Validation and Cost Analysis of a Calculator for Estimating the Probability of Urinary Tract Infection in febrile children 2 to 23 months of age

Background: Approximately 7% of children <2 years of age who present to an emergency department (ED) with fever have a urinary tract infection (UTI). The diagnosis of a UTI is challenging, and delayed treatment can result in morbidity such as renal scarring and serious bacterial infection. Shaikh and colleagues (University of Pittsburgh) designed a calculator (UTICalc) to estimate the probability of UTI using six clinical variables and four laboratory variables. As a result, evaluation could be tailored to reduce unnecessary testing and treatment. The objective of our study was to determine if the UTI Calc was applicable as a predictive tool and then analyze the cost savings when applied to our patient population. Methods: We performed a retrospective nested case control study to evaluate the UTICalc Version 3.0 at variable pretest probabilities (>=2, >=3, >=4, and >=5%) . Febrile patients aged 2 months to 23 months who presented to a free-standing tertiary care children’s ED and had a urinalysis and urine culture obtained by bladder catheterization from January 2016-December 2021 were included. Results: A total of 1049 children were included. When pretest probabilities were applied at >=2, >=3, >=4, and >=5%, there was a decreased need for catheterization by 16.6%, 31.3%, 32.3% & 45.1%, respectively. At cutoffs of >=2, >=3, >=4, and >=5%, the rate of missed UTI cases were 2.0%, 6.4%, 6.9% and 11.5%, respectively. When determining the cost savings, the cost savings related to catheterization was $139,846 at >=2%, $282,546 at >=3%, 293,962 at >=4% and $424,532.50 at >=5%. The incremental cost effectiveness ratios, which compare the additional cost per identified UTI when catheterizing all patients versus using the different cutoff points based on the tool, were $6,659.30 at >=2%, $ 4217.10 at >=3%, $4,082.80 at >=4% and $3,508.50 at >=5%. Conclusions: The UTICalc Version 3.0 was helpful to screen and determine treatment for a suspected UTI in children 2-23 months. Application of UTICalc Version 3.0 demonstrated a significant cost savings. Additional studies should seek to assess the value of UTICalc Version 3.0 to determine cutoffs and cost savings for children < 2 years with a suspected UTI.