This multicenter cohort study evaluates the effectiveness of the clinical prediction rules for brief resolved unexplained events (BRUE) compared with the higher-risk criteria of the American Academy of Pediatrics in estimating risk for serious underlying diagnosis.
Key Points
Question
Are recently derived clinical prediction rules for brief resolved unexplained events (BRUE) better than the American Academy of Pediatrics (AAP) higher-risk criteria in estimating risk for serious underlying diagnosis?
Findings
In a multicenter cohort study of 1042 infants with BRUE, the BRUE prediction rules demonstrated superior prediction performance over the AAP higher-risk criteria. The BRUE prediction rules showed significant improvements in discrimination, with area under the curve of 0.71, as opposed to a value of 0.53 for the AAP.
Meaning
The validated BRUE prediction rules offer a superior prediction performance of risk for serious underlying diagnosis than the widely used AAP higher-risk criteria.
Abstract
Importance
The American Academy of Pediatrics (AAP) higher-risk criteria for brief resolved unexplained events (BRUE) have a low positive predictive value (4.8%) and misclassify most infants as higher risk (>90%). New BRUE prediction rules from a US cohort of 3283 infants showed improved discrimination; however, these rules have not been validated in an external cohort.
Objective
To externally validate new BRUE prediction rules and compare them with the AAP higher-risk criteria.
Design, Setting, and Participants
This was a retrospective multicenter cohort study conducted from 2017 to 2021 and monitored for 90 days after index presentation. The setting included infants younger than 1 year with a BRUE identified through retrospective chart review from 11 Canadian hospitals. Study data were analyzed from March 2022 to March 2024.
Exposures
The BRUE prediction rules.
Main Outcome and Measure
The primary outcome was a serious underlying diagnosis, defined as conditions where a delay in diagnosis could lead to increased morbidity or mortality.
Results
Of 1042 patients (median [IQR] age, 41 [13-84] days; 529 female [50.8%]), 977 (93.8%) were classified as higher risk by the AAP criteria. A total of 79 patients (7.6%) had a serious underlying diagnosis. For this outcome, the AAP criteria demonstrated a sensitivity of 100.0% (95% CI, 95.4%-100.0%), a specificity of 6.7% (95% CI, 5.2%-8.5%), a positive likelihood ratio (LR+) of 1.07 (95% CI, 1.05-1.09), and an AUC of 0.53 (95% CI, 0.53-0.54). The BRUE prediction rule for discerning serious diagnoses displayed an AUC of 0.60 (95% CI, 0.54-0.67; calibration intercept: 0.60), which improved to an AUC of 0.71 (95% CI, 0.65-0.76; P < .001; calibration intercept: 0.00) after model revision. Event recurrence was noted in 163 patients (15.6%). For this outcome, the AAP criteria yielded a sensitivity of 99.4% (95% CI, 96.6%-100.0%), a specificity of 7.3% (95% CI, 5.7%-9.2%), an LR+ of 1.07 (95% CI, 1.05-1.10), and an AUC of 0.58 (95% CI, 0.56-0.58). The AUC of the prediction rule stood at 0.67 (95% CI, 0.62-0.72; calibration intercept: 0.15).
Conclusions and Relevance
Results of this multicenter cohort study show that the BRUE prediction rules outperformed the AAP higher-risk criteria on external geographical validation, and performance improved after recalibration. These rules provide clinicians and families with a more precise tool to support decision-making, grounded in individual risk tolerance.
