Development and evaluation of a kidney health questionnaire and estimates of chronic kidney disease prevalence in the Cooperative Health Research In South Tyrol (CHRIS) study

Introduction. Kidney diseases are a public health burden but, except for chronic kidney disease (CKD), they are poorly investigated in the general population. In light of inadequate survey tools for use in population studies, we developed a novel questionnaire to retrospectively assess the main kidney diseases, integrating it within the Cooperative Health Research In South Tyrol (CHRIS) study conducted between 2011 and 2018 in the Alpine district of Val Venosta/Vinschgau (Italy). Methods. The questionnaire covers general kidney diseases, reduced kidney function, and renal surgeries. It was applied to the cross-sectional assessment of self-reported kidney health among 11,684 adults, along with measures of fasting estimated glomerular filtration rate (eGFR) and urinary albumin-to-creatinine ratio (UACR). By factor analysis we contextualized the questionnaire content with respect to biochemical measurements. CKD was defined according to KDIGO guidelines, self-reported diagnosis, and their combination. Prevalence estimates were calibrated to the general target population via relative sampling weights. Results. In this population sample (median age=45 years; median eGFR=98.4 mL/min/1.73 m2; median UACR=5.7 mg/g), 8.3% of participants reported at least one kidney disease. Population-representative prevalence of glomerulonephritis, pyelonephritis, and congenital kidney diseases was 1.0%, 3.0%, and 0.2%, respectively, with corresponding odds ratio for females versus males of 1.4 (95% confidence interval: 1.0, 2.0), 8.7 (6.2, 12.3), and 0.7 (0.3, 1.6), respectively. CKD prevalence was 8.6% when based on KDIGO criteria and 0.7% when self-reported, indicating that 95.3% of affected individuals were unaware of having CKD, with a similar figure of 92.9% in those reporting diabetes or hypertension. Overall, 15.8% of the population was affected by a kidney disease of any kind. Conclusion. In this Alpine population, CKD prevalence aligned with Western European estimates. Kidney health questionnaire implementation in population studies is feasible and valuable to assess CKD awareness, which we found to be dramatically low.