Abstract
Background:
Cataracts are one of the leading causes of blindness in the world and disproportionately affect the elderly people and women. Sex- and race-related differences in cataract formation are not well understood. Furthermore, race and socioeconomic factors can play a role in developing systemic diseases. Earlier studies have supported a link between certain systemic diseases and cataract formation. Our study examined race-related differences in ocular and systemic comorbidities and analyzed differences among races and insurance types for cataract surgery visual outcomes among female patients with cataracts.
Materials and Methods:
Data were collected retrospectively and patients were grouped by race and insurance classifications. Female patients at a large tertiary center with an International Classification of Disease, 9th Edition (ICD-9) or ICD-10 cataract diagnosis or cataract extraction procedure code between January 2013 and June 2018 were included. A total of 909 female patients were included in the study. Frequency of systemic and ocular comorbidities was analyzed. Demographic factors were also compared among races. Finally, characteristics of cataract surgery patients, such as age at surgery, preoperative best-corrected visual acuity (BCVA), and visual outcomes among races and insurance types were analyzed.
Results:
There are differences among races for frequency of smoking, hemoglobin A1c, hypertension, and diabetes mellitus in female patients with cataracts and differences among races and insurance types for preoperative BCVA for patients who underwent cataract surgery (p < 0.001 for all).
Conclusions:
Female minority and non-minority patients with cataracts have a high frequency of systemic and ocular comorbidities at our county hospital. Patients with no insurance and white and Hispanic patients had worse preoperative BCVA.
Introduction
Cataracts are one of the leading causes of blindness in the world and pose a substantial economic and public health burden. Cataract surgery is one of the most frequently performed surgical procedures in the Medicare program, costing >3 billion dollars annually. 1 Studies have found that cataracts disproportionately affect the elderly people (≥65 years of age) and women more than men. 2
Patients with cataracts are often affected by systemic and ocular comorbidities. Previous literature has examined comorbidities of cataract patients in other countries such as Australia and China, and has found a high prevalence of comorbidities. However, there are no known studies conducted in the United States in the English language ophthalmic literature that have examined ocular and systemic comorbidities in minority patients or in women specifically. 3,4 Given the higher prevalence of cataracts in female patients, the high frequency of comorbidities among cataract patients, and the lack of understanding in sex-related differences in ocular comorbidities, we sought to examine specifically the frequency of systemic and ocular comorbidities in female cataract patients. 5 Moreover, prior studies have shown that some ophthalmologic diseases are more common among certain races. For example, glaucoma has been shown to predominantly affect Black patients more than White patients. 6 Understanding which ocular comorbidities occur at a high frequency in women and in certain minorities can help in the clinical setting by tailoring care toward them. In addition, it can help ensure that appropriate screening measures for these ocular comorbidities are taken at ophthalmologic visits.
In addition to examining ocular comorbidities, we wanted to understand differences, if any, in pre- and postoperative visual acuity not only among races, but also among patients with varying insurance statuses, to see if socioeconomic status plays a role in visual outcomes. Earlier studies have shown that a high percentage of patients with ocular conditions such as cataracts and glaucoma do not have vision insurance and were less likely to attend eye care visits. These ocular conditions, if untreated, can lead to worsening visual acuity. 7 We hoped to understand differences, if any, that race and insurance status play in visual outcomes.
Overall, the objective of this study was twofold. First, we sought to study the frequency of major systemic and ocular comorbidities among Black or African American, Hispanic White (henceforth referred to as “Hispanic”), and non-Hispanic White (henceforth referred to as “White”) female patients with cataracts at a county hospital over a 5-year period. Second, we sought to describe patterns in preoperative visual acuity, age at surgery, and postoperative visual outcomes among races and insurance types in the subset of female patients who underwent cataract surgery.
Materials and Methods
Data collection
A retrospective chart review of electronic health records (EHR) was performed at Ben Taub General Hospital (BTGH). This analysis was compliant under Institutional Review Board (IRB), Declaration of Helsinki, and Health Insurance Portability and Accountability Act of 1996 (HIPAA).
