The sweeping four-year-old federal privacy law known by the acronym HIPAA, for the Health Insurance Portability and Accountability Act, may be responsible for an unintended consequence: impeding biomedical research.

That's the conclusion of a study, one of the first to examine the issue, headed by physician-epidemiologist Roberta B. Ness of the University of Pittsburgh School of Public Health. It was published last month in the Journal of the American Medical Association.

Ness' anonymous, Web-based survey involved 1,527 medical researchers, most affiliated with academic medical centers or government agencies.

Nearly 70 percent said that HIPAA, which in most cases requires researchers to obtain individual written consent to examine a patient's medical records, had made research substantially more difficult and expensive to conduct.

By contrast, only 25 percent said they thought it enhanced confidentiality for research subjects.

In some cases, they complained, the rule has been construed so strictly that recruiting for studies has become nearly impossible.