This study population-based cohort identifies patient characteristics associated with receiving cataract surgery within the US Medicare and Veterans Health Administration populations.
Key Points
Question
What characteristics are associated with receiving cataract surgery within the US Medicare and Veterans Health Administration patient populations?
Findings
In this cohort study of 1.2 million Medicare patients and 1.9 million Veterans Health Association patients, a greater proportion of Medicare patients received cataract surgery within 1 and 5 years of cataract diagnosis. Within both groups, older vs younger age, residence in the southern vs other parts of the United States, and chronic pulmonary disease vs no such disease were associated with increased odds of cataract surgery at 1 and 5 years after diagnosis.
Meaning
Although a larger proportion of Medicare patients with cataract underwent surgery, both patient populations had similar characteristics associated with receiving cataract surgery.
Abstract
Importance
Considerable variation exists with respect to the profiles of patients who receive cataract surgery in the United States.
Objective
To identify patient characteristics associated with receiving cataract surgery within the US Medicare and Veterans Health Administration (VHA) populations.
Design, Setting, and Participants
In this population-based retrospective cohort study of 3 073 465 patients, Medicare and VHA patients with a cataract diagnosis between January 1, 2002, and January 1, 2012, were identified from the 2002-2012 Medicare Part B files (5% sample) and the VHA National Patient Care Database. Patient age, sex, race/ethnicity, region of residence, Charlson Comorbidity Index (CCI) scores, and comorbidities were recorded. Cataract surgery at 1 and 5 years after diagnosis was identified. Data analysis was performed from July 1, 2016, to July 1, 2017.
Main Outcomes and Measures
Odds ratios (ORs) of cataract surgery for selected patient characteristics.
Results
The study sample included 1 156 211 Medicare patients (mean [SD] age, 73.7 [7.0] years) and 1 917 254 VHA patients (mean [SD] age, 66.8 [10.2] years) with a cataract diagnosis. Of the 1 156 211 Medicare patients, 407 103 (35.2%) were 65 to 69 years old, 683 036 (59.1%) were female, and 1 012 670 (87.6%) were white. Of the 1 917 254 VHA patients, 905 455 (47.2%) were younger than 65 years, 1 852 158 (96.6%) were male, and 539 569 (28.1%) were white. A greater proportion of Medicare patients underwent cataract surgery at 1 year (Medicare: 213 589 [18.5%]; VHA: 120 196 [6.3%]) and 5 years (Medicare: 414 586 [35.9%]; VHA: 240 884 [12.6%]) after diagnosis. Factors associated with the greatest odds of surgery at 5 years were older age per 5-year increase (Medicare: OR, 1.24 [95% CI, 1.23-1.24]; VHA: OR, 1.18 [95% CI, 1.17-1.18]), residence in the southern United States vs eastern United States (Medicare: OR, 1.38 [95% CI, 1.36-1.40]; VHA: OR, 1.40 [95% CI, 1.38-1.41]), and presence of chronic pulmonary disease (Medicare: OR, 1.26 [95% CI, 1.24-1.27]; VHA: OR, 1.40 [95% CI, 1.38-1.41]). Within Medicare, female sex was associated with greater odds of surgery at 5 years (OR, 1.14; 95% CI, 1.13-1.15). Higher CCI scores (CCI score ≥3 vs 0-2) were associated with increased odds of surgery among VHA but not Medicare patients at 5 years (Medicare: OR, 0.94 [95% CI, 0.92-0.95]; VHA: OR, 1.24 [95% CI, 1.23-1.36]). Black race vs white race was associated with decreased odds of cataract surgery 5 years after diagnosis (Medicare: OR, 0.79 [95% CI, 0.78-0.81]; VHA: OR, 0.75 [95% CI, 0.73-0.76]).
Conclusions and Relevance
Within both groups, older age, residence in the southern United States, and presence of chronic pulmonary disease were associated with increased odds of cataract surgery. Findings from this study suggest that few disparities exist between the types of patients receiving cataract surgery who are in Medicare vs the VHA, although it is possible that a smaller proportion of VHA patients receive surgery compared with Medicare patients.
Introduction
Cataract surgery is one of the most commonly performed ambulatory procedures in the United States, and the incidence of cataract surgery in the United States has steadily increased during the past few decades.1,2,3,4 However, wide variation remains in the profiles of patients who receive cataract surgery in the United States. Previous studies5,6,7 have found that patients who are white, female, and insured are more likely to undergo cataract surgery. These studies were limited by a short period of assessment, cross-sectional design, use of self-reported data, and concentration in specific geographic regions.
