Effect of Obesity on Long-term Clinical Outcomes After Kidney Donation
Condition: Renal Dysfunction; Hypertension
MeSH terms: Renal Insufficiency
Study type: Observational

Summary: 
      Several studies have shown that renal function in patients who have donated a kidney (but are
      otherwise healthy) remains stable and within normal limits. However, it is unclear how donor
      nephrectomy affects patient subsets with comorbidities, an issue that becomes relevant in the
      current environment where inclusion criteria are continuously becoming less stringent and
      more patients are being considered as potential donors.

      In the present study, the investigators plan to evaluate long-term renal function in obese
      patients who have donated a kidney as part of a living donor renal transplant procedure. The
      investigators have selected this group because it is at higher risk for developing
      obesity-related complications such as diabetes and hypertension that may impair renal
      function, it is rapidly becoming a major subgroup in the kidney donor population, and no
      studies have systematically followed obese patients after kidney donation. Establishment of
      an appropriate control group is of primary importance in studies examining long-term
      outcomes. The investigators will also evaluate a 2-kidney control group to allow us to
      compare the individual and interactive effects of obesity and kidney donation on long-term
      renal function. Study participants will complete a medical questionnaire, undergo blood
      pressure measurements, and provide blood and urine samples for analysis of various metabolic
      parameters. Some study participants will have ambulatory blood pressure monitoring performed
      which involves application of an automated blood pressure cuff for 24 hours. Some study
      participants will also undergo direct measurements of glomerular filtration rate (GFR) with
      iohexol.

      In the proposed research, the investigators hypothesize that obesity in kidney donors
      increases the likelihood of developing renal dysfunction and risk factors for cardiovascular
      disease (CVD) and may increase the likelihood even more than in healthy controls.
    

Detailed description: 
      In order to meet the growing demand for living donor kidneys, the inclusion criteria for
      prospective donors have become less selective, allowing previously ineligible patients to
      donate kidneys. One donor group that has become increasingly more utilized is the overweight
      patient. There is substantial evidence that overweight individuals are more susceptible to
      the development of renal disease either as a direct result of their weight or as a
      consequence of their obesity-related co-morbidities such as diabetes and hypertension. In
      addition, it appears that even mild renal dysfunction can increase the risk of developing
      CVD, which is already more common in this population. Despite these findings, very little is
      known about the individual and interactive effects of obesity and donation on the overall
      health of kidney donors. Our study addresses some of these questions by examining the effects
      of obesity on long-term renal function and development of cardiovascular risk factors such as
      hypertension, dyslipidemia, and metabolic syndrome in patients who donated a kidney at the
      University of California, San Francisco (UCSF) more than 5 years ago (1967-2006). The control
      group will comprise of all potential kidney donors at UCSF during this period who passed an
      initial medical screening evaluation but did not donate because they were found to be ABO- or
      crossmatch incompatible. The investigators believe that the results of the proposed study
      will be important in developing more precise guidelines for the selection and long-term
      health care maintenance of kidney donors.maintenance at all.
    

Observational model: Cohort
Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        all patients who underwent donor nephrectomy at UCSF more than 5 years ago and a 2-kidney
        control group which consist of prospective donors evaluated at UCSF who were found to be
        eligible for donation on the basis of a medical screening evaluation, but then were
        excluded due to ABO-incompatibility or positive crossmatch with the recipient.