Association of early hyponatremia and the development of acute kidney injury in critically ill children.

BACKGROUND: Hyponatremia is an independent prognostic factor for mortality; however, the reason for this remains unclear. An observed relationship between hyponatremia and the development of acute kidney injury (AKI) has been reported in certain disease states, but hyponatremia has not been evaluated as a predictor of AKI in critically ill patients or children. METHODS: This is a single-center retrospective cohort study of critically ill children admitted to a tertiary care center. We performed regression analysis to assess the association between hyponatremia at ICU admission and the development of new or worsening stage 2 or 3 (severe) AKI on days 2-3 following ICU admission. RESULTS: Among the 5057 children included in the study, early hyponatremia was present in 13.3% of children. Severe AKI occurred in 9.2% of children with hyponatremia compared to 4.5% of children with normonatremia. Following covariate adjustment, hyponatremia at ICU admission was associated with a 75% increase in the odds of developing severe AKI when compared to critically ill children with normonatremia (aOR 1.75, 95% CI 1.28-2.39). Evaluating sodium levels continuously, for every 1 mEq/L decrease in serum sodium level, there was a 0.05% increase in the odds of developing severe AKI (aOR 1.05, 95% CI 1.02-1.08). Hyponatremic children who developed severe AKI had a higher frequency of kidney replacement therapy, AKI or acute kidney disease at hospital discharge, and hospital mortality when compared to those without. CONCLUSIONS: Hyponatremia at ICU admission is associated with the development of new or worsening AKI in critically ill children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Putting Theory to Practice: Applying Cognitive Load Theory to Resident Medical Education.

OBJECTIVE: We built 2 versions of an asynchronous pediatric orthopedic educational intervention for emergency medicine residents and sought to compare the two. We hypothesized that the version incorporating more instructional scaffolding in the form of a cognitive aid (CA) would optimize germane cognitive load for our target novice learners and result in higher test scores. METHODS: Learners were block randomized to either a "CA" or "non-CA" arm, each containing a random set of 18 modules. The CA arm incorporated an orthopedic fracture classification chart embedded within the diagnostic questions to guide the learner in forming a diagnosis. The non-CA arm was designed with more active learning as the classification chart was provided only after each diagnostic answer submission. For both arms, the final 6 modules completed per learner were scored. Learners also completed a perceived cognitive load assessment tool measured on a 10-point Likert scale. RESULTS: Learners in the non-CA arm had a mean total score on the testing modules of 33% correct compared with a mean total score of 44% correct for learners in the CA arm (mean difference, 11; 95% confidence interval, 4%-19%, P = 0.005). There was a trend for the CA arm to have lower perceived overall cognitive load scores; however, this did not reach statistical significance. CONCLUSIONS: Emergency medicine residents performed better after completing the CA version of our educational intervention. Applying cognitive load theory to an educational intervention may increase its success among target learners.

Weather and temporal models for emergency medical services: An assessment of generalizability.

BACKGROUND: Emergency medical services (EMS) response volume has been linked to weather and temporal factors in a regional EMS system. We aimed to identify if models of EMS utilization incorporating these data are generalizable through geographically disparate areas in the United States. METHODS: We performed a retrospective analysis of EMS dispatch data from four regions: New York City, San Francisco, Cincinnati, and Marin County for years 2016-2019. For each model, we used local weather data summarized from the prior 6 h into hourly bins. Our outcome for each model was EMS dispatches as count data. We fit and optimized a negative binomial regression model for each region, to estimate incidence rate ratios. We compared findings to a prior study performed in Western Pennsylvania. RESULTS: We included 5,940,637 EMS dispatches from New York City, 809,405 from San Francisco, 260,412 from Cincinnati, and 77,461 from Marin County. Models demonstrated consistency with the Western Pennsylvania model with respect to temperature, season, wind speed, dew point, and time of day; both in terms of direction and effect size when expressed as incidence rate ratios. Precipitation was associated with increasing dispatches in the New York City, Cincinnati, and Marin County models, but not the San Francisco model. CONCLUSION: With minor differences, regional models demonstrated consistent associations between dispatches and time and weather variables. Findings demonstrate the generalizability of associations between these variables with respect to EMS use. Weather and temporal factors should be considered in predictive modeling to optimize EMS staffing and resource allocation.

