What's New in Pediatric Septic Arthritis? A Review of Pertinent Clinical Questions.

BACKGROUND: The evaluation and treatment of children with septic arthritis (SA) is challenging and requires an organized approach to address the spectrum of pathogens which appear to aggregate in age-specific groups. Although evidence-based guidelines have recently been published for the evaluation and treatment of children with acute hematogenous osteomyelitis, there is a relative dearth of literature devoted exclusively to SA. METHODS: Recently published guidance for the evaluation and treatment of children with SA was reviewed and evaluated with respect to pertinent clinical questions to summarize what is new in this area of practice for pediatric orthopaedic surgeons. RESULTS: Evidence suggests that there is a profound difference between children with primary SA and those who have contiguous osteomyelitis. This disruption of the commonly accepted paradigm of a continuum of osteoarticular infections has important implications in the evaluation and treatment of children with primary SA. Clinical prediction algorithms have been established to help determine the applicability of magnetic resonance imaging during the evaluation of children suspected to have SA. Antibiotic duration for SA has been recently studied with some evidence in favor of short-course parenteral followed by short-course oral therapy may be successful if the pathogen is not methicillin-resistant Staphylococcus aureus . CONCLUSION: Recent studies of children with SA have provided better guidance for evaluation and treatment to improve diagnostic accuracy, processes of evaluation, and clinical outcomes. LEVEL OF EVIDENCE: Level 4.

Children with Primary Septic Arthritis Have a Markedly Lower Risk of Adverse Outcomes Than Those with Contiguous Osteomyelitis.

BACKGROUND: It is widely believed that septic arthritis poses a risk of joint destruction and long-term adverse outcomes for children if not treated emergently. In the present study, children who had primary confirmed septic arthritis were compared with those who had septic arthritis and adjacent osteomyelitis to evaluate differences that affect the relative risk of adverse outcomes. METHODS: Children who underwent multidisciplinary treatment for septic arthritis with or without contiguous osteomyelitis between 2009 and 2019 were retrospectively studied. Clinical, laboratory, treatment, and outcome data were compared between cohorts of children with primary confirmed septic arthritis and children with septic arthritis and contiguous osteomyelitis. RESULTS: One hundred and thirty-four children had primary confirmed septic arthritis, and 105 children had septic arthritis with contiguous osteomyelitis. Children with osteomyelitis were older (median, 7.4 versus 2.4 years), had higher initial C-reactive protein (median, 15.7 versus 6.4 mg/dL), and had a higher rate of thrombocytopenia (21.0% versus 1.5%). They also had a higher rate of bacteremia (69.5% versus 20.2%) for a longer duration (median, 2.0 versus 1.0 days). Detected pathogens in children with osteomyelitis as compared with those with primary septic arthritis were more likely to be Staphylococcus aureus (77.1% versus 32.1%) and less likely to be Kingella kingae (2.9% versus 32.1%). Children with contiguous osteomyelitis had longer hospitalizations (median, 8.0 versus 4.0 days), a higher rate of intensive care (21.0% versus 1.5%), a higher readmission rate (17.1% versus 5.2%), and a higher complication rate (38.1% versus 0.7%). CONCLUSIONS: Primary septic arthritis in children is dissimilar to septic arthritis associated with osteomyelitis. The present study demonstrates that long-term adverse outcomes in children with septic arthritis are likely due to the contiguous osteomyelitis. Children with primary septic arthritis are sufficiently distinguishable from those who have contiguous osteomyelitis to guide decisions for magnetic resonance imaging acquisition, duration of antibiotic therapy, and length of outpatient follow-up in order to recognize and address adverse outcomes. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Modelling and predicting the spatio-temporal spread of COVID-19, associated deaths and impact of key risk factors in England.

