazard ratio, 1.06; 95% confidence interval, 1.02-1.11) but not major CVD.