Prevalence of Self-Reported Hypertension in Deaf Adults Who Use American Sign Language

Abstract

BACKGROUND

In the United States, roughly one-third of adults have hypertension; another third have prehypertension. The prevalence of hypertension in deaf American Sign Language (ASL) users is unknown. We address this gap through a descriptive study for the prevalence of hypertension in the American Deaf community and discuss future directions to address this issue.

METHODS

Self-reported data for 1,388 ASL using deaf adults were compared with a secondary data of 2,830 English-speaking hearing adults. Frequency and percentages were used to describe the prevalence of hypertension in the deaf community. Age-weighted analysis was used to compare unmodifiable risk factors and hypertension rate between deaf and hearing adults.

RESULTS

Deaf and hearing samples’ hypertension rates for gender and age were similar. Significant group differences between deaf and hearing samples emerged across race. Compared with the hearing controls, our deaf sample demonstrated a significantly decreased risk for hypertension with a prevalence of 37% (compared with 45% in the hearing sample).

CONCLUSIONS

Although the hypertension rate for gender and age was similar across deaf and hearing samples, between-group disparities exist for race. The lower rate of hypertension in our deaf sample is likely a consequence of underdiagnoses due to lower health literacy and poor patient–physician communication. Furthermore, deaf black Americans’ lower rates compared with hearing black Americans may be due to poor patient–physician communication, not having regular providers or social stressors. It is recommended that modifiable risk factors and social determinants be investigated to determine their effect on hypertension within the deaf community.

Hypertension is an independent modifiable risk factor for cardiovascular diseases¹ and affects many other health issues such as stroke and kidney disease.² Historically, the prevalence of hypertension has steadily increased from 23.9% to 29.0% over a period of 20 years.³ Today, it is estimated that 33.5% of Americans have hypertension and approximately 30% Americans have prehypertension.^4,5 Hypertension rates and control have been studied within various minority groups, with varying rates as described below. However, there is no documented rate for hypertension among deaf adults who use American Sign Language (ASL), who represent another underserved health population. Deaf ASL users who are less proficient in English have experienced health disparities due to low health literacy,^6–9 low health knowledge,^10–13 and physician–patient communication barriers.^14,15 These 3 health-related barriers were linked to poorer hypertension awareness and control in the general population globally.^16,17 For deaf people in the United States, the national prevalence information for hypertension among those who use ASL users is unknown, largely due to the language barriers that prevented deaf ASL users from participating in telephone- or spoken English-administered health surveillance.¹⁸ The lack of hypertension prevalence in conjunction with the ongoing health disparity in this medically underserved population provides a rationale to compare deaf ASL users’ self-reported hypertension diagnosis data with existing self-reported hypertension data in the general US population. Because the majority of this general population speak English and are able to communicate with their providers who share the same language, this nondeaf population is likely to have accurate self-reported hypertension rate and therefore provides a convenient reference point for comparing the self-reported hypertension diagnosis among the deaf ASL user group. The comparative rates of hypertension among these 2 groups would provide important information about the current disparity status in the deaf ASL user group and whether some deaf ASL users might be underdiagnosed due to low health literacy, low knowledge, and communication barriers.

In a 2015 UK study of nearly 300 deaf people who use sign language,¹⁹ hypertension data collected via objective clinical data revealed 37% with high blood pressure. This is comparable to the UK general population, where the prevalence of hypertension via blood readings was 30%²⁰; this is the only known study to have documented the prevalence of hypertension within a deaf population using sign language. Since hypertension is a prevalent and treatable condition with preventable complications, it is important to investigate whether disparities in self-reported hypertension rates exist for deaf ASL users, as compared with the hearing population in the United States, with potential implications for public health measures for this underserved population.

Unmodifiable risk factors are indicators of disease that cannot be prevented or controlled for as these risk factors cannot be changed due to biology and genetics. While the prevalence rate for hypertension is approximately 30% in the general population, it is known that certain groups have higher rates due to unmodifiable risks. For example, black Americans are at a higher risk for hypertension, with 44% diagnosed with hypertension.^21–23 In fact, black Americans were more likely to be hospitalized for hypertension-related issues with a hospitalization rate of 128 per 100,000 populations compared with only 24 per 100,000 whites.²⁴ Also, Asian Americans and Hispanic Americans are at a slightly higher risk for hypertension compared with whites.^25,26 However, several studies also show Hispanic and Asian Americans having a lower prevalence of hypertension compared with whites, with some hypothesizing that the rates are underestimated due to lack of insurance and treatment.^27,28

