In addition to potentially being an independent risk factor for the initiation of chronic kidney disease (CKD), obesity can also affect the CKD progression among current patients with CKD. The relationship between obesity and CKD progression was examined in the Chronic Renal Insufficiency Cohort (CRIC) Study, a longitudinal study of about 4,000 CKD patients. CKD progression was defined as either a 50% reduction in estimated glomerular filtration rate (eGFR) or reaching end-stage renal disease. Obesity in this study was defined by body mass index (BMI) category (<20 kg/m2, 20 to <25 kg/m2, 25 to <30 kg/m2, and ≥30 kg/m2). Three models were built: one adjusting only for the clinical center of each patient, another adjusting for demographic (age, sex, race/ethnicity, and education) and clinical factors (diabetes, dyslipidemia, hypertension, any cardiovascular disease, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use) in addition to the clinical center of each patient, and finally adjusting for eGFR, 24-hour urine protein excretion, serum albumin and waist circumference in addition to the adjustment factors in the previous models. Overall, the study found those with a BMI ≥25 kg/m2 had a lower rate of CKD progression than those in the normal BMI category (20 to <25 kg/m2) after adjustment for many demographic and clinical factors.
Chart Explanation: The incidence rate of CKD in Model 1 (adjusted for CRIC clinical center) for those in the 25 to <30 kg/m2 groups is 22% lower (Hazard Ratio [HR]: 0.78, 95% confidence interval [CI]: 0.62, 0.99) than the incidence rate of the 20 to <25 kg/m2 group. The incidence rate in Model 1 for the ≥30 kg/m2 group is 16% lower than the incidence rate for the 20 to <25 kg/m2 group (HR: 0.84, 95% CI: 0.68, 1.04). After adjusting for several demographic and clinical factors, the HRs become more protective for the 25 to <30 kg/m2 group (HR: 0.66, 95% (0.52, 0.83)) and the ≥30 kg/m2 group (HR: 0.57, 95% CI: 0.46, 0.71) compared with the reference group. Further adjustment for eGFR, 24-hour urine protein excretion, serum albumin, and waist circumference attenuates the hazard ratio for these groups, but there remains a protective effect for each. The lack of precision in the estimates for the <20 kg/m2 group prevents strong conclusions from being made in this group.
The Chronic Renal Insufficiency Cohort (CRIC) study is a cohort study of 3,612 individuals 21-74 years of age with chronic kidney disease (CKD) of varying severity, recruited from 13 sites in 7 urban centers across the United States in 2003-2007. CRIC was designed to study consequences of CKD with a particular focus on cardiovascular illness like myocardial infarction (heart attack) and stroke. As with all cohort studies, participants may not be representative of all those who live in the communities from which they are recruited.
In the analysis by Ricardo, et al., they examined the association between several lifestyle factors (physical activity, body mass index [BMI], nonsmoking, and diet) and CKD progression. The indicator on the website displays the relationship between BMI and CKD progression. Three separate models were built to examine this relationship. The first simply adjusted for the clinical center of examination for each patient. The second adjusted for various demographic and clinical factors. The last further adjusted for several more clinical factors.
|Description of Measure||Hazard Ratio of CKD Progression|
|Data Source||CRIC Study|
|Type of Data Source||Longitudinal cohort study|
|Data Set||CRIC summarized data from published literature|
|Health Care Data System||No|
|Regional or National?||National |
|Demographic Group||3,939 men and women aged 21-74 years with estimated glomerular filtration rates (eGFRs) between 20 and 70 mL/min/1.73 m2 from 7 clinical centers in the United States (Ann Arbor, Michigan; Baltimore, Maryland; Chicago, Ilinois; Cleveland, Ohio; New Orleans, Louisiana; Philadelphia, Pennsylvania; Oakland, California)|
|Numerator||Incident number of participants with 50% decrease in eGFR from baseline or end-stage renal disease (ESRD)|
|Denominator||Time to occurrence of 50% decrease in eGFR from baseline or ESRD|
|Definition of CKD Progression||50% decrease in eGFR from baseline or ESRD|
|Glomerular filtration rate||CRIC-specific GFR equation (see citation in References on indicator page)|
|Primary Data Source Indicator||BMI|
|Primary Indicator Method of Measurement||Weight and height of participants|
|Secondary Data Source Indicator||Demographic variables (age, sex, race/ethnicity, education)|
|Secondary (1) Indicator Method of Measurement||Self-reported questionnaires |
|Secondary Data Source Indicator||Clinical variables (diabetes, dyslipidemia, hypertension, any cardiovascular disease, ACE inhibitor/ARB use)|
|Secondary (2) Indicator Method of Measurement||Self-administered questionnaire and clinical evaluations (see citations in References section for details)|
|Secondary Data Source Indicator||24-hour urine protein excretion, serum albumin, and waist circumference|
|Secondary (3) Indicator Method of Measurement||24-hour urine sample, blood test, and waist measurement|
|Period Currently Available||2008|
|Frequency of Measurement (Primary)||Outcome – annual in-person visits and six-month telephone interview; BMI – at baseline|
|U.S. Region Covered by Primary Variable||Ann Arbor, Michigan, Baltimore, Maryland; Chicago, Illinois; Cleveland, Ohio; New Orleans, Louisiana; Philadelphia, Pennsylvania; Oakland, California|
|Limitations of Indicator||Potential residual confounding; self-report of several study variables|
|Analytical Considerations||Analysis performed by CRIC Study investigators.|
References and Sources:
Ricardo AC, Anderson CA, Yang W, et al. Healthy lifestyle and risk of kidney disease progression, atherosclerotic events, and death in CKD: findings from the Chronic Renal Insufficiency Cohort (CRIC) study. Am J Kidney Dis. 2015;65(3):412-424