The effect of hypertension and diabetes on the degree of renal function deterioration after unilateral nephrectomy

Study Type – Prognosis (case series) Level of Evidence 4 What’s known on the subject? and What does the study add? Hypertension and diabetes have long been identified as both initiating and progressing factors in chronic kidney disease, as well as predictors of long‐term renal impairment in individuals undergoing nephrectomy. Radical nephrectomy itself is an independent risk factor for chronic kidney disease and its associated increased risk of morbid cardiac events and death. These data have been used to support the argument for greater use of partial nephrectomy when dealing with small renal masses. Whilst in the past it has always been seen as intuitive that patients with hypertension and diabetes would have worse renal function after removal of a kidney for malignancy, the present study is the first to quantify this fact. This information could be used to identify those patients who would benefit from early intervention to delay the progression of chronic kidney disease, as well as those for whom partial nephrectomy might be a more appropriate surgical option. OBJECTIVE To quantify the effect of hypertension and diabetes – which have been identified as both initiating and progressing factors in chronic kidney disease (CKD), as well as predictors of long‐term renal impairment in patients undergoing nephrectomy – on renal function after unilateral nephrectomy for malignancy. PATIENTS AND METHODS A retrospective analysis was carried out of 80 unilateral nephrectomies performed at the Wagga Wagga Base Hospital, Calvary Private Hospital and Austin Hospital from January 2007 to December 2009. Prognostic variables were patient age, sex and the presence of hypertension or diabetes. The percentage reduction in glomerular filtration rate (GFR) after nephrectomy was measured and compared between variables using a two‐sample Student’s t ‐test. RESULTS All patients who had diabetes also had hypertension. Of the 80 patients, 22 (27.5%) fulfilled the criteria for CKD with a preoperative GFR < 60 mL/min. Patients with hypertension and diabetes had a significantly greater percentage reduction in postoperative GFR (36 ± 2%) than those who had neither risk factor (23 ± 2%, P < 0.003). A similar finding was observed for patients with hypertension alone (32 ± 1%, P < 0.009). The difference in postoperative GFR reduction between diabetics and those with hypertension alone was not statistically significant ( P = 0.205). The differential reduction in GFR in patients with CKD risk factors persisted at 3–12 months follow‐up. CONCLUSIONS An increased percentage reduction in GFR is seen in patients with hypertension and diabetes undergoing unilateral nephrectomy for malignancy. These data could be used to identify those patients who would benefit from early referral and subsequent intervention to delay the progression of CKD, as well as those for whom nephron‐sparing surgery might be a more appropriate surgical option.