Changes in separate renal function in patients who underwent minimally invasive renal stone surgery according to the preoperative functional deterioration

Abstract

The significant predictors for the postoperative deterioration of separate renal function after minimally invasive stone surgery were investigated in the present prospective and observational study. A total of 117 consecutive patients who underwent retrograde intrarenal surgery or mini-percutaneous nephrolithotomy for renal calculi >10 mm were included in the present study. Perioperative changes in separate renal function were evaluated with Technetium-99m-Diethylene TriaminePenta acetic acid scan prior to intervention and at postoperative 3 months. Based on the functional differences between bilateral renal units, deterioration of separate renal function was graded into the following three groups: normal deterioration (<10%), moderate deterioration (10-20%), and severe deterioration (>20%). A total of 46 patients had a normal separate renal function, while 71 (60.7%) showed abnormal separate function in the involved side, including 29 (24.8%) moderate and 42 (35.9%) severe deterioration. Postoperatively, 48 patients (41.0%) showed aggravation or no recovery of separate renal function. Of the 46 patients with normal separate function, only 9 patients (19.5%) showed postoperative aggravation. Patients with moderate and severe deterioration showed aggravation (n = 7, 24.1%) or no recovery of separate renal function (n = 32, 76.1%, P < 0.001). Preoperative severe deterioration of separate renal function was an independent significant predictor for the postoperative deterioration of renal function (OR: 9.09, 95% CI: 4.007-20.624, P < 0.001). Lower preoperative deterioration of separate renal function showed a high probability of functional recovery. Therefore, it is hypothesized that early intervention might be necessary in cases where the patient exhibits severe aggravation of renal function.

Figure 1

The student paired t-test of perioperative separate functional changes in the involved kidneys according to the preoperative functional status. a. normal (<10%), b. moderate (10–20%), and c. severe (>20%). Data are presented as individual values and as a mean ± standard deviation.

Figure 2

Receiver Operating Characteristic-curve analyses of the postoperative severe deterioration of separate function in the involved kidney. The black line represents univariate analysis for [preoperative GFR]. The red line represents bivariate analysis for [preoperative GFR] and preoperative deterioration of relative separate renal function more than 20% on the involved kidney. GFR = glomerular filtration rate; CI = confidence interval; ROC = receiver operating characteristic.