Gaps Exist in the Comprehensive Care of Children with Inflammatory Bowel Diseases.

OBJECTIVES: To describe patterns of primary and specialty care delivery in pediatric patients with inflammatory bowel diseases (IBD), delineate which members of the healthcare team provided services, and identify gaps in care. STUDY DESIGN: Cross-sectional survey of parents of children (2-17 years) with IBD and adolescents with IBD (13-17 years) at a free-standing, quaternary children's hospital regarding healthcare receipt. RESULTS: There were 161 parents and 84 adolescents who responded to the survey (75% and 60% response, respectively). The mean patient age was 14 ± 3 years, 51% were male, 80% had Crohn's disease, 16% ulcerative colitis, and 4% IBD-unspecified. Most parents were white (94%), living in a suburban setting (57%). Sixty-nine percent of households had ≥1 parent with a bachelor's degree or higher. Most had private insurance (43%) or private primary with public secondary insurance (34%). Most patients received annual check-ups (70%), vaccinations (78%), and care for minor illnesses (74%) from their primary care provider. Check-ups for gastrointestinal symptoms, IBD monitoring, and changes in type/dosing of IBD treatment were provided by their gastroenterology provider (77%, 93%, and 86% of patients, respectively). Discussions about family/peer relationships, school/extracurricular activities, and mood were not addressed in 30%-40% of participants. Adolescents frequently reported that no one had talked to them about substance use (40%), sexual health (50%), or body image (60%); 75% of adolescents and 76% of their parents reported that no one had discussed transitioning to an adult provider. CONCLUSIONS: There were gaps in the psychosocial care of pediatric patients with IBD. Coordinated, comprehensive care delivery models are needed.

Enhanced recovery after surgery outcomes in minimally invasive nonhysterectomy gynecologic procedures.

BACKGROUND: Improved patient outcomes and satisfaction associated with enhanced recovery after surgery protocols have increasingly replaced traditional perioperative anesthesia care. Fast-track surgery pathways have been extensively validated in patients undergoing hysterectomies, yet the impact on fertility-sparing laparoscopic gynecologic operations, particularly those addressing chronic pain conditions, has not been examined. OBJECTIVE: The objective of the study was to determine the effects of enhanced recovery after surgery pathway implementation compared with conventional perioperative care in women undergoing laparoscopic minimally invasive nonhysterectomy gynecologic procedures. STUDY DESIGN: We conducted a retrospective cohort study of women undergoing uterine-sparing laparoscopic gynecologic procedures for benign conditions (tubal/adnexal pathology, endometriosis, or leiomyomas) during a 24 month period before and after enhanced recovery after surgery implementation at a tertiary care center. We compared immediate perioperative outcomes and 30 day complications. The primary outcome was same-day discharge rates. Factors influencing unplanned admissions, postoperative pain, sedation, nausea, and vomiting represented secondary analyses. RESULTS: A total of 410 women (enhanced recovery after surgery, n = 196; conventional perioperative care, n = 214) met inclusion criteria. Following enhanced recovery after surgery implementation, same-day discharge rates increased by 9.4% (P = .001). Reductions in postoperative pain and nausea/vomiting represented the primary driving factor behind lower unplanned admissions. Higher preoperative antiemetic medication administration in the enhanced recovery after surgery group resulted in a 57% reduction in postanesthesia care unit antiemetics (P < .001). Total perioperative narcotic medication use was also significantly reduced by 64% (P < .001), and the enhanced recovery after surgery cohort still demonstrated significantly lower postanesthesia unit care pain scores at hours 2 and 3 (P < .001). A 19 minute shorter postanesthesia care unit stay was noted in the enhanced recovery after surgery cohort (P = .036). Increased same-day discharge did not lead to higher postoperative complications or changes in 30 day emergency department visits or readmissions in patients with enhanced recovery after surgery. CONCLUSION: Enhanced recovery after surgery implementation resulted in increased same-day discharge rates and improved perioperative outcomes without affecting 30 day morbidity in women undergoing laparoscopic minimally invasive nonhysterectomy gynecologic procedures.

