Adult polycystic kidney disease: who needs hospital follow-up?

Clinical data from 120 adult patients with genetically undifferentiated polycystic kidney disease who had been followed up for more than 3 months (range 3-172) were reviewed in order to try to identify clinical indicators that might predict deterioration in renal function. They were split into two groups dependent on whether annualized fall in estimated glomerular filtration rate (ΔeGFR mL/min/1.73 m(2) /year) was statistically significant or not. Only 26 patients (22%) had a statistically significantly decreasing ΔeGFR with a median decrease of -2.6 mL/min/1.73 m(2) /year (range -6.2 to -0.7). There was no difference in initial age, gender, or racial distributions between the groups or in initial eGFR. Follow-up was longer (median 86, range 23-172 months vs. 46, range 3-161 months; P = 0.002) and initial blood pressure values tended to be lower (with mean systolic values of 128 vs. 148 mm Hg; P = 0.02) in the group with statistically significant fall in ΔeGFR, but this trend failed to achieve an a priori level of statistical significance. However, the proportion of patients with initial systolic blood pressure ≤ 144 developing a statistically significant fall in ΔeGFR was 0.26 (95% confidence interval = 0.13 to 0.45). No differences were found in initial hemoglobin or cholesterol concentrations. Overall, the annualized rate of decrease in eGFR tended to be greater in those with the higher initial eGFR (P = 0.04), but correlation was poor (rho(2) = 0.04) and failed to achieve an a priori level of statistical significance. No statistically significant correlation was found between ΔeGFR and any other variable. Only those patients with polycystic kidney disease with a statistically significant annualized decrease in eGFR may need to be referred for hospital follow-up in the renal clinic. This simple selection would reduce referrals by 78%.