Introduction
Brief resolved unexplained events (BRUE) are common in infants1 and involve transient symptoms such as apnea, color change, muscle tone alteration, or altered breathing patterns, resolving spontaneously without a clear cause.2 These events, often benign, raise substantial caregiver and health care professional anxiety due to their unexplained nature,3,4,5 potential recurrence in 9% to 14% of infants, and the small yet concerning possibility that a BRUE might be the first indication of a more serious underlying condition, seen in approximately 5% of cases.6,7
The 2016 clinical practice guidelines by the American Academy of Pediatrics (AAP) newly defined BRUE and categorized them into lower- and higher-risk groups, based on patient factors, to help clinicians identify infants at risk of serious conditions.2,8 These higher-risk criteria were based on the apparent life-threatening events literature available at the time. Although the higher-risk criteria were later demonstrated to have an excellent negative predictive value (NPV, 98%), they demonstrated a poor positive predictive value (PPV, 5%), overclassifying the vast majority (92%) of patients as higher risk when only 5% were eventually diagnosed with a serious underlying problem.6
In response, new BRUE prediction criteria were developed from a US retrospective study involving 3283 patients experiencing BRUE that showed improved discrimination in identifying serious underlying diagnoses (area under the curve (AUC, 0.61 vs 0.52) and predicting event recurrence (AUC, 0.68 vs 0.54) compared with the AAP higher-risk criteria.6 External geographical validation of these rules will confirm their generalizability and applicability across diverse populations and health care settings, by determining if the predictive accuracy observed in the initial study remains consistent in an independent sample.9,10,11
Therefore, this study was focused on externally validating the BRUE prediction rules within a Canadian cohort of infants experiencing BRUE. This is a critical step to verify the rules’ utility in clinical practice and improve risk estimation for 2 important outcomes of serious underlying diagnosis and event recurrence.
Methods
Study Design
This retrospective cohort study was conducted in the Canadian Paediatric Inpatient Research Network (PIRN). We identified patients from 11 hospitals, including a mix of tertiary pediatric centers and general hospitals. These sites were located across 5 of Canada’s 10 provinces, including 8 of the country’s 10 largest pediatric centers. The primary site and each participating center granted ethical approval for this study with waiver of consent (University of British Columbia Children’s and Women’s Research Ethics Board [H21-02357]). The study’s protocol was published a priori.12 The validation of the clinical prediction rules conducted in this study adheres to the principles outlined in the Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) reporting guidelines (eTable 1 in Supplement 1).13 This constitutes geographical validation of the BRUE prediction rules, as it evaluates their performance in a distinct country from where they were derived.14
Cohort Identification
Infants aged 1 to 365 days, presenting to the emergency department (ED) for a BRUE between January 1, 2017, and December 31, 2021, were identified through a validated method based on admission and discharge codes.15 Eligible patients had to meet the diagnostic criteria for BRUE,2 with the event remaining unexplained after a comprehensive history and physical examination. Trained research assistants at each participating site reviewed medical records for eligibility and data extraction (details in published protocol).12 Participant race and ethnicity data were not collected, as this is not reliably collected across Canadian hospitals.
Outcomes
The study evaluated 2 outcomes of interest. The primary outcome was the identification of a serious underlying diagnosis as the causative factor for the BRUE-like event. This category included conditions where a delay in diagnosis could lead to increased morbidity or mortality. Criteria for classification as serious or nonserious were determined a priori.12 Diagnoses with a range of presentations, like viral respiratory tract infections, were classified as serious if they necessitated medical interventions (eg, administration of oxygen, high-flow therapy, mechanical ventilation, or intensive care unit admission). The secondary outcome was the recurrence of BRUE either during the index hospital stay or based on representation to the ED. Monitoring for both outcomes was limited to 90 days after the index ED visit.
