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Racial/ethnic differences in rates of complex cataract surgery among United States Medicare beneficiaries

Mahr, Michael A. MD; Hodge, David O. MS; Erie, Jay C. MD*

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Journal of Cataract & Refractive Surgery: February 2018 - Volume 44 - Issue 2 - p 140-143
doi: 10.1016/j.jcrs.2017.10.049
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Abstract

Cataract surgery rates have increased 2.5-fold to 6.5-fold over the past several decades, resulting in cataract surgery being the most frequent surgical procedure in the United States.1 Reducing racial/ethnic disparities in healthcare, including cataract surgery, is a national priority.2 Several previous studies have characterized the utilization and outcomes of cataract surgery across various racial/ethnic groups3–11 and in general they have documented lower utilization rates and higher postoperative complication rates in African-American patients when compared with whites. However, no studies to date have evaluated racial/ethnic differences in rates of complex cataract surgery.

Our aim was to examine racial/ethnic differences in rates of complex cataract surgery among U.S. fee-for-service Medicare beneficiaries by using national public Medicare claims files data. The newly available Medicare databases provide a large and diverse population of senior Americans aged 65 years and older that allow for determining differences in complex cataract surgery rates across racial/ethnic groups.

Patients and methods

This was a retrospective cross-sectional cohort study using the 2014 Medicare Limited Data Set Carrier Standard Analytical File, obtained from the Centers for Medicare and Medicaid Services.A This publicly available dataset contains a deidentified 5% sample of all claims for approximately 28 million U.S. fee-for-service Medicare enrollees. The database excludes care to Medicare beneficiaries who selected Medicare Advantage plans in 2014. Informed consent is not required for retrospective use of a deidentified Medicare database. Because no direct patient-identifiable data were used, this study was exempt from review by the Mayo Clinic Institutional Review Board.

All beneficiaries receiving at least 1 cataract surgery between January 1, 2014, and December 31, 2014, were identified by records containing Current Procedural Terminology (CPT) codes 66984 and 66982. In the U.S., adult cataract surgery is billed as complex (CPT code 66982) if the procedure includes 1 or more of the following: a dye used to stain the anterior capsule, a mechanical device used for a poorly dilating pupil, a capsular tension ring used to support a compromised zonule, or suturing of an intraocular lens. Data were filtered to include sex, ages 65 years and older, and race/ethnicity of white, African American, Hispanic, and Asian. Race/ethnicity was self-reported by Medicare patients at the time of Social Security enrollment when using form SS-5.

In all beneficiaries with CPT code 66982, clinical comorbidities often associated with a poorly dilating pupil were identified by using the International Classification of Diseases, 9th Revision, Clinical modification (ICD-9-CM) diagnosis codes as follows: floppy iris syndrome (364.81); miosis, not due to miotics (379.42); pupillary abnormalities (364.75); other disorders of the iris and ciliary body (364.89); other anomalies of pupillary function (379.49); posterior synechiae of iris (354.71); adhesion of iris, unspecified (364.70); pseudoexfoliation glaucoma (365.52); and unspecified disorder of iris and ciliary body (364.90).

Data analyses were performed by using Excel software (2013) with Power Pivot and Power Query add-ins (Microsoft Corp.), and SAS software (version 9.4, SAS Institute, Inc.). The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a multivariate logistic regression model with all 3 factors in the model.

Results

Data from approximately 1 087 680 Medicare beneficiaries were analyzed by using the 2014 Medicare 5% Limited Data Set. Table 1 shows the clinical characteristics and rates of complex cataract surgery (CPT code 66982) among all fee-for-service Medicare beneficiaries having cataract surgery (CPT codes 66982 or 66984) in 2014.

Table 1
Table 1:
Clinical characteristics and rates of complex cataract surgery among fee-for-service Medicare beneficiaries having 1 or more cataract surgeries in 2014.*

Multivariable logistic regression analysis was used to document associations between selected clinical characteristics and complex cataract surgery rates (Table 2). African-American, Asian, and Hispanic beneficiaries were 90%, 57%, and 42%, respectively, more likely to have their cataract surgery coded as complex than whites after adjusting for age and sex. Across all racial/ethnic groups, men were 83% more likely than women to have complex cataract surgery and beneficiaries 85 years of age and older were 268% more likely to have complex cataract surgery than beneficiaries aged 65 to 69 years.

Table 2
Table 2:
Multivariate associations between clinical characteristics and complex cataract surgery rates (CPT code 66982) in U.S. fee-for-service Medicare beneficiaries in 2014.*

Within this 5% Limited Dataset, 11 500 (18%) of 63 240 women and 20 160 (28%) of 71 800 men having complex cataract surgery (CPT 66982) also had a concurrent ICD-9-CM code that is usually associated with a poorly dilating pupil and likely requires the use of a mechanical iris expansion device during surgery (P < .001). Of the 11 500 women, the percent of complex cases having a small pupil-related diagnosis code was 19% for whites, 17% for Asians, 12% for African Americans, and 12% for Hispanics. Of the 20 160 men, the percent of complex cases having a small pupil-related diagnosis code was 31% for Asians, 29% for whites, 17% for African Americans, and 15% for Hispanics. Overall, the combined group of whites and Asians were significantly more likely to have a concurrent small pupil-related diagnosis than the combined group of African Americans and Hispanics (OR, 1.98; 95% CI, 1.62-2.41).

