A patient's chance of death, harm or lingering illness after an operation can be 2 1/2 times as great in some hospitals as in other, a study of 17 "typical" hospitals in nine states has discovered.

The finding shows the need for a national monitoring system of hospital "outcomes" - or what happens to patients as a result of their treatment - Dr. William Forrest Jr. of Stanford University told a House subcommittee yesterday.

There are hospitals in many cities, including Washington, that doctors believe should be closed because they harm so many patients, Dr. Charles Child of the University of Michigan told the panel.

In an interview later, he said he had no specific local hospitals in mind but was only speaking "generally" based on what he hears from surgeons here and elsewhere.

Such testimony nonetheless shows that strong measures are needed to protect patients, said Rep. John E. Moss (D-Calif.), chairman of the Oversight and investigations Subcommittee, which began a new set of hearings on surgical care.

Child directed a 1973-75 study of 1,695 "untoward incidents" or complications in 1,493 operations, all less than wholly successful in some way. That study, cosponsored by two surgeon's groups and 95 cooperating hospitals concluded that 796 of the unfortunate incidents, including 85 deaths, were preventable.

Forrest headed a 1975 study by the National Academy of Sciences for the Department of Health, Education and Welfare's National Center for Health Services Research.

Child and Forrest agreed that not one knows how much careless, harmful or unnecessary surgery there may be, but someone ought to start to find out.

"And as soon as we get some confidence in the validity of the statistics," every hospital's rating should be made public, Forrest said, so the public will know how hospitals compare in post-surgical deaths and postsurgical illness.

The Forrest study focused on 17 hospitals picked at random in Arizona, California, Colorado, Kentucky, Massachusetts, North Carolina, New Jersey Pennsylvania and Wyoming. All were community hospitals rather than academic or university hospitals but they were "the tupical hospitals" that most people go to, said Forrest, "none very small and none very large," in that they ranged in size from 200 to "800 to 1,000" beds.

The study group examined results after common operations such as appendectomies and hysterectomies, after stomach, gall bladder, bone and arterial surgeries and after several categories of cancer surgery.

The hospital-by-hospital outcomes were not identified by name. But in the hospital with the best results, among a total of 192 patients there were only eight poor outcomes (either deaths within 40 days after surgery or some other poor result within seven days).

In the hospital with the poorest results, there were 49 deaths or other poor results among 965 patients.

After a mathematical correction to compensate for the difference in numbers of patients, this meant that the "best" hospital had hardly more than half the number of poor results that might have been expected, given its patient mix. But the "poorest" hospital had nearly 1 1/2 times as many deaths as it should have.

What is needed next, Forrest said, it a national effort to improve results in hospitals at the poor end of the scale.