Female patients with an International Classification of Disease, 9th Edition (ICD-9) or ICD-10 cataract diagnosis or cataract extraction procedure code recorded in the left (Oculus sinister [OS]), right (Oculus Dexter [OD]), or both (Oculus Uterque [OU]) eyes between January 2013 and June 2018 were included. These parameters returned 1038 patients, of which 909 patients were randomly selected for further chart review based on a random number generator. Sample size was determined based on sample size analysis of other epidemiologic studies in the ophthalmic literature. Earlier studies that have analyzed frequency of ocular comorbidities of patients in other counties have had comparable sample sizes but did not run statistical tests of significance. 4,8 All patients were grouped by their self-reported race and/or ethnicity classification documented in the EHR: “Black/African American,” “Hispanic/Latino,” and “White/Caucasian.” None of the patients who were included in the data set were classified as multi-ethnic or “Asian/Pacific Islander.” Although “Hispanic” is an ethnicity and not an U.S. Office of Management and Budget race classification, we deemed the differentiation between Hispanic White and non-Hispanic White patients to be necessary, given the well-documented health disparities between these populations in earlier literature. Patients were also grouped by their insurance status EHR classifications: “None,” which included no insurance and undocumented status; “Private,” which included all private insurance; and “Public,” which included Medicare, Medicaid, and county-sponsored insurance. Harris County sponsored public insurance, called the gold card, is given to county members who meet criteria based on income status. The qualification requirements for a gold card are analogous to those for Medicaid, which is why both gold card recipients and Medicaid recipients are designated as having “Public” insurance in this study.
Systemic and ocular comorbidities, demographic factors, and various characteristics of cataract surgery patients such as pre- and postoperative vision were collected and analyzed according to the information mentioned hereunder.
Hemoglobin A1c (A1c) and body mass index documented within 3 months before each patient's most recent cataract surgery was collected. The patient's most recent smoking status in the EHR was recorded.
Patients who had a diagnosis of myocardial infarction without corresponding elevation in the ST segment on electrocardiography (NSTEMI) or myocardial infarction with corresponding ST segment elevation on electrocardiography (STEMI), hypertension (HTN), or diabetes mellitus (DM) type 1 or 2 were documented. Ocular medical history was also collected. Because most patients underwent cataract extraction in both eyes, laterality of ocular comorbidities was not recorded. Keratoconus, dry eye syndrome, corneal transplants, keratitis, and other diseases of the cornea were classified as “Corneal Syndrome.” Only ocular comorbidities documented in the EHR before cataract documentation and extraction were recorded.
Patient cataracts were classified as “Nuclear,” “Posterior Subcapsular,” “Cortical,” “Mixed,” “Other,” or “Unknown.” Laterality of cataracts was also recorded.
For patients who had one or more cataract surgeries documented in the EHR, the best-corrected visual acuity (BCVA) using the manifest refraction was collected in each eye before and after the surgery. Postoperative BCVA was recorded 1 month after surgery. The change in visual acuity was calculated. BCVA was converted from Snellen to Logarithm of Minimal Angle of Resolution (log-MAR) units to standardize comparison and calculation. 9 Age at cataract extraction was calculated from date of the postoperative note. Most patients underwent cataract extraction in both eyes consecutively. For these patients, the age at earliest cataract surgery was calculated.
