Dataset Information

Bicarbonate Concentration, Acid-Base Status, and Mortality in the Health, Aging, and Body Composition Study.

ABSTRACT:

Background and objectives

Low serum bicarbonate associates with mortality in CKD. This study investigated the associations of bicarbonate and acid-base status with mortality in healthy older individuals.

Design, setting, participants, & measurements

We analyzed data from the Health, Aging, and Body Composition Study, a prospective study of well functioning black and white adults ages 70-79 years old from 1997. Participants with arterialized venous blood gas measurements (n=2287) were grouped into <23.0 mEq/L (low), 23.0-27.9 mEq/L (reference group), and ?28.0 mEq/L (high) bicarbonate categories and according to acid-base status. Survival data were collected through February of 2014. Mortality hazard ratios (HRs; 95% confidence intervals [95% CIs]) in the low and high bicarbonate groups compared with the reference group were determined using Cox models adjusted for demographics, eGFR, albuminuria, chronic obstructive pulmonary disease, smoking, and systemic pH. Similarly adjusted Cox models were performed according to acid-base status.

Results

The mean age was 76 years, 51% were women, and 38% were black. Mean pH was 7.41, mean bicarbonate was 25.1 mEq/L, 11% had low bicarbonate, and 10% had high bicarbonate. Mean eGFR was 82.1 ml/min per 1.73 m(2), and 12% had CKD. Over a mean follow-up of 10.3 years, 1326 (58%) participants died. Compared with the reference group, the mortality HRs were 1.24 (95% CI, 1.02 to 1.49) in the low bicarbonate and 1.03 (95% CI, 0.84 to 1.26) in the high bicarbonate categories. Compared with the normal acid-base group, the mortality HRs were 1.17 (95% CI, 0.94 to 1.47) for metabolic acidosis, 1.21 (95% CI, 1.01 to 1.46) for respiratory alkalosis, and 1.35 (95% CI, 1.08 to 1.69) for metabolic alkalosis categories. Respiratory acidosis did not associate with mortality.

Conclusions

In generally healthy older individuals, low serum bicarbonate associated with higher mortality independent of systemic pH and potential confounders. This association seemed to be present regardless of whether the cause of low bicarbonate was metabolic acidosis or respiratory alkalosis. Metabolic alkalosis also associated with higher mortality.

SUBMITTER: Raphael KL

PROVIDER: S-EPMC4741040 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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Publications

Bicarbonate Concentration, Acid-Base Status, and Mortality in the Health, Aging, and Body Composition Study.

Raphael Kalani L KL Murphy Rachel A RA Shlipak Michael G MG Satterfield Suzanne S Huston Hunter K HK Sebastian Anthony A Sellmeyer Deborah E DE Patel Kushang V KV Newman Anne B AB Sarnak Mark J MJ Ix Joachim H JH Fried Linda F LF

Clinical journal of the American Society of Nephrology : CJASN 20160114 2

<h4>Background and objectives</h4>Low serum bicarbonate associates with mortality in CKD. This study investigated the associations of bicarbonate and acid-base status with mortality in healthy older individuals.<h4>Design, setting, participants, & measurements</h4>We analyzed data from the Health, Aging, and Body Composition Study, a prospective study of well functioning black and white adults ages 70-79 years old from 1997. Participants with arterialized venous blood gas measurements (n=2287) w ...[more]