Comparing Derivation and Validation Cohorts
A comparative analysis was conducted between the derivation and validation cohorts to assess the frequency of the outcomes of interest and the prevalence of predictors outlined by the AAP higher-risk criteria and the BRUE prediction rules. The derivation cohort included 3283 patients diagnosed with BRUE, identified across 15 children’s hospitals within the US. These patients presented for care from October 1, 2015, to September 30, 2018, and from April 1, 2019, to June 30, 2020.6 The validation cohort, as described herein, was identified across 11 Canadian hospitals (2017-2021). Standardized mean differences (SMDs) were used to compare variables across cohorts.16 Variability observed in the predictors and outcomes between the cohorts is considered beneficial, as it facilitated external geographical validation within a distinct population, rather than one that identically mirrored the derivation cohort.14,17
AAP Higher-Risk Criteria
Predictors
According to the AAP clinical practice guidelines, infants with BRUE are stratified into lower-risk and higher-risk categories.2 An infant is considered higher risk if they meet any of the following: (1) age 60 days or younger, (2) gestational age younger than 32 weeks or corrected younger than 45 weeks, (3) event lasting 1 minute or longer, (4) multiple events or event clusters, (5) cardiopulmonary resuscitation by a medical professional, (6) concerning features in the medical history (eTable 2 in Supplement 1), or (7) concerning signs on physical examination.
Performance
We evaluated the AAP higher-risk criteria sensitivity, specificity, PPV, NPV, positive likelihood ratio (LR+), negative LR (LR−), and the AUC in relation to the study outcomes.
BRUE Prediction Rules
Predictors
The BRUE prediction rule for the outcome of serious underlying diagnosis included the following predictors: (1) history of a similar event, (2) abnormal medical history, and (3) age in days. The predictors for event recurrence included the following: (1) prematurity (defined in line with the AAP higher-risk criteria), (2) multiple events or event clusters, (3) color change, (4) abnormal respiratory pattern, and (5) change in muscle tone. The predictors of abnormal respiratory pattern and change in muscle tone were negatively associated with the outcome. Any patient or BRUE characteristics not documented in the patient’s chart were presumed absent.
Recalibration
For each outcome, we estimated the risk using the coefficients and intercept obtained from the derivation study original model. The BRUE prediction rule was then updated using 3 methods that progressively modified the model parameters18,19:
Recalibration in the large: this initial step involved adjusting the prediction rule’s intercept to mirror the difference in outcome prevalence between the derivation and validation cohorts.
Logistic recalibration: here, the intercept was re-estimated as mentioned previously, and a uniform (same for all variables) scaling factor was applied to modify all coefficients within the prediction rule.
Model revision: the final recalibration involved re-estimating the prediction rule parameters through logistic regression analysis within the validation cohort. This step involved updating both intercept and coefficients, keeping the predictor variables unchanged.
Model Comparisons
LR tests were used sequentially to compare the fits of the previously mentioned nested models. We used the DeLong test to quantify the difference in AUC between the original and revised models and the corresponding 95% CI.
Performance
In assessing the performance of clinical prediction rules, 2 aspects were evaluated11,20,21,22,23:
Discrimination: the capability of the prediction rule to distinguish between patients with and without each outcome was assessed using a receiver operating characteristic curve.19 The AUC provides a summary measure, with values ranging from 0.5, denoting random chance, to 1.0, indicating perfect discrimination. We additionally generated precision-recall curves comparing the original and the revised models (eFigure 1 in Supplement 1).
Calibration: the concordance between predicted and observed outcomes. Calibration was assessed visually using calibration plots and quantitatively through estimation of the calibration slope and intercept and corresponding 95% CIs.24
Sensitivity Analysis
To ensure robustness and reliability of the findings, a preplanned sensitivity analysis was conducted. First, to address potential variations in patient characteristics between those admitted and those discharged from the ED, the sensitivity analysis excluded data from 3 hospitals. These specific hospitals only provided data on admitted patients. Second, transferred patients were also excluded, as they may represent a more severely ill subset.
Sample Size
The study’s sample size was calculated a priori, using data from the derivation study.6 With an AUC of 0.61 for the primary outcome and a prevalence rate of 4.57%, a sample size of 1182 patients experiencing BRUE, including 54 with serious underlying diagnoses, was estimated to be necessary to achieve an 80% power at a 5% significance level to detect an AUC above 0.5.6 A post hoc analysis of the validation cohort demonstrated a prevalence of the primary outcome at 7.58%. With this higher than anticipated prevalence, a smaller sample size of 736 patients, including 56 cases, was required to achieve the same power.
