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02-04-2013 | Surgery | Article

Pediatric surgery study methodology ‘inconsistent’


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medwireNews: Research addressing the influence of surgeon or hospital experience on the outcome of children's surgery significantly varies in methodology and definition, a review suggests.

This inconsistency hinders cross comparisons, while the resulting limited risk adjustment impairs the internal validity of certain studies, the authors warn.

"Our review of the literature highlights a number of strengths and limitations in the present evidence base, and clarifying these may help inform the design of future studies that would be more amenable to comparison and meta-analysis," write Jarod McAteer (Seattle Children's Hospital, Washington, USA) and colleagues in JAMA Pediatrics.

McAteer and team reviewed 63 observational studies published between 1980 through to April 2012.

Studies included had a measure of hospital or surgeon experiences as a predictor variable, while postoperative outcomes were the dependent response variables.

The authors highlighted that 68% of the studies focused on hospital-level characteristics, which were often strongly associated with improved outcomes in less common, more complex problems, such as congenital heart surgery. Surgeon-level factors, on the other hand, were given importance when more common, less resource-demanding procedures (eg, appendectomy) were involved - as well as surgeries typically performed in adults (eg, thyroidectomy).

"Ideally, future research should evaluate surgeon- and hospital-level measures simultaneously, which will provide more information than evaluating either independently," the researchers suggest.

Over half (57%) of the studies used annual hospital or surgeon operative volume as a single specific exposure definition, depending on the procedure. The remaining studies used various definitions.

Exposure definitions also differed between specialties and procedures; 93% of the 11 congenital heart disease studies defined volume according to annual hospital volume, while just 33% of the nine appendicitis studies used annual surgeon or hospital volume, with the remainder preferring definitions based primarily on surgeon subspecialty or hospital designation.

Furthermore, 17% of studies that used volume measures treated the measure as a continuous variable, while the remainder defined volume in inconsistent ways, even across studies of similar procedures.

Variability in risk adjustment was another noted limitation, with 19% of studies failing to adjust for covariates, while several that did adjusted only for demographic factors.

Altogether, conclude the authors, a "great deal more work must be done...[to] standardize definitions, making results more applicable, and to differentiate procedures affected by surgeon experience from those more affected by hospital resources and system-level variables."

By Peter Sergo, medwireNews Reporter

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