Table 1.
Characteristics of the Patients.*
| Characteristic | Preoperative Testing (N = 232,889) | No Preoperative Testing (N = 207,968) |
|---|---|---|
| Age (yr) | 76.5±6.3 | 75.7±6.2 |
| Sex (%) | ||
| Male | 40 | 40 |
| Female | 60 | 60 |
| Race (%)† | ||
| White | 87 | 90 |
| Black | 7 | 6 |
| Other | 6 | 5 |
| Charlson comorbidity index score (%)‡ | ||
| 0–1 | 54 | 69 |
| 2 | 17 | 14 |
| ≥3 | 29 | 17 |
| Health system characteristics (%)§ | ||
| U.S. region | ||
| Northeast | 23 | 10 |
| Midwest | 23 | 25 |
| South | 37 | 46 |
| Mountain west | 4 | 8 |
| Pacific west | 13 | 10 |
| Population density | ||
| Urban | 84 | 81 |
| Rural | 16 | 19 |
| Surgical setting (%) | ||
| Ambulatory surgery center | 64 | 71 |
| Hospital outpatient department | 34 | 28 |
| Unknown | 2 | 1 |
| Preoperative office visit (%) | ||
| Yes | 73 | 28 |
| No | 27 | 72 |
*
Plus–minus values are means ±SD.
†
Data on race were obtained from the Master Beneficiary Summary file.
‡
Scores on the Charlson comorbidity index range from 0 to 33, with higher scores indicating greater disease burden and increased risk of death within 1 year.
§
Additional health system variables included primary care physicians per 100,000 residents, ophthalmologists per 100,000 residents, ophthalmologist annual cataract surgical volume, and Medicare expenditures per beneficiary in the hospital referral region; data on these variables are provided in the Supplementary Appendix.