SAN FRANCISCO—Investigators have documented substantial heterogeneity in the prevalence of high blood pressure among Asian-American subgroups.

The data, released at the American College of Cardiology annual meeting, also show that the Filipino subgroup has the highest rates of hypertension, followed by the Japanese subgroup.

“Our results suggest that susceptible populations like the Filipino and Japanese subgroups may warrant early and aggressive intervention in blood pressure reduction to help decrease cardiovascular risk,” Powell Jose, MD, Research Physician at the Palo Alto Medical Foundation Research Institute. “Physicians should attempt to better understand cultural differences and barriers that may influence diet and health behaviors in Asian-American subgroups. Nutrition and lifestyle counseling must be offered to these higher risk populations to help control hypertension in addition to medical therapy, when indicated.”

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Dr. Jose and his colleagues used electronic health records to compare the rates of hypertension for several Asian-American subgroups with other racial/ethnic groups. Their analysis included 242,790 patients who were enrolled in a large, mixed-payer, outpatient health maintenance organization in the San Francisco Bay Area,  and who were identified through self-report or by their name to be Asian-American (Asian-Indian, -Chinese , -Filipino, -Japanese, -Korean, or -Vietnamese), Hispanics, non-Hispanic blacks, or non-Hispanic whites. All study participants had made at least two primary care visits to their provider from 2008-2010.

Asian-Americans are a rapidly growing minority population in the U.S., and their numbers are expected to grow to nearly 34 million by 2050, Dr. Jose noted.

Higher rates of coronary heart disease have been reported for some Asian-American subgroups, especially Asian-Indians and Asian-Filipinos. Knowledge of cardiovascular risk factors among Asian-American subgroups is inadequate, he said.  For example, hypertension is a major coronary risk factor, but hypertension rates among Asian-American subgroups are unknown, which is primarily because of underrepresentation or aggregation of Asian-American subgroups in epidemiologic studies.

Individuals in the present analysis were deemed hypertensive if their blood pressure was 140/90 mm Hg or higher during two separate non-emergent office visits or if they had an ICD-9 coding for hypertension, or reported using any anti-hypertensive medication.

Results showed that hypertension rates controlled for age and sex were lower for aggregated Asian-Americans (34.9%) compared to non-Hispanic whites (38.9%).  However, when dissaggregated by Asian-American subgroups, Filipinos had markedly higher hypertension rates (51.9%) than non-Hispanic whites.

In addition, adjusted hypertension rates were lower among most Asian-American subgroups including Chinese (29.8%), Koreans (30.7%), Vietnamese (30.8%), and Asian-Indians (36.9%) than non-Hispanic whites.  The Japanese subgroup had hypertension rates (38.2%) that were similar to non-Hispanic whites.

Further analysis revealed that Filipinos and Japanese were the only high-risk Asian-American subgroups for hypertension compared with whites.

The study found no significant gender differences in racial/ethnic patterns of hypertension rates.

Dr. Jose cautioned that the study was confined to a single geographic area with small sample sizes in some Asian-American subgroups, thereby limiting the generalizability of the results. In addition, because of the study’s cross-sectional design, the researchers were not able to look for potential causal relationships.

Finally, the investigators were unable to control for some socioeconomic variables such as education and income, behavioral variables such as diet, and clinical variables such as medication adherence, all of which may influence prevalence rates. Dr. Jose added, however, that the study’s internal validity is bolstered by the relative homogeneity in economic status of the study population as evidenced by the fact that all patients were insured and had access to health care.