Proteinuria and reduced kidney function in living kidney donors: A systematic review, meta-analysis, and meta-regression

We reviewed any study where 10 or more healthy adults donated a kidney, and proteinuria, or glomerular filtration rate (GFR) was assessed at least 1 year later. Bibliographic databases were searched until November 2005. 31 primary authors provided additional information. Forty-eight studies from 27 countries followed a total of 5048 donors. An average of 7 years after donation (range 1–25 years), the average 24h urine protein was 154mg/day and the average GFR was 86ml/min. In eight studies which reported GFR in categories, 12% of donors developed a GFR between 30 and 59ml/min (range 0–28%), and 0.2% a GFR less than 30ml/min (range 0–2.2%). In controlled studies urinary protein was higher in donors and became more pronounced with time (three studies totaling 59 controls and 129 donors; controls 83mg/day, donors 147mg/day, weighted mean difference 66mg/day, 95% confidence interval (CI) 24–108). An initial decrement in GFR after donation was not accompanied by accelerated losses over that anticipated with normal aging (six studies totaling 189 controls and 239 donors; controls 96ml/min, donors 84ml/min, weighted mean difference 10ml/min, 95% CI 6–15; difference not associated with time after donation ( P =0.2)). Kidney donation results in small increases in urinary protein. An initial decrement in GFR is not followed by accelerated losses over a subsequent 15 years. Future studies will provide better estimates, and identify those donors at least risk of long-term morbidity.