Besides race, other unmodifiable risk factors for hypertension in the general population include age, gender, and family history. The prevalence of hypertension is higher in those aged 60 years or older at 65%.²⁹ Furthermore, men are more likely to get hypertension before the age of 55 years, while women are more likely to get hypertension after the age of 55 years.³⁰ Although behavioral factors contribute to the hypertension prevalence differences in gender and age, biological factors play a role; for example, certain factors such as sex hormones are protective against hypertension in women.³¹ These sex hormones decrease with age, which may explain why women over 55 years are more likely to get hypertension. Lastly, family history has been found to be a major predictor for hypertension.³²

While the unmodifiable risk factors for hypertension have been clearly documented in the general population and select minorities, there are no empirical data on whether these risk factors also apply to American deaf individuals who use ASL. Using a fully accessible, bilingual health survey with a national sample of over 1,500 deaf adults who use ASL and comparing this with secondary data drawn from a public dataset, we hypothesize that comparing unmodifiable risk factors between deaf and hearing Americans will result in a neutral estimate of hypertension rates, as these cannot be explained by sociocultural factors. We also expect that the self-reported prevalence rate for hypertension in the deaf ASL group will be similar to the US general population.

METHODS

Hypertension item

In this cross-sectional study spanning the United States, hypertension-specific data were gathered from deaf adult signers who participated in the HINTS-ASL survey³³ between October 2015 and April 2018 and then compared with secondary data on hypertension in hearing adults who participated in the HINTS, Cycle 4 survey. The item “Has a doctor or other health professional ever told you that you had high blood pressure or hypertension?” was used in both surveys. The validity of self-reported hypertension has been studied elsewhere in a variety of populations; this English question is used in the CDC’s Behavioral Risk Factors Surveillance Survey and may actually underestimate the prevalence of hypertension.^34,35 Details on the English-to-ASL translation procedure have been described elsewhere.³³

Recruitment procedure

After the university’s Institutional Review Board approved the study procedures, the research staff began recruitment through national channels, targeting deaf community members who used ASL. Purposive sampling was used to ensure adequate representation with respect to key demographic characteristics, such as age and education. We used several approaches to recruiting deaf signers across the United States, including Hawaii and Alaska, including snowball sampling through personal networks, distributing flyers, and advertising on deaf-centered organization websites and e-newsletters. Communication between the research staff and participants occurred through mail, email, social media, and video chat programs. We provided prospective participants with an information flyer and discussed the study purpose and procedures, reviewed inclusion and exclusion criteria, and answered any questions they might have to determine eligibility and interest. We included those who self-report using ASL as their primary language and excluded those who are 17 years old or younger as well as those who have unilateral hearing loss. We enrolled those who provided their signed consent. The survey took approximately 1 hour to complete. No names or identifying information were included in this online survey. Each participant received a gratuity in form of $25-valued American Express gift card for participating in the study.

Statistical analyses

Descriptive statistical analysis, including percentages, was used to describe the unweighted prevalence of hypertension in the deaf ASL users. Age groups were weighted using the following sample/proportion weights assigned to the age categories within the dataset: 0.188/0.205 for 18–34 age category, 0.223/0.227 for 35–49 age category, 0.308/0.298 for 50–64 age category, 0.173/0.175 for 65–74 age category, and 0.108/0.094 for 75 years and over age category. Using age-weighted data, chi-square analyses were conducted to test for equality of the proportions of various covariates between the deaf and hearing samples. Given the high prevalence of hypertension, multiple robust multivariable Poisson regression models were used to estimate the prevalence ratios of hypertension by unmodifiable risk factors. We performed all data analyses using SPSS version 25.

RESULTS

Characteristics of the deaf sample

Table 1 presents the unweighted sociodemographic characteristics for deaf ASL users (n = 1,735; 57% female; 64% white) who answered questions about hypertension and their demographics. A majority of the deaf sample had health insurance (93%) and regular provider (59%). When the deaf sample was asked to rank their overall health status, 55% of them ranked their health as excellent or very good.

Table 1.

Unweighted sociodemographic characteristics for deaf ASL users (N = 1,734)

Variable	N	%
Hypertension
Yes	530	30.5
No	1,128	65.0
Missing	74	3.9
Gender
Male	710	40.9
Female	986	56.8
Nonbinary/genderqueer	26	1.5
Missing	13	0.7
Age
18–34	634	36.6
35–49	453	26.1
50–64	391	22.5
65+	256	14.7
Race
White	1,109	63.9
Black	186	10.7
Hispanic	244	14.1
Other	184	10.6
Missing	12	0.7
BMI
Underweight (<18.5)	30	1.7
Normal (18.5–24.9)	604	34.8
Overweight (25–29.9)	571	32.9
Obese (30 or greater)	516	29.7
Missing	14	0.8
Education
High school or less	438	25.2
At least some college	1,287	74.2
Missing	10	0.6
Regular provider
Yes	1,028	59.3
No	610	35.2
Missing	97	5.6

Abbreviations: ASL, American Sign Language; BMI, body mass index.

