What’s New in the Patient Safety World

June 2010


The July Effect: Myth or Reality?



For years many have warned that the most dangerous time to be admitted to hospitals in the US was in July when new housestaff come on board. However, numerous studies in the past have been unable to corroborate that with good evidence. Now a new study published online first in the Journal of General Internal Medicine (Phillips and Barker 2010) provides some evidence to support the reality of the “July effect”. Using data from computerized death certificates from 1979 to 2006, they demonstrated that there was a consistent spike in deaths inside medical institutions coded as being due to fatal medication errors but only within counties having teaching hospitals. Moreover, the July spike was greater in those counties having a greater concentration of teaching hospitals. They found no similar spike for deaths of all causes or for deaths due to adverse medication effects (i.e. those medication-related deaths felt not to be preventable). Though the authors did consider potential alternative explanations (eg. more vacations in July, summer spikes in alcohol use and trauma, etc.) they conclude the most likely explanation for the “July effect” is the influx of new housestaff in teaching institutions. They also did not find evidence of a change in the July spike as new residency work hour rules came into effect.


Though this evidence is indirect and provides us only with an association, not a clearcut causal effect, the data are pretty striking. The authors discuss potential implications such as the need for better defining the responsibilities assigned to new housestaff, increasing supervision, and increasing education about medication safety.


We’d like to see if CPOE (computerized physician order entry) with clinical decision support systems (CDSS) has had any impact on the “July effect”. There is at least some anecdotal evidence that more junior physicians may be more amendable to following the recommendations in various alerts generated by CDSS. Most of the data in the study actually ended in 2004, a time at which a paucity of teaching institutions were using CPOE with good CDSS. So it would be interesting for them to extend their study and see whether the July spike has diminished at all over the last 5 years when the use of CPOE with CDSS has increased substantially.


Keep in mind also that lots of other things happen in hospitals in July. Not only is there an influx of new residents and interns, but housestaff who just completed their internships now take on supervising roles. You may also have new attendings starting in July and you often have new staff in other healthcare fields (nursing, pharmacy, etc.).


Our December 8, 2009 Patient Safety Tip of the Week “Prescribing Errors” mentioned the EQUIP study done in the UK that provided some interesting insights into prescribing errors. Though originally established to look at prescribing errors made by first year residents, the study demonstrated that prescribing errors were both common and made by physicians at all levels. Looking at over 100,000 medication orders across 20 hospital sites, they found an average error rate of 8.9 errors per 100 medication orders. The error rate for first year residents, responsible for about half the orders, was 8.4% - actually lower than that for the entire group. All physician levels, including attendings, made prescribing errors. The highest rate (10.3%) was actually seen for second year residents. Interestingly, nurses and pharmacists who were allowed to order medications, had much lower error rates. That UK study had some good insights and recommendations for improving the medication prescribing process.


So while cause of the “July effect” may not yet be clearly attributable to new housestaff, it is clearly there and needs to be further investigated.






Phillips DP, Barker  GEC. A July Spike in Fatal Medication Errors: A Possible Effect of New Medical Residents. J Gen Intern Med 2010; published online first June 2010




Dornan T, Ashcroft D, Heathfield H et al. An in depth investigation into causes of prescribing errors by foundation trainees in relation to their medical education. EQUIP study. December 2009
















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