There is a need for additional study of the factors associated with receiving cataract surgery in large US patient populations with cataract during an extended period. Medicare and the Veterans Health Administration (VHA), the largest integrated health care system in the United States, provide databases on 2 such populations. In addition to having a wide variety of demographic, ocular, systemic diagnosis, and procedure data available, these databases represent 2 distinct US adult patient populations who receive health care coverage through 2 unique systems. This study examined and compared the factors associated with cataract surgery use in Medicare and VHA patients.
Methods
Study Population and Databases
This population-based retrospective cohort study included 3 073 465 Medicare and VHA patients with cataract diagnosis between January 1, 2002, and January 1, 2012. Data for Medicare patients were obtained from a 5% random sample of Medicare beneficiaries from the 2002-2012 Denominator and Physician-Supplier Part B files from the Centers for Medicare & Medicaid Services. Medicare patients with the following characteristics were excluded: age younger than 65 years, residence outside the 50 states of the United States or the District of Columbia, lack of Medicare Part B coverage, and coverage from a health maintenance organization outside the Centers for Medicare & Medicaid Services. Data for VHA patients were obtained from the 2002-2012 acute care inpatient files, outpatient files, and Beneficiary Identification Records Locator Subsystem death file of the VHA national administrative databases. Patients from the VHA were excluded if they resided outside the 50 states of the United States or the District of Columbia. We excluded Medicare patients younger than 65 years because only patients younger than 65 years with specific disabilities qualify for Medicare, and their inclusion could lead to selection bias and decreased generalizability. Data were deidentified, and all data collection was retrospective using insurance billing codes for both databases. As such, written and/or oral consent was not collected from patients within either database. This study was approved by the institutional review boards of UCLA (University of California, Los Angeles) and the Greater Los Angeles Veterans Affairs Health System.
The study population in both databases included patients with an International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis code for cataract between January 1, 2002, and January 1, 2012.8 Patients from both databases with ICD-9-CM codes for pseudophakia or aphakia before the date of the diagnosis code for cataract were excluded from the study. Data analysis was performed from July 1, 2016, to July 1, 2017.
Outcome
The outcome of interest was cataract surgery. The occurrence of cataract surgery was defined by Current Procedural Terminology (CPT) codes in the Medicare database and by CPT or ICD-9-CM procedure codes in the VHA database. Two separate indicator variables were created to examine the occurrence of cataract surgery. The first variable examined whether patients received cataract surgery within 1 year of diagnosis. Time between the date of the first appearance of the ICD-9-CM diagnosis code for cataract and the date of the CPT or ICD-9-CM procedure code was calculated, and if this duration was less than 1 year, patients were designated as having received cataract surgery within 1 year of diagnosis. The second variable examined whether patients received cataract surgery within 5 years of diagnosis and was created in the same manner except that patients were designated as having received surgery if the duration between diagnosis and surgery was less than 5 years.
Exposures
Exposure variables included demographics, systemic comorbidities, and ocular comorbidities. Demographic information included age at time of cataract diagnosis, sex, race/ethnicity, and region of US residence. Systemic comorbidities included the Charlson Comorbidity Index (CCI) score, which determines 1-year mortality based on a set of 17 comorbidities using a score from 0 to 6, with 0 indicating lowest and 6 indicating highest risk of mortality. For this study, these comorbidities were grouped into cardiovascular disease, chronic pulmonary disease, chronic renal disease, liver and gastrointestinal disease, diabetes, malignant neoplasm, connective tissue disease, AIDS, dementia, and hemiplegia. Ocular comorbidities that were assessed included age-related macular degeneration, diabetic retinopathy, and glaucoma. Determination of systemic and ocular comorbidities was based on ICD-9-CM diagnosis codes for each condition in both databases.
Statistical Analysis
Age, race/ethnicity, and region of US residence were analyzed as categorical variables as indicated in Table 1. The remaining variables were analyzed as dichotomous variables. Region of residence was condensed from previous categorizations in the Medicare database and classified based on the US Census geographic divisions and regions (eAppendix in the Supplement). All baseline covariates were examined using descriptive statistics, and univariable comparisons were performed between patients with cataract in Medicare and patients with cataract in the VHA using χ2 tests for categorical variables and 2-tailed t tests for continuous variables. The number of patients who received cataract surgery within 1 year and 5 years of cataract diagnosis was compared between patients with cataract in Medicare and patients with cataract in the VHA by using χ2 tests. These comparisons were performed for the overall study population and in male patients and patients 65 years and older. To identify multivariable determinants of receiving cataract surgery in each population, logistic regression models were performed, including all baseline covariates in the model as exposures and cataract surgery as the outcome. Separate models were performed for receiving cataract surgery within 1 year of diagnosis and cataract surgery within 5 years of diagnosis. P values were calculated using χ2 tests for crude analyses of categorical variables, 2-tailed t tests for crude analyses of continuous variables, and logistic regression models for adjusted analyses. All reported P values are 2-sided. All statistical analyses were conducted using SAS, version 9.3 (SAS Institute).