Cost-effectiveness of levofloxacin prophylaxis against bacterial infection in pediatric patients with acute myeloid leukemia.

BACKGROUND: Infections are the leading cause of therapy-related mortality in pediatric patients with acute myeloid leukemia (AML). Although effectiveness of levofloxacin antibacterial prophylaxis in oncology patients is recognized, its cost-effectiveness is unknown. This study evaluated epidemiologic data regarding levofloxacin use and the cost-effectiveness of this strategy as the cost per bacteremia episode, intensive care unit (ICU) admission, and death avoided in children with AML. PROCEDURE: A retrospective cohort study using the Pediatric Health Information System (PHIS) database compared demographic and clinical characteristics and receipt of levofloxacin prophylaxis in children with AML admitted for chemotherapy from January 1, 2014, through December 31, 2018. We then developed a decision analysis model in this population that compared costs associated with bacteremia, ICU admission, or death secondary to bacteremia to levofloxacin prophylaxis cost from a healthcare perspective. Time horizon is one chemotherapy cycle. Probabilistic and one-way sensitivity analyses evaluated model uncertainty. RESULTS: Prophylaxis cost $8491 per bacteremia episode prevented compared with an average added hospital cost of $119 478. Prophylaxis cost $81 609 per ICU admission avoided, compared with an average added hospital cost of $94 181. Prophylaxis cost $220 457 per death avoided. In sensitivity analysis, at a willingness-to-pay threshold of $100 000 per bacteremia episode avoided, prophylaxis remained cost-effective in 94.6% of simulations. Prophylaxis use was more common in recent years in patients with relapsed disease and with chemotherapy regimens considered more intensive. CONCLUSION: Prophylaxis is cost-effective in preventing bacterial infections in patients with AML. Findings support increased use in patients considered at high risk of bacterial infection secondary to myelosuppression.

Pulmonary Complications of Opioid Overdose Treated With Naloxone.

STUDY OBJECTIVE: We aim to determine whether administration of higher doses of naloxone for the treatment of opioid overdose is associated with increased pulmonary complications. METHODS: This was a retrospective, observational, cross-sectional study of 1,831 patients treated with naloxone by the City of Pittsburgh Bureau of Emergency Medical Services. Emergency medical services and hospital records were abstracted for data in regard to naloxone dosing, route of administration, and clinical outcomes, including the development of complications such as pulmonary edema, aspiration pneumonia, and aspiration pneumonitis. For the purposes of this investigation, we defined high-dose naloxone as total administration exceeding 4.4 mg. Multivariable analysis was used to attempt to account for confounders such as route of administration and pretreatment morbidity. RESULTS: Patients receiving out-of-hospital naloxone in doses exceeding 4.4 mg were 62% more likely to have a pulmonary complication after opioid overdose (42% versus 26% absolute risk; odds ratio 2.14; 95% confidence interval 1.44 to 3.18). This association remained statistically significant after multivariable analysis with logistic regression (odds ratio 1.85; 95% confidence interval 1.12 to 3.04). A secondary analysis showed an increased risk of 27% versus 13% (odds ratio 2.57; 95% confidence interval 1.45 to 4.54) when initial naloxone dosing exceeded 0.4 mg. Pulmonary edema occurred in 1.1% of patients. CONCLUSION: Higher doses of naloxone in the out-of-hospital treatment of opioid overdose are associated with a higher rate of pulmonary complications. Furthermore, prospective study is needed to determine the causality of this relationship.

Patterns of Primary, Specialty, Urgent Care, and Emergency Department Care in Children With Inflammatory Bowel Diseases.

