Precious few who are under the weather skip happily into hospitals, a song on their lips, and not a care in the world. Typical inpatients worry about many things: the condition that’s caused them to be hospitalized, being away from their homes and families, and even the quality of medical care they will receive while hospitalized.

Example:

“Avoid hospitals in July like the plague.” If you can, stay out of the hospital during the summer, especially July. That’s the month when medical students become interns, interns become residents, and residents become fellows and full-fledged doctors. In other words, a good portion of the staff at any given teaching hospital is new on the job. Summer hospital horror stories aren’t just medical lore: The adjusted mortality rate rises 4% in July and August for the average major teaching hospital, according to the National Bureau of Economic Research. That means eight to 14 more deaths occur at major teaching hospitals than would normally without the turnover. Another scheduling tip: Try to book surgeries first thing in the morning and preferably early in the week, when doctors are at their best and before schedules get backed up.

The piece quoted above (which we began seeing circulated in e-mail in June 2010) speaks to that last concern. Its text was harvested from a 4 March 2010 Wall Street Journal‘s SmartMoney Magazine article titled “10 Things Your Hospital Won’t Tell You,” where its topic of July mortality rates in hospitals appeared as item nine.

That seemingly helpful heads-up is a summary of information pulled from another source, with some key aspects left out. The “10 Things” item drew its information from a 2005 National Bureau of Economic Research article titled “Cohort Turnover and Productivity: The July Phenomenon in Teaching Hospitals.” That paper examined what is termed “the July phenomenon,” “the July effect,” or “the new resident hypothesis”: a reduction in quality of service related to the annual turnover of house staff in teaching hospitals. Using patient-level data gathered from roughly 700 hospitals per year over the period from 1993 to 2001, it concluded that there is a measurable increase in both length of patient stay and rates of patient mortality during the July-August transition, when experienced residents and interns are replaced by new ones.

Key to the understanding that paper, however, is noting that its conclusions apply solely to teaching hospitals , institutions where residents and interns treat patients as part of their medical training. It’s therefore not true that all hospitals become a bit more dangerous in July. It’s also not true that all teaching hospitals experience this decline. As the paper noted, “In fact, the most-intensive teaching hospitals manage to avoid significant effects on mortality following this turnover” thanks to better supervision of new doctors.

However, at teaching institutions where oversight of new staff is less stringent, the “July effect” is real. Moreover, it lasts not merely throughout that month but for the rest of the calendar year as well. While risk-adjusted mortality rates may rise by roughly 4 percent in the July-August period, that increase remains at between 2 and 4 percent until the New Year, resulting in 8 to 14 additional deaths per annum at a typical teaching hospital.

The increase in patient deaths does not, as many people assume, have to do mostly with untrained surgeons running amok; it is instead largely attributable to fatal medication errors, according to a May 2010 study published in the Journal of General Internal Medicine. In that study, researchers from the University of California, San Diego examined computerized death certificates from 1979-2006, focusing on the certificates of inpatients, outpatients, and those who died in the emergency department, in which medication error was recorded as the primary cause of death. (Computerized death certificates do not record whether the patient died in a teaching hospital, but they do record the county of death, so researchers looked at the proportion of major teaching hospitals in each county.) Counties containing teaching hospitals experienced a 10% rise in fatal medication errors in July, whereas counties lacking teaching hospitals did not experience that spike. The lethal mistakes included dispensing the wrong drugs, overdoses, and accidents involving drugs or biological agents.

In a bit that didn’t come from any of the studies discussed above, the e-mailed item asserts:

Try to book surgeries first thing in the morning and preferably early in the week, when doctors are at their best and before schedules get backed up.

Surgeons aren’t necessarily at their best first thing in the morning: like other mere mortals, some are bright-eyed and bushy-tailed as soon as their eyes snap open but fade as the day goes on, others hit their strides no earlier than the afternoon, and others are everywhere in between. Similarly, the day of the week doesn’t appear to affect the skill level of surgeons.

According to an October 2009 article in the journal Anesthesiology (produced by the American Society of Anesthesiologists), there is no bad time of the day, week, or year to have elective coronary artery bypass graft surgery, thus one needn’t worry about being a Thursday or Friday operation. It had been postulated the crazy hours surgeons work would impart fatigue-related disadvantages to patients who underwent operations later in the week, yet that did not prove to be the case: results from surgeries performed early and late in the week and at different times of the day were all similar. The reason why coronary artery bypass grafting was studied was because that procedure is the most common heart surgery, and there are well-established protocols for it. The analysis was limited to elective operations because emergency procedures are inherently riskier and are often performed on patients that have additional medical problems.

Yet being the first under the knife on any given day may confer certain advantages to the patient. Being early on the day’s roster means one’s surgery will start on time, whereas patients booked later in the day may find their procedures pushed back as complications in the operating room work to make a mess of the day’s schedule. Also, the operating room is at its cleanest prior to the first operation, a factor for those concerned about the risk of post-operative infection.