Obesity, albuminuria, and gamma-glutamyl transferase predict incidence of hypertension in indigenous Australians in rural and remote communities in northern Australia

Aldosterone and renin concentrations and blood pressure in young Indigenous and non-Indigenous adults in the Northern Territory: a cross-sectional study

OBJECTIVES

To evaluate aldosterone and renin levels and aldosterone-to-renin ratios (ARRs) in young Indigenous and non-Indigenous adults in the Northern Territory, and their association with blood pressure levels.

DESIGN

Cross-sectional study; single time point sub-study of two prospective birth cohort studies.

SETTING, PARTICIPANTS

Participants in the Aboriginal Birth Cohort (ABC) - born to Indigenous mothers at the Royal Darwin Hospital during 1987-1990 - and the Top End Cohort (TEC) - people born to non-Indigenous mothers in Darwin, recruited during 2007-2009 - aged 32-35 years at the time of this sub-study.

MAIN OUTCOME MEASURES

Plasma aldosterone and direct renin concentrations; ARRs (positive screening test result for primary aldosteronism defined as > 70 pmol/mU); systolic and diastolic blood pressure.

RESULTS

A total of 255 ABC (205 in remote, 50 in urban locations) and 76 TEC members participated. Median aldosterone concentration was similar for all three groups. The median renin concentration was 7.5 mU/L (interquartile range [IQR], 4.1-12.4 mU/L) in the TEC group, 12.4 mU/L (IQR, 5.1-19 mU/L) in the urban ABC group, and 29.3 mU/L (IQR, 15.0-52.9 mU/L) in the remote ABC group. The median ARR was 10 pmol/mU (IQR, 6-19 pmol/mU) in the remote ABC group, 28 pmol/mU (IQR, 16-70 pmol/mU) in the urban ABC group, and 43 pmol/mU (IQR, 26-74 pmol/mU) in the TEC group. Thirteen urban ABC participants (26%), 21 TEC participants (28%), and six people in the remote ABC group (3%) had ARR values above 70 pmol/mU. Adjusted for age and body mass index (BMI), mean systolic and diastolic blood pressure were lower for women than men in all participant groups; after adjusting for age, sex, and BMI, larger ARR was associated with higher systolic blood pressure in the TEC group but not the two ABC groups.

CONCLUSION

Screening test results for primary aldosteronism were positive for about one-quarter of urban Indigenous and non-Indigenous participants. A prospective study that includes confirmatory testing would more accurately assess the prevalence of primary aldosteronism among Indigenous Australians in the Northern Territory.

Cardiometabolic Risk Markers for Aboriginal and Torres Strait Islander Children and Youths: A Systematic Review of Data Quality and Population Prevalence

Cardiovascular disease and type 2 diabetes mellitus are leading contributors to the health inequity experienced by Aboriginal and Torres Strait Islander peoples, and their antecedents can be identified from early childhood. We aimed to establish the quality of available data and the prevalence of cardiometabolic risk markers among Aboriginal and Torres Strait Islander children and youths (0-24-year-olds) to inform public health approaches. A systematic review of the peer-reviewed and grey literature was conducted between 1 January 2000-28 February 2021. Included studies reported population prevalence of cardiometabolic risks, including elevated blood pressure, obesity, central adiposity, dyslipidaemia, hyperglycaemia, and 'metabolic syndrome' for Aboriginal and Torres Strait Islander people aged 0-24 years. Fifteen studies provided population estimates. Data quality was limited by low response rates (10/15 studies) and suboptimal outcome measurements. Obesity is the most reported risk (13/15 studies). Aboriginal and Torres Strait Islander children have an excess risk of obesity from early childhood and prevalence increases with age: 32.1% of Aboriginal and Torres Strait Islander 18-24-year-olds had obesity and 50.8% had central adiposity. In a cohort of 486 9-14-year-olds in Darwin, 70% had ≥1 component of metabolic syndrome; 14% met the full criteria for the syndrome. The prevalence of cardiometabolic risk in Aboriginal and Torres Strait Islander young people is difficult to estimate due to limitations in measurement quality and sampling representativeness. Available data suggest that cardiometabolic risk markers are evident from early childhood. The establishment of national and state-level datasets and a core outcome set for cardiometabolic screening would provide opportunities for preventative action.

