Health Care Utililization, Costs, and Financing

Inpatient lumbar surgery rates remained stable from 1994 to 2000, but outpatient surgery increased

Technological advances and financial incentives have shifted various types of health care from the hospital to outpatient settings. Lumbar spine surgery for degenerative conditions is no exception. A new study found that, while inpatient lumbar surgery rates remained relatively stable for 1994 to 2000, outpatient surgery increased over time. Discectomy was the most common procedure performed on an outpatient basis. Outpatient surgery was rarely used for spinal fusions and was not commonly used for laminectomies, notes Darryl T. Gray, M.D., Sc.D., of the Agency for Healthcare Research and Quality (AHRQ).

Dr. Gray and colleagues from the University of Washington used diagnosis and procedure code data from several databases to identify lumbar spine operations among individuals 20 years of age and older. The data sources included databases from AHRQ's Healthcare Cost and Utilization Project, namely State Inpatient Databases and State Ambulatory Surgery Databases from several geographically diverse states, as well as the National Inpatient Sample (NIS). The other data sources were the National Hospital Discharge Survey and the National Survey of Ambulatory Surgery. NIS data indicated that nationwide inpatient lumbar spine surgery rates were stable between 1994 and 2000 (159 cases/100,000 in 1994 vs. 162 cases/100,000 in 2000).

Combined data from all sources suggested only a modest rise in total inpatient and outpatient lumbar spine surgery rates (164 cases/100,000 in 1994 vs. 201 cases/100,000 in 2000), mostly due to increases in outpatient discectomies. Outpatient cases rose from 4 to 13 percent of lumbar surgery procedures (mostly discectomies) performed from 1994 to 1996 to 9 to 17 percent from 1997 to 2000. Yet the proportion of discectomies performed on an outpatient basis jumped from 4 percent in 1994 to 26 percent in 2000. Outpatient fusions and laminectomies were uncommon. Other researchers suggest that outpatient lumbar spine procedures are safe and effective. However, the authors of the current study call for more research to document whether or not the shorter postoperative monitoring and immobilization periods accompanying this approach are associated with higher rates of complications such as bleeding or infection.

See "Population-based trends in volumes and rates of ambulatory lumbar spine surgery," by Dr. Gray, Richard A. Deyo, M.D., M.P.H., William Kreuter, M.P.A., and others, in the August 2006 Spine 31(17), pp. 1957-1963; an accompanying editorial is on page 1964. Reprints of the article (AHRQ Publication No. 07-R010) are available from the AHRQ Publications Clearinghouse.

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