Table 1. Baseline Characteristics of Patients With Cataract in the Medicare and VHA Systems From 2002 to 2012.
| Characteristic | No. (%) of Medicare Patients (n = 1 156 211) | No. (%) of VHA Patients (n = 1 917 254) |
|---|---|---|
| Age group, y | ||
| <65 | 0 | 905 455 (47.2) |
| 65-69 | 407 103 (35.2) | 288 052 (15.0) |
| 70-74 | 273 442 (23.7) | 261 747 (13.7) |
| 75-79 | 227 950 (19.7) | 239 197 (12.5) |
| 80-84 | 152 479 (13.2) | 157 718 (8.2) |
| ≥85 | 95 237 (8.2) | 65 085 (3.4) |
| Sex | ||
| Male | 473 175 (40.9) | 1 852 158 (96.6) |
| Female | 683 036 (59.1) | 65 096 (3.4) |
| Race/ethnicity | ||
| White | 1 012 670 (87.6) | 539 569 (28.1) |
| Black | 84 110 (7.3) | 134 932 (7.0) |
| Hispanic | 18 914 (1.6) | 54 366 (2.8) |
| Other or unknown | 40 517 (3.5) | 1 188 387 (62.0) |
| Region of US residence | ||
| East | 478 961 (41.4) | 694 751 (36.2) |
| West | 190 387 (16.5) | 363 615 (19.0) |
| Midwest | 291 188 (25.2) | 432 892 (22.6) |
| South | 195 675 (16.9) | 362 352 (18.9) |
| Unknown | 0 | 63 644 (3.3) |
| Charlson Comorbidity Index scorea | ||
| 0-2 | 876 821 (75.8) | 897 734 (46.8) |
| ≥3 | 279 390 (24.2) | 1 019 520 (53.2) |
| Systemic comorbidities | ||
| Cardiovascular diseaseb | 370 506 (32.0) | 518 427 (27.0) |
| Chronic pulmonary disease | 227 065 (19.6) | 459 520 (24.0) |
| Chronic renal disease | 70 119 (6.1) | 132 127 (6.9) |
| Liver or gastrointestinal diseasec | 56 538 (4.9) | 150 793 (7.9) |
| Diabetes | 312 087 (27.0) | 617 872 (32.2) |
| Malignant neoplasmd | 161 813 (14.0) | 255 584 (13.3) |
| Connective tissue disease | 46 316 (4.0) | 44 333 (2.3) |
| AIDS | 730 (0.1) | 8251 (0.4) |
| Dementia | 43 943 (3.8) | 28 009 (1.5) |
| Hemiplegia | 12 036 (1.0) | 29 112 (1.5) |
| Ocular comorbidities | ||
| Age-related macular degeneration | 191 401 (16.6) | 221 439 (11.6) |
| Diabetic retinopathy | 65 695 (5.7) | 212 613 (11.1) |
| Glaucoma | 223 066 (19.3) | 401 371 (20.9) |
Abbreviation: VHA, Veterans Health Administration.
Assigns patients a score of 0 to 6 where 0 indicates lowest risk and 6 highest risk of mortality.
Includes myocardial infarction, congestive heart failure, peripheral vascular disease, and cerebrovascular disease.
Includes peptic ulcer disease and mild, moderate, and severe liver disease.
Includes solid neoplasm, metastatic tumor, leukemia, lymphoma, and multiple myeloma.
Results
Study Population Characteristics
The study sample included 1 156 211 Medicare patients (mean [SD] age, 73.7 [7.0] years) and 1 917 254 VHA patients (mean [SD] age, 66.8 [10.2] years) with cataract diagnosis. Baseline characteristics of the Medicare and VHA study groups are given in Table 1. Our 5% sample identified 1 156 211 Medicare patients with cataract diagnosis from 2002 through 2012; a total of 1 917 254 VHA patients had cataract diagnosis in the same period. In the VHA group, 905 455 patients (47.2%) were younger than 65 years. In the Medicare population, 473 175 (40.9%) were male. A total of 876 821 patients (75.8%) in the Medicare cohort had a CCI score of 0 to 2, whereas 1 019 520 patients (53.2%) in the VHA cohort had a CCI score of 3 or greater. Within both groups, the 3 most prevalent systemic comorbidities were cardiovascular disease (Medicare: 370 506 [32.0%]; VHA: 518 427 [27.0%]), diabetes (Medicare: 312 087 [27.0%]; VHA: 617 872 [32.2%]), and chronic pulmonary disease (Medicare: 227 065 [19.6%]; VHA: 459 520 [24.0%]). Glaucoma was the most prevalent ocular comorbidity in both cohorts (Medicare: 233 066 [19.3%]; VHA: 401 371 [20.9%]).
