Serum uric acid and risk of prehypertension: a dose-response meta-analysis of 17 observational studies of approximately 79 thousand participants

BACKGROUND

Studies examining the association between levels of serum uric acid (SUA) and risk of prehypertension still remained controversial conclusions. Also, a quantitative assessment of the dose-response association between them has not been reported. We aimed to quantitatively evaluate risk of prehypertension with levels of SUA based on observational study.

METHODS

We searched the PubMed, Embase, and Web of Science databases up to December 3, 2019 for relevant studies. Pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random-effects models. The possible linear or non-linear SUA-prehypertension association was modelled by restricted cubic splines.

RESULTS

We included 17 articles (17 studies) with a total of 79,358 participants and 34,591 cases of prehypertension. Compared with lowest levels of SUA, risk of prehypertension increased 46% (RR 1.46, 95% CI 1.28-1.66) for highest levels of SUA. For per 1 mg/dL increment in levels of SUA, risk of prehypertension increased by 12% (RR 1.12, 95% CI 1.08-1.17). Also, we found evidence of a linear SUA-prehypertension association (P_{non-linearity}=.368).

CONCLUSION

Elevated levels of SUA may be associated with increased risk of prehypertension. Present findings provide the evidence that lowering levels of SUA should be suggested in order to reduce the risk of prehypertension. More longitudinal and intervention studies are needed to clarify the optimal protective levels and whether reducing levels of SUA could prevent or control prehypertension and the progression of prehypertension to hypertension.

Age and sex dependent association of uric acid and incident hypertension

BACKGROUND AND AIMS

A previous meta-analysis suggested that the relationship between hyperuricemia and hypertension may be stronger in younger individuals and women. We aimed to investigate the age and sex dependent association of uric acid (UA) and incident hypertension.

METHODS AND RESULTS

We analyzed data from the Health Examinees Study, a community-based prospective cohort study conducted in Korea from 2004 to 2013. It included 29,088 non-hypertensive subjects aged 40-79 (age, 52.5 ± 7.8 years; men, 31.4%) who had serum UA measurement and participated in the follow-up survey. The risk factors of hypertension were assessed using Cox regression. Over a mean 3.8 years of follow-up, 1388 men (15.2%) and 1942 women (9.7%) were newly diagnosed with hypertension. Upon age- and sex-based stratification, the risk of hypertension was highest in hyperuricemic subjects aged 40-49 years (HR: women, 2.16; men, 1.30). Across the entire cohort, the risk of incident hypertension was higher in groups with higher serum UA levels, and highest in women aged 40-49 years (HR, 1.44; P < 0.001). On multivariable linear regression analysis, the higher the baseline serum UA level, the greater the increase in blood pressure during follow-up, and this effect was strongest in women aged 40-49 years (β = 0.87 and P < 0.01 for systolic blood pressure).

CONCLUSIONS

The relationship between uric acid and incident hypertension tended to be dependent on age and sex. Younger women are at highest risk of UA-related incident hypertension.

Baseline and change in serum uric acid predict the progression from prehypertension to hypertension: a prospective cohort study

Evidence is lacking about the role of serum uric acid (SUA) in the progression from prehypertension to hypertension. Herein, we aimed to investigate the association of both baseline and dynamic change in SUA with the risk of hypertension developing from prehypertension. The study enrolled 11,488 participants with prehypertension during 2006-2010 from the Kailuan study. Change in SUA was assessed as % change of SUA from 2006 (baseline) to 2010. Participants were categorized into four groups by quartiles of baseline and change in SUA, separately. Multivariable logistic regressions were used to calculation the odds ratio (OR) and 95% confidence interval (CI). During a median follow-up of 7.06 years, 2716 (23.64%) participants developed hypertension from prehypertension. In the multivariable-adjusted model, the OR for hypertension comparing participants in the highest versus the lowest quartile of baseline SUA were 1.18 (95% CI, 1.02-1.36). Increased SUA over time was also associated with elevated risk of hypertension (OR in the highest quartile was 1.41 [95% CI, 1.23-1.62] versus the lowest quartile), especially in those with baseline SUA ≥ median (OR, 1.48; 95% CI, 1.21-1.81). Moreover, the addition of SUA to a conventional risk model had an incremental effect on the predictive value for hypertension (integrated discrimination improvement 0.30%, P < 0.0001; category-free net reclassification improvement 12.36%, P < 0.0001). Both high initial SUA and increased SUA over time can independently predict the progression from prehypertension to hypertension. Strategies aiming at controlling SUA level in prehypertensive subjects may impede the onset of hypertension.