Statistical Analysis
Statistical analyses were carried out using R software, version 4.3.2 (R Project for Statistical Computing), with the pROC, version 1.18.5, and the CalibrationCurves, version 2.0.3, packages.24,25 Hypothesis testing was 2-sided, with a threshold of .05 set for statistical significance. Study data were analyzed from March 2022 to March 2024.
Results
Study Population
The validation cohort included 1042 eligible infants (median [IQR] age, 41 [13-84] days; 529 female [50.8%]; 513 male [49.2%]) with BRUE (Table 1).6 The majority of the cohort were infants aged 60 days or younger (658 [63.1%]). There was documentation of an abnormal medical history in 320 infants (30.7%), concerning family history in 133 infants (12.8%), and concerning social history in 48 infants (4.6%). Hospital admission was common, in 665 infants (63.8%). The primary outcome of serious underlying diagnosis was observed in 79 patients (7.6%) (eTable 3 in Supplement 1).26 The secondary outcome of event recurrence occurred in 163 patients (15.6%).
Table 1. Demographic and Clinical Characteristics of Patients in the Brief Resolved Unexplained Events (BRUE) Group in the Derivation and Validation Cohorts.
| Characteristic | Derivation cohort (US 2015-2020)a | Validation cohort (Canada 2017-2021) | Standardized mean differenceb |
|---|---|---|---|
| No. of patients | 3283 | 1042 | NA |
| Age (IQR), d | 48 (18-116) | 41 (13-84) | NA |
| Sex, No. (%) | |||
| Female | 1705 (51.9) | 529 (50.8) | 0.023 |
| Male | 1578 (48.1) | 513 (49.2) | |
| Patient risk factors | |||
| Gestational age, No. (%) | |||
| Term (≥37 wk)/not indicated | 2429 (74.0) | 890 (85.4) | 0.322 |
| Late preterm (34-36+ wk) | 541 (16.5) | 102 (9.8) | |
| Moderate preterm (32-33+ wk) | 246 (7.5) | 26 (2.5) | |
| Very preterm (28-31+ wk) | 67 (2.0) | 24 (2.3) | |
| Prematurity (<32 wk) or corrected <45 wk,c No. (%) | 636 (19.4) | 180 (17.3) | 0.054 |
| Age ≤60 d, No. (%) | 1874 (57.1) | 658 (63.1) | 0.124 |
| Family history concerning for serious condition, No. (%) | 312 (9.5) | 133 (12.8) | 0.104 |
| Social history concerning for abuse, No. (%) | 129 (3.9) | 48 (4.6) | 0.034 |
| Abnormal medical history, No. (%) | 993 (30.2) | 320 (30.7) | 0.010 |
| BRUE characteristics,d No. (%) | |||
| Color change | 1645 (50.1) | 514 (49.3) | 0.016 |
| Abnormal breathing | 2278 (69.4) | 686 (65.8) | 0.076 |
| Tone change | 1481 (45.1) | 607 (58.3) | 0.265 |
| Altered responsiveness | 1167 (35.5) | 377 (36.2) | 0.013 |
| Event duration ≥1 min | 958 (29.2) | 354 (34.0) | 0.103 |
| History of similar event | 1192 (36.3) | 343 (32.9) | 0.071 |
| History of multiple events or event clusters | 996 (30.3) | 325 (31.2) | 0.018 |
| CPR performed and indicated | 60 (1.8) | 44 (4.2) | 0.140 |
| Higher-risk BRUE as defined by the AAP guidelines | 3005 (91.5) | 977 (93.8) | 0.086 |
| Clinical outcomes, No. (%) | |||
| Hospital admission | 2063 (62.8) | 665 (63.8) | 0.020 |
| Serious underlying diagnosise | 150 (4.6) | 79 (7.6) | 0.126 |
| Recurrent eventf | 469 (14.3) | 163 (15.6) | 0.038 |
| Rehospitalizatione | 281 (8.6) | 64 (6.1) | 0.093 |
| Deathe | 1 (0.03) | 1 (0.1) | 0.026 |
Abbreviations: AAP, American Academy of Pediatrics; CPR, Cardiopulmonary Resuscitation.
