The 'July Effect' of New Hospital Staff Seems Real, but Better Studies Needed

Two weeks into the annual changeover of U.S. clinical trainees, a meta-analysis finds evidence of a long-suspected "July effect," during which healthcare quality decreases. But the evidence isn't strong.

Researchers, who report their findings in the Annals of Internal Medicine, examined 39 studies. Only a third of the studies were judged to be of "good" or "very good" quality. Higher-quality studies tended consistently to report increases in patient mortality at the time of trainee changeover. Similarly, measures of institutional efficiency, such as patients' length of stay, tended to show deterioration when examined by higher-rated study designs.

The authors point out that the annual cohort turnover at teaching hospitals in July is accompanied by a decline in average experience levels within those institutions. They conclude that although their survey "suggests that the 'July effect' exists, methodologic limitations and study heterogeneity make deeper conclusions more difficult to draw."