Uric Acid and Hypertension: Prognostic Role and Guide for Treatment

The relationship between serum uric acid (SUA) and hypertension has been a subject of increasing interest since the 1870 discovery by Frederick Akbar Mahomed. Several epidemiological studies have shown a strong association between high SUA levels and the presence or the development of hypertension. Genetic analyses have found that xanthine oxidoreductase (XOR) genetic polymorphisms are associated with hypertension. However, genetic studies on urate transporters and Mendelian randomization studies failed to demonstrate a causal relationship between SUA and hypertension. Results from clinical trials on the role of urate-lowering therapy in the management of patients with hypertension are not uniform. Our study sought to analyze the prognostic and therapeutic role of SUA in the hypertensive disease, from uric acid (UA) biology to clinical trials on urate-lowering therapies.

Association of serum uric acid, morning home blood pressure and cardiovascular risk factors in a population with previous prehypertension: a cross-sectional study

OBJECTIVE

To observe the changes in blood pressure (BP) over 10 years and to investigate current BP association to serum uric acid (SUA) levels and cardiovascular risk factors in the epidemiological data of a target group of patients with prehypertension in 2007.

DESIGN

Cross-sectional study.

SETTING

Mlati Subdistrict, Sleman District, Yogyakarta Province, Indonesia.

PARTICIPANTS

A total of 733 patients from 'Mlati Study Database' in 2007 were selected by simple random sampling using statistical software. Subjects had both physical and laboratory examinations.

OUTCOME MEASURES

Morning home BP and laboratory examination of urine (uric acid excretion and creatinine) and blood samples (SUA, blood urea nitrogen, creatinine, a lipid profile and fasting blood glucose levels).

RESULTS

About 31.1% of 733 subjects with prehypertension became hypertensive after 10 years, 24.6% returned to normal tension and the rest of it remained in prehypertensive state. Mean (SD) of SUA levels in 2017 was significantly higher in men than in women (5.78 (1.25) mg/dL vs 4.52 (1.10) mg/dL, p<0.001). Furthermore, men tended to have high-normal (5-7 mg/dL) or high SUA levels (≥7 mg/dL) compared with women (p<0.001, Relative Risk (RR)=2.60). High-normal and high SUA levels in population with a history of prehypertension were significantly associated with current prehypertension and hypertension only in women (p=0.001, RR=1.21). Age and body mass index was found to be significantly associated with both systolic and diastolic BP in men, but only with systolic BP in women. Fasting blood glucose and SUA levels were significantly associated with systolic and diastolic BP only in women.

CONCLUSION

We concluded that after 10 years, of 733 subjects with prehypertension, 31.1% became hypertensive. The SUA levels in men are significantly higher than those in women. Moreover, high-normal and high SUA levels were significantly associated with prehypertension and hypertension in women but not in men.

The interaction between serum uric acid and triglycerides level on blood pressure in middle-aged and elderly individuals in China: result from a large national cohort study

Background

The purpose of the research was to explore the extent of interaction between triglycerides (TG) and serum uric acid (SUA) level with blood pressure (BP) in middle-aged and elderly individuals in China.

Methods

Data were selected from the China Health and Retirement Longitudinal Study (CHARLS), a cross-sectional study. 3345(46.99%) men with average ages of 60.24 ± 9.24 years and 3774 (53.01%) women with average ages of 59.91 ± 9.95 years were included in the study. Differences between gender, or between categories of blood pressure levels were evaluated by t-test or chi-square test. The adjusted associations between various characteristics and BP status were first compared using linear regression models, as appropriate. Then, A general linear model adjusted for confounding factors (socio-demographic characteristics [age, educational levels, marital status, place of residence], health behaviors [cigarette smoking, alcohol drinking, eating habits, social and leisure activities, accidental injury, physical activities], medical history [history of cardiovascular diseases, hepatitis history, antidiabetic drugs, history of antilipidemic medication, anti-hypertensive therapy], metabolic measures [C-reactive protein (CRP), hemoglobin A1c (HbA1c), fasting plasma glucose (FPG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), estimated glomerular filtration rate (eGFR), body mass index (BMI)]) was used to examine the synergistic effect of SUA and TG level on BP in middle-aged and elderly individuals in China.

