The trend continues toward more outpatient surgery at hospitals - along with shorter in-hospital stays in general.

The American Hospital Association said Tuesday in an annual report that hospitals registered 367 million outpatient visits in 1993, up 5.3 percent from 1992 and up 75 percent from a decade earlier.Of 22.8 million operations performed during 1993, 55 percent were done on an outpatient basis, compared with 54 percent in 1992 and 24 percent in 1983.

The 30.7 million people admitted to the country's 5,261 acute-care hospitals spent seven days on average in the hospital - down from 7.1 days in 1992. Admissions were off by almost 1 percent.

The association said hospital expenses rose 7.3 percent in 1993, the lowest rise since 1985, but still more than twice the general rate of inflation.

Hospitals added 57,000 workers in 1993, a 1.6 percent increase. The 3.7 million hospital workers were paid an average of $31,130 plus $7,041 in benefits.

The association, a nonprofit advocacy group for hospitals, health networks and patients, gathered data from almost 6,000 hospitals and health organizations for its report.

It found that more than a third of the country's 919,000 hospital beds are empty on any given night. The average hospital has 175 beds.

Thirty-four hospitals closed last year and 18 merged, according to the report. Including new hospitals opening, there was a net decline of 31 hospitals.

Advances in technology have fueled the spurt in outpatient activities.