Patients Undergoing Cataract Surgery
Table 2 gives the number (%) of patients with cataract in each group who underwent cataract surgery within 1 and 5 years of cataract diagnosis. Compared with the VHA population, more Medicare patients underwent cataract surgery at both the 1-year (Medicare: 213 589 [18.5%]; VHA: 120 196 [6.3%]; odds ratio [OR], 3.39 [95% CI, 3.36-3.41]; P < .001) and 5-year (Medicare: 414 586 [35.9%]; VHA: 240 884 [12.6%]; OR, 3.89 [95% CI, 3.87-3.91]; P < .001) time points. When examining only male patients, a greater proportion of male patients within Medicare underwent cataract surgery at the 1-year (Medicare: 85 624 [18.1%]; VHA: 117 115 [6.3%]; OR, 3.27 [95% CI, 3.24-3.31]; P < .001) and 5-year (Medicare: 160 938 [34.0%]; VHA: 234 386 [12.7%]; OR, 3.56 [95% CI, 3.53-3.58]; P < .001) time points compared with male patients within the VHA. Similarly, when only patients 65 years and older were examined, a greater proportion of Medicare patients 65 years and older underwent cataract surgery at the 1-year (Medicare: 213 589 [18.5%]; VHA: 72 085 [7.1%]; OR, 2.95 [95% CI, 2.93-2.98]) and 5-year (Medicare: 414 586 [35.9%]; VHA: 159 252 [15.8%]; OR, 2.99 [95% CI, 2.97-3.01]; P < .001) time points compared with VHA patients 65 years and older.
Table 2. Patients in the Medicare and VHA Systems Who Underwent Cataract Surgery From 2002 to 2012.
| Timing of Cataract Surgery | No. (%) of Medicare Patients | No. (%) of VHA Patients | OR (95% CI) for Percentage of Medicare vs VHA Patients | P Valuea for χ2 Test |
|---|---|---|---|---|
| Overall study population (1 156 211 Medicare patients and 1 917 254 VHA patients) | ||||
| Within 1 y of cataract diagnosis | 213 589 (18.5) | 120 196 (6.3) | 3.39 (3.36-3.41) | <.001 |
| Within 5 y of cataract diagnosis | 414 586 (35.9) | 240 884 (12.6) | 3.89 (3.87-3.91) | <.001 |
| Male patients (473 175 Medicare patients and 1 852 158 VHA patients) | ||||
| Within 1 y of cataract diagnosis | 85 624 (18.1) | 117 115 (6.3) | 3.27 (3.24-3.31) | <.001 |
| Within 5 y of cataract diagnosis | 160 938 (34.0) | 234 386 (12.7) | 3.56 (3.53-3.58) | <.001 |
| Patients ≥65 y (1 156 211 Medicare patients and 1 011 799 VHA patients) | ||||
| Within 1 y of cataract diagnosis | 213 589 (18.5) | 72 085 (7.1) | 2.95 (2.93-2.98) | <.001 |
| Within 5 y of cataract diagnosis | 414 586 (35.9) | 159 252 (15.8) | 2.99 (2.97-3.01) | <.001 |
Abbreviations: OR, odds ratio; VHA, Veterans Health Administration.
P values refer to comparisons for χ2 tests between the Medicare and VHA populations across columns for the same row.
Factors Associated With Receiving Cataract Surgery
Table 3 and Table 4 list factors associated with receiving cataract surgery at 1 and 5 years after diagnosis, respectively. Within 1 year of cataract diagnosis, demographic factors associated with increased odds of receiving cataract surgery in both cohorts per 5-year increase were older age (Medicare: OR, 1.10; 95% CI, 1.09-1.10; VHA: OR, 1.11 [95% CI, 1.10-1.11]) and residence in the southern United States vs eastern United States (Medicare: OR, 1.38 [95% CI, 1.36-1.40]; VHA: OR, 1.44 [95% CI, 1.41-1.46]). Within Medicare, female sex was associated with greater odds of surgery at 1 year (OR, 1.03; 95% CI, 1.02-1.04). A higher CCI score (≥3 vs 0-2) was associated with greater odds of receiving cataract surgery in the VHA (OR, 1.41; 95% CI, 1.39-1.43). Comorbidities associated with increased odds of cataract surgery in both groups within 1 year included chronic pulmonary disease (Medicare: OR, 1.24 [95% CI, 1.22-1.25]; VHA: OR, 1.11 [95% CI, 1.09-1.13]) and diabetic retinopathy (Medicare: OR, 1.27 [95% CI, 1.25-1.30]; VHA: OR, 1.17 [95% CI, 1.14-1.19]). Comorbidities associated with decreased odds of cataract surgery in both groups within 1 year included dementia (Medicare: OR, 0.54 [95% CI, 0.53-0.56]; VHA: OR, 0.79 [95% CI, 0.75-0.83]) and hemiplegia (Medicare: OR, 0.84 [95% CI, 0.80-0.88]; VHA: OR, 0.76 [95% CI, 0.72-0.80]).