OBJECTIVES: Pediatric patients with inflammatory bowel diseases (IBD) require treatment, monitoring, and health maintenance services. We described patterns of primary, specialty, emergency department (ED) and urgent care delivery, and explored patient- and system-related variables that impact ED/urgent care utilization. METHODS: We conducted a cross sectional survey of parents of children with IBD at a large tertiary children's hospital. RESULTS: One hundred sixty-one parents completed the survey (75% response). Mean patient age 13.9 years (51% boys); 80% Crohn disease, 16% ulcerative colitis, 4% IBD-unspecified. Mean disease duration 4 years (standard deviation [SD] 2.7). Thirty percent had at least 1 other chronic disease, 31% had a history of IBD-related surgery. Parents were predominantly Caucasian (94%), well-educated (61% bachelor's degree/higher), part of a 2-parent household (79%) living in a suburban setting (57%). Seventy-seven percent of patients had private insurance. In the past year, most children had 1 to 2 IBD-related office visits (54%) with their gastroenterology (GI) doctor and no IBD-related hospitalizations (79%). Eighty-eight percent (N = 141) had a primary care provider (PCP), and most (70%) saw their PCP 1 to 2 times. Even so, 86% (N = 139) received medical care from places other than their PCP or GI doctor; 27% in the ED and 45% at urgent care. Children of parents with less than a bachelor's degree, families that lived further from their GI doctor, and children who saw their PCP more often were more likely to utilize ED/urgent care. CONCLUSIONS: ED/urgent care utilization in pediatric patients with IBD was greater than expected, potentially contributing to fragmented, costly care and worse outcomes.

Comparing acne follow-up: teledermatology versus outpatient dermatology visits.

The application of teledermatology for evaluating acne patients has yielded comparable therapeutic outcomes with traditional face-to-face evaluation, but follow-up compliance between these modalities is not well-studied. Our objective is to compare the rate and duration of follow-up between acne patients initially evaluated by teledermatology versus in-person outpatient consultation. Electronic medical review of acne patients, 18-35 years-old seen via teledermatology and face-to-face evaluation at the University of Pittsburgh Medical Center between 2010-2018 was performed. Teledermatology patients were less likely to follow-up in the first 90 days (13.0% versus 31.0%, P<0.001) compared to patients seen face-to-face with overall follow-up rates of 22% among both modalities. The median time to follow-up was 45.5 days (IQR: 13/57) in the teledermatology group compared to 64 days (IQR: 56/77) in the face-to-face group (P<0.001). Teledermatology patients were more likely to be treated with oral antibiotics (43.0% versus 28.5%) or oral spironolactone (18.5% versus 12.5%) compared to patients seen face-to-face (P<0.001). Teledermatology poses a promising solution to extend dermatologic care with earlier access to follow-up. Our data demonstrates a need to improve teledermatology follow-up education to improve follow-up care.

Shared Decision Making About Starting Anti-TNFs: A Pediatric Perspective.

Shared decision making (SDM) is central to patient-centered medicine and has the potential to improve outcomes for pediatric patients with inflammatory bowel diseases. We surveyed specialists about their use of SDM in the decision to start a tumor necrosis factor-α inhibitor in pediatric patients. Results were compared between those who reported using SDM and those who did not. Of 209 respondents, 157 (75%) reported using SDM. Physician/practice characteristics were similar between users and nonusers. There were no statistically significant differences between groups in the components deemed important to the decision-making process nor the number of barriers or facilitators to SDM. Exploratory analyses suggested that physicians using SDM were more accepting of adolescent involvement in the decision-making process. Our results question the effectiveness of using reported barriers and facilitators to guide interventions to improve use of SDM, and suggest further work is needed to understand the adolescent role in decision making.

Seasonal, Weather, and Temporal Factors in the Prediction of Admission to a Pediatric Trauma Center.

BACKGROUND: Our objective is to identify seasonal and weather trends associated with pediatric trauma admissions. METHODS: We reviewed all trauma activations leading to admission in patients ≤18 years admitted to a regional pediatric trauma center from January 1, 2000, to December 31, 2015. We reviewed climatologic measures of the mean temperature, mean visibility, and precipitation for each admission in the 6 h prior to each presentation in addition to time of arrival, weekday/weekend presentation, and season. We used a negative binomial regression model with multivariable analysis to estimate associations between weather and rate of trauma admissions. Results were presented as incidence rate ratios (IRR) with 95% confidence intervals (CI). RESULTS: In total, 3856 encounters [2539 males (65.8%), mean age 10.2 years ± SD 5.1 years] were included. Results from multivariable analysis (IRR, 95% CI) suggested an association of admissions with rain (0.82, 0.75-0.90) and overnight hours (23:51-05:50; 0.69, 0.58-0.82) as compared to morning (05:51-11:50). The IRR of trauma increased during the afternoon (11:51-17:50; 4.05, 3.57-4.61), night periods (17:51-23:50; 5.59, 4.94-6.33), and weekends (1.24, 1.15-1.32), and with every 1 °C increase in temperature (1.04, 1.03-1.04). After accounting for other variables, season was not found to be independently predictive of trauma admission. CONCLUSION: Trauma admissions had a higher rate during afternoon, evening hours, and weekends. The presence of rain lowered the rate of pediatric trauma admission. Each degree increase in temperature increased the rate of trauma admissions by 4%. The findings provide information from the perspective of emergency preparedness, resource utilization, and staffing to pediatric trauma centers.

