To characterize population-based 30-day procedure-related readmissions (revisits) following cataract surgery.
Ambulatory cataract surgery performed in California, Florida, or New York.
Retrospective cohort study.
This study used all-capture state administrative datasets. Cataract procedures from California, Florida, and New York state ambulatory surgery settings were identified using ICD-9-CM and CPT codes. Thirty-day readmissions (revisits) were identified in inpatient, ambulatory, and emergency department settings across each state.
Across the 3 states, the all-cause 30-day readmission rate was 6.0% and the procedure-related readmission (revisit) rate was 1.0%. Procedure-related revisits were highest for patients aged 20–29 (2.9%) and 30–39 (2.3%) and lowest for patients aged 70–79 (0.9%). Multivariate associations between clinical characteristics and 30-day procedure-related revisits included age 20–29 (odds ratio [OR]: 3.13; 95% confidence intervals [CI]: 2.33–4.20) and age 30–39 (OR: 2.35; CI: 1.91–2.89) compared with age 70–79, male sex (OR: 1.29; CI: 1.24–1.34), races black (OR: 1.37; CI: 1.27–1.48) and Hispanic (OR: 1.16; CI: 1.08–1.24) compared with white, and Medicaid insurance (OR: 1.18, CI: 1.07–1.30) compared with Medicare. Diabetes was also associated with increased 30-day procedure-related revisits (OR: 1.093, CI: 1.024–1.168).
Cataract surgery is a common and, in aggregate, expensive procedure. Complication-related revisits follow a similar trend as surgical complications in large-scale population data, and may be useful as a preliminary, screening outcome measure. Our results highlight the importance of age as a risk factor for cataract surgery readmissions, and suggest a relationship between black or Hispanic race, Medicaid insurance, and diabetes associated with higher risk for cataract surgery complications.
Cataract surgery is the single most frequent surgical procedure in developed countries, including the United States, where approximately 3 million cases are performed annually on Medicare patients. It is presently the largest single source of Medicare expenditures, and rates of surgery are rising. Between 1990 and 2010, incidence of cataract surgery increased between 2.5- and 6.5-fold, varying by region. This is a trend likely only to continue, given improved technology, an aging population with higher expectations for visual function, and expanding surgical criteria, including lower visual acuity thresholds for surgery, more bilateral surgery, and surgery in younger patients. Despite extremely high rates of surgical success, broader criteria and large surgical volume yield a significant number of complications, simply as a proportion of total cases.
Several international population studies have examined aggregate incidence and risk factors for surgery-related complications —including national efforts in the United Kingdom, Australia, Sweden, and Malaysia, among others, as well as newer initiatives to collect internationally standardized outcomes data (International Consortium for Health Outcomes Measurement, American Academy of Ophthalmology Intelligent Research In Sight registry, and the European Registry of Quality Outcomes for Cataract and Refractive Surgery). There is more limited evidence in the United States regarding complication rates, risk factors, and their relative impact. A retrospective cross-sectional analysis of Medicare claims data examined adjusted 1-year rates of severe postoperative complications (endophthalmitis, suprachoroidal hemorrhage, and retinal detachment) and found declining rates of serious adverse events between 1994 and 2006, with a 0.5% rate of at least 1 severe complication.
National quality analysis and reporting is increasingly relying on standardized metrics across specialties—particularly post-hospitalization readmissions, or post-procedure readmissions for surgical disciplines. Although cataract patients (and ophthalmology patients more generally) are seldom admitted or readmitted to the hospital, readmissions—broadly defined as revisits, including return to the operating room or unscheduled visits in an ambulatory care setting—are a robust choice for analyzing significant complications in cataract surgery. Detected events may encompass retained cataract lens fragments, wound leakage/dehiscence, severe endophthalmitis, and retinal detachment, among others. With the exception of a 1999 Canadian study that looked broadly at readmissions following outpatient (including cataract) surgeries at a single high-volume ambulatory surgery center with a 0.2% rate of complication-related readmissions for cataract surgery after 30 days, little has been published regarding readmissions as a marker for cataract surgery quality.
Although they do not capture all complications, readmissions do identify the most serious that have an impact on cost as well as on quality of life. Readmissions are also less subject to the accuracy concerns implicit in using claims data to identify specific complications by International Classification of Diseases, Ninth Revision (ICD-9) diagnosis and Current Procedural Terminology (CPT) procedure codes. And, with increased focus on value-based payment systems, including Affordable Care Act mandates to tie payments to quality outcomes, understanding how cataract surgery will be viewed by policymakers in a broader context is increasingly important—part of identifying, tracking, and predicting complications as well as their cost and outcomes.