Table 3. Characteristics Associated With Cataract Surgery Within 1 Year of Cataract Diagnosis in Medicare Patients and VHA Patients With Cataract From 2002 to 2012.
| Characteristic | Medicare (n = 1 156 211) | VHA (n = 1 917 254) | ||
|---|---|---|---|---|
| Unadjusted OR (95% CI) | Adjusted ORa (95% CI) | Unadjusted OR (95% CI) | Adjusted ORa (95% CI) | |
| Age per 5-y increase | 1.09 (1.08-1.09) | 1.10 (1.09-1.10) | 1.11 (1.10-1.11) | 1.11 (1.10-1.11) |
| Female vs male | 1.09 (1.08-1.09) | 1.03 (1.02-1.04) | NA | NA |
| Race/ethnicity | ||||
| Black vs white | 1.01 (0.99-1.03) | 1.03 (1.01-1.05) | 0.73 (0.71-0.75) | 0.79 (0.77-0.81) |
| Hispanic vs white | 1.46 (1.41-1.51) | 1.40 (1.36-1.45) | 0.96 (0.93-0.99) | 1.13 (1.08-1.17) |
| Other or unknown vs white | 1.09 (1.06-1.16) | 1.10 (1.07-1.13) | 0.74 (0.73-0.75) | 0.81 (0.80-0.82) |
| Region | ||||
| West vs East | 1.15 (1.13-1.17) | 1.13 (1.12-1.15) | 1.23 (1.21-1.25) | 1.24 (1.22-1.26) |
| Midwest vs East | 1.17 (1.16-1.19) | 1.18 (1.16-1.19) | 1.05 (1.03-1.06) | 1.05 (1.03-1.06) |
| South vs East | 1.36 (1.34-1.38) | 1.38 (1.36-1.40) | 1.43 (1.40-1.45) | 1.44 (1.41-1.46) |
| Unknown vs East | NA | NA | 0.94 (0.91-0.97) | 0.82 (0.78-0.85) |
| CCI score ≥3 vs 0-2 | 1.01 (0.99-1.02) | 0.96 (0.95-0.98) | 1.38 (1.36-1.39) | 1.41 (1.39-1.43) |
| Cardiovascular disease | 1.05 (1.04-1.06) | 1.01 (1.00-1.02) | 1.18 (1.16-1.19) | 1.01 (0.99-1.02) |
| Chronic pulmonary disease | 1.22 (1.20-1.23) | 1.24 (1.22-1.25) | 1.20 (1.19-1.22) | 1.11 (1.09-1.13) |
| Chronic renal disease | 1.00 (0.98-1.02) | 0.95 (0.93-0.97) | 1.24 (1.22-1.27) | 1.11 (1.08-1.13) |
| Liver or gastrointestinal disease | 1.00 (0.98-1.02) | 1.01 (0.99-1.03) | 0.92 (0.90-0.95) | 0.92 (0.89-0.94) |
| Diabetes | 1.06 (1.05-1.07) | 1.03 (1.01-1.04) | 0.71 (0.70-0.72) | 0.63 (0.62-0.63) |
| Malignant neoplasm | 0.90 (0.89-0.91) | 0.91 (0.89-0.92) | 1.04 (1.02-1.06) | 0.84 (0.83-0.86) |
| Connective tissue disease | 1.01 (0.99-1.04) | 0.99 (0.98-1.02) | 0.92 (0.88-0.95) | 0.83 (0.80-0.87) |
| AIDS | 0.87 (0.71-1.05) | 0.95 (0.77-1.15) | 0.70 (0.63-0.78) | 0.74 (0.67-0.82) |
| Dementia | 0.61 (0.60-0.63) | 0.54 (0.53-0.56) | 1.00 (0.95-1.05) | 0.79 (0.75-0.83) |
| Hemiplegia | 0.81 (0.77-0.85) | 0.84 (0.80-0.88) | 0.86 (0.81-0.90) | 0.76 (0.72-0.80) |
| Age-related macular degeneration (yes vs no) | 1.24 (1.22-1.25) | 1.17 (1.15-1.18) | 0.90 (0.88-0.92) | 0.77 (0.76-0.79) |
| Glaucoma (yes vs no) | 1.09 (1.07-1.10) | 1.07 (1.06-1.08) | 0.86 (0.85-0.87) | 0.86 (0.85-0.88) |
| Diabetic retinopathy (yes vs no) | 1.26 (1.24-1.29) | 1.27 (1.25-1.30) | 0.95 (0.93-0.97) | 1.17 (1.14-1.19) |
Abbreviations: CCI, Charlson Comorbidity Index (assigns patients a score of 0 to 6 where 0 indicates lowest risk and 6 highest risk of mortality); NA, not applicable; OR, odds ratio; VHA, Veterans Health Administration.
