Chronic kidney disease (CKD) contributes to premature mortality directly and as a risk factor for other non-communicable diseases, including cardiovascular diseases.
It has been estimated that the global prevalence of CKD has increased by 29.3% since 1990 and that CKD was the 12th leading cause of death worldwide in 2017. Early detection of CKD and identification and management of Modifiable risk factors for CKD and its progression are important in reducing the risk of end-stage renal disease and non-renal complications, including cardiovascular mortality.
Microscopic hematuria is a common incidental finding in urinalysis and its prevalence has varied between studies, ranging between 0.12 and 30%.
More than 50% of patients with microscopic hematuria have no definitive identifiable cause and low-level hematuria is considered a benign condition. In contrast, hematuria has been proposed as an early marker of CKD; however, its role in CKD risk is not well established in the general population.
Two studies have reported an association between microscopic hematuria and the risk of end-stage kidney disease or increased risk of CKD, defined using estimated glomerular filtration rates (eGFR).
However, no study has evaluated the association between microscopic changes in hematuria and CKD, based on two measurements separated in time. Furthermore, unlike hematuria in men, microscopic hematuria in young women is usually considered a benign finding. However, it is not known whether there are sex-specific differences in the association between microscopic hematuria and CKD.
Our objective was to evaluate the relationship between persistent hematuria, single episodes of hematuria and no evidence of hematuria, and the risk of CKD; and tested whether the association between hematuria and CKD risk differed by sex.
Justification and objective
Microscopic hematuria is an uncertain risk factor for chronic kidney disease (CKD). We investigated the association between single or persistent episodes of microscopic hematuria and the development of incident CKD overall and separately among men and women.
Study design
Retrospective cohort study.
Setting and Participants
A total of 232,220 Korean adults without CKD at baseline who underwent repeated periodic health examinations in the Kangbuk Samsung Health Study formed the study cohort.
Exposure
Microscopic hematuria was defined by ≥5 red blood cells per high-power field. Participants were classified into one of four groups based on the presence of hematuria at two consecutive examinations: a) no hematuria at both examinations (reference group); b) hematuria followed by absence of hematuria (regressing hematuria group); c) without hematuria followed by hematuria (developed hematuria group); and d) hematuria on both examinations (persistent hematuria).
CKD was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m2 or proteinuria defined as 1+ or more on dipstick examination.
Analytical approach
Semiparametric proportional hazards models were used to estimate hazard ratios (95% CI).
Results
During a median follow-up of 4.8 years, 2392 participants developed CKD.
The multivariable-adjusted hazard ratios (95% CI) for incident CKD, comparing the "regressing," "developed," and "persistent" hematuria groups with the "no hematuria" group were 1.85 (1, 35–2.53), 3.18 (2.54–3.98), and 5.23 (4.15–6.59), respectively.
The association between persistent hematuria and incident CKD was stronger in men than in women (Pinteraction < 0.001), although a significant association was observed in both sexes.
Limitations
Absence of albuminuria and inability to consider specific glomerular diseases.
Conclusion
Men and women with microscopic hematuria, especially persistent hematuria, may be at increased risk of CKD.
Our results showed that single or persistent episodes of microscopic hematuria were associated with the risk of CKD in men and women. Further studies are needed to evaluate whether hematuria, especially persistent hematuria, can help identify both men and women at high risk for CKD and whether appropriate management of hematuria can help decrease the risk of subsequent CKD and progression. to kidney failure.
Comments
Data, recently published in the American Journal of Kidney Disease (AJKD), from a large South Korean cohort show a five-fold increased risk of incident CKD for adults with persistent hematuria compared to those without hematuria, but the associations were significantly stronger in men vs. women.
Hematuria, which refers to the presence of blood in the urine, has been reported to be associated with an increased risk of chronic kidney disease (CKD). However, the relationship between hematuria that persists over time and renal function is unclear. In this large study consisting of relatively young and healthy Korean adults, researchers investigated the association between episodes of microscopic hematuria and the development of CKD.
They found that microscopic hematuria, especially when persistent, was associated with worse kidney function. These associations were stronger in men compared to women, but were evident in both sex groups. This study, recently published in the American Journal of Kidney Disease (AJKD), suggests that people with long-term hematuria should be monitored and may be candidates for early preventive strategies to decrease the risk of subsequent CKD.