Results

Age-adjusted partial Pearson’s correlation coefficient showed that SUA and TG level positively correlated with both systolic blood pressure (SBP) and diastolic blood pressure (DBP) in both men and women. Multiple linear regression analysis showed the TG level was significantly and positively associated with SBP and DBP in both men (SBP: β =0.068, P = 0.001; DBP: β =0.064, P = 0.002) and women (SBP: β =0.061, P = 0.002; DBP: β =0.084, P = 0.000), but SUA were significantly and positively associated with SBP in both men (SBP: β =0.047, P = 0.013) and women (SBP: β =0.040, P = 0.028), regardless of other confounding factors. After adjusting for related potential confounders, evidence of interaction between SUA and TG level on SBP (men: β = − 1.090, P = 0.726; women: β = − 0.692, P = 0.861) and DBP (men: β = − 1.026, P = 0.572; women: β = − 0.794, P = 0.842) was not observed.

Conclusion

The interaction effect of SUA and TG level on BP was not observed in our study. Moreover, high SUA level was significantly associated with SBP, while high TG level was strongly related to both DBP and SBP.

Body mass index and serum uric acid level: Individual and combined effects on blood pressure in middle-aged and older individuals in China

Few studies on the individual and combined analysis between serum uric acid (SUA) and body mass index (BMI) and blood pressure (BP) were conducted in individuals aged ≥45 years. We aimed to assess the extent to which BMI and SUA and their interaction affect BP in Chinese middle-aged and older adults.Data were selected from the China Health and Retirement Longitudinal Study (CHARLS). A total of 5888 individuals aged 45 to 96 was included. Differences between BMI, or between categories of blood pressure were evaluated by t test or chi-square test. The trend of related variables according to four BMI categories was also tested using contrast analysis. The adjusted associations between various characteristics and BP status were first compared using linear regression models, as appropriate. Then, general linear models adjusting for related potential confounders were used to examine the synergistic effect of SUA and BMI level on BP for middle-aged and elderly individuals in China.Age-adjusted partial Pearson correlation coefficient showed that BMI was significantly and positively correlated with BP both in male and female, SUA positively correlated with both systolic blood pressure (SBP) and diastolic blood pressure (DBP) in males with BMI <24.0 kg/m and females with BMI <24.0 kg/m. However, SUA level significantly and positively correlated with DBP, but not with SBP, in females with BMI ≥24.0 kg/m. Multiple linear regression analysis showed that BMI was independently associated with BP both in male and female, SUA significantly and positively associated with SBP in both males and females with BMI <24.0 kg/m, However, SUA level positively correlated with DBP in females with BMI <24.0 kg/m, but not with males with BMI <24.0 kg/m, independent of other confounding factors. A general linear model analysis adjusted for confounding factors did not reveal interaction between BMI, SUA levels and SBP (β=-1.404, P = .686 in males; β=-2.583, P = .575 in females) and DBP (β=-2.544, P = .263 in males; β=-2.619, P = .622 in females).No interaction between BMI, SUA levels, and BP was observed in either males or females; However, BMI was independently associated with BP both in male and female, SUA independently associated with SBP both in males and females with BMI <24.0 kg/m, and SUA independently associated with DBP in females with BMI ≥24.0 kg/m.

Adipokines and Adipose Tissue-Related Metabolites, Nuts and Cardiovascular Disease

Adipose tissue is a complex structure responsible for fat storage and releasing polypeptides (adipokines) and metabolites, with systemic actions including body weight balance, appetite regulation, glucose homeostasis, and blood pressure control. Signals sent from different tissues are generated and integrated in adipose tissue; thus, there is a close connection between this endocrine organ and different organs and systems such as the gut and the cardiovascular system. It is known that functional foods, especially different nuts, may be related to a net of molecular mechanisms contributing to cardiometabolic health. Despite being energy-dense foods, nut consumption has been associated with no weight gain, weight loss, and lower risk of becoming overweight or obese. Several studies have reported beneficial effects after nut consumption on glucose control, appetite suppression, metabolites related to adipose tissue and gut microbiota, and on adipokines due to their fatty acid profile, vegetable proteins, l-arginine, dietary fibers, vitamins, minerals, and phytosterols. The aim of this review is to briefly describe possible mechanisms implicated in weight homeostasis related to different nuts, as well as studies that have evaluated the effects of nut consumption on adipokines and metabolites related to adipose tissue and gut microbiota in animal models, healthy individuals, and primary and secondary cardiovascular prevention.

Uric acid: from a biological advantage to a potential danger. A focus on cardiovascular effects

Non-communicable diseases represent nowadays the most common cause of death worldwide, having largely overcome infectious diseases. Among them, cardiovascular diseases constitute the majority. Given these premise, great efforts have been made by scientific societies to emphasize the fundamental role of cardiovascular prevention and risk factors control. In addition to classical cardiovascular risk factors such as smoking, arterial hypertension, hypercholesterolemia and male gender, new risk factors are emerging from international literature. Among them, uric acid is the protagonist. Several evidences show a direct role of hyperuricemia in the determinism of metabolic and vascular disorders. From the other hand, some researchers have demonstrated that uric acid is only a marker of cardiovascular damage and not a risk factor for its development. Aim of this review is to evaluate the scientific evidences on the role of uric acid in cardiovascular diseases in order to shed light on this confusing topic.

