Cardiovascular disease is the leading cause of death both nationally(1) and in New York City (NYC),(2) and hypertension (HTN) is a leading modifiable risk factor affecting approximately 1 in 4 NYC adults.(3) Since the Immigration Act of 1965, immigration from Latin America and Asian countries has increased steadily,(4) with many individuals settling in metropolitan areas such as NYC.(5, 6) Population-level surveillance of HTN in these populations is critical for understanding health patterns, identifying health disparities, and developing targeted interventions.

Self-reported HTN has been validated in white, black, and Mexican-American populations using national data with the lowest sensitivity and specificity values observed in Mexican-American men.(7) Validity was also lower among those who reported no medical visits compared to those with at least one visit in the past year, implying that access to care may have bearing on the ability to accurately self-report HTN. To date, only one other study on validation of self-reported HTN has been performed in a diverse population living in an urban area using local data.(8) The study used representative data from Detroit (~80% black or Hispanic), and found few differences between racial/ethnic groups in terms of validity of self-reported HTN. The racial/ethnic composition of NYC, differs from Detroit and from the nation; 2.7 million NYC adults (44%) are foreign-born, and foreign-born adults are more likely to be uninsured than U.S.-born adults (22% vs. 9%).(9) Further, the majority of Hispanics in NYC are from the Dominican Republic (18.8%) or Puerto Rico (36.5%) rather than from Mexico (3.5%), and there is also a substantial Asian American population(13%).(10-13) Given that limited access to health care and language barriers may impact a respondent's ability to report HTN accurately, validation in these recent immigrant groups is important for ensuring the accuracy of chronic disease surveillance in diverse populations.

The objective of this analysis was 1) to assess validity of self-reported HTN in foreign-born, Hispanic, and Asian American adults living in NYC and 2) to recalibrate the prevalence of self-reported HTN to clinically measured HTN in a representative NYC sample.

The participant characteristics for the HFUS and CHS samples displayed in Table 1 were similar overall. Those who agreed to participate in the HFUS, compared with those who did not, were slightly more likely to be Hispanic, <65 years of age, lower income, and obese; there were no meaningful differences in self-reported general health status between CHS and HFUS participants.(15) About half of both samples were female (54%), black or Hispanic (47%), had an education level of high school or less (41-46%), and were foreign-born (43%). The majority had insurance (82-83%); spoke English at home (70-72%); and of those who were foreign born, had been in the U.S. for 10+ years (76-79%). For self-reported HTN among the 1,568 HFUS participants, 449 were labeled as true positive, 918 as true negative, 88 as false positive, and 109 as false negatives. The sensitivity and specificity were 80% (95% CI: 77, 84) and 91% (95% CI: 89, 93), respectively (Table II). A lower sensitivity was observed in men (74%, [95% CI: 67, 79]) compared to women (85%, [95% CI: 88, 93]). Sensitivity was also lower in those without insurance compared to those with insurance (67% [95% CI: 54, 79] vs. 82% [95% CI: 78, 85]) and in those in the US for <10 years compared to 10+ years (63% [95% CI: 41, 81] vs. 85% [95% CI: 78, 89]), though the confidence intervals overlapped with referent groups. Specificity was lower in those with a less than high school education compared to those with a college education (80% [95% CI: 73, 87] vs. 94% [95% CI: 92, 96]). Though the confidence intervals overlapped, blacks had a slightly lower specificity than whites (88% [95% CI: 83, 92] vs. 94% [95% CI: 91, 96]. No meaningful differences for sensitivity and specificity measures were observed for Puerto Ricans, Dominicans or Asians compared to whites, or between acculturation-related factors overall

The prevalence of HTN in the CHS was 27.8 (95% CI: 27.3, 28.3), while the recalibrated HTN prevalence was 24.7 (95% CI: 24.2, 25.1). In men, HTN prevalence before and after recalibration did not differ (27.2, [95% CI: 26.4, 28.0] vs. 27.0, [95% CI: 26.2. 27.7], respectively), while in women, the self-reported prevalence was higher than the recalibrated value (28.1, [95%CI: 27.5, 28.8] vs. 22.6, [95%CI: 22.1, 23.2], respectively). The prevalence estimates of HTN in the CHS in Hispanics overall, Puerto Ricans, Dominicans and Asians were 29.6, 34.1, 36.0, and 24.4, respectively; and the recalibrated estimates were 24.4, 28.2, 27.9 and 23.2, respectively (Supplemental Table). The self-reported and recalibrated HTN prevalence estimates stratified by the remaining covariates are displayed in the Supplemental Table.

