Outcomes Associated With High- Versus Low-Frequency Laboratory Testing Among Hospitalized Children.

Background And Objectives: Previous pediatric studies have revealed substantial variation in laboratory testing for specific conditions, but clinical outcomes associated with high- versus low-frequency testing are unclear. We hypothesized that hospitals with high- versus low-testing frequency would have worse clinical outcomes.

Methods: We conducted a multicenter retrospective cohort study of patients 0 to 18 years old with low-acuity hospitalizations in the years 2018-2019 for 1 of 10 common All Patient Refined Diagnosis Related Groups. We identified hospitals with high-, moderate-, and low-frequency testing for 3 common groups of laboratory tests: complete blood cell count, basic chemistry studies, and inflammatory markers. Outcomes included length of stay, 7- and 30-day emergency department revisit and readmission rates, and hospital costs, comparing hospitals with high- versus low-frequency testing.

Results: We identified 132 391 study encounters across 44 hospitals. Laboratory testing frequency varied by hospital and condition. We identified hospitals with high- (13), moderate- (20), and low-frequency (11) laboratory testing. When we compared hospitals with high- versus low-frequency testing, there were no differences in adjusted hospital costs (rate ratio 0.89; 95% confidence interval 0.71-1.12), length of stay (rate ratio 0.98; 95% confidence interval 0.91-1.06), 7-day (odds ratio 0.99; 95% confidence interval 0.81-1.21) or 30-day (odds ratio 1.01; 95% confidence interval 0.82-1.25) emergency department revisit rates, or 7-day (odds ratio 0.84; 95% confidence interval 0.65-1.25) or 30-day (odds ratio 0.91; 95% confidence interval 0.76-1.09) readmission rates.

Conclusions: In a multicenter study of children hospitalized for common low-acuity conditions, laboratory testing frequency varied widely across hospitals, without substantial differences in outcomes. Our results suggest opportunities to reduce laboratory overuse across conditions and children's hospitals.