Risk of CKD Following Detection of Microscopic Hematuria: A Retrospective Cohort Study

Abstract

Rationale & objective: Microscopic hematuria is an uncertain risk factor for chronic kidney disease (CKD). We investigated the association between persistent or single episodes of microscopic hematuria and the development of incident CKD, overall and separately among men and women.

Study design: Retrospective cohort study.

Setting & participants: A total of 232,220 Korean adults without CKD at baseline who underwent repeated regular health examinations at Kangbuk Samsung Health Study formed the study cohort.

Exposure: Microscopic hematuria was defined by≥5 red blood cells per high-power field. Participants were categorized into 1 of 4 groups according to the presence of hematuria at 2 consecutive examinations: (1) no hematuria at both examinations (reference group); (2) hematuria followed by no hematuria (regressed hematuria group); (3) no hematuria followed by hematuria (developed hematuria group); and (4) hematuria at both examinations (persistent hematuria group).

Outcome: CKD was defined as an estimated glomerular filtration rate<60mL/min/1.73m² or proteinuria (1+or more on dipstick examination).

Analytical approach: Semiparametric proportional hazards models were used to estimate hazard ratios.

Results: During a 4.8-year median follow-up period, 2,392 participants developed CKD. Multivariable-adjusted hazard ratios for incident CKD, comparing the regressed, developed, and persistent hematuria groups to the no-hematuria group were 1.85 (95% CI, 1.35-2.53), 3.18 (95% CI, 2.54-3.98), and 5.23 (95% CI, 4.15-6.59), respectively. The association between persistent hematuria and incident CKD was stronger in men than women (P for interaction<0.001), although a statistically significant association was observed in both sexes.

Limitations: Lack of albuminuria and inability to consider specific glomerular diseases.

Conclusions: Men and women with microscopic hematuria, especially persistent hematuria, may be at increased risk of CKD.

Keywords: CKD risk factor; Chronic kidney disease (CKD); estimated glomerular filtration rate (eGFR); health screening; microscopic hematuria; proteinuria; renal function; sex differences; urinalysis.