Spinal surgery outcomes put ‘July effect’ in myth category

Feb 4 2013

By Peter Sergo, medwireNews Reporter

The supposed commotion caused by an influx of new residents and fellows that typically takes place at teaching hospitals during the month of July has an negligible effect on periprocedural outcomes after spinal surgery.

This is the conclusion of a retrospective review in the Journal of Neurosurgery: Spine of almost one million hospital admissions for spinal surgery, which found a minor to negligible so-called "July effect" - a controversial idea claiming lowered quality of care that stems from the introduction of new hospital staff.

"We hope that our findings will reassure patients that they are not at higher risk of medical complications if they undergo spinal surgery during July as compared to other times of the year," said study co-author, Jennifer McDonald (Mayo Clinic, Rochester, Minnesota, USA), in a press statement. "While we only looked at spinal surgeries, we think it's likely we'd find similar outcomes among other surgeries and procedures."

Using the US Nationwide Inpatient Sample (NIS), the researchers analyzed the outcomes of spinal surgery cases that took place in both teaching and nonteaching hospitals over July and compared them with other months of the year during 2001 to 2008.

Although teaching hospitals had significantly higher rates of discharge to a long-term care facility (12.1%) and post-operative infection (1.3%) in July compared with other months (11.5 and 1.1%, respectively), the difference was considered minimal due to the study's large sample size.

Differences in in-hospital mortality at teaching hospitals were found to be nonsignificant between patients admitted in July compared with any other month (0.4% for both admissions). In addition, no observable difference in outcomes was observed among cases of higher-risk patients, electively admitted patients, or simple spinal procedures.

While patients admitted to a teaching hospital in July had a significantly higher likelihood for overall postoperative complications compared with other months of the year (2.0 vs 1.8%), significant disparities were absent when comparing reaction to an implanted device or instrument (0.6% for both admissions) as well as wound dehiscence (0.3% for both admissions).

The authors consider their findings weaken the case for the July effect, partly based on the strength of having used records from the largest all-payer national inpatient database, which allowed several potential cofounders to be taken into account when carrying out the statistical comparisons.

By contrast, McDonald and team explain, the conflicting results of previous studies likely stemmed from limitations that arose form analyzing only certain demographics or area-specific routines, while some studies did not have a nonteaching hospital control group.

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