Adjusted for all covariates in Table 1.
Table 4. Variables Associated With Cataract Surgery Within 5 Years of Cataract Diagnosis in Medicare and VHA Patients With Cataract From 2002 to 2012.
| Variable | Medicare (n = 1 156 211) | VHA (n = 1 917 254) | ||
|---|---|---|---|---|
| Unadjusted OR (95% CI) | Adjusted ORa (95% CI) | Unadjusted OR (95% CI) | Adjusted ORa (95% CI) | |
| Age per 5-y increase | 1.23 (1.22-1.23) | 1.24 (1.23-1.24) | 1.20 (1.20-1.21) | 1.18 (1.17-1.18) |
| Female vs male | 1.34 (1.32-1.36) | 1.14 (1.13-1.15) | NA | NA |
| Race | ||||
| Black vs white | 0.81 (0.79-0.82) | 0.79 (0.78-0.81) | 0.71 (0.70-0.73) | 0.75 (0.73-0.76) |
| Hispanic vs white | 1.15 (1.11-1.18) | 1.05 (1.02-1.08) | 0.92 (0.89-0.94) | 1.05 (1.02-1.08) |
| Other or unknown vs white | 0.94 (0.92-0.95) | 0.95 (0.93-0.97) | 0.68 (0.67-0.68) | 0.81 (0.80-0.81) |
| Region | ||||
| West vs East | 1.10 (1.09-1.11) | 1.11 (1.09-1.12) | 1.19 (1.17-1.20) | 1.22 (1.20-1.23) |
| Midwest vs East | 1.16 (1.15-1.17) | 1.16 (1.15-1.17) | 1.07 (1.06-1.09) | 1.08 (1.07-1.09) |
| South vs East | 1.30 (1.28-1.33) | 1.38 (1.36-1.40) | 1.33 (1.32-1.35) | 1.40 (1.38-1.41) |
| Unknown vs East | NA | NA | 0.99 (0.96-1.01) | 0.89 (0.86-0.91) |
| CCI score ≥3 vs 0-2 | 1.10 (1.09-1.11) | 0.94 (0.92-0.95) | 1.73 (1.71-1.74) | 1.24 (1.23-1.25) |
| Cardiovascular disease | 1.16 (1.15-1.17) | 1.04 (1.03-1.05) | 1.76 (1.75-1.78) | 1.28 (1.27-1.29) |
| Chronic pulmonary disease | 1.26 (1.25-1.27) | 1.26 (1.24-1.27) | 1.61 (1.59-1.62) | 1.40 (1.38-1.41) |
| Chronic renal disease | 1.11 (1.09-1.12) | 1.02 (1.00-1.04) | 1.93 (1.91-1.96) | 1.31 (1.29-1.33) |
| Liver or gastrointestinal disease | 0.98 (0.97-1.00) | 0.99 (0.97-1.01) | 1.16 (1.15-1.18) | 1.12 (1.10-1.14) |
| Diabetes | 1.12 (1.11-1.13) | 1.12 (1.11-1.13) | 1.10 (1.09-1.11) | 0.85 (0.84-0.86) |
| Malignant neoplasm | 0.99 (0.98-1.00) | 0.99 (0.98-1.01) | 1.39 (1.37-1.40) | 1.04 (1.03-1.06) |
| Connective tissue disease | 1.17 (1.14-1.19) | 1.13 (1.11-1.16) | 1.29 (1.26-1.32) | 1.10 (1.08-1.14) |
| AIDS | 0.75 (0.64-0.88) | 0.97 (0.83-1.15) | 0.71 (0.66-0.76) | 0.88 (0.82-0.95) |
| Dementia | 0.58 (0.56-0.59) | 0.43 (0.42-0.44) | 1.30 (1.26-1.35) | 0.83 (0.80-0.86) |
| Hemiplegia | 0.72 (0.69-0.75) | 0.71 (0.74-0.77) | 1.19 (1.15-1.23) | 0.97 (0.94-1.00) |
| Age-related macular degeneration (yes vs no) | 1.59 (1.57-1.60) | 1.37 (1.36-1.39) | 1.62 (1.60-1.64) | 1.24 (1.23-1.26) |
| Glaucoma (yes vs no) | 1.32 (1.31-1.33) | 1.29 (1.28-1.31) | 1.35 (1.34-1.36) | 1.30 (1.29-1.31) |
| Diabetic retinopathy (yes vs no) | 1.34 (1.32-1.36) | 1.35 (1.33-1.38) | 1.58 (1.56-1.60) | 1.59 (1.56-1.61) |
Abbreviations: CCI, Charlson Comorbidity Index (assigns patients a score of 0 to 6 where 0 indicates lowest risk and 6 highest risk of mortality); NA, not applicable; OR, odds ratio; VHA, Veterans Health Administration.