Data from source.6
Comparison between the derivation and validation cohorts using standardized mean differences. Age as a continuous variable was not compared, as we do not have access to the raw data for the derivation cohort.
Defined as per the AAP higher-risk criteria.
Patient may present with BRUE episodes including multiple characteristics.
At or within 90 days of index presentation.
Recurrent events were limited to the index hospitalization in the derivation cohort, whereas in the validation cohort, they included representations to the emergency department within 90 days.
When compared with the 3283 patients in the derivation cohort, the 1042 patients in the validation cohort demonstrated a higher prevalence of term births (890 [85.4%] vs 2429 [74.0%]; SMD = 0.322), age 60 days or younger (658 [63.1%] vs 1874 [57.1%]; SMD = 0.124), and concerning family history (133 [12.8%] vs 312 [9.5%]; SMD = 0.103). Events in the validation cohort were more likely to be associated with changes in muscle tone (607 [58.3%] vs 1481 [45.1%]; SMD = 0.265). The incidence of serious underlying diagnoses was higher in the validation cohort (79 [7.6%] vs 150 [4.6%]; SMD = 0.126), whereas event recurrence rate was similar between cohorts (163 [15.6%] vs 469 [14.3%]; SMD = 0.038).
Serious Underlying Diagnosis
For the primary outcome, the AAP higher-risk criteria demonstrated high sensitivity at 100.0% (95% CI, 95.4%-100.0%) but poor specificity at 6.7% (95% CI, 5.2%-8.5%) (Table 2)6 and an LR+ of 1.07 (95% CI, 1.05-1.09). The AUC for discrimination was poor, at 0.53 (95% CI, 0.53-0.54) (Figure 1). Improved discrimination was achieved with the BRUE prediction rules, yielding an AUC of 0.60 (95% CI, 0.54-0.67; P = .02), comparable with an AUC of 0.61 (95% CI, 0.49-0.72) in the derivation cohort (Table 2).6 However, the BRUE prediction rule’s calibration was suboptimal (Figure 2 and eTable 4 in Supplement 1), tending to underestimate the risk of a serious underlying diagnosis (intercept: 0.60, slope: 0.81). After model revision, both the discrimination, with an AUC of 0.71 (95% CI, 0.65-0.76; P < .001), and calibration (intercept: 0.00, slope: 1.00) were considered satisfactory. Age in days had a coefficient of −0.0046 (SE = 0.0021) in the revised model, suggesting that the increasing age is associated with lower risk of a serious underlying diagnosis.
Table 2. Performance Metrics of the American Academy of Pediatrics (AAP) Higher-Risk Criteria and the Brief Resolved Explained Events (BRUE) Prediction Rules.
| Metric | Estimate (95% CI) | |
|---|---|---|
| Serious underlying diagnosis | Event recurrence | |
| Patients, No. (%) | 79 (7.6) | 163 (15.6) |
| AAP higher-risk criteria | ||
| Sensitivity, % | 100.0 (95.4-100.0) | 99.4 (96.6-100.0) |
| Specificity, % | 6.7 (5.2-8.5) | 7.3 (5.7-9.2) |
| PPV, % | 8.1 (6.5-10.0) | 16.6 (14.3-19.1) |
| NPV, % | 100.0 (94.5-100.0) | 98.5 (91.7-100.0) |
| LR+ | 1.07 (1.05-1.09) | 1.07 (1.05-1.10) |
| LR− | 0.00 (NAa) | 0.08 (0.01-0.60) |
| AUC | 0.53 (0.53-0.54) | 0.53 (0.52-0.54) |
| BRUE Prediction Rules (AUC) | ||
| Performance in the derivation cohortb | 0.61 (0.49-0.72) | 0.68 (0.62-0.74) |
| Performance in the validation cohort | ||
| Original model | 0.60 (0.54-0.67) | 0.67 (0.62-0.72) |
| Recalibration in the large | 0.61 (0.54-0.67) | 0.67 (0.63-0.71) |
| Logistic recalibration | 0.61 (0.55-0.67) | 0.67 (0.62-0.72) |
| Model revision | 0.71 (0.65-0.76) | 0.69 (0.66-0.74) |
Abbreviations: AUC, area under the curve; LR, likelihood ratio; NA, not applicable; NPV, negative predictive value; PPV, positive predictive value.