PMID: 26769766

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Project description:BackgroundIn populations with prevalent chronic kidney disease (CKD), lower serum bicarbonate levels are associated with more rapid CKD progression, but whether lower bicarbonate levels also are associated with risk of incident estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m(2) and CKD progression among community-living persons with predominantly preserved kidney function is unknown.Study designLongitudinal observational cohort study.Setting & participantsWell-functioning community-living elders aged 70-79 years at inception.PredictorSerum bicarbonate level measured at the time of collection by arterialized venous blood sample using an arterial blood gas analyzer.OutcomesChange in eGFR over 7 years, and new eGFR < 60 mL/min/1.73 m(2) with a rate of loss of at least 1 mL/min/1.73 m(2) per year.MeasurementsLinear and logistic regressions were used to evaluate associations of baseline serum bicarbonate level with change in eGFR and incident eGFR < 60 mL/min/1.73 m(2).ResultsAt baseline, mean eGFR was 84 ± 16 (SD)mL/min/1.73 m(2), and serum bicarbonate level was 25.2 ± 1.9 mmol/L. Compared with participants with higher bicarbonate concentrations (23.0-28.0 mmol/L), those with bicarbonate concentrations < 23 mmol/L (n = 85 [8%]) lost eGFR0.55 (95% CI, 0.13-0.97) mL/min/1.73 m(2) per year faster in models adjusted for demographics, CKD risk factors, baseline eGFR, and urine albumin-creatinine ratio. Among the 989 (92%) participants with baseline eGFRs > 60 mL/min/1.73 m(2), 252 (25%) developed incident eGFRs < 60 mL/min/1.73 m(2) at follow-up. Adjusting for the same covariates, participants with bicarbonate concentrations < 23 mmol/L had nearly 2-fold greater odds of incident eGFRs < 60 mL/min/1.73 m(2) (OR, 1.72; 95% CI, 0.97-3.07) compared with those with higher bicarbonate concentrations.LimitationsOnly 2 measurements of kidney function separated by 7 years and loss to follow-up due to intervening mortality in this elderly population.ConclusionsLower serum bicarbonate concentrations are associated independently with decline in eGFR and incident eGFR < 60 mL/min/1.73 m(2) in community-living older persons. If confirmed, serum bicarbonate levels may give insight into kidney tubule health in persons with preserved eGFRs and suggest a possible new target for intervention to prevent CKD development.

Project description:IMPORTANCE:Additional information is needed about the role of dietary sodium on health outcomes in older adults. OBJECTIVE:To examine the association between dietary sodium intake and mortality, incident cardiovascular disease (CVD), and incident heart failure (HF) in older adults. DESIGN, SETTING, AND PARTICIPANTS:We analyzed 10-year follow-up data from 2642 older adults (age range, 71-80 years) participating in a community-based, prospective cohort study (inception between April 1, 1997, and July 31, 1998). EXPOSURES:Dietary sodium intake at baseline was assessed by a food frequency questionnaire. We examined sodium intake as a continuous variable and as a categorical variable at the following levels: less than 1500 mg/d (291 participants [11.0%]), 1500 to 2300 mg/d (779 participants [29.5%]), and greater than 2300 mg/d (1572 participants [59.5%]). MAIN OUTCOMES AND MEASURES:Adjudicated death, incident CVD, and incident HF during 10 follow-up years. Analysis of incident CVD was restricted to 1981 participants without prevalent CVD at baseline. RESULTS:The mean (SD) age of participants was 73.6 (2.9) years, 51.2% were female, 61.7% were of white race, and 38.3% were black. After 10 years, 881 participants had died, 572 had developed CVD, and 398 had developed HF. In adjusted Cox proportional hazards regression models, sodium intake was not associated with mortality (hazard ratio [HR] per 1 g, 1.03; 95% CI, 0.98-1.09; P?=?.27). Ten-year mortality was nonsignificantly lower in the group receiving 1500 to 2300 mg/d (30.7%) than in the group receiving less than 1500 mg/d (33.8%) and the group receiving greater than 2300 mg/d (35.2%) (P?=?.07). Sodium intake of greater than 2300 mg/d was associated with nonsignificantly higher mortality in adjusted models (HR vs 1500-2300 mg/d, 1.15; 95% CI, 0.99-1.35; P?=?.07). Indexing sodium intake for caloric intake and body mass index did not materially affect the results. Adjusted HRs for mortality were 1.20 (95% CI, 0.93-1.54; P?=?.16) per milligram per kilocalorie and 1.11 (95% CI, 0.96-1.28; P?=?.17) per 100 mg/kg/m2 of daily sodium intake. In adjusted models accounting for the competing risk for death, sodium intake was not associated with risk for CVD (subHR per 1 g, 1.03; 95% CI, 0.95-1.11; P?=?.47) or HF (subHR per 1 g, 1.00; 95% CI, 0.92-1.08; P?=?.92). No consistent interactions with sex, race, or hypertensive status were observed for any outcome. CONCLUSIONS AND RELEVANCE:In older adults, food frequency questionnaire-assessed sodium intake was not associated with 10-year mortality, incident CVD, or incident HF, and consuming greater than 2300 mg/d of sodium was associated with nonsignificantly higher mortality in adjusted models.

Dataset Information

Bicarbonate Concentration, Acid-Base Status, and Mortality in the Health, Aging, and Body Composition Study.

Background and objectives

Design, setting, participants, & measurements

Results

Conclusions

Publications

Bicarbonate Concentration, Acid-Base Status, and Mortality in the Health, Aging, and Body Composition Study.

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