COST-EFFECTIVENESS OF FOUR DIFFERENT STRATEGIES FOR EVALUATION OF FEVER IN INFANTS LESS THAN 60 DAYS OF AGE

Purpose:    To assess the cost-effectiveness of four different diagnostic strategies for well-appearing infants less than 60 days of age presenting to emergency department settings with fever.

Methods:    We constructed a decision analytic model to evaluate the cost and effectiveness of four common diagnostic strategies for febrile neonates.  The Philadelphia strategy is the most comprehensive and sensitive including complete blood count (CBC), urinalysis (UA), and cerebrospinal fluid (CSF) as well as blood, urine and CSF cultures.  The Rochester and Rochester variant strategies use the CBC, urinalysis, blood and urine cultures but only pursue lumbar puncture if the initial test results do not fall within a “low-risk” range.  The Lab Score uses urinalysis and urine culture paired with newer, more expensive blood tests (c-reactive protein and procalcitonin) to determine if patients are low enough risk to forego lumbar puncture.  Parental values and preferences for the major long-term sequelae of bacterial infections were obtained from the published literature.  Costs included short-term elements for diagnostic testing, treatment and hospitalization (if appropriate) and long-term complications.  Cost and effectiveness were discounted at 3%/year. Sensitivity analyses were done to explore uncertainty in parameter values.

Results:   The Philadelphia and Lab Score strategies were most effective (29.98 QALYs) but the Lab Score was significantly less expensive ($7652 vs. 9419).  Using baseline estimates for the prevalence of significant infection the Lab Score cost $36458 per quality-adjusted life year (QALY) gained compared with the Rochester-variant strategy.  In particular, the pre-test probability of bacterial meningitis had the strongest influence on cost-effectiveness.  As the prevalence of bacterial meningitis decreased below the base case of 0.5%, the marginal cost-effectiveness ratio of the Lab Score increased, and was >$50,000 below 0.45%.  The Rochester-Variant strategy is the most cost-effective at these lower probabilities.  These results were stable over a range of disease prevalence estimates as well as varying probabilities of adverse outcomes.

Conclusions:    At current prevalence estimates, the Lab Score is a cost-effective method to screen for invasive bacterial infections in well appearing, febrileinfants < 60 days of age.  While more sensitive decision tools were reasonable in an era when the prevalence of bacterial meningitis was higher, a newer more specific strategy that does not mandate lumbar puncture in all infants is cost-effective given the declining prevalence of invasive bacterial infections.