Association Between Sex-Specific Serum Gamma-Glutamyltransferase and Incidence of Hypertension in a Chinese Population Without Metabolic Syndrome: A Prospective Observational Study

Background: Higher serum gamma-glutamyltransferase (GGT) is associated with high risk of hypertension. We aimed to examine the association between sex-specific serum GGT levels and incident of hypertension in a Chinese population without metabolic syndrome. Methods: Participants who were free of hypertension and metabolic syndrome from the First Affiliated Hospital of Wenzhou Medical University between 2009 and 2014 were included. Participants were grouped into sex-specific quartiles of GGT levels (Q1-Q4) defined as: ≤19, 20-26, 27-38, and ≥39 U/L for male; ≤12, 13-15, 16-19, and ≥20 U/L for female. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for incidence of hypertension according to sex-specific quartiles of GGT levels. Kaplan-Meier analysis and interaction analysis were conducted. Results: Among 38,806 participants included (average age 36.0 years, 54.0% men), 4,505 of them developed hypertension. In the overall study population, using Q1 as the reference group, participants in Q2, Q3, and Q4 showed a higher risk of developing hypertension, with HRs (95% CIs) of 1.126 (1.029-1.232), 1.187 (1.083-1.302), and 1.300 (1.182-1.431), respectively (P < 0.001), after adjusting for known confounders. Sex-specific analysis showed that the adjusted HRs for participants in Q4 (reference: Q1) were greater in females [1.321 (1.100-1.586, P < 0.001)] than in males [1.268 (1.133-1.420, P < 0.001)] (P for interaction = 0.047). Moreover, interaction analysis showed that this association was consistently observed when the participants were stratified by age, body mass index, and fatty liver status. Conclusion: Among Chinese adults without metabolic syndrome, serum GGT level was positively associated with incidence of hypertension, and the association was stronger in females than in males.

Long-term trends and regional variations of hypertension incidence in China: a prospective cohort study from the China Health and Nutrition Survey, 1991-2015

OBJECTIVE

The aim is to explore the trends of hypertension incidence and regional variations in China from 1991 to 2015.

DESIGN

A dynamic prospective cohort study.

SETTING

China Health and Nutrition Survey 1991-2015.

PARTICIPANTS

12 952 Chinese adults aged 18+ years.

PRIMARY OUTCOME MEASURES

Incident hypertension from 1993 to 2015.

RESULTS

Age-standardised hypertension incidence increased from 40.8 per 1000 person-years (95% CI 38.3 to 43.4) between 1993 and 1997 to 48.6 (95% CI 46.1 to 51.0) between 2011 and 2015. The increasing trends were further supported by results from subsequent extended Cox proportional hazard model. In addition, results from the modelling analysis showed that individuals in eastern, central and northeastern China had greater risks of hypertension occurrence in comparison with their counterparts in western China.

CONCLUSION

Hypertension incidence increased during the study period. The growth called for more attention on the health education and health promotion of individuals with great risks.

Elevated fasting glucose and albuminuria may be a marker for all-cause mortality in Indigenous adults in North Queensland - a follow up study, 1998-2006

AIMS

To document risk factors of all-cause mortality in a cohort of indigenous Australians from 23 communities of North Queensland during 1998-2006.

METHODS

Among 2787 indigenous adults, baseline weight, waist circumference, blood pressure, fasting glucose, lipids, gamma-glutamyl transferase, urine albumin creatinine ratio, smoking, alcohol intake and physical activity were measured in 1998-2000. Deaths were ascertained from State Registry of Deaths, hospitalization and clinical records till 2006. Mortality risk factors were assessed using a Cox proportional-hazards model.

RESULTS

The standardized all-cause mortality rate was 23.2/1000 person-years (95% CI 20.3-26.3/1000 pys). After adjusting for age, sex, and ethnicity, baseline plasm fasting glucose >=5.5mmol/L was associated with a 50% increased risk of death (HR 1.5, 95% CI 1.2-2.0). Albuminuria was associated with all-cause mortality with a hazards ratio of 1.4 for microalbuminuria (95% CI 1.0-1.9) and 2.6 (95% CI 1.8-3.7) for macroalbuminuria. Gamma-glutamyl transferase >=50IU was associated with an increased risk of all-cause mortality by 40% (95% CI 1.04-1.8).

CONCLUSIONS

Fasting glycaemia, albuminuria, and gamma-glutamyl transferase, may be a marker for all-cause mortality within this cohort.

Depression and diabetes in the remote Torres Strait Islands

Issue addressed Diabetes is associated with significant depression, which can result in poorer clinical outcomes, including increased mortality. Little is known about the prevalence of depression among Torres Strait Islander adults with diabetes. Methods Self-reported depression was measured using the Patient Health Questionnaire (PHQ)-9 translated into Torres Strait Creole, and associations with socioeconomic, behavioural and clinical indicators in Torres Strait Islander adults with diabetes in five remote Torres Strait Islands were examined. Results Seventy-three men and 115 women completed interviews. The median PHQ-9 score was 5.5 (IQR 0-7); 42% of respondents scored 0-4 (none-minimal), 46% scored 5-9 (mild) and 12% scored 10+ (moderate-severe). Mean HbA1c was 8.3% (67.4mmol). HbA1c was not related to PHQ-9 scores (β=0.20, P=0.323), however exercise in hours (β=-0.34, P<0.001) and screen time in hours (β=0.11, P<0.001) were significant predictors of depression after adjusting for other study variables. Conclusions This sample of remote living Torres Strait Islanders reported relatively low rates of depression compared with national samples, and depression was not related to glycaemic control. Exercise and screen time were the strongest predictors of depression based on PHQ-9 scores. This represents an opportunity for health promotion. So what? These findings provide an indication of the health impact of physical activity in rural and remote communities. Local health and education services, councils and sporting bodies should work collaboratively to promote sustainable physical activity programs.

