Changing disease definitions: implications for disease prevalence. Analysis of the Third National Health and Nutrition Examination Survey, 1988-1994.

CONTEXT: In the hope of extending treatment benefits to patients with early disease, various professional societies have recommended changing several common disease definitions by lowering the threshold value for diagnosis. COUNT: Number of Americans labeled "diseased" under new definitions for diabetes, hypertension, hypercholesterolemia, and being overweight. CALCULATION: [symbol: see text] DATA SOURCE: Adult participants (age > 17 years) in the Third National Health and Nutrition Examination Survey (1988-1994).
RESULTS: Adopting the new definitions would dramatically inflate disease prevalence. Changing the threshold for diabetes from a fasting glucose level of > or = 140 mg/dL to > or = 126 mg/dL would result in 1.7 million new cases. Redefining hypertension as systolic blood pressure > or = 140 mm Hg instead of > or = 160 mm Hg or diastolic blood pressure > or = 90 mm Hg instead of > or = 100 mm Hg would create 13 million new hypertensive patients. For hypercholesterolemia (a cholesterol level of > or = 200 mg/dL instead of > or = 240 mg/dL) and being overweight (body mass index > or = 25 kg/m2 instead of > or = 27 kg/m2), the number of new cases would be 42 million and 29 million, respectively. The new definitions ultimately label 75% of the adult U.S. population as diseased.
CONCLUSIONS: If these modest changes in disease definition were adopted, great numbers of people would be considered diseased. The extent to which new "patients" would ultimately benefit from early detection and treatment of these conditions is unknown. Whether they would experience important physical or psychological harm is an open question.