Some second thoughts would seem to be in order about the advisability of making out a "living will."

That's because of a new study showing that the medical profession doesn't always pay attention to such documents, which instruct physicians and family members not to provide extraordinary treatment if it will only prolong dying.The study, published Thursday in the prestigious New England Journal of Medicine, is particularly timely. It comes after new impetus was given to living wills by a 1990 Supreme Court decision. The high court declared that gravely ill or dying people have a constitutional right not to have their lives artificially prolonged against their wishes.

Even more impetus should be provided next December, when a new federal law will require all hospitals participating in Medicare and Medicaid to ask patients whether they have a living will.

Anyway, the new study reports that in about 25 per cent of cases involving living wills, doctors and nurses have been making treatment decisions that contradict the will's instructions.

Even when treatment decisions were in line with the patients' wishes, the concurrence was often only coincidental. For example, when patients were transferred from a nursing home to a hospital, the living will never made it into the hospital records in most cases. Even when the document appeared in the patient's hospital chart, the study showed that its presence did not increase the likelihood that subsequent treatment would reflect the patient's preferences.

Clearly, the medical profession has some explaining to do. Meanwhile, it's clear that gravely ill patients can't always assume their wishes will be followed just because they have a living will.

Fortunately, there's a better alternative to the living will. It's a document called a "durable power of attorney," which designates a relative or friend to take responsibility for treatment decisions. For patients who want better control, that's the option to take.