INTRODUCTION
Heart failure (HF) management requires medication and diet adherence, as well as daily weight and fluid monitoring.1 In addition, patients are often asked to follow specific written instructions after hospital discharge. All of these activities require adequate visual acuity (VA). Yet, to date, little is known about the visual function of adults with HF.
Herein, we provide the first national estimates of the prevalence of visual impairment (VI) among adults with HF.
METHODS
We analyzed data from adults ≥ 50 years of age who underwent VA assessments in the 2005–2008 waves of the National Health and Nutrition Examination Survey (NHANES), a series of ongoing cross-sectional surveys of the civilian, non-institutionalized US population.2 These waves were used because they offer the most recent, objective VA assessments of adults. Since the majority of HF management requires near VA, objective and functional assessments of near vision were studied. All assessments were conducted on each eye, using the individuals’ presenting correction (if any).
Presenting (objective) near visual impairment (PNVI) was defined as seeing worse than 20/40 on a near card. Functional limitations due to vision were assessed using two items from the National Eye Institute’s 25-item Visual Functioning Questionnaire, a previously validated instrument.3 Functional near visual impairment (FNVI) was defined as having at least moderate difficulty with reading ordinary newsprint or doing work that requires seeing close-up. Participants with either PNVI or FNVI were considered to have global near visual impairment (NVI). Finally, self-rated vision was assessed. Like other NHANES studies, participants were classified as having HF if they answered yes to “Has a doctor ever diagnosed you with heart failure?”4, 5
All analyses were weighted to provide national estimates using Stata statistical software (StataCorp LP). We compared differences in participant characteristics, as well as the prevalence of VI, by HF status. All analyses were adjusted for age. The study was approved by the National Center for Health Statistic’s Institutional Review Board and all participants provided written informed consent.
RESULTS
The characteristics of our study sample, weighted to the US population, are displayed in Table 1. Overall, 6.2% (n = 168) of the sample had HF. Participants with HF were older and had more cardiovascular comorbidities those without HF. With respect to ocular comorbidities, diabetic retinopathy and a history of cataract surgery were more prevalent among participants with HF, compared to those without HF. The majority of participants wore glasses for near work (86.5%); however, there was not a statistically significant difference in the use of glasses by HF status.
Table 1.
Characteristics of the study population by heart failure status, from the 2005–2008 National Health and Nutrition Examination Survey (NHANES)
| Characteristics | Overall prevalence* % (95% CI) | Prevalence* % (95% confidence interval) | Age-adjusted P values | |
|---|---|---|---|---|
| Participants without heart failure | Participants with heart failure | |||
| Age group, years | – | |||
| 50–59 | 43.6 (40.9–46.2) | 45.3 (42.6–48.0) | 14.3 (96–20.8) | |
| 60–69 | 27.6 (25.9–29.4) | 27.3 (25.6–29.0) | 34.1 (26.8–42.1) | |
| 70–79 | 18.2 (16.7–19.7) | 17.7 (16.1–19.3) | 27.9 (22.2–34.6) | |
| 80–89 | 10.7 (9.3–12.2) | 9.8 (8.5–11.2) | 23.6 (17.6–31.0) | |
| Male Sex | 46.1 (44.6–47.6) | 45.5 (43.9–47.1) | 54.9 (48.4–61.1) | 0.005 |
| Race/Ethnicity | 0.03 | |||
| Non-Hispanic White | 78.2 (73.3–82.34) | 78.4 (73.3–82.3) | 75.5 (68.1–81.6) | |
| Non-Hispanic Black | 9.7 (7.2–12.8) | 9.5 (7.0–12.6) | 13.8 (10.4–18.2) | |