Analytic approach
Statistical analysis was performed with R (The R Foundation, Vienna, Austria), an open source programming language. Data were assessed for a normal distribution using Shapiro–Wilk tests with an α of 0.05. Analysis of variance (ANOVA) or Kruskal–Wallis tests were used to compare the continuous patient characteristics between the racial and insurance status groups. Categorical variables were analyzed with Fisher exact tests and chi-squared tests, determined by the presence of five or less or more than five entries per category, respectively. Additional head-to-head analysis was performed between groups with independent t-tests or Mann–Whitney U-tests, depending on parametric status. Forty-eight statistical tests were performed, and a Bonferroni correction was applied to calculate an adjusted α value of 0.001. 10
Results
Our results revealed that 81% of female cataract patients had at least one or more ocular comorbidities. The most frequent ocular comorbidities were glaucoma, proliferative diabetic retinopathy, and nonproliferative diabetic retinopathy. Black patients had the highest frequency of glaucoma. Hispanic patients had the highest frequency of a number of retinal pathologies, specifically, proliferative diabetic retinopathy, nonproliferative diabetic retinopathy, diabetic macular edema, epiretinal membrane, retinal detachment, and macular hole. White patients had the highest frequency of age-related macular degeneration, retinal artery/vein occlusion, and corneal syndromes. The frequency of each ocular comorbidity is given in Table 1.
Frequency of Ocular Comorbidities by Race (Absolute Number of Patients and Frequency in Percentage)
OD, Oculus Dexter; OS, Oculus Sinister; OU, Oculus Uterque.
HTN and DM type 2 were highly prevalent among female patients with cataracts. Seventy-nine percent of all patients had a diagnosis of HTN and 63% of all patients had a diagnosis of DM type 2. Less than 3% of patients had a diagnosis of STEMI or NSTEMI.
Racial differences were noted for HTN, DM, A1c, smoking status, and insurance status (Table 2). White patients had a lower frequency of HTN (54%) compared with that of Black (85%) and Hispanic (79%) patients (p < 0.001). Hispanic patients had a higher frequency of type 2 diabetes (71%) compared with that of Black (59%) and White (43%) patients (p < 0.001). White patients recorded lower A1c levels than Black or Hispanic patients (p < 0.001). Smoking frequency differed between all three races (p < 0.001), with White patients having the highest percentage of patients who reported currently smoking and Hispanic patients having the lowest percentage. The majority of patients had no insurance, followed by public and then private insurance. There was a difference among races for insurance types, specifically between Black and White patients and Hispanic and White patients (p < 0.001). The majority (70%) of Hispanic patients had no insurance, surpassing rates of no insurance for White (45%) patients and Black patients (40%).
Medical and Demographic Factors by Race
Values in bold indicate statistically significant omnibus test with Bonferroni α = 0.001.
Results from independent t-tests/Mann–Whitney U-tests performed between races for each comorbidity are listed to the right of each comorbidity (α = 0.001).
BMI, body mass index.
A statistical significance was found for cataract laterality between Black and Hispanic patients (Table 3). The most common type of cataract in either OD or OS was the Mixed type or Nuclear.
Cataract Characteristics by Race, Including Laterality of Cataracts and Type of Cataract OD and OS
Values in bold indicate statistically significant omnibus test with Bonferroni α = 0.001.
Not included in statistical calculations.
Insurance comparisons
There was no difference among insurance types for laterality of cataracts. Patients with no insurance had the highest number of Mixed or Nuclear cataracts (Table 4).
Cataract Characteristics by Insurance Status, Including Laterality of Cataracts and Type of Cataract OD and OS
Not included in statistical calculations.
Subanalysis of female patients who underwent cataract surgery
Race comparisons
For patients who received cataract surgery, Black patients had less severe preoperative BCVA compared with White and Hispanic patients (p < 0.001). There was no difference among races for age at surgery or postoperative change in BCVA (Table 5).
Comparisons of Age at Surgery, Preoperative Best-Corrected Visual Acuity, and Surgery Outcomes by Race for Patients Who Received Cataract Surgery
Values in bold indicate statistically significant omnibus test with Bonferroni α = 0.001.
BCVA, best-corrected visual acuity; logMAR, logarith of minimal angle of resolution; SD, standard deviation.
Insurance comparisons
A difference in preoperative BCVA was noted among patients with different insurance types. Patients with no insurance had a worse preoperative BCVA than those with public or private insurance (p < 0.001). There was a higher mean age at cataract extraction among patients with public insurance than patients with no insurance or private insurance (p < 0.001). There was no difference in change in visual outcome after cataract surgery among patients with different insurance types (Table 6).
