Epidemiological estimates and early detection of polycystic kidney disease by ultrasonographic assessment in Japan.

Aims: To estimate the prevalence of autosomal dominant polycystic kidney disease (ADPKD) and provide the evaluation of new ultrasonographic criteria and clinical indicators to help its early detection. Materials and methods: A total of 30750 individuals for health check-up with abdominal ultrasonography (US) were included, in which 231 suspects of ADPKD based on the number of renal cysts were extracted. They were divided into 4 groups by the grade of suspicion (definitive, a strong suspect, a fair suspect and a weak suspect). Longitudinal data of US and renal function tests were compared between the groups. The estimated prevalence rate was 0.068% from the study subjects. The level of eGFR did not differ between the definitive and suspects, while the annual estimated glomerular filtration ratio (eGFR) decline was significantly larger in the former (p<0.001). The subjects with growing renal cysts showed a larger annual eGFR decline than those without growth (p=0.0324). The proposed cut-off set at the first quartile of the annualized eGFR change efficiently divided the subjects according to the presence of cyst growth (p= 0.027) and the grade of suspicion of ADPKD (p=0.028). Conclusion: The prevalence rate of ADPKD was higher than the corresponding rate previously reported in Japan (0.025%), suggesting that health check-ups may be an efficient opportunity to pick up undiagnosed ADPKD. The large annual eGFR decline and the presence of growing cysts may be feasible indicators to isolate ADPKD and should be introduced into US based screening to facilitate early detection of ADPKD.