Key Points
Question
What percentage of US adults with diabetes and those at high risk of missing recommended eye examinations have contact with primary care physicians and could potentially receive screening for diabetic retinopathy in primary care settings?
Findings
In this study using a sample of adults with self-reported diabetes from the 2016 National Health Interview Survey, 87.7% of the full sample and more than 78% of each high-risk subgroup, except the uninsured subgroup, visited a primary care physician in the past year.
Meaning
Screening for diabetic retinopathy in primary care settings has the potential to reach most US adults, including high-risk adults, with diabetes.
This brief report provides an empirical analysis of the National Health Interview Survey to estimate the percentages of US adults with diabetes and who have regular primary care encounters in which screening for diabetic retinopathy may be performed.
Abstract
Importance
Prior studies found that screening for diabetic retinopathy (DR) in primary care settings using telemedicine increased screening rates among individuals with diabetes. This finding has led to interest in expanding the use of primary care–based screening for DR.
Objective
To estimate the percentages of US adults with diabetes and high-risk US adults with diabetes who have regular contact with primary care physicians and therefore could potentially receive timely screening for DR in primary care settings.
Design, Setting, and Participants
The empirical analyses used data from the cross-sectional population-based 2016 National Health Interview Survey on US adults 18 years or older with self-reported diabetes (n = 3229). Based on previous research, individuals who had lower income, lower educational levels, or type 2 diabetes; who were African American or Hispanic, uninsured, or not using insulin or oral medication for diabetes; or who did not have DR were defined as being at high risk of missing recommended eye examinations. Data were collected throughout 2016 and analyzed from July 17 through November 5, 2018.
Main Outcomes and Measures
Outcomes were whether an individual visited a primary care physician and whether an individual missed having a dilated eye examination in the past year.
Results
The survey sample included 3229 participants. Using weighted percentages of the full sample, 15.3% (95% CI, 13.8%-17.0%) had lower income, 19.7% (95% CI, 17.8%-21.6%) had lower educational levels, 15.4% (95% CI, 13.5%-17.4%) were African American, 16.0% (95% CI, 13.7%-18.6%) were Hispanic, 6.1% (95% CI, 4.9%-7.5%) were uninsured, and 50.1% (95% CI, 47.7%-52.4%) were female; the mean age was 60.1 years (95% CI, 59.4-60.8 years). In addition, 87.7% (95% CI, 85.9%-89.3%) visited a primary care physician in the past year. Of those who did not receive a dilated eye examination in the past year, 82.2% (95% CI, 78.4%-85.4%) visited a primary care physician during the year. Except for the uninsured subgroup, more than 78% of each high-risk subgroup had visited a primary care physician in the past year.
Conclusions and Relevance
Screening for DR in primary care settings has the potential to provide timely screening to a large portion of US adults with diabetes because most US adults with diabetes, including those at high-risk of missing recommended eye examinations, have regular contact with primary care physicians.
Introduction
Prior studies have found that screening for diabetic retinopathy (DR) in primary care settings using telemedicine (hereafter referred to as primary care–based DR telemedicine screening) increased screening rates among individuals with diabetes and among subgroups of individuals with diabetes who are at high risk of missing recommended eye examinations.1,2,3,4,5 These findings have led to interest in expanding the use of primary care–based DR telemedicine screening.6,7,8 Gibson9 suggested that primary care–based DR telemedicine screening has the potential to reach many adults with diabetes who do not receive regular eye care based on the finding that although 33.8% of a sample of US adults with diabetes from the 2007-2013 Medical Expenditure Panel Survey did not receive a dilated eye examination during the prior year, 77.5% of those who did not receive an eye examination did visit a primary care physician for diabetes preventive care services during that year. This brief report builds on the findings of Gibson9 by using data from the 2016 National Health Interview Survey (NHIS) to examine access to primary care among US adults with diabetes and among subgroups of individuals with diabetes who are at high-risk of missing annual dilated eye examinations.
Methods
Sample
The empirical analyses used publicly available data on adults 18 years or older from the 2016 wave of the NHIS. The NHIS is an annual cross-sectional survey, and NHIS samples are designed to be nationally representative of the US noninstitutionalized civilian population. The 2016 wave of the NHIS was chosen for this study because it is the most recent wave of the NHIS to include a question about the receipt of a dilated eye examination (this question was asked of NHIS sample adults). The 2016 NHIS Sample Adult File contains observations on 3519 individuals 18 years or older who self-reported having diabetes. After excluding individuals who were missing information on primary care visits, dilated eye examination receipt, or the risk variables described below (n = 290), the final sample included 3229 individuals. Data were collected throughout 2016. Owing to the use of publicly available data, this study was not subject to institutional review board review. The NHIS interviewers obtained verbal consent for survey participation.