| Hispanic | 7.2 (5.4–9.5) | 7.3 (5.6–9.6) | 4.4 (2.8–7.0) | |
| Other | 5.0 (3.8–6.6) | 4.9 (3.6–6.5) | 6.2 (3.0–12.4) | |
| Education Level | 0.005 | |||
| < High school | 20.9 (18.6–23.3) | 19.9 (17.8–22.2) | 36.1 (28.6–44.3) | |
| High school | 27.3 (25.3–29.3) | 27.3 (25.3–29.3) | 26.9 (22.4–32.0) | |
| Some college or higher | 51.8 (48.1–55.6) | 52.8 (49.3–56.2) | 37.0 (27.8–47.4) | |
| Income | 0.25 | |||
| Below poverty level | 8.8 (7.3–10.5) | 8.6 (7.2–10.3) | 11.7 (7.7–17.3) | |
| At poverty level to two times above it | 21.9 (20.0–23.9) | 21.2 (19.2–23.2) | 35.3 (26.8–44.7) | |
| Two times poverty level and above | 69.3 (66.1–72.3) | 70.2 (67.0–73.3) | 53.0 (42.2–63.6) | |
| Insured | 90.2 (88.0–92.0) | 90.0 (87.8–91.9) | 92.5 (87.2–95.7) | 0.83 |
| Marital status | 0.24 | |||
| Married or living with a partner | 65.2 (62.1–68.1) | 65.9 (62.9–68.7) | 52.9 (44.0–61.6) | |
| Widowed, separated or divorced | 29.9 (27.4–32.6) | 29.2 (26.7–31.8) | 42.9 (33.9–52.4) | |
| Never married | 4.9 (4.1–5.9) | 4.9 (4.1–5.9) | 4.2 (2.3–7.6) | |
| Social Support | 93.9 (92.6–95.0) | 94.2 (93.0–95.2) | 91.0 (85.4–94.6) | 0.27 |
| Smoking status | 0.26 | |||
| Never | 47.7 (45.3–50.2) | 48.0 (45.5–50.5) | 43.6 (36.9–50.5) | |
| Former | 35.4 (33.5–37.3) | 35.0 (33.1–37.0) | 41.5 (35.5–47.7) | |
| Current | 16.9 (15.2–18.8) | 17.0 (15.2–19.0) | 15.0 (11.9–18.7) | |
| Coronary Heart Disease | 2.0 (1.5–2.5) | 1.1 (0.8–1.4) | 17.4 (12.7–23.3) | < 0.001 |
| Diabetes | 23.6 (21.6–25.8) | 22.1 (20.1–24.3) | 49.2 (43.8–54.6) | < 0.001 |
| Hypertension | 47.0 (45.2–48.7) | 45.4 (43.8–47.0) | 73.1 (66.1–79.1) | < 0.001 |
| Chronic Kidney Disease | 3.3 (2.7–4.0) | 2.5 (2.0–3.1) | 17.4 (13.4–22.3) | < 0.001 |
| Stroke | 6.1 (5.1–7.2) | 5.1 (4.3–6.1) | 22.8 (16.7–30.2) | < 0.001 |
| Diabetic Retinopathy^ | 0.04 | |||
| None | 62.9 (59.6–66.2) | 65.1 (61.2–68.7) | 44.4 (36.0–53.2) | < 0.001 |
| Mild | 14.1 (12.4–16.0) | 13.3 (11.5–15.4) | 20.8 (13.6–30.6) | 0.05 |
| Moderate/severe/proliferative | 5.5 (4.4–7.0) | 5.1 (3.8–6.7) | 9.6 (5.4–16.5) | |
| Not measured | 17.4 (15.0–20.2) | 16.5 (13.9–19.5) | 25.1 (19.7–31.5) | |
| History of cataract surgery | 15.1 (13.6–16.6) | 14.2 (12.8–15.7) | 31.9 (25.9–38.5) | 0.02 |
| Glaucoma | ||||
| None | 94.4 (93.1–95.4) | 94.6 (93.4–95.6) | 90.0 (85.4–93.3) | 0.79 |
| Possible | 2.8 (2.1–3.7) | 2.6 (1.9–3.6) | 5.3 (3.6–7.8) | |
| Probable/definite | 2.9 (2.3–3.6) | 2.8 (2.2–3.5) | 4.7 (2.4–8.8) | |
| Age-related macular degeneration | 0.42 | |||
| None | 91.1 (89.8–92.3) | 91.5 (90.2–92.6) | 85.2 (79.1–89.7) | |
| Early/late | 8.9 (7.7–10.2) | 8.5 (7.4–9.8) | 14.8 (10.3–20.9) | |
| Glasses for near work | 86.5 (85.2–87.8) | 86.7 (85.2–88.1) | 83.1 (77.5–87.5) | 0.09 |
| Glasses for distance | 63.6 (61.4–65.8) | 63.9 (61.6–66.2) | 57.7 (50.6–64.4) | 0.16 |
Overall, 168 participants had HF and 2541 did not have HF
*Prevalence estimates are computed using MEC examination weights to provide estimates for the total US population and are age-standardized to the US 2010 Census population, given that we used NHANES 2005–2008 data
^The prevalence of diabetic retinopathy among participants with Diabetes
Italicized P values are significant, after age-adjustment
Overall, 23.8% of adults with HF had NVI (Table 2). While the prevalence of PNVI was higher among adults with HF (20.1% [95% CI: 15.2–25.9%]) compared with those without HF (13.2% [11.5–15.1%]), the difference was not statistically significant (p = 0.64). Notably, participants with HF had significantly more FNVI than those without HF (11.05% [CI: 7.6–15.9%] vs. 5.4% [4.6–6.4%], p = 0.002). Finally, the prevalence of self-rated VI was significantly higher among participants with HF (p < 0.001).
Table 2.
