NCHStats

Questions for Margaret J. Hall, Health Statistician and Lead Author of “Ambulatory Surgery Data From Hospitals and Ambulatory Surgery Centers: United States, 2010.”

Q: Why did you decide to do a report on national estimates of surgical and nonsurgical ambulatory procedures performed in hospitals and ambulatory surgery centers?

MH: The National Center for Health Statistics (NCHS), Division of Health Care Statistics, gathers national data on health care utilization. Included are surveys of inpatient care, physicians’ office care, and emergency department and outpatient department care. From 1994 to 1996, and again in 2006, NCHS gathered ambulatory surgery data through the National Survey of Ambulatory Surgery. Ambulatory surgery, also called outpatient surgery, refers to surgical and nonsurgical procedures that are nonemergency, scheduled in advance, and generally do not result in an overnight hospital stay. The nationally representative data from our inpatient and ambulatory surgery surveys showed that ambulatory surgery procedures made up a large part of the total surgery performed in the United States. In 2010, we were able to expand the National Hospital Ambulatory Medical Care Survey (NHAMCS), which has gathered data on hospital emergency and outpatient department utilization since 1992, to also gather data on ambulatory surgery in hospitals and in ambulatory surgery centers. This meant that we could provide more recent estimates of this important component of health care utilization.

Data were gathered on patient characteristics including age, sex, expected payment source, duration of surgery, and discharge disposition, as well as on the number and types of procedures performed in these settings. As is the case in our other health care surveys, sample data are collected and are then weighted to produce nationally representative estimates.

Q: Is the first time NCHS has published a report on this topic? Is there trend data?

MH: NCHS has published ambulatory surgery data for 1994 through 1996 and again for 2006. This report primarily contains 2010 data but it does note that the estimated number of ambulatory surgery visits decreased from 34.7 million to 28.6 million from 2006 to 2010. This 18% drop was statistically significant. But the 48.3 million ambulatory surgery procedures estimated using 2010 NHAMCS data was not significantly different from the 53.3 million ambulatory surgery procedures estimated using 2006 NSAS data.

Q: How do ambulatory surgery procedures by sex and age break down?

MH: For both males and females, 39% of procedures were performed on those aged 45–64. For females, about 24% of procedures were performed on those aged 15–44 compared with 18% for males, whereas the percentage of procedures performed on those under 15 was lower for females than for males (4% compared with 9%). About 19% of procedures were performed on those aged 65–74, with about 14% performed on those aged 75 and over. For the latter two age groups, there was no significant difference between males and females.

Q: What types of ambulatory surgery procedures are most patients getting?

MH: Seventy percent of the 48.3 million ambulatory surgery procedures were in the following clinical categories: operations on the digestive system (10 million or 21%), operations on the eye (7.9 million or 16%), operations on the musculoskeletal system (7.1 million or 15%), operations on the integumentary system (4.3 million or 9%), and operations on the nervous system (4.2 million or 9%). These procedure categories made up 72% of procedures performed on females and 67% of those performed on males.

• Examples of operations on the digestive system include endoscopy of large intestine—which included colonoscopies—which was performed 4.0 million times; endoscopy of small intestine which was performed 2.2 million times; and endoscopic polypectomy of large intestine which was performed an estimated 1.1 million times.
• Eye operations included extraction of lens, performed 2.9 million times, and insertion of lens, performed 2.6 million times, both for cataracts; and operations on eyelids, performed 1.0 million times.
• Musculoskeletal procedures included operations on muscle, tendon, fascia, and bursa, performed 1.3 million times.
• Operations on the integumentary system included excision or destruction of lesion or tissue of skin and subcutaneous tissue, performed 1.2 million times.
• Operations on the nervous system included injection of agent into spinal canal, performed 2.9 million times, including injections for pain relief.

Q: Were there any findings that surprised you?

MH: It was surprising that the number of ambulatory surgery visits and procedures performed did not increase from 2006 to 2010. Instead our 2010 data showed that there was a significant decrease of 18% in the number of ambulatory surgery visits since 2006. The number of procedures performed during 2010 did not differ significantly from the number performed in 2006.

One reason for these findings could be an under count in the survey in 2010. There were some problems in hospitals identifying in-scope ambulatory surgery visits since they were more dispersed throughout the hospitals in 2010 than they had been in 2006. Another reason that ambulatory surgery visit estimates could have decreased could be the deep economic recession that began in 2007. By 2010, when our survey began gathering ambulatory surgery data in both hospitals and Ambulatory Service Centers, the economy had not fully recovered and, due to this, some patients may have decided not to schedule ambulatory surgery. Some ambulatory surgery procedures are elective.