Weather and Temporal Factors Associated with Use of Emergency Medical Services.

Background: Fluctuations in emergency medical services (EMS) responses can have a substantial impact on the ability of agencies to meet resource needs within an EMS system. We aimed to identify weather characteristics as potentially predictable factors associated with EMS responses. Methods: We reviewed hourly counts of scene responses documented by 24 EMS agencies in Western Pennsylvania from January 1, 2014 to December 31, 2017 and compared rates of responses to weather characteristics. Responses to counties nonadjacent to the studied weather reporting station and interfacility/scheduled transports were excluded. We identified the mean temperature, meters visibility, dew point, wind speed, total millimeters of precipitation, and presence of rain or snow in 6-hour windows prior to dispatch, in addition to temporal factors of time of day and weekend vs. weekday. Analysis was performed using multivariable linear regression of a negative binomial distribution, reporting incidence rate ratios (IRR) with 95% confidence intervals (CI). Secondary analyses were performed for transports to the hospital and cases involving transports for traumatic complaints and pediatric patients (age <18 years). Results: We included 529,058 responses (54.8% female, mean age 57.2 ± SD 24.7 years). In our multivariable model, responses were associated with (IRR, 95% CI) rain (1.10, 1.08-1.11) snow (1.07, 1.05-1.09), and both rain and snow (1.15, 1.11-1.19). A lower incidence of responses occurred on weekends (0.84, 0.83-0.85) and at night (0.62, 0.61-0.62). Increasing temperature in 5 °C increments was associated with an increase in responses across seasons with an effect that varied between 1.16 (1.15-1.17) in winter to 1.31 (1.28-1.33) in summer. Windy weather was associated with increased responses from light breeze (1.10, 1.09-1.11) to fresh breeze or greater (1.23, 1.16-1.30). Transports occurred in a similar pattern to responses. Trauma transports (n = 64,235) occurred more during weekends (1.04, 1.02-1.06). Pediatric transports (n = 21,880) were not significantly associated with precipitation or season. Conclusion: EMS responses increased with rising temperature and following rain and snow. These findings may assist in planning by EMS agencies and emergency departments to identify periods of greatest resource utilization.

Presenting predictors and temporal trends of treatment-related outcomes in diabetic ketoacidosis.

OBJECTIVE: This study examines temporal trends in treatment-related outcomes surrounding a diabetic ketoacidosis (DKA) performance improvement intervention consisting of mandated intensive care unit admission and implementation of a standardized management pathway, and identifies physical and biochemical characteristics associated with outcomes in this population. METHODS: A retrospective cohort of 1225 children with DKA were identified in the electronic health record by international classification of diseases codes and a minimum pH less than 7.3 during hospitalization at a quaternary children's hospital between April, 2009 and May, 2016. Multivariable regression examined predictors and trends of hypoglycemia, central venous line placement, severe hyperchloremia, head computed tomography (CT) utilization, treated cerebral edema and hospital length of stay (LOS). RESULTS: The incidence of severe hyperchloremia and head CT utilization decreased during the study period. Among patients with severe DKA (presenting pH < 7.1), the intervention was associated with decreasing LOS and less variability in LOS. Lower pH at presentation was independently associated with increased risk for all outcomes except hypoglycemia, which was associated with higher pH. Patients treated for cerebral edema had a lower presenting mean systolic blood pressure z score (0.58 [95% confidence interval (CI) -0.02-1.17] vs 1.23 [1.13-1.33]) and a higher maximum mean systolic blood pressure (SBP) z score during hospitalization (3.75 [3.19-4.31] vs 2.48 [2.38-2.58]) compared to patients not receiving cerebral edema treatment. Blood pressure and cerebral edema remained significantly associated after covariate adjustment. CONCLUSION: Treatment-related outcomes improved over the entire study period and following a performance improvement intervention. The association of SBP with cerebral edema warrants further study.

