Background

Compared with normal weight, obesity might be associated with worse clinical outcomes, including chronic kidney disease. Whether this association is modified by age is not known. We investigated the association of BMI with progressive loss of kidney function and all-cause mortality in US veterans.

Methods

In a national cohort of 3,376,187 US veterans with an estimated glomerular filtration rate (eGFR) of more than 60 mL/min per 1·73 m(2), we assessed the association of BMI in patients of different ages (<40 years, 40 years to <50 years, 50 years to <60 years, 60 years to <70 years, 70 years to <80 years, and ≥80 years) with loss of kidney function and with all-cause mortality in logistic regression models and Cox proportional hazards models adjusted for ethnic origin, sex, comorbidities, medications, and baseline eGFR.

Findings

274,764 (8·1%) of 3,376,187 veterans had a rapid decline in kidney function (decrease in slope of >5 mL/min per 1·73 m(2)). The lowest risk for loss of kidney function was noted in patients with BMI of at least 25 kg/m(2) but less than 30 kg/m(2). A generally consistent U-shaped association was noted between BMI and rapid loss of kidney function that was more prominent with increasing age, except in the patients younger than 40 years, in whom BMI did not seem to be predictive of renal function impairment. 672,341 veterans died (28·7 per 1000 patient-years, 95% CI 28·6-28·7) over a median follow-up of 6·8 years (IQR 6·5-7·7). BMI also showed a U-shaped association with mortality, which was similar in all age groups.

Interpretation

A BMI of 30 kg/m(2) or more is associated with rapid loss of kidney function in patients with eGFR of at least 60 mL/min per 1·73 m(2), and this association is accentuated in older patients. A BMI of 35 kg/m(2) or more is also associated with high mortality. A BMI of at least 25 kg/m(2) but less than 30 kg/m(2) is associated with the best clinical outcomes.

Funding

National Institute of Health, Memphis VA Medical Center, Long Beach VA Healthcare System, Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, Health Services Research and Development, and VA Information Resource Center.

Background

Intraindividual blood pressure (BP) fluctuates dynamically over time. Previous studies suggested an adverse link between greater visit-to-visit variability in systolic blood pressure (SBP) and various outcomes. However, these studies have significant limitations, such as a small size, inclusion of selected populations, and restricted outcomes.

Objectives

This study investigated the association of increased visit-to-visit variability and all-cause mortality, cardiovascular events, and end-stage renal disease (ESRD) in a large cohort of U.S. veterans.

Methods

From among 3,285,684 U.S. veterans with and without hypertension and normal estimated glomerular filtration rates (eGFR) during 2005 and 2006, we identified 2,865,157 patients who had 8 or more outpatient BP measurements. Systolic blood pressure variability (SBPV) was measured using the SD of all SBP values (normally distributed) in 1 individual. Associations of SD quartiles (<10.3, 10.3 to 12.7, 12.7 to 15.6, and ≥15.6 mm Hg) with all-cause mortality, incident coronary heart disease (CHD), stroke, and ESRD was examined using Cox models adjusted for sociodemographic characteristics, baseline eGFR, comorbidities, body mass index, SBP, diastolic BP, and antihypertensive medication use.

Results

Several sociodemographic variables (older age, male sex, African-American race, divorced or widowed status) and clinical characteristics (lower baseline eGFR, higher SBP and diastolic BP), and comorbidities (presence of diabetes, hypertension, cardiovascular disease, and lung disease) were all associated with higher intraindividual SBPV. The multivariable adjusted hazard ratios and 95% confidence intervals for SD quartiles 2 through 4 (compared with the first quartile) associated with all-cause mortality, CHD, stroke, and ESRD were incrementally higher.

Conclusions

Higher SBPV in individuals with and without hypertension was associated with increased risks of all-cause mortality, CHD, stroke, and ESRD. Further studies are needed to determine interventions that can lower SBPV and their impact on adverse health outcomes.