Variables
Visit to a Primary Care Physician in the Past Year
Whether or not an individual had visited a primary care physician in the past year was defined based on the response to the question, “During the past 12 months, have you seen or talked to a general doctor who treats a variety of illnesses (a doctor in general practice, family medicine, or internal medicine)?” The 2016 NHIS did not ask about visits to endocrinologists or diabetologists.
Receipt of Dilated Eye Examination in the Past Year
Whether or not an individual had had a dilated eye examination in the past year was defined based on the response to the question, “When was the last time you had an eye exam in which the pupils were dilated? This would have made you temporarily sensitive to bright light.”
Groups at High Risk of Missing an Annual Dilated Eye Examination
Based on previous research, individuals who had lower income, lower educational levels, or type 2 diabetes; who were African American or Hispanic, uninsured, or not using insulin or oral medication for diabetes; or who did not have DR were defined as being at high risk of missing recommended eye examinations.6,9,10,11 This definition is not intended to identify a complete set of groups at high risk for missing recommended eye care.6,9,10,11 Table 1 presents the definitions of the lower income and lower educational level categories.
Table 1. Characteristics of the Sample of US Adults With Diabetes, 2016 NHIS.
Characteristic | Weighted 2016 NHIS Sample Estimate of Adults With Diabetes (95% CI)a |
---|---|
PCP Visits and Dilated Eye Examinations | |
Visited a PCP in the past year, % | 87.7 (85.9-89.3) |
Did not receive a dilated eye examination in the past year, % | 34.7 (32.5-37.1) |
Among those who did not receive a dilated eye examination in the past year, visited a PCP in that year, % | 82.2 (78.4-85.4) |
Sociodemographic Characteristics | |
Family income-to-poverty ratio, %b | |
<1 | 15.3 (13.8-17.0) |
≥1 | 84.7 (83.0-86.2) |
Educational level, % | |
<12 y | 19.7 (17.8-21.6) |
≥12 y or GED diploma | 80.3 (78.4-82.2) |
Race/ethnicity, % | |
African American | 15.4 (13.5-17.4) |
Hispanic | 16.0 (13.7-18.6) |
Other | 6.1 (4.9-7.7) |
Non-Hispanic white | 62.5 (59.5-65.4) |
Lower income, lower educational level, and minority race/ethnicity, % | |
Yes | 4.7 (3.8-5.9) |
No | 95.3 (94.1-96.2) |
Health insurance status, % | |
Uninsured | 6.1 (4.9-7.5) |
Insured | 93.9 (92.5-95.1) |
Age, mean, y | 60.1 (59.4-60.8) |
Female, % | 50.1 (47.7-52.4) |
Diabetes-Related Characteristics | |
Type of diabetes, % | |
Type 1 | 11.4 (9.9-13.0) |
Type 2 | 84.9 (83.1-86.7) |
Unknown | 3.7 (2.8-4.9) |
Diabetes severity, % | |
Current use of insulin or oral medication | |
Yes | 85.5 (83.7-87.1) |
No | 14.5 (12.9-16.3) |
Has a physician ever told you that you have DR? | |
Yes | 8.3 (7.2-9.7) |
No | 91.7 (90.3-92.8) |
Abbreviations: DR, diabetic retinopathy; GED, General Educational Development; NHIS, National Health Interview Survey; PCP, primary care physician.
Full sample includes 3229 individuals. The descriptive statistics were estimated using the Stata software (version 15; StataCorp) svy command with the subpop option to account for the complex design features of the NHIS and the focus on the subsample of adults with diabetes or on the subsample of adults with diabetes who did not receive a dilated eye examination in the past year. Taylor series linearization was used for variance estimation and the calculation of the 95% CIs.
Calculated as the ratio of total family income in the previous calendar year divided by the poverty threshold appropriate to the family’s size. The official US poverty measure defines a family as in poverty if this ratio is less than 1.
