The general point of the authors, while acknowledging the limitations of this sort of data-dredging, is that testing strategies by Emergency Physicians appear to be generally non-conforming with the American Academy of Pediatrics recommendations for testing in otherwise well-appearing children. They are hesitant to critique the patients who received laboratory testing - because they have no data on how well-appearing the child may have been or other comorbidities that might indicate testing - but they do take issue with the fact that only 43% of females under age 2 with a fever received a urinalysis and culture. The 2008 Pediatrics guidelines - not endorsed by ACEP - would recommend that all of them receive UA and culture. Considering the prevalence of UTI in febrile females under 2 years of age ranges from 8-17%, their criticism is probably valid.
Other trivia: 20% of children with no testing performed received antibiotics. This could be due to missing ICD-9 data about another clinical diagnosis - but more likely due to simply treating fever unnecessarily.
And, finally, children from zip codes with higher median incomes were more likely to receive CBC and UA. More UAs, probably good. More CBCs, probably bad.
Just an interesting summation of observational data.