Original Investigation
Pathogenesis and Treatment of Kidney Disease
Trajectories of Kidney Function Decline in Young Black and White Adults With Preserved GFR: Results From the Coronary Artery Risk Development in Young Adults (CARDIA) Study

https://doi.org/10.1053/j.ajkd.2013.01.012Get rights and content

Background

Strong racial discrepancies in end-stage renal disease exist. Whether there are race differences in kidney function loss in younger healthy persons is not well established.

Study Design

Longitudinal.

Setting & Participants

3,348 black and white adults with at least 2 measurements of cystatin C–based estimated glomerular filtration rate (eGFRcys) at scheduled Coronary Artery Risk Development in Young Adults (CARDIA) examinations (years 10, 15, and 20).

Predictor

Race.

Outcomes & Measurements

We used linear mixed models to examine race differences in annualized rates of eGFRcys decline, adjusting for age, sex, lifetime exposure to systolic blood pressure >120 mm Hg, diabetes, and albumin-creatinine ratio. We used Poisson regression to compare racial differences in rapid decline (eGFRcys decline >3% per year) by study period (10-15 years after baseline examination [defining period 1] and >15-20 years after baseline examination [defining period 2]).

Results

Mean age was 35 ± 3.6 (SD) years, and mean eGFRcys was 110 ± 20 mL/min/1.73 m2 for blacks and 104 ± 17 mL/min/1.73 m2 for whites at baseline. For both blacks and whites, eGFRcys decline was minimal at younger ages (<35 years) and eGFRcys loss accelerated at older ages. However, acceleration of eGFRcys decline occurred at earlier ages for blacks than whites. Blacks had somewhat faster annualized rates of decline compared with whites, but differences were attenuated after adjustment in period 1 (0.13 mL/min/1.73 m2 per year faster; P = 0.2). In contrast, during period 2, blacks had significantly faster annualized rates of decline, even after adjustment (0.32 mL/min/1.73 m2 per year faster; P = 0.003). The prevalence of rapid decline was significantly higher for blacks versus whites, with prevalence rate ratios of 1.31 (95% CI, 1.04-1.63) for period 1 and 1.24 (95% CI, 1.09-1.41) for period 2. Differences were attenuated after full adjustment: adjusted prevalence rate ratios were 1.20 (95% CI, 0.95-1.49) for period 1 and 1.10 (95% CI, 0.96-1.26) for period 2.

Limitations

No measured GFR.

Conclusions

eGFRcys decline differs by race at early ages, with faster annualized rates of decline for blacks. Future studies are required to explain the observed differences.

Section snippets

Participants

We included participants from the CARDIA Study. CARDIA is a prospective cohort study sponsored by the National Heart, Lung and Blood Institute designed to study early determinants of cardiovascular disease. Detailed methods for CARDIA have been published previously.12 Briefly, CARDIA recruited 5,115 black and white persons aged 18-30 years between 1985 and 1986 from 4 sites in the United States (Birmingham, AL; Chicago, IL; Minneapolis, MN; and Oakland, CA). After the first examination,

Cohort Characteristics

For the 3,348 CARDIA participants included in this study, mean age at baseline (CARDIA year 10) was 35 ± 3.6 (SD) years, 288 (9%) had hypertension, and 225 (7%) had diabetes. Blacks were more likely to have diabetes, hypertension, and a higher prevalence of albuminuria. eGFRcys at baseline was ∼6 mL/min/1.73 m2 higher for blacks compared with whites (Table 1).

Trajectories of eGFRcys Decline by Race

In Fig 1, we present the trajectories of adjusted mean eGFRcys as a function of age for blacks and whites separately. Each point on the

Discussion

In this large cohort of young black and white persons with largely preserved kidney function, we found that on average, decline in eGFR is minimal prior to age 35 years, and that rates of decline accelerate at older ages. However, we found important racial differences in these kidney function trajectories. Specifically, prior to age 35, eGFRcys decline was fairly similar by race. After age 35, eGFRcys decline was significantly steeper for blacks compared with whites, and this decline started at

Acknowledgements

Support: Dr Peralta is funded by grant 1K23DK082793-01 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the Robert Wood Johnson Harold Amos Program. Dr Bibbins-Domingo was in part supported by grant R01DK078124 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), grant N01HC48050 from the National Heart, Lung and Blood Institute (NHLBI), from grant 1P60MD006902 from the National Institute on Minority Health and Health Disparities

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Originally published online March 8, 2013.

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