COVID-19 caseloads in England have passed through a first peak, and at the time of this analysis appeared to be gradually increasing, potentially signalling the emergence of a second wave. To ensure continued response to the epidemic is most effective, it is imperative to better understand both retrospectively and prospectively the geographical evolution of COVID-19 caseloads and deaths at small-area resolution, identify localised areas in space-time at significantly higher risk, quantify the impact of changes in localised population mobility (or movement) on caseloads, identify localised risk factors for increased mortality and project the likely course of the epidemic at high spatial resolution in coming weeks. We applied a Bayesian hierarchical space-time SEIR model to assess the spatiotemporal variability of COVID-19 caseloads (transmission) and deaths at small-area scale in England [Middle Layer Super Output Area (MSOA), 6791 units] and by week (using observed data from week 5 to 34 of 2020), including key determinants, the modelled transmission dynamics and spatial-temporal random effects. We also estimate the number of cases and deaths at small-area resolution with uncertainty projected forward in time by MSOA (up to week 51 of 2020), the impact mobility reductions (and subsequent easing) have had on COVID-19 caseloads and quantify the impact of key socio-demographic risk factors on COVID-19 related mortality risk by MSOA. Reductions in population mobility during the course of the first lockdown had a significant impact on the reduction of COVID-19 caseloads across England, however local authorities have had a varied rate of reduction in population movement which our model suggest has substantially impacted the geographic heterogeneity in caseloads at small-area scale. The steady gain in population mobility, observed from late April, appears to have contributed to a slowdown in caseload reductions towards late June and subsequent start of the second wave. MSOA with higher proportions of elderly (70+ years of age) and elderly living in deprivation, both with very distinct geographic distributions, have a significantly elevated COVID-19 mortality rates. While non-pharmaceutical interventions (that is, reductions in population mobility and social distancing) had a profound impact on the trajectory of the first wave of the COVID-19 outbreak in England, increased population mobility appears to have significantly contributed to the second wave. A number of contiguous small-areas appear to be at a significant elevated risk of high COVID-19 transmission, many of which are also at increased risk for higher mortality rates. A geographically staggered re-introduction of intensified social distancing measures is advised and limited cross MSOA movement if the magnitude and geographic extent of the second wave is to be reduced.

Primary Septic Arthritis Among Children 6 to 48 Months of Age: Implications for PCR Acquisition and Empiric Antimicrobial Selection.

INTRODUCTION: Primary septic arthritis requires unique evaluation and treatment considerations for children in the 6- to 48-month age range because of the spectrum of identified pathogens and high rate of negative cultures. The purpose of this study is to evaluate primary septic arthritis in this age group in order to differentiate children with infection caused by Kingella kingae from those with other confirmed pathogens and those with no identified pathogen. METHODS: Preschool children who underwent multidisciplinary evaluation and treatment for septic arthritis between 2009 and 2019 were retrospectively studied. Three cohorts were established for comparison of clinical and laboratory features of primary septic arthritis: (1) confirmed K. kingae, (2) confirmed other pathogen, and (3) presumed (without identified pathogen). RESULTS: Among 139 children with septic arthritis, 40 (29%) were confirmed K. kingae, 29 (21%) other pathogen, and 70 (50%) presumed. Children with Kingella and those with presumed septic arthritis had significantly lower initial C-reactive protein (4.8 and 4.5 vs. 9.3 mg/dL) and fewer febrile hospital days (0.2 and 0.4 vs. 1.3 d) than children with other confirmed pathogens. Children with other pathogens had higher rates of bacteremia (38% vs. 0%) and positive joint fluid cultures (86% vs. 15%) than that of children with Kingella. The rate of polymerase chain reaction (PCR) acquisition was 38 of 40 (95.0%) Kingella cases, 18 of 29 (62.1%) other pathogen cases, and 33 of 70 (47.1%) presumed cases. CONCLUSIONS: K. kingae was the most commonly identified pathogen among 6-month to 4-year-old children. The Kingella and other identified pathogens in this study serve to guide empiric antimicrobial recommendations for this age range. Because of similarities between children with septic arthritis because of K. kingae and those with no identified pathogen, it is likely that an unrecognized burden of Kingella resides in culture negative cases, particularly if no PCR is sent. Systematic evaluation, including PCR acquisition, and a high index of suspicion for K. kingae are recommended to thoroughly evaluate septic arthritis in preschool children. LEVEL OF EVIDENCE: Level III-Retrospective cohort comparison.