In this study, we sought to evaluate the incidence of complications and revisits requiring a return for additional evaluation or treatment (in the clinic, operating room, or emergency department setting) as a reliable quality indicator for cataract surgery in a large, multipayer, population-based observational study. We characterized patterns of readmissions following cataract surgery, identified key patient characteristics (such as age and comorbidities) associated with higher readmission rates, and analyzed data at the state level to identify important geographic trends.
This study was a retrospective cohort study using all-capture state administrative datasets. Cataract procedures from California, Florida, and New York state ambulatory surgery settings were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and CPT codes. Thirty-day readmissions (revisits) were identified in inpatient, ambulatory, and emergency department settings across each state. The Stanford Institutional Review Board (IRB) determined that this study was exempt from IRB approval in adherence to all state and federal laws.
The study examined discharge data from the State Inpatient Databases, State Ambulatory Databases, and State Emergency Department Databases of the Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality, between 2008 and 2011 in California and Florida and between 2009 and 2011 in New York. These states were selected owing to their geographic spread and the quality of available data, including all-capture discharges and unique identifiers to track patients across hospital and outpatient or emergency settings. Available data included patient sociodemographics, primary expected payer, and clinical variables related to diagnoses, comorbidities, and procedures performed.
Adult patients receiving cataract surgery in the ambulatory setting were identified by records containing one of the ICD-9 diagnosis codes 366.* (excluding 366.52 and 366.53) and also containing CPT codes 66984 or 66982 or one of the ICD-9 procedure codes 13.* (used in ambulatory records in Florida but not in California or New York); 19% of the records had multiple cataract procedure codes. We excluded patients under 20 and over 100 years of age, owing to limited number of patients and patients lacking the encounter linkage identifier.
Main Outcome Measures
Our primary outcome was 7-day and 30-day procedure-related readmissions. We defined a procedure-related readmission as an emergency room visit, return to ambulatory care, or inpatient admission with complication-related ICD-9-CM codes ( Supplemental Table 1 ; Supplemental Material available at AJO.com ). Planned postoperative visits were identified using the primary diagnosis code (V5*, V67*, V68*) and were not considered as readmissions. Records for second cataract surgery procedures were also not considered as readmissions, presuming that they represented cataract surgery on the opposite eye.
As a secondary outcome we analyzed all-cause readmissions, again excluding planned postoperative visits and cataract surgery on the opposite eye.
Patient and Organizational Characteristics
Our descriptive statistics were based on patient characteristics obtained during the index visit (first cataract procedure). Evaluated patient and health system variables included age, sex, race/ethnicity, primary expected payer, number of chronic conditions (available in the ambulatory care records starting in 2009), and coded clinical comorbidities (diabetes, myopic or hyperopic refractive error, vascular disease, hypertension, and prostate disease—selected as a proxy for alpha blocker medication use, which is associated with intraoperative complexity and complications). Clinical comorbidities were identified by ICD-9 diagnosis code: diabetes (250.*), hypertension (401.*–405.*), hyperopia (367.0), myopia (367.1), prostate hyperplasia (600.*), and vascular disease (central and peripheral arterial atherosclerosis, thrombosis, or embolism, ischemic heart disease, or cerebrovascular disease—410–414.*, 431.*, 433–435.*, 437.0–437.1, 438.*440.*, 443.9, 444–445.*).
We calculated descriptive statistics for our sample of patients and analyzed procedure-related readmission and all-cause readmission rates by patient characteristics, using 2-sided Wald tests of univariate logistic regression coefficient estimates. We used the Pearson-Clopper method to construct 95% confidence intervals for procedure-related readmission rates by decade of age. We compared clinical comorbidity and readmission rates by state using the Pearson χ 2 test. We built multivariate models of readmission using mixed-effects logistic regression, with a random effect by hospital. Using Census Bureau population data for 2010 as denominators, we computed the total number of cataract procedures per 1000 persons according to patient age and the state in which care occurred.
All analyses were conducted using SAS version 9.3 (SAS Institute Inc, Cary, North Carolina, USA) or R version 3.0.3 (R Foundation for Statistical Computing, Vienna, Austria). Because no direct patient-identifiable data were used, this study was exempt from review by the Stanford University Institutional Review Board.