Screening strategies for chronic kidney disease in the general population: follow-up of cross sectional health survey

Objective To find an effective screening strategy for detecting patients with chronic kidney disease and to describe the natural course of the disease. Design Eight year follow-up of a cross sectional health survey (the HUNT II study). Setting Nord-Tr�ndelag County, Norway Participants 65�604 people (70.6 % of all adults aged ≥20 in the county). Main outcome measures Incident end stage renal disease (ESRD) and cardiovascular mortality monitored by individual linkage to central registries. Results 3069/65 604 (4.7%) people had chronic kidney disease (estimated glomerular filtration rate <60 ml/min/1.73 m2), so we would need to screen 20.6 people (95% confidence interval 20.0 to 21.2) to identify one case. Restriction of screening to those with hypertension, diabetes, or age >55 would identify 93.2% (92.4% to 94.0%) of patients with chronic kidney disease, with a number needed to screen of 8.7 (8.5 to 9.0). Restriction of screening according to guidelines of the United States kidney disease outcomes quality initiative (US KDOQI) gave similar results, but restriction according to the United Kingdom's chronic kidney disease guidelines detected only 60.9% (59.1% to 62.8%) of cases. Screening only people with previously known diabetes or hypertension detected 44.2% (42.7% to 45.7%) of all cases, with a number needed to screen of six. During the eight year follow-up only 38 of the 3069 people with chronic kidney disease progressed to end stage renal disease, and the risk was especially low in people without diabetes or hypertension, women, and those aged ≥70 or with a glomerular filtration rate 45-59 ml/min/1.73 m2 at screening. In contrast, there was a high cardiovascular mortality: 3.5, 7.4, and 10.1 deaths per 100 person years among people with a glomerular filtration rate 45-59, 30-44, and <30 ml/min/1.73 m2, respectively. Conclusion Screening people with hypertension, diabetes mellitus, or age >55 was the most effective strategy to detect patients with chronic kidney disease, but the risk of end stage renal disease among those detected was low.