Prevalence of visual impairment among adults in the USA, by heart failure status from the 2005–2008 National Health and Nutrition Examination Survey (NHANES)
| Visual characteristics | Prevalence* (95% confidence interval) | Age-adjusted P value | ||
|---|---|---|---|---|
| Overall | Participants without heart failure | Participants with heart failure | ||
| Near visual impairment (VI) | 0.26 | |||
| Not Impaired | 83.3% (81.6–84.9%) | 83.8% (82.1–85.4%) | 76.2% (70.5–81.1%) | |
| Impaired | 16.7% (15.1–18.4%) | 16.2% (14.6–17.9%) | 23.8% (18.9–29.5%) | |
| Presenting near visual impairment (PNVI) | 0.64 | |||
| Not Impaired | 86.4% (84.5–88.1%) | 86.8% (84.9–88.5%) | 79.9% (74.1–84.8%) | |
| Impaired | 13.6% (11.9–15.5%) | 13.2% (11.5–15.1%) | 20.1% (15.2–25.9%) | |
| Functional near visual impairment (FNVI) | 0.002 | |||
| Not Impaired | 94.2% (93.3–95.1%) | 94.6% (93.6–95.4%) | 88.9% (84.1–92.4%) | |
| Impaired | 5.8% (4.9–6.7%) | 5.4% (4.6–6.4%) | 11.05% (7.6–15.9%) | |
| Self-rated vision | < 0.001 | |||
| Excellent | 28.2% (26.3–30.2%) | 28.8% (26.7–30.9%) | 16.8% (12.4–22.4%) | |
| Good | 51.8% (49.4–54.2%) | 52.0% (49.5–54.5%) | 48.5% (41.0–56.2%) | |
| Fair | 15.6% (14.0–17.3%) | 15.2% (13.5–17.1%) | 22.3% (15.1–31.6%) | |
| Poor | 3.1% (2.4–3.8%) | 2.8% (2.2–3.5%) | 7.8% (5.5–11.1%) | |
| Very poor | 1.4% (1.1–1.8%) | 1.2% (0.9–1.6%) | 4.4% (2.7–7.2%) | |
*Prevalence estimates are computed using MEC examination weights to provide estimates for the total US population and are age-standardized to the US 2010 Census population, given that data from the 2005–2008 waves of NHANES were used
Definitions: Presenting near visual impairment (PNVI) was defined as near VA worse than 20/40 (could not read lines 4 or 5 on the near vision card). Functional near visual impairment (FNVI) was defined as having at least moderate difficulty with either reading ordinary newsprint or doing work or hobbies that require seeing well up close. Near visual impairment (VI) was defined as having PNVI, FNVI, or both. Self-rated vision: participants were asked to rate their eyesight with their usual glasses or contact lenses (if used) as excellent, good, fair, poor, or very poor
Bolded P values are significant, after age-adjustment
DISCUSSION
Our study provides the first national prevalence estimates of VI in HF. Objective near VA assessments revealed that one out of five adults with HF has difficulty seeing up close, even when wearing their corrective lenses. Additionally, our findings suggest that HF patients have more functional limitations due to vision compared to those without HF, after accounting for age. While we were unable to assess participants’ ability to perform HF-related tasks, it is likely that difficulty with reading newsprint or doing work up-close would also impose problems with reading medication and nutrition labels,6 as well as HF management handouts and hospital discharge instructions.
One limitation of our study is that HF status in NHANES was ascertained by self-report. Additionally, our estimates likely underestimate the prevalence of VI in HF since nursing home and long-term care residents were not included. Thus, future research is needed to examine VI in HF in a more validated and representative sample.
Nevertheless, given the burden of near and functional VI that exists in this patient population, increased awareness by treating health professionals is warranted. Furthermore, increased collaboration between general internists, ophthalmologists, cardiologists, pharmacists, and caregivers is needed to identify, screen, and potentially treat HF patients who may be at risk.
Acknowledgements
We thank all of the NHANES participants without whom this study would not be possible.
Funders
Dr. Sterling is supported by T32HS000066 from the Agency for Healthcare Research and Quality. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Agency for Healthcare Research and Quality.
The NHANES was supported by the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC). Funding for the National Health and Nutrition Examination Survey (NHANES) retinal component was provided by the Intra Agency Agreement 05FED47304 from the Division of Diabetes Translation, CDC. Funding for the vision component was provided by the National Eye Institute, National Institutes of Health, Intramural Research Program grant Z01EY000402. The content of this article does not necessarily represent the official position of the National Eye Institute or the CDC.
Compliance with ethical standards
Conflicts of interest
M. Sterling, D. Jannat-Khah, and S. Vitale have no conflicts to report.
M. Safford receives salary support for investigator initiated research from Amgen, Inc.
Footnotes
Prior Presentations
This study was presented as an oral presentation at the Society of General Internal Medicine’s (SGIM) Mid-Atlantic Regional Meeting in Newark, Delaware, on November 10, 2017.
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