Pediatric Type II Supracondylar Humerus Fractures: Factors Associated With Successful Closed Reduction and Immobilization.

PURPOSE: The debate on the treatment of type IIa supracondylar humerus fractures has yet to be resolved. The purpose of this study was to assess the factors associated with successful closed reduction and immobilization and to assess the efficacy of a novel radiographic "hourglass" angle measurement in the management of type IIa supracondylar humerus fractures within the pediatric population. METHODS: An institutional review board-approved retrospective review of all children who underwent closed reduction and casting or splinting of an isolated type IIa supracondylar humerus fractures treated at 2 pediatric hospitals from January 1, 2009 to August 31, 2016. Analyzed radiographic parameters included Baumann angle (BA), humerocondylar angle (HCA), perpendicular distance (PD) from the anterior humeral line to the capitellum, and the hourglass angle (HGA). These parameters were measured on injury radiographs (XR), postreduction XR, and at the first and final follow-up XR. The success of closed reduction was defined as maintenance of an acceptable reduction without a secondary procedure. The interobserver reliability was calculated. RESULTS: There were 77 elbows treated with closed reduction and long-arm cast or splint immobilization. Of those closed reductions, 76.62% of elbows (59/77) maintained their reduction alignment and did not require surgical treatment for percutaneous pinning. In this series, the BA was not significantly different following closed reduction ([INCREMENT]1.04 degrees; P=0.081); however, the PD ([INCREMENT]1.89 mm), HGA ([INCREMENT]7.38 degrees), and HCA ([INCREMENT]5.07 degrees) had significant improvement following closed reduction (P<0.001 for all). The use of procedural sedation during reduction was strongly associated with success, 83.05% (49/59) with sedation compared with 55.56% (10/18) success without sedation (P=0.025). Furthermore, fractures that underwent a secondary procedure had 6.20 degrees less HGA following a closed reduction (P=0.016) and required additional follow-up visits (P=0.0037). The success of type IIa supracondylar humerus fractures did not significantly differ based on sex (P=0.5684), laterality (P=0.6975), mechanism of injury (P>0.9999), location of care-emergency department versus clinic (P=0.1160), or type of fracture immobilization (P=0.7411). The mean HGA in normal elbows was 177.8 degrees. The interobserver reliability for HCA was poor [intraclass correlation coefficient (ICC)=0.342]; fair for BA (ICC=0.458); and excellent for both PD and HGA (ICC=0.769 and 0.805, respectively) (P<0.001 for all). CONCLUSIONS: Improved and acceptable radiographic parameters were achieved by a closed reduction in the majority of minimally displaced type IIa fractures treated by closed reduction and immobilization in this series. HCA upon presentation was significantly greater in successful cases, and failure to improve and maintain HGA and PD following closed reduction was associated with loss of reduction. Procedural sedation during reduction was strongly associated with success. The HGA and PD were consistent parameters used to determine effective management of type IIa fractures. This study adds support for a nonoperative closed reduction under sedation with immobilization of selected type IIa supracondylar humerus fractures.

A data-driven approach for estimating the change-points and impact of major events on disease risk.

Considering the impact of events on disease risk is important. Here, a Bayesian spatio-temporal accelerated failure time model furnished an ideal situation for modeling events that could impact survival experience via spatial and temporal frailty estimates. Through a hierarchical structure, this model allowed the data to detect the change-point(s) in addition to generating the event-related estimates. Both a real data case study and a simulation study were employed for testing these methods. The results suggested that meaningful and accurate change-points could be detected. Further, accurate event-related estimates for individuals in relation to those change-points could be obtained. By allowing the data to drive the change-point choices, the models were better fitting and the inference was more accurate.

