The country is deep in winter, but attention again is returning to that summertime phenomenon dubbed “the July effect.” That’s the name given to a supposed spike in medical mistakes and poor patient outcomes at teaching hospitals during the seventh month of the year, when newly minted MDs start providing care.

Numerous studies have reached conflicting conclusions about the extent of the July effect and whether it even exists. A massive study of spinal surgery outcomes published Jan. 29 online further complicates the picture, finding that patients going under the knife at teaching hospitals in July largely fare just as well as their counterparts during the rest of the year but do slightly worse on a couple of metrics.

Researchers examined nearly 1 million spinal procedures between 2001 and 2008, and found that patients who underwent surgery in July had similar rates of in-hospital mortality, adverse reactions to implanted devices and wounds reopening post-operatively. However, the July patients were 3% likelier to be discharged to a long-term-care facility instead of home, and had 11% greater odds of having post-op infections, said the study, published in the Journal of Neurosurgery: Spine.

“The patients admitted in July didn’t have substantially higher risk of any of these mortality or morbidity outcomes versus patients admitted in other months,” said Jennifer S. McDonald, PhD, lead author of the study. “I feel very confident that in this particular cohort, looking at patients getting spinal surgery, we don’t see evidence of a July effect.”

She said one telling piece of evidence arguing against a July effect is that there was no difference in outcomes by complexity of the spinal surgery. Patients having a relatively simple procedure in July, such as removal of a herniated disk, fared just as well as patients having it done in other months, and so did patients who got more complicated procedures such as spinal fusion.

“This doesn’t mean the July effect doesn’t exist at all, or that it doesn’t exist in patients presenting for other treatments,” said McDonald, a radiologist at Mayo Clinic in Rochester, Minn.

A systematic review of 39 July effect studies in the Sept. 6, 2011, Annals of Internal Medicine found higher mortality rates during the summertime transition, but researchers cautioned about overstating the findings. “The existing literature does not permit firm conclusions about the degree of risk posed, how changeover affects morbidity and rates of medical errors, or whether particular models are more or less problematic,” said the study.

The full and original article can be found at: