Age-related cataracts are a common cause of visual impairment in patients 65 years and older.1 Due to decreased visual acuity, patients with cataracts often suffer from mobility deficits, increasing the risk for trauma-related injuries such as falls — a major cause of morbidity and mortality in this patient population.2,3 Cataract surgery has been shown to improve patients’ visual acuity and reduce falls.3 However, as the population continues to age, the prevalence of comorbid eye diseases, such as age-related macular degeneration (AMD), has increased.4 For patients with cataracts and concurrent AMD, the recommended timing of cataract surgery is variable due to more limited post-surgical visual potential and incomplete restoration of vision.4 Complications of comorbid cataracts and AMD have been examined by prior studies; however, the functional impact has not been explored. The International Classification of Diseases (ICD) external cause of injury codes, or “E-codes”, are a validated system to identify broad causes of injuries and offer an opportunity to investigate the impact of cataract surgery on the incidence of falls in this population. This study seeks to utilise data from the National Emergency Department Sample (NEDS) database, a nationally representative database of emergency department (ED) visits in the United States (U.S.), to determine the associations between ocular diseases and patients presenting to EDs with fall-related injuries.
We conducted a retrospective cohort study from January 2006 to December 2018 of the NEDS database. ED visits of patients ages 65 and older with ICD codes corresponding with both age-related cataracts (366.*, H26.*) and age-related macular degeneration (362.5*, H35.3*) were included. Within this cohort, patients with an artificial intraocular lens were identified (Z96.1, V43.1) as a measure for prior cataract surgery preceding the ED encounter. All causes of ED admissions were collected, and ICD E-codes were used to identify patients presenting with causes of injury due to falls (E88*). Statistical analysis was performed using Stata v15 (StataCorp, College Station, Texas). Descriptive statistics were calculated for relevant demographic characteristics. Univariable analyses were performed comparing patient, hospital, and ED admission characteristics between patients with and without the presence of an intraocular lens. Covariables that were of high clinical importance, or which were statistically significant predictors (P > 0.2) were included in the multivariable regression model. Multivariable logistic regression was used to determine the demographics and outcomes of cataracts and AMD patients associated with presentation to the ED due to a fall. This study was deemed exempt by the Institutional Review Board at the University of North Carolina at Chapel Hill.
Our study identified 12,808 patients meeting inclusion criteria, amounting to an estimated 240,036 patients seen in EDs throughout the U.S. within the study period. Within the cohort, 4,154 patients were male (33.6%) with a median age of 84 (IQR: 78, 89). Furthermore, 1,448 (12.8%) patients presented due to an injury caused by a fall. Patients who had a history of cataract surgery were less likely to be admitted to the hospital compared to those who had not undergone cataract surgery (61.8% vs 55.1%, p<0.001) (Table 1).
Table 1.
Cohort characteristics
| Factor | Level | Phakic | Pseudophakic |
|---|---|---|---|
| N | 8352 | 4456 | |
| Age, median (IQR) | 84 (77, 89) | 85 (79, 90) | |
| Gender | Men | 2716 (33.5%) | 1438 (34.0%) |
| Women | 5401 (66.5%) | 2792 (66.0%) | |
| Median Income | 0–25 Percentile | 1156 (17.4%) | 746 (18.8%) |
| 26–50 Percentile | 1515 (22.8%) | 714 (18.0%) | |
| 51–75 Percentile | 1829 (27.5%) | 1205 (30.4%) | |
| 76–100 Percentile | 2140 (32.2%) | 1296 (32.7%) | |
| Method of Payment | Medicare | 7320 (90.3%) | 3743 (88.8%) |
| Medicaid | 118 (1.5%) | 29 (0.7%) | |
| Private | 538 (6.6%) | 377 (8.9%) | |
| Other | 134 (1.7%) | 68 (1.6%) | |
| ED Charge, median (IQR) | 3021.517 (5333.499) | 3251.369 (5041.282) | |
| Length of Stay | Short (<3 days) | 1624 (19.4%) | 826 (18.5%) |
| Intermediate (3–6 days) | 2487 (29.8%) | 1143 (25.7%) | |
| Prolonged (>6 days) | 4241 (50.8%) | 2487 (55.8%) | |
| Region of Hospital | Northeast | 1317 (18.9%) | 371 (8.8%) |
| Midwest | 1721 (24.7%) | 970 (22.9%) | |
| South | 1801 (25.9%) | 1123 (26.5%) | |
| West | 2118 (30.4%) | 1773 (41.8%) | |
| Injury Due to Fall | No fall | 7374 (88.3%) | 3986 (89.5%) |
| Fall | 978 (11.7%) | 470 (10.5%) | |
| Type of ED Admission | Treated and Released | 3031 (37.5%) | 1866 (44.2%) |
| Admitted | 4991 (61.8%) | 2326 (55.1%) | |
| Transferred | 54 (0.7%) | 28 (0.7%) |
Multivariable regression analysis controlling for age, gender, race/ethnicity, median income, insurance status, and length of stay demonstrated that patients with prior cataract surgery were significantly less likely to present to the ED due to falls than patients without cataract surgery (aOR: 0.72, 95% CI: [0.60–0.87], p<0.001) (Table 2). Factors that were associated with increased risk of falls included increased patient age (aOR: 1.06, 95% CI: [1.04–1.07], p-value<0.001], female-identifying patients (aOR: 1.40, 95% CI: [1.16–1.68], p-value<0.001) and intermediate (aOR: 2.08, 95% CI: [1.61–2.70], p-value<0.001) or prolonged length of hospital stay (aOR: 1.48, 95% CI: [1.06–2.05], p-value=0.02).
Table 2.
Multivariable logistic regression
| Factor | Level | Adjusted Odds Ratio | Std. Err. | z | P>z | [95% Conf. Interval] |
|---|---|---|---|---|---|---|
| Age | 1.06 | 0.01 | 8.04 | <0.001 | 1.04 – 1.07 | |
| Gender | Men | 1 (ref) | ||||
| Women | 1.40 | 0.13 | 3.56 | <0.001 | 1.16 – 1.68 | |
| Median Income | 75–100 Percentile | 1 (ref) | ||||
| 0–25 Percentile | 0.67 | 0.09 | −3.15 | <0.01 | 0.52 – 0.86 | |
| 26–50 Percentile | 0.84 | 0.10 | −1.52 | 0.13 | 0.67 – 1.05 | |
| 51–75 Percentile | 0.81 | 0.09 | −1.94 | 0.05 | 0.65 – 1.00 | |
| Method of Payment | Private | 1 (ref) | ||||
| Medicare | 1.09 | 0.18 | 0.54 | 0.59 | 0.79 – 1.52 | |
| Medicaid | 0.72 | 0.39 | −0.61 | 0.54 | 0.25 – 2.08 | |
| Other | 0.76 | 0.30 | −0.70 | 0.49 | 0.35 – 1.66 | |
| Length of Stay | Short (<3 days) | 1 (ref) | ||||
| Intermediate (3–6 days) | 2.08 | 0.28 | 5.55 | <0.001 | 1.61 – 2.70 | |
| Prolonged (>6 days) | 1.48 | 0.25 | 2.31 | 0.02 | 1.06 – 2.05 | |
| Presence of Intraocular Lens | Phakic | 1 (ref) | ||||
| Pseudophakic | 0.72 | 0.07 | −3.51 | <0.001 | 0.60 – 0.87 |
This study used a representative sample of ED visits to examine the characteristics associated with falls in elderly patients with cataracts and concurrent AMD. Our analysis demonstrates that cataract surgery was independently associated with a lower risk of falls in patients with AMD. This finding adds to the current literature regarding the benefits of cataract surgery for patients with cataracts and concurrent AMD. To our knowledge this study is the first to utilise a large, national database of ED visits to make the association between cataract surgery and reduced risk of falls in elderly patients.
This study has several limitations. While there were statistically significant differences in the incidence of falls in patients with and without cataract surgery, the absolute difference was only 1.2%. Due to the nature of the NEDS dataset, there is a lack of information regarding ophthalmologic factors such as visual acuity and severity of AMD, as well as comorbid medical conditions such as alcohol use, diabetes, and overall health of patients, that have impacts on the interpretation of clinical significance. However, we believe our findings represent valuable insights into the utility of cataract surgery for patients with comorbid AMD, and that further investigations are warranted in databases with more granular information related to these measurements to better understand the clinical impact of cataract surgery in patients with varying degrees of vision impairment. Another limitation is that patients without previous diagnoses of cataracts and/or AMD may have been erroneously excluded from this study due to these conditions not being properly diagnosed or recorded within the ED setting.
This study has implications on the utility of cataract surgery in patients with AMD. Several studies have demonstrated loss of independence, autonomy, and quality of life in older patients following falls.7 By reducing the risk of falls secondary to visual impairment, older patients with cataracts and concurrent AMD who receive cataract surgery have an opportunity to continue their independence and autonomy and maintain their current quality of life.
FUNDING INFORMATION:
This research was conducted as part of the University of North Carolina at Chapel Hill Medical Student Training in Ageing Research (MSTAR) Program, NIH 2-T35-AG038047
Footnotes
CONFLICT OF INTEREST STATEMENT: None
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