Sample characteristics of deaf and hearing adults with hypertension: Age-weighted

In our deaf sample, the age-weighted prevalence for hypertension was significantly lower in the deaf sample at 33% compared with 46% in the hearing sample (χ²: 75.730, P value = 0.001). Table 2 demonstrates the proportions of the demographic variables among hypertensive individuals in the deaf ASL user (n = 532) and hearing English speaker (n = 1,436) groups. Significant age-weighted group differences were found for age, race, and education. Differences between having health insurance were not found to be significantly different (χ²: 2.545, P value = 0.111).

Table 2.

Age-weighted sociodemographic characteristics of the study participants diagnosed with hypertension

Variable	Group (N = 1,968)				t (P value)
	Hypertensive deaf ASL users, N = 532		Hypertensive hearing English speakers N = 1,436
	Mean	SD	Mean	SD
Age (continuous)	53.55	16.67	63.56	13.44	−13.58 (<0.001)
	N	%	N	%	χ 2 (P value)
Age group					185.41 (<0.001)
18–34	82	15.4	34	2.4
35–49	121	22.7	166	11.6
50–64	179	33.6	542	37.7
65–74	97	18.2	390	27.2
75+	54	10.1	304	21.2
Gender					0.83 (0.36)
Male	247	47.0	615	44.7
Female	278	53.0	760	55.3
Race					8.14 (0.04)
White	360	68.3	802	62.3
Black	75	14.2	248	19.3
Hispanic	58	11.0	139	10.8
Other	34	6.5	98	7.6
BMI					3.28 (0.35)
Underweight	3	0.6	14	1.0
Normal	122	23.1	283	20.1
Overweight	177	33.5	467	33.1
Obese	226	42.8	646	45.8
Education					9.31 (<0.01)
<High school	176	33.3	585	40.9
>Some college	352	66.7	845	59.1
Regular provider					33.94 (<0.01)
Yes	349	67.2	1,148	79.9
No	170	32.8	289	20.1

Abbreviations: ASL, American Sign Language; BMI, body mass index.

Association between unmodifiable risk factors and hypertension

After controlling for the unmodifiable risk factors, deaf ASL users demonstrated a significantly decreased risk for hypertension (prevalence ratio (PR): 0.731, 95% confidence interval (CI): 0.673–0.794) compared with hearing English speakers. When the unmodifiable risk factors were entered in separate robust multivariable Poisson models, the models were significant [χ²(7) = 160.661, P = 0.001] in the deaf ASL users model and [χ²(7) = 292.842, P = 0.001] in the hearing English speakers model. The adjusted prevalence ratios of hypertension according to selected unmodifiable risk factors are shown in Table 3. The pattern of increasing risk for hypertension as age increases is similar for both the deaf and hearing samples. However, among those aged 65 years and older, the risk for hypertension in the hearing sample was higher than in the deaf sample (PR: 6.234, 95% CI: 4.539–8.562, and PR: 4.223, 95% CI: 3.384–5.269, respectively). In both models, those who self-identified as non-Hispanic black were significantly more likely to have hypertension. This risk was higher in the deaf sample (PR: 1.691, 95% CI: 1.407–2.033) than in the hearing sample (PR: 1.556, 95% CI: 1.422–1.704). As for gender, both deaf and hearing groups demonstrated a decreased risk for hypertension among females (PR: 0.735, 95% CI: 0.644–0.838 among deaf women; PR: 0.869, 95% CI: 0.804–0.940 among hearing women).

Table 3.

Prevalence ratios of hypertension adjusted for unmodifiable risk factors across hearing status

Variable	Deaf ASL users			Hearing English speakers
	Coefficient (SE)	Prevalence ratio (95% CI)	P value	Coefficient (SE)	Prevalence ratio (95% CI)	P value
Age groupa
35–49	0.66 (0.12)	1.93 (1.51–2.46)	<0.001	0.92 (0.17)	2.51 (1.79–3.52)	<0.001
50–64	1.17 (0.11)	3.22 (2.59–4.01)	<0.001	1.57 (0.16)	4.79 (3.48–6.59)	<0.001
65+	1.44 (0.11)	4.22 (3.38–5.27)	<0.001	1.83 (0.16)	6.23 (4.54–8.56)	<0.001
Raceb
Black	0.52 (0.09)	1.69 (1.41–2.03)	<0.001	0.44 (0.05)	1.56 (1.42–1.70)	<0.001
Hispanic	0.07 (0.12)	1.07 (0.85–1.34)	0.57	−0.01 (0.07)	0.99 (0.87–1.14)	0.92
Other	−0.22 (0.16)	0.80 (0.59–1.09)	0.15	0.10 (0.08)	1.10 (0.95–1.28)	0.21
Genderc
Female	−0.31 (0.07)	0.74 (0.64–0.84)	<0.001	−0.14 (0.04)	0.87 (0.80–0.94)	<0.001

Abbreviations: ASL, American Sign Language; CI, confidence interval.