Calculation of the 95% CI for LR− cannot be performed when LR− is equal to 0.
Data from source.6
Figure 1. Receiver Operating Characteristic Curves.
The Brief Resolved Unexplained Events (BRUE) prediction rules (original model [blue] and after model revision [gray] are compared with the American Academy of Pediatrics [AAP] higher-risk criteria [orange]).
Figure 2. Calibration Plots for the Brief Resolved Unexplained Events (BRUE) Prediction Rule for Serious Underlying Diagnosis.
Calibration of the prediction rules began with the original model and underwent 3 incremental modifications. First, recalibration in the large adjusted the original model’s intercept to align with the prevalence of the outcome in the Canadian validation dataset. Next, logistic recalibration modified both the intercept and slope. The final adjustment was a model revision, resulting in a new logistic regression with updated coefficients and intercept.
Event Recurrence
Event recurrence was noted in 163 patients (15.6%). For this secondary outcome, the AAP higher-risk criteria were highly sensitive at 99.4% (95% CI, 96.6%-100.0%), the specificity remained low at 7.3% (95% CI, 5.7%-9.2%) (Table 2), LR+ was 1.07 (95% CI, 1.05-1.10), and AUC was 0.58 (95% CI, 0.56-0.58). The estimated AUC for discrimination was 0.53 (95% CI, 0.52-0.54). The BRUE prediction rule’s discrimination was higher, with an AUC of 0.67 (95% CI, 0.62-0.72; P < .001), which was on par with the derivation cohort’s AUC of 0.68 (95% CI, 0.62-0.74). Calibration for the BRUE prediction rule was deemed acceptable (intercept: 0.15, slope: 0.82) (Figure 3), and subsequent adjustments through the 3-step model refinement did not markedly enhance discrimination (AUC = 0.69; 95% CI, 0.66 to 0.74; P = .05).
Figure 3. Calibration Plots for the Brief Resolved Unexplained Events (BRUE) Prediction Rule for Event Recurrence.
Calibration of the prediction rules began with the original model and underwent three incremental modifications. First, recalibration in the large adjusted the original model’s intercept to align with the prevalence of the outcome in the Canadian validation dataset. Next, logistic recalibration modified both the intercept and slope. The final adjustment was a model revision, resulting in a new logistic regression with updated coefficients and intercept.
Sensitivity Analysis
In sensitivity analysis, transferred patients as well as those from 3 hospitals that only had access to admitted patients were excluded. A serious underlying diagnosis was noted in 33 of 691 patients (4.8%), and the discrimination of the BRUE prediction rules remained similar to the overall cohort, with an AUC of 0.60 (95% CI, 0.51-0.69) and 0.66 (95% CI, 0.58-0.75) after model revision (eTable 5 and eFigure 2 in Supplement 1). Calibration of the BRUE prediction rule was improved without evidence of underestimation of the risk (intercept: 0.14) (eFigure 3 in Supplement 1). Event recurrence was noted in 92 of 691 infants (13.3%), and the discrimination of the clinical prediction rules remained similar to the overall cohort, with an AUC of 0.67 (95% CI, 0.60-0.73) (eTable 5 and eFigure 2 in Supplement 1).
