Prevalence of chronic kidney disease in persons with undiagnosed or prehypertension in the United States

Abstract

Hypertension is both a cause and a consequence of chronic kidney disease, but the prevalence of chronic kidney disease throughout the diagnostic spectrum of blood pressure has not been established. We determined the prevalence of chronic kidney disease within blood pressure categories in 17 794 adults surveyed by the National Health and Nutrition Examination Survey during 1999-2006. Diagnosed hypertension was defined as self-reported provider diagnosis (n=5832); undiagnosed hypertension was defined as systolic blood pressure > or = 140 mm Hg or diastolic blood pressure > or = 90 mm Hg, without report of provider diagnosis (n=3046); prehypertension was defined as systolic blood pressure > or = 120 and <140 mm Hg or diastolic blood pressure > or = 80 and <90 mm Hg (n=3719); and normal was defined as systolic blood pressure <120 mm Hg and diastolic blood pressure <80 mm Hg (n=5197). Chronic kidney disease was defined as estimated glomerular filtration rate <60 mL/min per 1.73 m(2) or urinary albumin:creatinine ratio >30 mg/g. Prevalences of chronic kidney disease among those with prehypertension and undiagnosed hypertension were 17.3% and 22.0%, respectively, compared with 27.5% with diagnosed hypertension and 13.4% with normal blood pressure, after adjustment for age, sex, and race in multivariable logistic regression. This pattern persisted with varying definitions of kidney disease; macroalbuminuria (urinary albumin:creatinine ratio >300 mg/g) had the strongest association with increasing blood pressure category (odds ratio: 2.37 [95% CI: 2.00 to 2.81]). Chronic kidney disease is prevalent in undiagnosed and prehypertension. Earlier identification and treatment of both these conditions may prevent or delay morbidity and mortality from chronic kidney disease.

Figure 1. Population prevalence (%) of CKD stages 1–4, by hypertension status, NHANES 1999–2006

Diagnosed hypertension is defined as self-report of provider diagnosis; undiagnosed hypertension is defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg, without a report of provider diagnosis; pre-hypertension is defined as systolic blood pressure ≥120 and <140 mmHg or diastolic blood pressure ≥80 and <90 mmHg; and normal is defined as systolic blood pressure <120 mmHg and diastolic blood pressure <80 mmHg. CKD defined by eGFR 15–60 ml/min/1.73 m² or a single determination of albuminuria measurement. CKD stages defined as stage 1, eGFR > 90 ml/min per 1.73 m² and presence of albuminuria at a single measurement; stage 2, eGFR 60–89 ml/min per 1.73 m² and presence of albuminuria at a single measurement; stage 3, eGFR 30–59 ml/min per 1.73 m²; stage 4, 15–29 ml/min per 1.73 m²). Values in parentheses represent 95% confidence intervals.

Figure 2. Prevalence of CKD awareness (%), by hypertension status, NHANES 1999–2006

Diagnosed hypertension is defined as self-report of provider diagnosis; undiagnosed hypertension is defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg, without a report of provider diagnosis; pre-hypertension is defined as systolic blood pressure ≥120 and <140 mmHg or diastolic blood pressure ≥80 and <90 mmHg; and normal is defined as systolic blood pressure <120 mmHg and diastolic blood pressure <80 mmHg. CKD defined by eGFR 15–60 ml/min/1.73 m² or a single determination of albuminuria measurement. Values in parentheses represent 95% confidence intervals. *Statistically different from other awareness estimates (P<0.001).