Protective Effect of Salicornia europaea Extracts on High Salt Intake-Induced Vascular Dysfunction and Hypertension

High salt intake causes and aggravates arterial hypertension and vascular dysfunction. We investigated the effect of Salicornia europaea extracts (SE) on vascular function and blood pressure. SE constituents were analyzed using high performance liquid chromatography, and SE's effect on vascular function was evaluated in isolated porcine coronary arteries. SE's vascular protective effect was also evaluated in vivo using normotensive and spontaneous hypertensive rats (SHRs). SE mainly contained sodium chloride (55.6%), 5-(hydroxymethyl)furfural, p-coumaric acid, and trans-ferulic acid. High sodium (160 mmol/L) induced vascular dysfunction; however, SE containing the same quantity of sodium did not cause vascular dysfunction. Among the compounds in SE, trans-ferulic acid accounts for the vascular protective effect. Normotensive rats fed a high-salt diet showed significantly increased systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP), which decreased significantly in the SE-treated groups. In SHRs, high edible salt intake significantly increased SBP, DBP, and MAP, but SE intake was associated with a significantly lower MAP. Thus, SE did not induce vascular dysfunction, and trans-ferulic acid might be at least partly responsible for the vasoprotective effect of SE. Taken together, SE could be used as an alternative to purified salt to prevent and ameliorate hypertension.

Gamma-glutamyltransferase and risk of hypertension: a systematic review and dose-response meta-analysis of prospective evidence

The objective of this review was to obtain a reliable estimate of the magnitude of the prospective association between gamma-glutamyltransferase (GGT) and risk of hypertension, and to characterize the nature of the dose-response relationship. We conducted a systematic review and dose-response meta-analysis of published prospective studies. Relevant studies were identified in a literature search of MEDLINE, EMBASE, and Web of Science databases up to May 2015. Study-specific relative risks (RRs) were meta-analyzed using random effects models. We examined a potential nonlinear relationship using restricted cubic splines. Of the 612 titles reviewed, we included 14 cohort studies with data on 44 582 participants and 5 270 hypertension cases. In a comparison of extreme thirds of baseline levels of GGT, RR for hypertension in pooled analysis of all 14 studies was 1.32 (95% confidence interval: 1.23-1.43). There was heterogeneity among the studies (P < 0.001), which was to a large part explained by average age of participants at baseline, average duration of follow-up, and the degree of confounder adjustment. In a pooled dose-response analysis of 10 studies with relevant data, there was evidence of a linear association between GGT and hypertension risk (P for nonlinearity = 0.37). The pooled RR of hypertension per 5 U/l increment in GGT levels was 1.08 (95% confidence interval: 1.04-1.13). Baseline circulating GGT level is associated with an increased risk of hypertension in the general population, consistent with a linear dose-response relationship. Further investigation of any potential relevance of GGT in hypertension prevention is warranted.

Albuminuria and its associated biomedical factors among indigenous adults in Far North Queensland: a 7-year follow up study

BACKGROUND

To document albuminuria prevalence and its associated factors in Aboriginal and Torres Strait Islander (TSI) adults with high renal and metabolic risks from 19 rural and remote north Queensland communities.

METHODS

One thousand nine hundred seventy-one indigenous adults were enrolled in 1998 and 566 completed follow up in 2007 in this population-based study. Measurements included weight, waist circumference (WC), blood pressure (BP), fasting glucose, lipids, gamma-glutamyltransferase (GGT), urinary albumin creatinine ratio (UACR), smoking, alcohol intake and physical activity (PA). Albuminuria was defined as an UACR > =2.5 g/mol in males and > =3.5 g/mol in females. The association between albuminuria and biomedical factors was assessed with generalised linear modelling.

RESULTS

Baseline albuminuria prevalence was 19.7 % (95 % CI: 18.0-21.6 %). Follow up prevalence was 42.4 % (95 % CI: 38.4-46.5 %) among the 566 adults having the 2(nd) UACR measurements. Follow-up albuminuria was associated with fasting glucose of 5.4 mmol/L (OR 2.5, 95 % CI 1.5-4.2), GGT tertiles in a dose-response manner (OR 2.0 for 2(nd) and 3.7 for 3(rd) tertile, p for trend <0.001), and abdominal overweight and obesity (OR 2.1, 95 % CI 1.1-3.9 and 5.4, 95 % CI: 2.2-13.5 respectively). Aboriginal people with diabetes were three times more likely of having albuminuria compared to TSI counterparts, while TSI smokers had twice the likelihood (95 % CI 1.2-3.2). At both baseline and follow up, albuminuria was more prevalent among older participants.

CONCLUSIONS

Indigenous Australians in north Queensland are at high risk of albuminuria. Overweight and obesity, glycaemia, increased GGT, and smoking were associated with albuminuria at baseline and/or follow up.