Undiagnosed chronic kidney disease in Hungary: Insights from the H-UNCOVER cross-sectional study

Abstract Background Chronic kidney disease (CKD) is often undiagnosed in older adults, where renal decline may be age-related. The lack of age-adjusted CKD classification may contribute to overdiagnosis and unnecessary interventions in otherwise healthy individuals. This study examined the prevalence of undiagnosed CKD (uCKD) across age groups, highlighting individuals with risk factors where diagnosis may be more relevant. Methods Data were obtained from the H-UNCOVER study, a cross-sectional, nationally representative survey of individuals aged ≥14 years in Hungary (HU) (n = 10474; 59% response). CKD was defined as eGFR <60 mL/min/1.73m². Diagnosed CKD (dCKD) was self-reported, while uCKD was defined as reduced eGFR without prior diagnosis. Sampling weights were applied. Sex-stratified logistic regression was used to assess factors associated with uCKD, adjusting for age, demographics and clinical factors. Results CKD prevalence was 9.6%[8.8-10.4%] in women and 5.5%[4.3-6.8%] in men using the HU standard; European standard estimates were 9.2%[8.4-9.9%] and 5.8%[4.6-7.0%], respectively. uCKD exceeded dCKD in both sexes and rose with age. In women, uCKD was 6.8%[6.1-7.5%] in HU and 6.5%[5.8-7.1%] using the European standard; in men, 3.6%[3.1-4.1%] and 3.8%[3.3-4.4%], respectively. Fully adjusted models showed higher uCKD odds in women aged 60-74 (OR:3.3[1.2-8.9]) and ≥75 years (OR:7.2[2.8-18.3], and in men ≥75 years (OR:3.6[1.2-11.1]). uCKD was less likely among women with comorbidities (OR:0.2[0.0-0.6]), particularly in those with heart disease (OR:0.5[0.3-0.8]). In men, having one comorbidity and elevated LDL cholesterol were associated with lower odds of uCKD (OR:0.2[0.0-0.6] and OR:0.3[0.1-0.9], respectively). Conclusions Older adults without comorbidities were more likely to have uCKD, suggesting that detection in this group may have limited clinical relevance. These findings suggest a need to prioritize risk-based over age-based screening in public health efforts. Key messages • Undiagnosed CKD is more common in older adults without comorbidities, suggesting the need to align screening strategies with clinical risk rather than age alone. • Adjusting CKD diagnosis based on age and risk factors may help avoid unnecessary interventions.