Background. Inpatient utilization review remains a useful approach for hospitals to achieve cost sav ings, however utilization review efforts need to be come more focused and sophisticated.

Methods. In order to identify physicians with a higher percentage of unnecessary hospital days, and to analyze how their practice characteristics distin guished them from their colleagues, 364 consecutive admissions of 57 primary care internists were re viewed concurrently, on a daily basis. Days without acute hospital level of care that occurred while pa tients were awaiting placement in a rehabilitation or in a chronic care facility were adjusted out of the calculation. Analysis was undertaken to assess the impact of physician age, location of training, Board Certification, practice location, participation in med ical training programs, years of experience, and par ticipation in various types of managed-care programs on the level of unnecessary hospital days. Character istics of the patients and their illnesses were included in the analysis.

Results. A large number of unnecessary hospital days occurred although there was no useful segrega tion of good from poor physician utilizers. Board certification and suburban practice location were as sociated with a significantly lower percentage of ad justed unnecessary days. Physician members of a closed-panel health maintenance organization had a lower percentage of adjusted unnecessary hospital days (14% vs. 41%, P < .001) when compared with the other primary care internists. Explanations for the difference are discussed.

Conclusions. 1) The patients of primary care in ternists are still responsible for a large number of unnecessary hospital days; 2) Utilization review ef forts need to become more sophisticated and focused; and 3) A change in physician incentives coupled with appropriate staff and systems possibly would be the simplest, large-scale remedy.