Comparisons of Age at Surgery, Preoperative Best-Corrected Visual Acuity, and Surgery Outcomes by Insurance Type
Values in bold statistically significant omnibus test with Bonferroni α = 0.001.
Discussion
This study documents the frequency of various ocular and systemic comorbidities among female cataract patients at a large public county hospital serving the Harris County area over a 5-year period and analyzes associations among races for various demographic and medical factors. Our study of female cataract patients also evaluates preoperative BCVA, age at cataract surgery, visual outcomes, and other cataract characteristics of patients by race and insurance status.
Our study found a high frequency of ocular comorbidities among female cataract patients. The most highly prevalent ocular comorbidities included glaucoma, proliferative and nonproliferative diabetic retinopathy. Previous studies have examined differences in frequency of diabetic retinopathy among races and have shown that the frequency and severity of diabetic retinopathy is higher in non-Hispanic Blacks and in Mexican Americans compared with non-Hispanic Whites, but results were not subdivided based on sex. 11 In our female population, Hispanic women had almost 3.5 times the frequency of proliferative diabetic retinopathy compared with White women and almost 2 times that of Black women.
Diabetes is one example of a medical comorbidity linked to ocular complications. Specifically, it is understood that diabetes can result in the formation of cataracts through the polyol pathway. 12 Our study of female cataract patients revealed a higher frequency of type 2 DM for Hispanic patients compared with Black and White patients; higher average A1c levels of Black and Hispanic patients compared with White patients; and higher frequency of HTN between White and Black patients and White and Hispanic patients (p < 0.001)—all of which are similar to previous studies of combined men and women in the United States. 13 Earlier studies have found that reducing A1c by 1% can reduce risk of cataracts. 14 As stated previously in the results, Hispanic patients had worse preoperative visual acuity, or cataract severity compared with Black patients (Table 5). It is possible that these systemic comorbidities, specifically diabetes and higher A1c, could be contributing to increased cataract severity for Hispanic patients.
Our results found that there was a difference among races in terms of smoking status for all race comparisons (p < 0.001). White patients had the highest percentage of patients who reported currently smoking compared with other races. Previous studies have found that current smokers are twice as likely as nonsmokers to develop cataracts and have progression of cataracts. 15 This is because of the fact that smoking is associated with formation of free radicals and lowers levels of antioxidants, which can lead to ocular pathogenesis through oxidative stress. 16
We found that there was an association between race and laterality of cataracts, specifically between Black and Hispanic patients (p < 0.001). A higher percentage of Hispanic patients received cataract surgery on both eyes compared with Black patients. Because it is most common that patients have bilateral cataracts (as indicated by the data in Table 3), this result could indicate that Black patients had either a delay in cataract formation between the two eyes or delay in diagnosis of cataract in the fellow eye. Of note, of the 909 patients, 4 Black patients had a history of ocular trauma and one Hispanic patient had a history of ocular trauma. The majority of cataracts were of the “Mixed” type, with the second most common being “Nuclear.” The high percentage of patients with nuclear cataracts in our study is consistent with a previous study that found women were more likely to have nuclear and cortical opacity incidence compared with men. 15
Subanalysis of female patients who underwent cataract surgery
In our subset of female patients who underwent cataract surgery, we found a difference between Black and Hispanic patients and Black and White patients in preoperative BCVA (p < 0.001). Black patients had the least severe preoperative BCVA compared with White patients and Hispanic patients. Preoperative and postoperative BCVA for patients with ocular comorbidities were representative of the totality of ocular pathologies and not representative of the severity of cataracts alone. These data could indicate that at the time of cataract extraction, White and Hispanic patients had either more severe cataracts, more severe ocular comorbidities, or both. Another reason for differences by race in presenting visual acuity may be attributed to differences in types of cataracts. For example, The Salisbury Eye Evaluation project found that Black patients are more likely to have cortical cataracts compared with White patients. Cortical cataract affects central vision less than nuclear cataracts, which could explain why our Black female patients had the least severe BCVA as compared with other races. 15,17