Adjusted for all covariates in Table 1.
Within 5 years of cataract diagnosis, demographic factors associated with increased odds of receiving cataract surgery in both groups per 5-year increase included older age (Medicare: OR, 1.24 [95% CI, 1.23-1.24]; VHA: OR, 1.18 [95% CI, 1.17-1.18]) and residence in the southern vs eastern United States (Medicare: OR, 1.38 [95% CI, 1.36-1.40]; VHA: OR, 1.40 [95% CI, 1.38-1.41]). Within the Medicare group, female sex was associated with greater odds of surgery at 5 years (OR, 1.14; 95% CI, 1.13-1.15). Within both groups, black vs white race/ethnicity was associated with decreased odds of receiving cataract surgery (Medicare: OR, 0.79 [95% CI, 0.78-0.81]; VHA: OR, 0.75 [95% CI, 0.73-0.76]) at 5 years after diagnosis. A higher CCI score (≥3 vs 0-2) was associated with increased odds of cataract surgery in the VHA (OR, 1.24; 95% CI, 1.23-1.25) at 5 years. Within both groups, chronic pulmonary disease was the comorbidity most strongly associated with increased odds of surgery (Medicare: OR, 1.26 [95% CI, 1.24-1.27]; VHA: OR, 1.40 [95% CI, 1.38-1.41]) at 5 years. Dementia was associated with decreased odds of receiving cataract surgery in both groups (Medicare: OR, 0.43 [95% CI, 0.42-0.44]; VHA: OR, 0.83 [95% CI, 0.80-0.86]) at 5 years. All selected ocular comorbidities (age-related macular degeneration, glaucoma, and diabetic retinopathy) were associated with increased odds of cataract surgery within 5 years of diagnosis in the Medicare and VHA patients (Table 4).
Discussion
This study provides a comprehensive view of patient-level factors associated with receiving cataract surgery in 2 large cohorts within the US population. We found a nearly 3-fold higher proportion of patients receiving cataract surgery within Medicare at 1 and 5 years after diagnosis compared with patients within the VHA, a finding that persisted in the groups comparing male patients and patients 65 years and older. Such findings may represent inherent differences in these 2 systems. The Medicare database offers a comprehensive view of cataract surgery in the US population of patients 65 years and older who are covered under a uniform administrative system and accounts for an estimated 80% or more of all cataract operations performed in the United States.2 The VHA is the largest nationally integrated health care system in the country, employs salaried physicians, and services a unique population of patients who carry a higher disease burden than the typical US patient.9,10,11,12 Differences in factors at the patient level (eg, patient demographics, social supports, and preferences), practitioner level (eg, practitioner motivation for surgery and incentives), and institutional level (eg, availability and accessibility of surgery centers) may affect who receives cataract surgery in each group.5,7,13,14,15,16,17,18,19,20,21,22,23
Given that cataract surgery requires multiple preoperative and postoperative visits, distance to a medical center and accessibility of transportation may play important roles in patient willingness and ability to undergo surgery.13,14 Likelihood of receiving cataract surgery in the VHA has been associated with proximity to VHA medical centers, suggesting that distance to medical centers represents a potential barrier to veterans seeking eye care in the VHA.15 Furthermore, we found that a higher CCI score was associated with increased odds of receiving cataract surgery in the VHA but not in Medicare. Higher service-connected disability among veterans has been associated with seeking VHA care in multiple prior studies.15,16,17,18,19 Such findings may reflect patients’ reliance on service-connected disability benefits within the VHA; veterans eligible for higher levels of VHA services and benefits may have greater utilization of VHA medical care because of the increased support within the system.
At the patient level, differences in age may play a role in explaining why the proportion of patients receiving cataract surgery was lower in the VHA than in Medicare. Higher rates of eye care use among older individuals, who tend to have higher rates of visually significant cataracts, are likely to account for the association of age with cataract surgery.5,7,13,14,20 We found that a higher proportion of veterans older than 65 years had cataract surgery compared with the general veteran population; why this proportion was still significantly lower compared with the Medicare group merits additional study.