Overall the absolute difference between the recalibrated and the self-reported HTN prevalence was 3.1%; the relative difference was 11.0%. The difference between the recalibrated and self-reported prevalence estimates was largest in Hispanics overall (4.7% absolute, 17.6% relative differences); Puerto Ricans (7.8% absolute, 21.7% relative); Dominicans (6.2% absolute, 18.2% relative); those with less than a high school education (6.3% absolute, 19.3% relative); and in those speaking Spanish at home (4.5% absolute, 15.2% relative; Figure 1). Large differences were also observed but were similar across categories by insurance status, nativity, length of time in the U.S., and in those with higher education. Recalibration did not produce substantial changes for HTN estimates in Asian Americans.

Validity of self-reported HTN was good-to-fair in this ethnically diverse sample. Sensitivity was lowest among Hispanics, the uninsured, those who spoke Spanish at home, and foreign-born adults who had been in the U.S. for <10 years. Specificity did not differ markedly across groups. Interestingly, sensitivity and specificity in Puerto Ricans, Dominicans (but not in Hispanics overall), Asians and foreign-born NYC residents were similar to whites and those who were U.S.-born. Previously published analyses in national samples have demonstrated that self-reported HTN is the least accurate in the Mexican American subgroup.(7) Similarly in the current analysis, Hispanics who were not Dominican or Puerto Rican had the lowest likelihood of reporting HTN when clinical HTN was present. Lack of health insurance or limited access to care may help explain some of these differences since Puerto Ricans and Dominicans are more likely to have health insurance than other Hispanic subgroups.(22)

After applying the recalibration methodology, self-reported HTN prevalence in the CHS tended to be slightly overestimated in all groups, with the largest differences observed in women; in Hispanics (overall, Puerto Ricans, and Dominicans); and in those with less than a high school education. Low health literacy related to HTN and health in general might have also led to reporting errors in these groups; previous studies have shown that underreporting is less likely due to misreporting and more related to a lack of diagnosis.(23). These findings also suggest that cultural differences in the definition of HTN may lead to misreporting, and may be a factor that affects HTN self-reporting. In addition to misreporting, those who self-reported HTN but did not have clinical HTN according to the study definition may have been able to achieve control through lifestyle modification (e.g., physical activity, reducing sodium intake, quitting smoking, etc.). The sample size of false positives (n=88) and false negatives (n=109) precluded meaningful exploration of these factors. This may be an important consideration when using self-reported HTN as the definition for tracking and surveillance in Hispanics.

The similarity in validity of self-reported HTN for Asians compared to whites is a novel contribution to the current understanding of these population surveillance measures. The ability to accurately self-report HTN may be linked to having health insurance. Overall, health insurance coverage among Asians is similar, or slightly lower, than that among whites in NYC;(24) however this access differs widely when data are stratified by specific Asian subgroups (e.g., Chinese, Korean, Asian Indians), with Koreans being the least likely to have health insurance.(25) We were unable to explore Asian American subgroup in this analysis due to limited sample size. Thus, it is critical to conduct validation studies of self-reported HTN by specific Asian subgroups and health insurance status where data are available.

The current analysis contributes to understanding the validity of self-reported hypertension in rapidly growing, yet understudied minority subgroups. Among this study's strengths is that clinical hypertension was assessed using measured values derived from a rigorous clinical protocol that was based on the NHANES blood pressure measurement methods using validated BP monitors.(16, 17) Also, results were weighted to be representative of the NYC non-institutionalized adult population as a whole. Limitations include the potential misclassification of HTN from BP measured at one time point, although an average of three BP measurements was used at that one time point. The small sample size of Asians restricted the ability to explore specific Asian subgroups.

Self-reported HTN performed relatively well in this diverse urban population. Practical consideration of health literacy, access to health care and HTN control by lifestyle modification are critical to the use of self-reported HTN for surveillance. In the absence of annually recurring measured data, surveillance measures can be recalibrated to help improve the individual-level validity of estimates in a given year, potentially in areas with a high percentage of Hispanics. More recent acknowledgement to these smaller subgroups have been reflected to changes to the sampling strategy of NHANES, the primary national surveillance system for health and related behaviors; oversampling of Hispanics other than Mexican-Americans began in 2007, and of Asian Americans in 2011. Local or urban areas with racial/ethnic population distributions that differ markedly from the national distribution may consider recalibrating self-reported HTN in their populations to ensure valid estimates.