CRIC-Visceral Adiposity and Physical Fitness in Chronic Kidney Disease

Obesity and chronic kidney disease (CKD) are major public health problems. Obesity
independent of its relationship with diabetes and hypertension is associated with the
development and progression of kidney disease. However, higher body mass index (BMI) in those
with pre-existing CKD is associated with lower mortality (obesity paradox). This may be due
to the inability of BMI to differentiate fat mass and muscle mass, which may have opposite
relationship with cardiovascular disease and death. Body fat distribution is a major factor
of metabolic health with metabolic abnormalities correlating better with visceral than
subcutaneous adipose tissue. Further, higher fitness levels among those with higher BMI is
associated with a lower prevalence of cardiovascular risk factors and mortality that might
explain this obesity paradox. Therefore, among Chronic Renal Insufficiency Cohort (CRIC)
study participants, the investigators propose (a) to examine whether visceral adiposity is
associated with a higher incidence of composite outcomes (i.e., mortality, cardiovascular
events, end stage renal disease, and 50% decline in estimated glomerular filtration rate),
(b) to determine if physical fitness modifies the association between adiposity and outcomes,
and (c) to study whether visceral adiposity and physical fitness are associated with altered
adipokine profile, inflammation, insulin resistance, and oxidative stress. The study proposes
to enroll 526 patients with varying degrees of kidney disease from 7 clinical centers
involved in the CRIC study. Visceral adiposity will be measured by magnetic resonance imaging
(MRI) of the abdomen using a standard protocol, and physical fitness will be measured using a
400 m walk test during routine CRIC study visits. Results from this study will help the
Investigators understand the independent and combined effects of visceral adiposity and
physical fitness on cardiovascular disease and kidney disease progression among CKD patients.
This study will also highlight potential pathways that mediate the relationship between
adiposity and outcomes, which will become the focus of future therapeutic investigations in
CKD.

Inclusion Criteria:

- Age 21-79

- Estimated Glomerular Filtration Rate 20-74 ml/min/1.73m^2

Exclusion Criteria:

- Pacemaker

- Metallic prosthesis or foreign body (joints, heart valves, clips)

*Sites may include patients with cardiac stents and/or dental implants based on the
local Radiology department criteria i.e. if there are no restrictions, they can
include patients with stents and/or dental implants. If the Radiology department
mandates the type of stent details and/or dental implants, site coordinator should
provide this to the local Radiology department and obtain permission before enrolling
the subject.

- Severe claustrophobia

- Severe osteoarthritis (use of walker or other assisted devices)

*Sites may include patients with cane (single or quad).

- Recent cardiovascular or cerebrovascular events (within 6 months prior to enrollment)

- Kidney transplant

- Currently on dialysis

- Peripheral vascular disease limiting long distance walking