Patient characteristics associated with receiving cataract surgery were similar in the Medicare and VHA patients. In both systems, residence in the southern United States was associated with increased odds of receiving cataract surgery at 1 and 5 years after diagnosis; increased strength of UV radiation at southerly latitudes may promote cortical and posterior subcapsular cataract formation.13,24,25,26 In addition, chronic pulmonary disease was the systemic comorbidity most strongly correlated with cataract extraction in both cohorts at 1 and 5 years after diagnosis, which may reflect the higher risk for cataract with cigarette smoking and/or with inhaled and oral corticosteroid use.27,28,29,30 Patients with ocular comorbidities were also more likely to have cataract surgery in both systems at 1 and 5 years after diagnosis. Comorbid glaucoma has been associated with higher risk of cataract secondary to use of intraocular pressure–lowering medications; in addition, removal of cataract in patients with glaucoma is known to reduce intraocular pressure.31,32 Finally, patients with multiple ocular comorbidities experience increased contact with ophthalmic care practitioners.14 Such factors may contribute to increased likelihood of undergoing cataract surgery within the Medicare and VHA systems.
Black race was associated with decreased odds of receiving cataract surgery within both cohorts at 5 years after diagnosis. The difference in cataract surgery frequency between black and white patients has previously been noted and cannot be explained fully by differences in cataract prevalence.5,6,13,33,34 A study of Medicare from 2003 to 2004 by Schein et al5 found that black patients had a 30% lower annual rate of cataract surgery than white patients and noted that such racial variation had persisted since the study by Javitt et al13 of a 1986-1987 Medicare population. In contrast to these prior findings, our study found no association between black race/ethnicity and decreased odds of cataract surgery in Medicare within 1 year, suggesting an improvement in this disparity within the 2002-2012 Medicare population at 1 year after diagnosis. Practitioner-related factors, regional health disparities, socioeconomic status, and educational level have been correlated with racial factors and may affect utilization of medical care.6,21,33,34,35,36,37 Within the VHA, previous studies22,23 of patients with glaucoma have found that decreased trust in the physician is associated with nonwhite race/ethnicity. How these variables influence utilization of cataract surgery within these US populations merits further study.
Dementia was also associated with decreased odds of receiving cataract surgery in both groups at 1 and 5 years after diagnosis. Prior studies38,39,40,41 have found an association between poor cognitive function and vision impairment, along with lower rates of cataract surgery among patients with cognitive impairment, most likely because of the unique challenges that dementia poses in cataract surgery. These challenges include difficulty arranging transportation for individuals residing in nursing facilities, issues with anesthesia and patient safety, questions regarding informed consent, and uncertain visual improvement because of the overlap between visual impairment attributable to cataract and visual symptoms of neurodegenerative diseases.38,40,42 However, after cataract surgery, patients with Alzheimer disease have neuropsychological and behavioral improvement, which significantly reduces caregiver burden.43 These findings highlight a need for improved perioperative planning in the treatment of patients with visually significant cataract and dementia.
Strengths and Limitations
A main strength of this study is its large sample size using patient data from both Medicare and the VHA, 2 major health care databases that represent unique US patient populations. Limitations of this study include its use of a large administrative database and its retrospective design. Because Medicare claims data and the National Patient Care Database are used primarily for administrative rather than clinical data, their accuracy varies with respect to ICD-9-CM codes across medical centers, and some information may have been missed during data collection.44 Coding of location is limited to state boundaries, and residence is recorded at the time of cataract diagnosis. Because this study did not perform any formal adjustments for multiple comparisons, it is possible that some effect estimates in our study were significant because several potential determinants for cataract surgery were examined. However, because the study was aimed at providing a general description of potential factors associated with cataract surgery in the Medicare and VHA populations rather than attempting to prove specific associations, we thought it would not be beneficial to perform formal statistical testing for multiple comparisons, such as the Bonferroni correction.45 In addition, inherent to the retrospective nature of the study, causation cannot be inferred. Finally, our findings cannot be generalized to uninsured patient populations.
Conclusions
We found that a larger proportion of Medicare patients with cataract diagnosis received cataract surgery at 1 and 5 years after diagnosis compared with VHA patients. Patient characteristics associated with likelihood of cataract surgery were similar in both groups. Such findings suggest that few disparities exist with respect to selection of candidates for surgery between both systems. However, reasons for the lower overall likelihood of cataract surgery in the VHA merit further study. Finally, we found that similar characteristics were associated with decreased likelihood of cataract surgery within both cohorts. Future population-based surveys are needed to identify any potential gaps that affect utilization of cataract surgery in these cohorts to ensure that all patients who require cataract surgery can receive it.
eAppendix. List of States in Each Region Grouped by US Census Divisions
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eAppendix. List of States in Each Region Grouped by US Census Divisions