Rates of Routine Cataract Surgery Among Medicare Beneficiaries

Substantial variation in rates of cataract surgery among Medicare beneficiaries has been documented since the 1990s, with greater than 50% variation between selected states.¹ More than 80% of all cataract surgery is covered by Medicare, so trends among Medicare beneficiaries are a barometer of national trends.² Past estimates of Medicare surgery rates are limited, however, due to the reliance on 5% samples, exclusion of Medicare health maintenance organizations (HMOs), and the use of data more than a decade old.^1,3 Identifying variations in practice patterns is an important step in improving quality of health care including access.³ We explored the rates of cataract surgery among Medicare beneficiaries with the goal of shedding light on geographic variation at the US county level.

Medicare’s Ambulatory Surgical Center (ASC) Payment System File contains a summary of services by ASC, including both independent ASCs and hospital-based outpatient surgery centers.⁴ Files include services, charges, procedure codes, and geographic information for the centers. A limited data set for 2014 was purchased from the Research Data Assistance Center.⁵ We used the Healthcare Common Procedure Coding System code 66984 to identify routine cataract surgery (extracapsular cataract removal with insertion of intraocular lens, manual or mechanical, using irrigation-aspiration or phacoemulsification, but not requiring any special devices or technique). We counted the total number of procedures by the National Provider Index number of the ASC then grouped by counties for descriptive statistics and geographical mapping. ArcGIS and ArcMap version 10.3 software (Esri) was used for cartographic work and SAS version 9.4 (SAS Institute Inc) for data calculations. Rates were determined per 10 000 beneficiaries at the county level and adjusted for number of Medicare beneficiaries aged 65 years or older with 2010 US Census data. Several anomalously small boroughs of Alaska and independent cities of Virginia were too small for map resolution but were included in summary statistics. The Northwestern University Institutional Review Board granted the project exemption from the need for participant consent.

A total of 2 298 446 routine cataract surgical procedures were performed in Medicare beneficiaries in ASCs in 2014. The national overall rate of routine cataract surgery was 769 per 10 000 beneficiaries aged 65 years or older (Table). Age-adjusted rates varied by region from a high of 1025 in the South to a low of 538 in the Northeast. There was a substantially higher rate of surgery among rural counties (1120 per 10 000 beneficiaries) vs urban (741 per 10 000 beneficiaries) (Table). Highest rates were typically found in ASCs in rural counties (Figure).

The absolute number of cataract surgeries in 2014 (769) was 24% greater than reported in 2004, when the age-adjusted rate was 618 per 10 000 beneficiaries.¹ Earlier data, however, did not include patients enrolled in HMOs.¹ The observation that higher rates of surgery are performed in rural counties is likely explained by the relative lack of ASCs in many remote areas of the country. The majority of rural counties in the United States perform no cataract surgery. Those that have ASCs have large catchment areas from which to draw patients. Because age-adjusted rates are based on the population of counties with ASCs, they can become inflated. Even taking into consideration the large catchment areas of rural counties, the geographic variation in routine cataract surgery is substantial and remains largely unexplained. Given the link between practice variation and health care quality, national data sets need to include more deidentified patient- and provider-level variables to better understand the etiologies of substantial variations in practice patterns.⁶ Future studies of the current data set might shed light on variation by analyzing surgery rates on an individual surgery center level or using economic areas defined by the Bureau of Economic Analysis.

Corresponding Author: Dustin D. French, PhD, Center for Healthcare Studies, Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N Michigan Ave, Ste 440, Chicago, IL 60611 (Dustin.French@northwestern.edu).

Published Online: January 5, 2017. doi:10.1001/jamaophthalmol.2016.5174

Author Contributions: Dr French had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: French, Margo, Behrens.

Acquisition, analysis, or interpretation of data: French, Margo, Greenberg.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: French, Margo, Greenberg.

Statistical analysis: French, Margo, Behrens.

Obtained funding: French.

Administrative, technical, or material support: French, Margo, Behrens.

Supervision: French.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Funding/Support: Dr French is supported by an unrestricted grant from Research to Prevent Blindness and Department of Health and Human Services, National Institutes of Health, National Eye Institute grant 1R21EY024050-01A1.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the Department of Veterans Affairs or the US government.

Additional Contributions: We thank Karl Y. Bilimoria, MD, MS, of the Surgical Outcomes Quality Improvement Center at Northwestern University, who assisted in obtaining Medicare data and Zuber Mulla, PhD, Texas Tech University Health Sciences Center, El Paso, for statistical assistance and interpretation.