Comparison of self-reported survey (SHIELD) versus NHANES data in estimating prevalence of dyslipidemia

Abstract

Objectives: The study purpose was to compare the prevalence of dyslipidemia between a self-reported survey, Study to Help Improve Early evaluation and management of risk factors Leading to Diabetes (SHIELD), and survey and laboratory data from National Health and Nutrition Examination Survey (NHANES 1999-2002).

Methods: A SHIELD questionnaire was mailed to 200,000 households representative of US adult population (64% response, n = 211,097 individuals) and included if ever diagnosed with diabetes, high blood pressure or cholesterol problems, high total cholesterol (TC), high bad cholesterol (LDL-C), low good cholesterol (HDL-C), or high triglycerides (TG). In NHANES using a combination of interviewer-administered survey and clinical and laboratory data, dyslipidemia was defined as any one of: TC > or = 240 mg/dL or diagnosis of high cholesterol; TG > 200 mg/dL; LDL-C > or = 160 mg/dL; or HDL-C < 40 mg/dL. NHANES diabetes mellitus definition was doctor diagnosis or fasting glucose > 125 mg/dL and hypertension was elevated blood pressure or taking anti-hypertensive medication. Prevalence of dyslipidemia was determined for SHIELD in 2004 and compared to NHANES 1999-2002. Prevalence of diabetes and hypertension was estimated for broader contextual comparison within cardiometabolic diseases.

Results: In contrast to the prevalence of diabetes (8% in SHIELD and 9% in NHANES, p < 0.01) and hypertension (23% in SHIELD and 29% in NHANES, p < 0.01), dyslipidemia was reported only half as frequently in SHIELD (26%) as in NHANES (53%), p < 0.01. Components of dyslipidemia were uniformly less in SHIELD than NHANES: high TC = 17 vs. 35%, high LDL-C = 10 vs. 14%, high TG = 7 vs. 17% and low HDL-C = 5 vs. 24%; all comparisons p < 0.01.

Limitations: Differences in survey methodology, non-response and timing may have impacted the comparison of SHIELD to NHANES.

Conclusions: Dyslipidemia prevalence was lower in self-reported SHIELD than the objectively assessed NHANES, with especially low self-report of high TG and low HDL-C. Self-reported prevalence of dyslipidemia may under-report the prevalence based on laboratory data.