Discussion

This descriptive epidemiology of fee-for-service Medicare beneficiaries having cataract surgery in 2014 suggests racial/ethnic differences in the likelihood of receiving complex cataract surgery. After adjustment for age and sex, racial/ethnic minorities including African-American, Asian, and Hispanic beneficiaries, were approximately 1.9-fold, 1.6-fold, and 1.4-fold, respectively, more likely than white beneficiaries to have cataract surgery coded as complex. Whether this association represents underlying genetic or environmental differences, differences in access to care, or other unknown or confounding influences requires further study.

Racial/ethnic differences in the utilization of cataract surgery in the U.S. have been reported. Several studies3–8,10 found lower overall cataract surgery rates in African Americans when compared with whites. By contrast, studies found Hispanics6,9 and Asians6 have higher rates of cataract surgery than whites. Because previous reports suggest that African Americans are less likely than whites to see eyecare providers,7,12 Wang et al.7 attempted to correct for African American’s lower rate of eye examinations by limiting their analysis to beneficiaries who only saw an eyecare provider. After this adjustment, they found cataract surgery rates were higher in African Americans than in whites.

Race has also been associated with variable complication rates after cataract surgery. Higher complication rates after cataract surgery are reported in African Americans and Hispanics than in whites.11 It has been suggested that African Americans might be less aware of the benefits of cataract surgery,13 as well as less likely to see an eyecare provider.7,12 One can speculate that delayed access to eyecare might lead to more advanced cataract formation at presentation, contributing to our observed higher rates of complex cataract surgery and the previously reported higher complication rates.11 This possibility, however, could not be examined in this study.

We found that men were significantly more likely than women to have their cataract surgery coded as complex. Men were also 1.5 times more likely to have a small pupil-related ICD-9-CM diagnosis coded in association with a complex cataract surgery code. This might be explained by the higher use of α1a adrenergic receptor antagonists in men than women and its association with floppy iris syndrome.14 Whites and Asians were significantly more likely than African Americans and Hispanics to have a concurrent small pupil-related ICD-9-CM diagnosis code at the time of complex cataract surgery. Possible reasons include race-based differences in α1a adrenergic receptor antagonist use, ethnicity-based anatomic factors affecting pupil dilation, or other known or unknown comorbidities. Medicare claims data do not have the specificity to clarify this association.

The analysis of Medicare claims data is valid,15 is high quality,16 and does not rely on patient input, but rather on specific coding performed by healthcare providers. In addition, the number of patients and treatments is an order of magnitude larger than many other sources. Despite these advantages, study limitations must be acknowledged. First, retrospective Medicare claims-based data is subject to potential coding inaccuracies caused by missing data, incomplete data, and coding errors.15 Second, Medicare claims files are composed of observational data and this limits the interpretation of significant differences to associations rather than causal effects. Third, race identification is a problem for any study on race-related issues. In this study, we identified race on self-reported numbers by beneficiaries at the time of Medicare enrollment. Previous studies have questioned the sensitivity of self-reported race/ethnicity in Medicare enrollment databases for groups other than whites and blacks.17 Fourth, fee-for-service Medicare claims data do not include patients enrolled in Medicare Advantage plans and the findings might not be generalizable to the entire Medicare Advantage population.18 In 2014, an estimated 30% of Americans aged 65 years and older were enrolled in a Medicare Advantage Plan.B Last, although racial/ethnic differences in fee-for-service Medicare enrollment rates could have existed in 2014, census data in 2010 indicates that 8.5% of the U.S. population aged 65 years and older was African American,19 which is consistent with the 8.5% Medicare proportion in 2014.

These limitations notwithstanding, the results indicate racial/ethnic differences in rates of complex cataract surgery exist among U.S. fee-for-service Medicare beneficiaries. The findings represent an association, not a cause-and-effect relationship. Further studies are warranted to better understand and to identify the underlying reasons for such disparities.

What Was Known

  • African Americans have lower cataract surgery utilization rates and higher postoperative complication rates when compared with whites. Racial/ethnic differences in rates of complex cataract surgery have not been studied.

What This Paper Adds

  • Racial/ethnic minorities, including African-American, Asian, and Hispanic Medicare beneficiaries, had significantly higher rates of complex cataract surgery than white Medicare beneficiaries.

References

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Disclosures

None of the authors has a financial or proprietary interest in any material or method mentioned.

Other cited material

A. Centers for Medicare and Medicaid Services. Medicare Provider Utilization and Payment Data: Physician and Other Supplier, 2017. Available at: http://www.cms.gov/Research-Statistics-Data-and-Systems/Statistics-Trends-and-Reports/Medicare-Provider-Charge-Data/Physician-and-Other-Supplier.html. Accessed November 27, 2017
B. Gold M, Jacobson G, Damico A, Neuman T. Medicare Advantage 2014 spotlight: enrollment market update (May 2014). Kaiser Family Foundation. Available at: http://kff.org/report-section/medicare-advantage-2014-spotlight-enrollment-market-update-overall-trends/. Accessed November 27, 2017
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