Statistical Analysis
Data were analyzed from July 17 through November 5, 2018. We used the Stata software (version 15; StataCorp) svy command with the subpop option to account for the complex design features of the NHIS and to calculate weighted descriptive statistics for the full diabetes sample and for subgroups defined by categories of family income, educational level, race/ethnicity, health insurance status, type of diabetes, diabetes medications, and DR status. Taylor series linearization was used for variance estimation and the calculation of 95% CIs. Of particular interest are the percentages of the full sample and subgroups who in the past year had visited a primary care physician, did not receive a dilated eye examination, and visited a primary care physician if a dilated eye examination was missed. Pearson design–based F tests were used to determine whether percentages differed significantly (P ≤ .05) between subgroups.
Results
The survey sample included 3229 participants. Using weighted percentages of the full sample, 15.3% (95% CI, 13.8%-17.0%) had lower income, 19.7% (95% CI, 17.8%-21.6%) had lower educational levels, 15.4% (95% CI, 13.5%-17.4%) were African American, 16.0% (95% CI, 13.7%-18.6%) were Hispanic, 6.1% (95% CI, 4.9%-7.5%) were uninsured, and 50.1% (95% CI, 47.7%-52.4%) were female; the mean age was 60.1 years (95% CI, 59.4-60.8 years). Table 1 presents weighted descriptive statistics for the full sample. Of the full sample of adults with diabetes, 87.7% (95% CI, 85.9%-89.3%) visited a primary care physician and 34.7% (95% CI, 32.5%-37.1%) did not receive a dilated eye examination in the past year. Of those who did not receive a dilated eye examination, 82.2% (95% CI, 78.4%-85.4%) visited a primary care physician during the past year. Table 2 and Table 3 present descriptive statistics by subgroup. Except for the uninsured subgroup, more than 78% of each of the other high-risk subgroups visited a primary care physician in the past year. Relative to the lower-risk subgroup categories, missing a dilated eye examination was significantly more likely for individuals in the subgroups with lower income (41.8%; 95% CI, 35.9%-47.9%), with lower educational levels (41.0%; 95% CI, 35.4%-46.0%), who were Hispanic (43.2%; 95% CI, 36.5%-50.3%), who did not have health insurance (69.6%; 95% CI, 59.8%-77.8%), who were not using diabetes medications (44.6%; 95% CI, 38.6%-50.8%), or who did not have DR (36.0%; 95% CI, 33.6%-38.5%). Of those who did not receive a dilated eye examination in the past year, except for the subgroups who were uninsured, did not know what type of diabetes they had, and used no diabetes medications, more than 72% of each of the other high-risk subgroups visited a primary care physician in the past year.
Table 2. Primary Care Physician Visits and the Receipt of a Dilated Eye Examination in the Past Year Among Subgroups of US Adults With Diabetes Defined by Sociodemographic Characteristics From the 2016 NHISa.
Variable | Weighted % (95% CI) | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Income-to-Poverty Ratiob | Educational Level | Race/Ethnicity | Lower Income, Lower Educational Level, and Minority Race/Ethnicity | Health Insurance Status | |||||||
<1 | ≥1 | <12 y | ≥12 y or GED Diploma | African American | Hispanic | Other | White | Uninsured | Insured | ||
Visited a PCP in the past year | 85.9 (81.7-89.2) | 88.0 (86.0-89.8) | 86.4 (82.6-89.5) | 88.0 (86.0-89.7) | 89.2 (85.0-92.3) | 82.5 (76.7-87.1) | 85.2 (74.6-91.9) | 88.9 (86.9-90.7) | 84.8 (77.7-89.9) | 65.8 (55.1-75.1) | 89.2 (87.4-90.7) |
Did not receive a dilated eye examination in the past year | 41.8 (35.9-47.9) | 33.5 (31.1-35.9) | 41.0 (35.4-46.0) | 33.3 (30.9-35.8) | 31.6 (26.8-36.8) | 43.2 (36.5-50.3) | 37.5 (26.1-50.4) | 33.1 (30.6-35.7) | 41.8 (32.4-51.8) | 69.6 (59.8-77.8) | 32.5 (30.2-34.8) |
Among those who did not receive a dilated eye examination in the past year, visited a PCP in that year | 79.7 (72.6-85.3) | 82.7 (78.4-86.4) | 78.2 (71.1-84.0) | 83.3 (79.0-87.0) | 84.3 (75.5-90.3) | 74.5 (65.0-82.2) | 73.3 (51.1-87.9) | 85.2 (81.0-88.6) | 72.8 (57.4-84.2) | 62.7 (49.1-74.5) | 85.0 (81.4-88.1) |
Abbreviations: GED, General Educational Development; NHIS, National Health Interview Survey; PCP, primary care physician.
