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ObjectivesHypertension guidelines recommend screening for chronic kidney disease (CKD) using serum creatinine and urine dipstick; this strategy may lead to misclassification. Persons with occult CKD [i.e. missed by creatinine but detected by cystatin C or albumin-to-creatinine ratio (ACR)] have higher risks for death, cardiovascular events, and end-stage renal disease.MethodsWe studied occult CKD prevalence among nondiabetic, hypertensive adults in National Health and Nutrition Examination Survey 1988-1994 (N = 2088) and 1999-2002 (N = 737). We defined occult CKD as estimated glomerular filtration rate by cystatin C (eGFRcys) less than 60 ml/min per 1.73 m and/or ACR at least 30 mg/g among persons with eGFRcreat more than 60 ml/min per 1.73 m. We studied occult CKD prevalence by either marker, stratified by age, race/ethnicity, and assessed clinical predictors associated with occult CKD presence.ResultsIn 1988-1994, occult CKD was prevalent among 25% of nondiabetic hypertensive persons, and it was 22% in 1999-2002. Each marker's ability to detect occult CKD varied by age and race. Cystatin C detected occult CKD among 8.9% of persons more than 65 years, and among 3.8% of whites. ACR detected occult CKD among 9.3% of persons less than 45 years, 16.6% of Blacks, and 20.6% of Mexican-Americans. In multivariate models, each decade of advancing age was associated with a higher occult CKD prevalence by cystatin C (OR 3.1, 95% CI 2.5-3.8) in 1988-1994 and 1999-2002 (OR 2.9, 1.8-4.6).ConclusionCurrent hypertension guidelines may fail to detect a large proportion of high-risk individuals with CKD who can be identified by cystatin C or ACR. Future studies are needed to evaluate targeted use of multimarker renal panels among hypertensives.

ObjectiveHIV-infected persons have substantially higher risk of kidney failure than persons without HIV, but serum creatinine levels are insensitive for detecting declining kidney function. We hypothesized that urine markers of kidney injury would be associated with declining kidney function among HIV-infected women.MethodsIn the Women's Interagency HIV Study, we measured concentrations of albumin-to-creatinine ratio, interleukin-18 (IL-18), kidney injury marker-1 (KIM-1), and neutrophil gelatinase-associated lipocalin from stored urine among 908 HIV-infected and 289 HIV-uninfected participants. Primary analyses used cystatin C-based estimated glomerular filtration rate (CKD-EPI eGFRcys) as the outcome, measured at baseline and 2 follow-up visits over 8 years; secondary analyses used creatinine (CKD-EPI eGFRcr). Each urine biomarker was categorized into tertiles, and kidney decline was modeled with both continuous and dichotomized outcomes.ResultsCompared with the lowest tertiles, the highest tertiles of albumin-to-creatinine ratio (-0.15 mL/min per 1.73 m, P < 0.0001), IL-18 (-0.09 mL/min per 1.73 m, P < 0.0001) and KIM-1 (-0.06 mL/min per 1.73 m, P < 0.001) were independently associated with faster eGFRcys decline after multivariate adjustment including all 3 biomarkers among HIV-infected women. Among these biomarkers, only IL-18 was associated with each dichotomized eGFRcys outcome: ≥3% (relative risk = 1.40; 95% confidence interval: 1.04 to 1.89); ≥5% (1.88; 1.30 to 2.71); and ≥10% (2.16; 1.20 to 3.88) for the highest versus lowest tertile. In alternative models using eGFRcr, the high tertile of KIM-1 had independent associations with 5% (1.71; 1.25 to 2.33) and 10% (1.78; 1.07 to 2.96) decline, and the high IL-18 tertile with 10% decline (1.97; 1.00 to 3.87).ConclusionsAmong HIV-infected women in the Women's Interagency HIV Study cohort, novel urine markers of kidney injury detect risk for subsequent declines in kidney function.