Interaction between body mass index and serum uric acid in relation to blood pressure in community-dwelling Japanese men

Background

Few data is available on the association between body mass index (BMI), serum uric acid (SUA) levels and blood pressure (BP) categories in the disease continuum, when efforts for its prevention may be applicable.

Methods

We performed a cross-sectional study to examine the association between BMI, SUA and BP in a community-dwelling sample of Japanese men. Individuals not on antihypertensive and uric acid lowering medications, and aged 50 to 90 years [817men aged 66 ± 9 (mean ± standard deviation) years] were recruited for the survey during a community based annual medical check-up. The main outcome was the presence of prehypertension [systolic BP (SBP) 120-139 mmHg and/or diastolic BP (DBP) 80-89 mmHg] and hypertension [SBP ≥ 140 and /or DBP ≥ 90].

Results

In participants with a BMI of < 21.0 kg/m², increased SUA levels were positively associated with SBP and DBP, but in those with a BMI of ≥ 21.0 kg/m², increased SUA levels were negatively associated with SBP and DBP. The interaction between BMI and SUA as well as BMI and SUA was a significant and independent determinant for both SBP (β = − 1.125, p = 0.001) and DBP (β = − 0.995, p = 0.005). Among participants, the respective prevalence of normotension, prehypertension, and hypertension was 19.5% and 53.7%, and 19.8%. The prevalence of normotension and prehypertension decreased with increasing BMI and the prevalence of hypertension increased with increasing BMI. In participants with a BMI ≥ 21.0 kg/m², the adjusted-odds ratio of SUA for hypertension was 0.75 (95% CI, 0.59-0.95) compared with normotension and 0.82 (0.70-0.96) compared with prehypertension. In those with a BMI of < 21.0 kg/m², these associations were not shown.

Conclusion

BMI may modify the association between SUA and blood pressure status among community-dwelling men.

Serum uric acid levels and multiple health outcomes: umbrella review of evidence from observational studies, randomised controlled trials, and Mendelian randomisation studies

Objective To map the diverse health outcomes associated with serum uric acid (SUA) levels.Design Umbrella review.Data sources Medline, Embase, Cochrane Database of Systematic Reviews, and screening of citations and references.Eligibility criteria Systematic reviews and meta-analyses of observational studies that examined associations between SUA level and health outcomes, meta-analyses of randomised controlled trials that investigated health outcomes related to SUA lowering treatment, and Mendelian randomisation studies that explored the causal associations of SUA level with health outcomes.Results 57 articles reporting 15 systematic reviews and144 meta-analyses of observational studies (76 unique outcomes), 8 articles reporting 31 meta-analyses of randomised controlled trials (20 unique outcomes), and 36 articles reporting 107 Mendelian randomisation studies (56 unique outcomes) met the eligibility criteria. Across all three study types, 136 unique health outcomes were reported. 16 unique outcomes in meta-analyses of observational studies had P<10-6, 8 unique outcomes in meta-analyses of randomised controlled trials had P<0.001, and 4 unique outcomes in Mendelian randomisation studies had P<0.01. Large between study heterogeneity was common (80% and 45% in meta-analyses of observational studies and of randomised controlled trials, respectively). 42 (55%) meta-analyses of observational studies and 7 (35%) meta-analyses of randomised controlled trials showed evidence of small study effects or excess significance bias. No associations from meta-analyses of observational studies were classified as convincing; five associations were classified as highly suggestive (increased risk of heart failure, hypertension, impaired fasting glucose or diabetes, chronic kidney disease, coronary heart disease mortality with high SUA levels). Only one outcome from randomised controlled trials (decreased risk of nephrolithiasis recurrence with SUA lowering treatment) had P<0.001, a 95% prediction interval excluding the null, and no large heterogeneity or bias. Only one outcome from Mendelian randomisation studies (increased risk of gout with high SUA levels) presented convincing evidence. Hypertension and chronic kidney disease showed concordant evidence in meta-analyses of observational studies, and in some (but not all) meta-analyses of randomised controlled trials with respective intermediate or surrogate outcomes, but they were not statistically significant in Mendelian randomisation studies.Conclusion Despite a few hundred systematic reviews, meta-analyses, and Mendelian randomisation studies exploring 136 unique health outcomes, convincing evidence of a clear role of SUA level only exists for gout and nephrolithiasis.