Effect of insomnia treatments on depression: A systematic review and meta-analysis.

BACKGROUND: Insomnia is frequently co-morbid with depression, with a bidirectional relationship between these disorders. There is evidence that insomnia-specific interventions, such as cognitive behavioral therapy for insomnia, may lead to improvements in depression. The purpose of this systematic review and meta-analysis is to determine whether treatment of insomnia leads to improved depression outcomes in individuals with both insomnia and depression. METHODS: We conduct a systematic review and meta-analysis to explore the effect of treatment for insomnia disorder on depression in patients with both disorders. RESULTS: Three thousand eight hundred and fifteen studies were reviewed, and 23 studies met inclusion criteria. Although all of the studies suggested a positive clinical effect of insomnia treatment on depression outcomes, most of the results were not statistically significant. Although the interventions and populations were highly variable, the meta-analysis indicates moderate to large effect size (ES) improvement in depression as measured with the Hamilton Depression Rating Scale (ES = -1.29, 95%CI [-2.11, -0.47]) and Beck Depression Inventory (ES = -0.68, 95%CI [-1.29, -0.06]). CONCLUSIONS: These results support that treating insomnia in patients with depression has a positive effect on mood. Future trials are needed to identify the subtypes of patients whose depression improves during treatment with insomnia-specific interventions, and to identify the mechanisms by which treating insomnia improves mood.

The AIDS Epidemic Model 2023 for Estimating HIV Trends and Transmission Dynamics in Asian Epidemic Settings.

BACKGROUND: Thirteen Asian countries use the AIDS Epidemic Model (AEM) as their HIV model of choice. This article describes AEM, its inputs, and its application to national modeling. SETTING: AEM is an incidence tool used by Spectrum for the Joint United Nations Programme on HIV/AIDS global estimates process. METHODS: AEM simulates transmission of HIV among key populations (KPs) using measured trends in risk behaviors. The inputs, structure and calculations, interface, and outputs of AEM are described. The AEM process includes (1) collating and synthesizing data on KP risk behaviors, epidemiology, and size to produce model input trends; (2) calibrating the model to observed HIV prevalence; (3) extracting outputs by KP to describe epidemic dynamics and assist in improving responses; and (4) importing AEM incidence into Spectrum for global estimates. Recent changes to better align AEM mortality with Spectrum and add preexposure prophylaxis are described. RESULTS: The application of AEM in Thailand is presented, describing the outputs and uses in-country. AEM replicated observed epidemiological trends when given observed behavioral inputs. The strengths and limitations of AEM are presented and used to inform thoughts on future directions for global models. CONCLUSIONS: AEM captures regional HIV epidemiology well and continues to evolve to meet country and global process needs. The addition of time-varying mortality and progression parameters has improved the alignment of the key population compartmental model of AEM with the age-sex-structured national model of Spectrum. Many of the features of AEM, including tracking the sources of infections over time, should be incorporated in future global efforts to build more generalizable models to guide policy and programs.

Dynamics of SARS-CoV-2 Seroprevalence in a Large US population Over a Period of 12 Months.

Due to a combination of asymptomatic or undiagnosed infections, the proportion of the United States population infected with SARS-CoV-2 was unclear from the beginning of the pandemic. We previously established a platform to screen for SARS-CoV-2 positivity across a representative proportion of the US population, from which we reported that almost 17 million Americans were estimated to have had undocumented infections in the Spring of 2020. Since then, vaccine rollout and prevalence of different SARS-CoV-2 variants have further altered seropositivity trends within the United States population. To explore the longitudinal impacts of the pandemic and vaccine responses on seropositivity, we re-enrolled participants from our baseline study in a 6- and 12- month follow-up study to develop a longitudinal antibody profile capable of representing seropositivity within the United States during a critical period just prior to and during the initiation of vaccine rollout. Initial measurements showed that, since July 2020, seropositivity elevated within this population from 4.8% at baseline to 36.2% and 89.3% at 6 and 12 months, respectively. We also evaluated nucleocapsid seropositivity and compared to spike seropositivity to identify trends in infection versus vaccination relative to baseline. These data serve as a window into a critical timeframe within the COVID-19 pandemic response and serve as a resource that could be used in subsequent respiratory illness outbreaks.