Discussion
In this large, multicenter cohort study of patients with BRUE, we found that the BRUE prediction rules outperformed the AAP higher-risk criteria on external geographical validation. Specifically, the BRUE prediction rule consistently underestimated risk to diagnose serious underlying condition. This underestimation was predominantly due to the higher incidence of these outcomes within our cohort than in the cohort used for model derivation. After appropriate model revisions, both discrimination and calibration metrics reached acceptable performance levels. For event recurrence, the original model demonstrated good performance not requiring revision. These BRUE prediction rules offer a valuable tool for clinicians, enabling the provision of individualized risk assessments. Consequently, health care professionals and families are better equipped to engage in informed discussions regarding potential risks, thereby guiding management decisions in alignment with their risk tolerance.
The findings from this study provide compelling evidence to reconsider the continued application of the AAP higher-risk criteria within the context of BRUE. Notably, the AAP criteria classified a significant majority (94%) of patients as higher risk, a trend that aligns with observations from various BRUE studies, where 74% to 93% of participants were similarly categorized as higher-risk.6,27,28,29,30,31 Furthermore, the discriminative ability of this stratification approach was markedly poor, approximating the efficacy of random chance for both evaluated outcomes. This observation echoes the results from a large US-based cohort study, which also reported notably inadequate discrimination by the AAP criteria.6 The propensity of the criteria to designate most individuals as higher risk may inadvertently escalate anxiety levels among health care providers and caregivers. Studies have shown that patients identified as higher risk under these criteria are more frequently subjected to hospital admissions and undergo diagnostic testing.32,33 This trend reinforces the argument for discontinuing the use of the AAP stratification.34
Regression models and clinical prediction rules often demonstrate optimal performance on the datasets from which they are derived.9,21 Unfortunately, this performance does not always generalize to other datasets, frequently resulting in diminished accuracy.23,35 The exponential increase in the derivation of these rules across clinical practices, and specifically in pediatric settings, has been accompanied by a concerning lack of external validation.36,37,38,39 In our external geographical validation, the original BRUE prediction rules performed similarly in terms of discrimination to what was observed in the derivation cohort and even better for the primary outcome after model revision. Notably, the original model for serious underlying diagnosis initially underestimated risk. This underestimation was resolved after recalibration, likely due to the higher prevalence in our cohort, influenced by including patients from 3 hospitals that only had access to admitted patients. This inclusion likely led to a selection bias toward a population with a higher risk profile, thereby increasing the prevalence of serious underlying diagnoses. A sensitivity analysis, excluding these hospitals, demonstrated minimized risk underestimation. For clinical application concerning serious underlying outcomes, reliance on the revised BRUE prediction rule is recommended due to its improved performance. However, the original BRUE prediction rule is advised for event recurrence, given the minimal gains observed with revision. Despite its fair discrimination, the original model represents the best available evidence, significantly outperforming the AAP stratification. When compared with other commonly used pediatric prediction tools, the performance of the BRUE prediction rules was similar. For instance, the urinary tract infection (UTI) calculator, UTICalc (University of Pittsburgh), a tool for assessing UTI risk in febrile children, demonstrated an AUC of 0.73 (95% CI, 0.68-0.79) in recent external validation.9 Similarly, the AAP guidelines for febrile infants yielded an AUC of 0.67 (95% CI, 0.65-0.69) for the identification of invasive bacterial infections.40
Incorporating precise risk percentages, as determined by clinical prediction rules, into clinical practice significantly enhances the nuanced understanding of patient risk, facilitating a more informed shared decision-making (SDM) process.41 This nuanced approach allows for a more tailored discussion between caregivers and health care providers, accommodating individual risk tolerance levels that broad risk categories cannot capture. For instance, a 5% risk of event recurrence might prompt some caregivers to opt for inpatient observation, whereas others may consider it low enough to monitor at home.3,4 There has been a growing focus on incorporating this risk tolerance variability into clinical guidelines and practices. A notable example is the AAP’s guidelines for managing febrile infants.42 These guidelines exemplify how SDM is integral in making informed decisions about antibiotic use, the necessity of lumbar punctures, and hospital admissions, all while respecting the varied risk tolerances among caregivers. Embracing the wide range of risk tolerance enables health care professionals to create a more collaborative decision-making environment, ensuring that care plans are closely aligned with the unique needs of each family.
