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Lower blood pressure cutoffs reduced the rate of missed hypertension in living kidney donor candidates
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While hypertension diagnoses differed for prospective kidney donors based on modality and which guidelines were used, lower blood pressure cutoffs reduced the overall prevalence of missing the condition, according to a recently published study.
“The living donor population is carefully prescreened for the absence of a history of overt uncontrolled hypertension,” Sherif Armanyous, MD, of the department of nephrology and the Glickman Urological and Kidney Institute at the Cleveland Clinic in Ohio, and colleagues wrote. “Clinic blood pressure measurements typically are the basis for clinical screening. However, they exhibit considerable variability, and the measurements are complicated by the occurrence of masked or white coat hypertension.”
To determine whether lowering blood pressure cutoffs for office and automated blood pressure measurement modalities would reduce the rate of missed hypertension, researchers measured the blood pressure of 578 prospective donors using a single office-based blood pressure reading, an office-based automated blood pressure reading and an ambulatory blood pressure (mean patient age, 43 years; 44% were men; average office blood pressure: 119/77 mm Hg; average automated blood pressure: 114/74 mm Hg; average ambulatory blood pressure: 123/77 mm Hg). Automated blood pressure consisted of the average of five consecutive automated readings separated by 1 minute and ambulatory daytime blood pressure — considered the “gold standard”— was measured every 20 minutes during the day with a blood pressure monitor fitted on the arm.
Researchers categorized the diagnosis of hypertension according to both the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-7) — which defined hypertension by office blood pressure as at least 140/90 mm Hg, hypertension by automated blood pressure as at least 134/85 mm Hg and hypertension by home ambulatory blood pressure as at least 135/85 mm Hg — and the American College of Cardiology/the American Heart Association High BP Clinical Practice Guidelines, which defined hypertension by office blood pressure, automated blood pressure and ambulatory blood pressure as at least 130/80 mm Hg.
Researchers defined white coat hypertension as potential donors with hypertension by office blood pressure or automated blood pressure methods but not by ambulatory blood pressure, and they defined masked hypertension as potential donors with normal blood pressure by office blood pressure or automated blood pressure methods but hypertension by ambulatory testing.
Optimal cutoff points for systolic and diastolic blood pressure for both office blood pressure and automated blood pressure were calculated using Youden statistic. Based on JNC-7 definitions, the cutoffs were less than 123/82 for office BP and less than 120/78 mm Hg for automated BP. Based on ACC/AHA definitions, the cutoffs were less than 119/79 for office BP and less than 116/76 mm Hg for automated BP.
Researchers found 16% of prospective donors received a diagnosis of hypertension and 3% had masked hypertension when using the JNC-7 criteria and a combination of office or automated blood pressure. When using the ACC/AHA guidelines, researchers found 34% had a diagnosis of hypertension and 24% had masked hypertension.
When using the lower cutoffs derived from the Youden index, researchers observed that the sensitivity for detecting hypertension improved from 79% to 87% for JNC-7 and from 32% to 87% for ACC/AHA. In addition, missed hypertension was reduced to 2% using JNC-7 guidelines and 4% using ACC/AHA guidelines.
“We found that office blood pressure and automated blood pressure are not sufficient to rule out hypertension in living kidney donor candidates using routine cutoffs and definitions, illustrating the value of ambulatory blood pressure in screening of living donors,” the researchers wrote. “Using lower optimal cutoffs improved the sensitivity of office readings and reduced the prevalence of masked hypertension in donor candidates to a lower percentage. Donor candidates above these lower office and automated cutoffs may benefit the most of ambulatory monitoring to avoid missing hypertension in the office setting.” – by Melissa J. Webb
Disclosures: The authors report no relevant financial disclosures.
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