Forty years ago, virtually all surgery was performed in hospitals.

Now, ambulatory surgery centers (ASCs) are health care facilities that offer patients the convenience of having surgeries and procedures performed safely outside the hospital setting. At a time when most developments in health care services and technology typically come with a higher price tag, ASCs stand out as an exception to the rule.

The Workers Compensation Research Institute found an overall shift away from hospital care in workers comp systems across 18 states, with the trend toward receiving care at less-expensive ambulatory surgical centers and nonhospital settings.

Using data from 2002 to 2016, virtually all study states saw a downturn in the percentage of claims with both hospital inpatient and outpatient services, according to Rebecca Yang, a senior public policy analyst with the Cambridge, Massachusetts-based institute.

Business Insurance reports that “Part of the shift follows the trend in general health care and part of it might be influenced by states,” Ms. Yang told listeners on a webinar, noting that several states have introduced medical fee schedule changes and other reforms that caused payers to rethink more-expensive hospital care as a first resort.

The study states included California, Connecticut, Florida, Georgia, Illinois, Indiana, Iowa, Louisiana, Massachusetts, Michigan, Minnesota, New York, North Carolina, Pennsylvania, Tennessee, Texas, Virginia and Wisconsin.

Technological advances, now in place at surgical centers and other nonhospital locations, are helping to fuel the trend away from hospital care for injured workers, she said.

Lower prices at surgical centers are also spurring the switch, she added. The WRCI data found that care in the nonhospital setting is typically 40% less expensive than that at hospitals.

Surgeries, among the most costly care, were focus of the research, she said. Knee surgeries performed at ambulatory surgical centers cost 21% to 76% less than at hospitals at 14 states included in the study, according to Ms. Yang’s presentation.

For treatment performed at hospitals, outpatient services are increasing, with cumulative data from 2000 to 2016 showing 39.6% more outpatient activity and only 1.7% more inpatient admissions over that same time, according to data presented during the webinar.