Use of a metalearner to predict emergency medical services demand in an urban setting.

OBJECTIVE: To develop and internally validate a metalearner algorithm to predict the hourly rate of emergency medical services (EMS) dispatches in an urban setting. METHODS: We performed an analysis of EMS data from New York City between years 2015-2019. Our outcome was hourly EMS dispatches, expressed as continuous data. Hours were split into derivation (75%) and validation (25%) datasets. Candidate variables included averages of prior rates, temporal and weather characteristics. We used a metalearner to evaluate and aggregate individual learners (generalized linear model, generalized additive model, random forest, multivariable adaptive regression splines, and extreme gradient boost). Four models were investigated: 1) temporal variables, 2) weather and temporal variables, and datasets in which weather data were lagged by 3) six and 4) twelve hours. In exploratory analyses, we constructed learners for high acuity and trauma encounters. RESULTS: 7,364,275 EMS dispatches occurred during the 43,823-hour period. When using temporal variables, the mean absolute error (MAE) rate was 11.5 dispatches in the validation dataset. These were slightly improved following incorporation of weather variables (MAE 11.3). When using 6- and 12-hour lagged weather variables, learners demonstrated lower accuracy (MAE 11.8 in 6-hour lagged datasets; 12.2 in 12-hour lagged dataset). All models had a coefficient of determination (R2) ≥0.91. The extreme gradient boosting and random forest learners were assigned the highest coefficients. In an investigation of variable importance, hour of day and average EMS dispatches over the previous six hours were the most important variables in both the extreme gradient boosting and random forest learners. The algorithm performed well at predicting frequently occurring peaks, with greater challenges at both extremes. Learners created high-acuity and for trauma-related encounters demonstrated superior MAE, but with lower R2 in the validation cohort (MAE 6.9 and R2 0.84 for high acuity encounters; MAE 5.3 and R2 0.79 for trauma in learners using time and weather variables). CONCLUSION: We developed an ensemble machine learning algorithm to predict EMS dispatches in an urban setting. These models demonstrated high accuracy, with MAEs <12 per hour in all. These algorithms may carry benefit in the real-time prediction of EMS responses, allowing for improved resource utilization.

Mapping a Pandemic: SARS-CoV-2 Seropositivity in the United States.

Asymptomatic SARS-CoV-2 infection and delayed implementation of diagnostics have led to poorly defined viral prevalence rates. To address this, we analyzed seropositivity in US adults who have not previously been diagnosed with COVID-19. Individuals with characteristics that reflect the US population (n = 11,382) and who had not previously been diagnosed with COVID-19 were selected by quota sampling from 241,424 volunteers (ClinicalTrials.gov NCT04334954). Enrolled participants provided medical, geographic, demographic, and socioeconomic information and 9,028 blood samples. The majority (88.7%) of samples were collected between May 10th and July 31st, 2020. Samples were analyzed via ELISA for anti-Spike and anti-RBD antibodies. Estimation of seroprevalence was performed by using a weighted analysis to reflect the US population. We detected an undiagnosed seropositivity rate of 4.6% (95% CI: 2.6 - 6.5%). There was distinct regional variability, with heightened seropositivity in locations of early outbreaks. Subgroup analysis demonstrated that the highest estimated undiagnosed seropositivity within groups was detected in younger participants (ages 18-45, 5.9%), females (5.5%), Black/African American (14.2%), Hispanic (6.1%), and Urban residents (5.3%), and lower undiagnosed seropositivity in those with chronic diseases. During the first wave of infection over the spring/summer of 2020 an estimate of 4.6% of adults had a prior undiagnosed SARS-CoV-2 infection. These data indicate that there were 4.8 (95% CI: 2.8-6.8) undiagnosed cases for every diagnosed case of COVID-19 during this same time period in the United States, and an estimated 16.8 million undiagnosed cases by mid-July 2020.