Investigating kidney donation as a risk factor for hypertension and microalbuminuria: findings from the Swiss prospective follow-up of living kidney donors

OBJECTIVES: To assess the role of nephrectomy as a risk factor for the development of hypertension and microalbuminuria. DESIGN: Prospective, long-term follow-up study. SETTING: Swiss Organ Living-Donor Health Registry. PARTICIPANTS: All living kidney donors in Switzerland between 1993 and 2009. INTERVENTIONS: Data on health status and renal function before 1 year and biennially after donation were collected. PRIMARY AND SECONDARY OUTCOME MEASURES: Comparison of 1-year and 5-year occurrences of hypertension among normotensive donors with 1-year and 5-year estimates from the Framingham hypertension risk score. Multivariate random intercept models were used to investigate changes of albumin excretion after donation, correcting for repeated measurements and cofactors such as age, male gender and body mass index. RESULTS: A total of 1214 donors contributed 3918 data entries with a completed biennial follow-up rate of 74% during a 10-year period. Mean (SD) follow-up of donors was 31.6 months (34.4). Median age at donation was 50.5 years (IQR 42.2–58.8); 806 donors (66.4%) were women. Donation increased the risk of hypertension after 1 year by 3.64 (95% CI 3.52 to 3.76; p<0.001). Those participants remaining normotensive 1 year after donation return to a risk similar to that of the healthy Framingham population. Microalbuminuria before donation was dependent on donor age but not on the presence of hypertension. After nephrectomy, hypertension became the main driver for changes in albumin excretion (OR 1.19; 95% CI 0.13 to 2.25; p=0.03) and donor age had no effect. CONCLUSIONS: Nephrectomy propagates hypertension and increases susceptibility for the development of hypertension-induced microalbuminuria.