We also found that patients with no insurance had the worst preoperative BCVA followed by patients with public insurance and then private insurance. Previous studies have found that patients below the median income and of lower socioeconomic status (SES) have more severe cataracts. 18 Patients with no insurance are also least likely to visit an eye doctor, have yearly dilated examinations, or be able to afford eye glasses. 19 In this study we used insurance as a surrogate for SES, but race can also serve as surrogate for SES. 20 These results stress the importance of the accessibility of ophthalmic examination to patients of all SES and all races to minimize worsening of visual acuity owing to cataracts. This can potentially increase survival, as severe visual impairment from ocular conditions such as cataracts is a risk indicator for poor survival. 21,22 On average, patients with public insurance were older at cataract extraction (mean age 66.3) than patients with no insurance or private insurance (p < 0.001). This result is likely owing to the fact that Medicare requires patients be at least 65 years of age to receive cataract surgery. There was no difference found among races or insurance types in terms of change in BCVA after cataract surgery. These results could suggest that cataract surgery had an equal effect on patients regardless of race or insurance status. To our knowledge, no studies have compared racial differences or differences in insurance status in visual outcomes among female patients only after cataract surgery in the United States like in our study.
Limitations of this study include that the county hospital from which patients were selected serves a very specific demographic, which may not be representative of other cities or populations. For example, >50% of patients are uninsured at this county hospital. The data are somewhat reflective of the metropolitan Houston, Texas demographics, where 19.7% of residents are uninsured. Furthermore, the White population in our study is underrepresented compared with the general population in the United States. In Houston, non-Hispanic Whites make up the second largest ethnic group in Houston after Hispanic Whites, which is the largest ethnic group. 23 It is important to note that the limited sample size of White patients in our data did not pose any limitation to the statistical methods. These data can be generalizable to areas with similar demographics. The study was also limited in its retrospective design, and prospective studies could control for confounding variables. Fourth, all ocular comorbidities documented in this study were present before diagnosis or extraction of cataracts. Patients with certain pathologies, such as diabetic retinopathy or glaucoma, likely presented to clinic for ophthalmic evaluation earlier and more frequently than patients in the general population. For this reason, it is possible that cataracts in these patients were documented and extracted before patients in the general population.
Conclusion
Our study is a female-focused study and aims to shed light on the frequency of systemic and ocular comorbidities in female minority and non-minority patients with cataracts and to analyze any potential associations among medical comorbidities, cataract characteristics, race, and insurance status. We found that a higher percentage of minority women with cataracts carried diagnoses of diabetes and HTN compared with non-minority White women. We also found that patients with no insurance had worse preoperative BCVA compared with patients with public and private insurance, regardless of race. There were no differences among patients from different races or insurance statuses in terms of change in visual acuity after surgery, suggesting that cataract surgery served as an equalizer for all patients. To our knowledge, there are no known studies in the English language ophthalmic literature comparing the frequency of systemic and ocular comorbidities, demographic factors, and visual outcomes of female minority and non-minority patients with cataracts. Our study hopes to increase awareness of female ocular pathologies and eliminate barriers to access to health care for these patients. Future prospective studies are needed to make formal recommendations regarding targeted treatment for female cataract patients with systemic and/or ocular comorbidities.
Footnotes
Authors' Contributions
A.K.: conceptualization, methodology, validation, investigation, resources, writing—original draft preparation; article writing—review and editing. J.A.G.: software, formal analysis, validation, investigation, data curation, writing—original draft preparation. S.W.: investigation, validation. P.U.: investigation. M.K.: validation, article writing—review and editing, validation. Z.A.-M.: conceptualization, supervision, article writing—review and editing.
Author Disclosure Statement
No competing financial interests exist.
Funding Information
No funding was received for this article.