Strengths and Limitations
Our study presents several key strengths. Primarily, it provides the first, to our knowledge, external validation of the BRUE prediction rules. Contrasting with the AAP higher-risk criteria, which lacked prior validation, our findings highlight prior risk stratification’s limitations and underscore the superior performance of our clinical prediction rules. This validation draws on a large multicenter cohort across diverse Canadian health care settings, from tertiary to community hospitals, enhancing the generalizability of our results. Furthermore, our approach facilitates obtaining more precise risk estimates, offering a more nuanced assessment than mere risk stratification.
However, our study is not without limitations. First, the discrimination of the BRUE prediction rules, while the best evidence available to date, was only fair. Future prospective studies with better ascertainment of the predictors and outcomes may improve the BRUE prediction rules discrimination. Additionally, our sample size (and the number of events) was not sufficient to conduct more sophisticated machine-learning techniques. Second, the diverse and heterogeneous nature of serious underlying diagnoses presents a challenge, particularly for patients identified as higher risk, complicating the determination of specific tests required. Third, the practical application of these clinical prediction rules can be complex due to the necessity for logistic regression analysis. To address this, we have developed a user-friendly calculator on MDCalc, and future integration into the electronic health record could further facilitate their use.43
Conclusions
In conclusion, in this large, multicenter cohort study, our BRUE prediction rules demonstrated significantly improved performance in identifying risks for serious conditions and event recurrence, compared with the widely applied AAP higher-risk criteria. Future studies should investigate if the use of the BRUE prediction rules, when integrated into SDM processes, can reduce unnecessary hospital admissions and excessive testing, while improving patient-centered outcomes like reducing caregiver anxiety and decisional conflict.
eTable 1. Checklist From Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) Statement
eTable 2. Examples of Findings for Abnormal Medical History, Concerning Family History, and Concerning Social History
eTable 3. Primary Outcome—Serious Underlying Diagnosis Among Patients With a Brief Resolved Unexplained Event (BRUE)
eTable 4. BRUE Prediction Rules With Regression Coefficients and Model Intercept for Each of the Two Outcomes of Interest
eTable 5. Sensitivity Analysis—Area Under the Curve for the AAP Higher-Risk Criteria and the BRUE Prediction Rules
eFigure 1. Precision-Recall Curves
eFigure 2. Sensitivity Analysis—Receiver Operating Characteristic (ROC) Curves
eFigure 3. Sensitivity Analysis—Calibration Plots for the BRUE Prediction Rules
Nonauthor Collaborators. Canadian BRUE Collaboration (C-BRUE-C) and the Canadian Paediatric Inpatient Research Network (PIRN).
Data Sharing Statement.
References
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
eTable 1. Checklist From Transparent Reporting of a Multivariable Prediction Model for Individual Prognosis or Diagnosis (TRIPOD) Statement
eTable 2. Examples of Findings for Abnormal Medical History, Concerning Family History, and Concerning Social History
eTable 3. Primary Outcome—Serious Underlying Diagnosis Among Patients With a Brief Resolved Unexplained Event (BRUE)
eTable 4. BRUE Prediction Rules With Regression Coefficients and Model Intercept for Each of the Two Outcomes of Interest
eTable 5. Sensitivity Analysis—Area Under the Curve for the AAP Higher-Risk Criteria and the BRUE Prediction Rules
eFigure 1. Precision-Recall Curves
eFigure 2. Sensitivity Analysis—Receiver Operating Characteristic (ROC) Curves
eFigure 3. Sensitivity Analysis—Calibration Plots for the BRUE Prediction Rules
Nonauthor Collaborators. Canadian BRUE Collaboration (C-BRUE-C) and the Canadian Paediatric Inpatient Research Network (PIRN).
Data Sharing Statement.



