Inpatient hospital admission and death after outpatient surgery in elderly patients: importance of patient and system characteristics and location of care.

HYPOTHESIS

Surgery at different outpatient care locations in the higher-risk elderly (age >65 years) population is associated with similar rates of inpatient hospital admission and death.

DESIGN

Claims analysis of patients undergoing 16 different surgical procedures in a nationally representative (5%) sample of Medicare beneficiaries for the years 1994 through 1999.

SETTING

Hospital-based outpatient centers, freestanding ambulatory surgery centers (ASCs), and physicians' office facilities.

PATIENTS

Medicare beneficiaries older than 65 years.

MAIN OUTCOME MEASURES

Rate of death, emergency department risk, and admission to an inpatient hospital within 7 days of outpatient surgery.

RESULTS

We studied 564,267 outpatient surgical procedures: 360,780 at an outpatient hospital, 175,288 at an ASC, and 28,199 at a physician's office. There were no deaths the day of surgery at a physician's office, 4 deaths the day of surgery at an ASC (2.3 per 100,000 outpatient procedures), and 9 deaths the day of surgery at an outpatient hospital (2.5 per 100,000 outpatient procedures). The 7-day mortality rate was 35 per 100,000 outpatient procedures at a physician's office, 25 per 100,000 outpatient procedures at an ASC, and 50 per 100,000 outpatient procedures at an outpatient hospital. The rate of admission to an inpatient hospital within 7 days of outpatient surgery was 9.08 per 1000 outpatient procedures at a physician's office, 8.41 per 1000 outpatient procedures at an ASC, and 21 per 1000 outpatient procedures at an outpatient hospital. In multivariate models, more advanced age, prior inpatient hospital admission within 6 months, surgical performance at a physician's office or outpatient hospital, and invasiveness of surgery identified those patients who were at increased risk of inpatient hospital admission or death within 7 days of surgery at an outpatient facility.

CONCLUSION

This study represents an initial effort to demonstrate the risk associated with outpatient surgery in a large, diverse population of elderly individuals.