Full sample includes 3229 individuals. The descriptive statistics were estimated using the Stata software (version 15; StataCorp) svy command with the subpop option to account for the complex design features of the NHIS and the focus on the subsample of adults with diabetes or on the subsample of adults with diabetes who did not receive a dilated eye examination in the past year. Taylor series linearization was used for variance estimation and the calculation of the 95% CIs.
Calculated as the ratio of total family income in the previous calendar year divided by the poverty threshold appropriate to the family’s size. The official US poverty measure defines a family as in poverty if this ratio is less than 1.
Table 3. PCP Visits and the Receipt of a Dilated Eye Examination in the Past Year Among Subgroups of US Adults With Diabetes Defined by Diabetes Status Characteristics From the 2016 NHISa.
Variable | Weighted % (95% CI) | ||||||
---|---|---|---|---|---|---|---|
Type of Diabetes | Use of Diabetes Medicationsb | DR Present | |||||
Type 1 | Type 2 | Unknown | No | Yes | No | Yes | |
Visited a PCP in the past year | 81.3 (74.9-86.4) | 89.0 (87.2-90.7) | 79.2 (66.4-87.9) | 78.8 (72.0-84.3) | 89.2 (87.4-90.8) | 87.5 (85.5-89.2) | 91.1 (85.5-94.6) |
Did not receive a dilated eye examination in the past year | 34.5 (27.7-42.0) | 34.4 (31.9-37.0) | 41.9 (28.6-56.5) | 44.6 (38.6-50.8) | 33.1 (30.6-35.6) | 36.0 (33.6-38.5) | 20.9 (15.6-27.5) |
Among those who did not receive a dilated eye examination in the past year, visited a PCP in that year | 77.5 (68.0-84.8) | 83.7 (79.7-87.1) | 69.9 (49.2-84.8) | 66.4 (54.9-76.1) | 85.8 (82.2-88.8) | 82.2 (78.3-85.6) | 83.6 (69.9-91.8) |
Abbreviations: DR, diabetic retinopathy; NHIS, National Health Interview Survey; PCP, primary care physician.
Full sample includes 3229 individuals. The descriptive statistics were estimated using the Stata software (version 15; StataCorp) svy command with the subpop option to account for the complex design features of the NHIS and the focus on the subsample of adults with diabetes or on the subsample of adults with diabetes who did not receive a dilated eye examination in the past year. Taylor series linearization was used for variance estimation and the calculation of the 95% CIs.
Includes insulin or oral medications.
Discussion
Similar to the findings of previous research, this brief report found that approximately one-third of a population-based sample of US adults with diabetes did not receive an annual dilated eye examination.6,9,10,11 The findings further suggest that primary care–based DR telemedicine screening has the potential to help remedy this situation and provide timely DR screening because most US adults with diabetes and most high-risk US adults with diabetes had regular contact with primary care physicians. However, alternative approaches are needed to provide care to the still sizeable number of individuals with diabetes who do not have regular contact with eye care or primary care physicians, particularly those who do not have health insurance or who are not using diabetes medications.
Limitations
A major limitation of this study is that all information is self-reported. Previous research found that use of eye care services and annual physician visits tend to be overestimated by self-reported information.12,13 Therefore, the need for DR screening may be higher and the potential reach of primary care–based DR telemedicine screening may be lower than what is suggested by the estimates in this report. A further limitation is that the publicly available NHIS data used in this study do not include information about rural residence, which prevented the consideration of a high-risk group for which telemedicine could be particularly important.6
Conclusions
The estimates provided in this report offer upper bounds on the potential reach of primary care–based DR telemedicine screening. Many primary care practices do not currently have the financial, administrative, or time resources that would be necessary to add DR telemedicine screening, and individuals with diabetes may choose not to avail themselves of screening for DR even if it is available in primary care.3,6,14 Furthermore, screening for DR that does not lead to the receipt of recommended follow-up care is of limited value to public health.7,8,15 However, despite the existence of real-world barriers to widespread and effective implementation, the findings of this report suggest that the potential for primary care–based DR telemedicine screening to provide timely screening is large.
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