The primary outcome specified in the protocol is deimplementation sustainment, a "difference in differences" outcome based on statistical comparisons based on pulse oximetry overuse across trial phases and arms. Pulse oximetry overuse is operationally defined as percent of patient observations monitored using continuous pulse oximetry while not receiving supplemental oxygen (measured using direct observation).

The least metabolized form of the data for pulse oximetry overuse, raw proportions across trial phases and arms, is reported here. Results of the specific analysis used to report the trial's pre-specified primary outcome of deimplementation sustainment is reported in Statistical Analysis 1.

Each hospital has multiple participants. Each participant may have 1 or more observations of pulse oximetry use.

This measure is assessed as the count of patient observations monitored using continuous pulse oximetry while not receiving supplemental oxygen (measured using direct observation) in the baseline phase.

In order to assist in interpretation, this can also be viewed below as a proportion or a percent of the total number of observations. The denominator is the count of observations of patients not receiving supplemental oxygen. The numerator is the count of observations of patients not receiving supplemental oxygen who are also monitored using continuous pulse oximetry. The numerator count is divided by the denominator count to calculate a proportion. The proportion is multiplied by 100 to obtain a percent. This is expressed below as a count with the percentage automatically calculated by the clinicaltrials.gov system.

This outcome is restricted to the baseline phase of the trial. Hence the total participants and observations is lower than the primary outcome total participants and observations. In addition, each hospital has multiple participants. Each participant may have 1 or more observations of pulse oximetry use. Hence the different units.

This measure is assessed as the count of patient observations monitored using continuous pulse oximetry while not receiving supplemental oxygen (measured using direct observation) in the active deimplementation phase.

In order to assist in interpretation, this can also be viewed below as a proportion or a percent of the total number of observations. The denominator is the count of observations of patients not receiving supplemental oxygen. The numerator is the count of observations of patients not receiving supplemental oxygen who are also monitored using continuous pulse oximetry. The numerator count is divided by the denominator count to calculate a proportion. The proportion is multiplied by 100 to obtain a percent. This is expressed below as a count with the percentage automatically calculated by the clinicaltrials.gov system.

This outcome is restricted to the active deimplementation phase of the trial. Hence the total participants and observations is lower than the primary outcome total participants and observations. In addition, each hospital has multiple participants. Each participant may have 1 or more observations of pulse oximetry use. Hence the different units.

This measure is assessed as the count of patient observations monitored using continuous pulse oximetry while not receiving supplemental oxygen (measured using direct observation) in the sustainment phase.

In order to assist in interpretation, this can also be viewed below as a proportion or a percent of the total number of observations. The denominator is the count of observations of patients not receiving supplemental oxygen. The numerator is the count of observations of patients not receiving supplemental oxygen who are also monitored using continuous pulse oximetry. The numerator count is divided by the denominator count to calculate a proportion. The proportion is multiplied by 100 to obtain a percent. This is expressed below as a count with the percentage automatically calculated by the clinicaltrials.gov system.

This outcome is restricted to the sustainment phase of the trial. Hence the total participants and observations is lower than the primary outcome total participants and observations. In addition, each hospital has multiple participants. Each participant may have 1 or more observations of pulse oximetry use. Hence the different units.

The oxygen supplementation duration is the total duration of time during which a patient is documented as receiving supplemental oxygen during hospitalization.

The length of hospital stay is the duration of time that elapses between the time a patient is admitted with bronchiolitis to an inpatient unit of the hospital until the time they are discharged from the hospital, using data manually abstracted from the electronic health record chart.

Underuse is defined as failing to continuously SpO2 -monitor bronchiolitis patients receiving ≥2L/min supplemental oxygen (a marker of more severe disease). It is calculated as the percentage of bronchiolitis patient observations in patients who are receiving ≥2L/min supplemental oxygen, and are not being continuously SpO2-monitored. It is measured using direct observation.

Counts of participants and observations differ from the primary outcome because patients included for this outcome underwent a different data collection process.

Exploratory long-term sustainability is calculated based on penetration. Penetration is the percentage of bronchiolitis patients who are in room air (not receiving any supplemental oxygen) and are receiving guideline-concordant care (this means they are not being continuously SpO2-monitored). The continuous monitoring status is determined using direct observation on hospital units.

In this exploratory outcome investigators are using an alternative definition of sustainability in which, in order to meet criteria for having successfully sustained a practice change, hospitals must first (a) experience a significant increase in penetration between baseline and active deimplementation, and then (b) maintain the increased penetration at ≥90% of the active deimplementation phase level through the end of the sustainability period.