^a18–34 is the reference group.

^bWhite is the reference group.

^cMale is the reference group.

DISCUSSION

Our data indicate that age-weighted prevalence for hypertension among deaf ASL users is lower than the general population. This is inconsistent with the only other known study documenting the prevalence of hypertension in the United Kingdom,¹⁹ with deaf UK sample having higher prevalence of hypertension than the UK general population. However, as previously mentioned, in this UK study, blood pressure readings were obtained for the deaf sample and then compared with self-reported data in the hearing sample, whereas in our study, both hypertension data were self-reported in both samples.

The lower prevalence rate of self-reported hypertension within the US deaf sample compared with the United States general population may be explained by an underdiagnosis of hypertension, as previously suggested among other underserved health minority populations. Such underdiagnosis could potentially be due to disparities in health literacy and knowledge about hypertension. A systematic review on 96 studies found that low health literacy is associated with poorer health outcomes and poorer use of health care services.³⁶ Furthermore, several studies have demonstrated low cardiovascular knowledge and literacy among deaf ASL users.^6,12,13 With the significant relationship between hypertension and cardiovascular health, it is possible that some respondents in our study have low levels of health literacy or knowledge and therefore may be more likely to have undiagnosed hypertension.

After controlling for unmodifiable factors, deaf ASL users demonstrated a significantly decreased risk for hypertension compared with their hearing counterparts. Investigation into unmodifiable risk factors can identify subgroups that may need more attention, as these are factors that are not influenced by sociodemographics. The risk for hypertension was similar among gender and race within both deaf and hearing groups. Women within both deaf and hearing samples in our study were at an approximately 30% decreased risk for hypertension. Both of our samples showed a significantly increased risk for hypertension among black Americans compared with white Americans. These 2 results are consistent with general literature as it has been documented that men and blacks were significantly more likely to have hypertension than other races and women.^21–23,31 Taken together, these suggest that deaf and hearing adults have similarly affected rates for hypertension across gender and race.

The pattern of risk for age groups was also similar, with both comparison groups showing a continuously increased risk for hypertension with age. This is consistent with documented research that the risk for hypertension increases with age. Data from the 2011–2014 National Health and Nutrition Examination Survey demonstrated that, among the general US population, the prevalence of hypertension increased progressively with age starting with the 18- to 39-year-old group at 7.3% and ending with the 60-year-old and over group at 64.9%.²⁸ However, in elderly adults (those aged 65+ years), there was almost a 2-fold difference in the risk for hypertension in elderly hearing adults compared with elderly deaf adults (PR: 6.234, 95% CI: 4.539–8.562 in hearing adults, and PR: 4.223, 95% CI: 3.384–5.269 in deaf adults). Since there is only a slight overlap in confidence intervals, there is a statistically significant difference for the risk of hypertension in elderly individuals. Since higher education has been identified as a protective factor for cardiovascular disease in deaf Americans,³⁷ further investigation into sociodemographic factors and other modifiable risk factors within the deaf community would be useful to implement effective behavioral or education programs targeted at reducing risk for hypertension in elderly deaf Americans.

Limitations include the possibility that our sampled population may not accurately represent the larger population of American deaf ASL users, although no larger sample has been surveyed to date. Another major limitation is the self-reported nature of the data, a method which generally has low sensitivity among individuals at risk and high specificity among those who do not have hypertension, potentially leading to ascertainment bias in where deaf individuals with hypertension were not included in the study and thus lowering the true prevalence. Dave et al.³⁸ found that individuals in the US general population who were at high risk for hypertension were less likely to accurately report their hypertension status. This poses a particular concern for deaf ASL users who experience barriers to accessing health information or communicating with their health care providers. Although self-reported data for hypertension using identical question were gathered from both deaf and hearing samples, the disparity in self-reported hypertension diagnosis within the deaf sample, particularly among deaf black Americans, warrants further investigation into modifiable factors that can be addressed in interventions or educational programs. Future research should also explore direct blood pressure measurements to augment our findings on hypertension among deaf ASL users.

DISCLOSURE

The authors declared no conflict of interest.