Multivariate Air Pollution Prediction Modeling with partial Missingness.

Missing observations from air pollution monitoring networks have posed a longstanding problem for health investigators of air pollution. Growing interest in mixtures of air pollutants has further complicated this problem, as many new challenges have arisen that require development of novel methods. The objective of this study is to develop a methodology for multivariate prediction of air pollution. We focus specifically on tackling different forms of missing data, such as: spatial (sparse sites), outcome (pollutants not measured at some sites), and temporal (varieties of interrupted time series). To address these challenges, we develop a novel multivariate fusion framework, which leverages the observed inter-pollutant correlation structure to reduce error in the simultaneous prediction of multiple air pollutants. Our joint fusion model employs predictions from the Environmental Protection Agency's Community Multiscale Air Quality (CMAQ) model along with spatio-temporal error terms. We have implemented our models on both simulated data and a case study in South Carolina for 8 pollutants over a 28-day period in June 2006. We found that our model, which uses a multivariate correlated error in a Bayesian framework, showed promising predictive accuracy particularly for gaseous pollutants.

Kingella kingae Septic Arthritis in an Older-Than-Expected Child.

Kingella kingae typically causes musculoskeletal infection in young children between the ages of 6 months and 4 years who may be in close contact with other similarly aged children who are colonized with the organism in their oropharynx. Kingella infections have rarely been described in older individuals with chronic medical conditions or immune compromise. This is a case report of a healthy, older child who developed an invasive infection due to Kingella kingae. Clinical and laboratory details are provided of an otherwise healthy 11-year-old female who developed an acute onset of septic arthritis of her shoulder. The organism was identified by culture and 16S polymerase chain reaction. Her clinical course necessitated an antibiotic change after the organism was correctly identified. The affected child had close contact with a 2-year-old sibling who recently had a viral upper respiratory infection. This case illustrates the potential for Kingella kingae to rarely cause invasive infection in older, healthy children. Supplemental laboratory techniques may be helpful to identify this organism. Although it is reasonable to limit the antibiotic spectrum for older children, clinicians should be aware of this possibility, particularly if there is a history of close contact with young children.

Differentiation of Deep Venous Thrombosis Among Children With or Without Osteomyelitis.

BACKGROUND: Children with osteomyelitis are at risk for deep venous thrombosis (DVT). This study evaluates the characteristics of DVT among children to differentiate between those with and without osteomyelitis. METHODS: Children with DVT of any cause were studied between 2008 and 2016. Children with DVT and osteomyelitis were compared with those with DVT without osteomyelitis. Another comparison cohort included children with osteomyelitis but without DVT. Comorbidities, severity of illness (SOI), and clinical course were compared between cohorts. RESULTS: DVT was identified in 224 children, a prevalence of 2.5 per 10,000 children. Among those with DVT, 28 (12.1%) had osteomyelitis. The DVT rate among 466 children with osteomyelitis was 6.0%. Children with osteomyelitis and DVT had greater SOI (9.1 vs. 2.7), bacteremia rate (82.1% vs. 38.4%), methicillin-resistant Staphylococcus aureus rate (89.3% vs. 21.2%), surgeries per child (2.1 vs. 0.7), and intensive care unit admission rate (67.9% vs. 5.9%) than that of children without DVT (P<0.00001). Of 196 children who had DVT without osteomyelitis, 166 (84.7%) had comorbidities including defined hypercoagulability (27 or 13.8%). Children with DVT due to osteomyelitis were without comorbidities or hypercoagulability (P<0.00001). The rate of pulmonary embolism was similar for children with DVT with or without osteomyelitis (3/28, or 10.7% vs. 18/196, or 9.2%). CONCLUSIONS: Children with DVT and osteomyelitis differ substantially from other children with DVT by the absence of comorbidities or post-thrombotic syndrome. They also differ from children with osteomyelitis without DVT by higher SOI, methicillin-resistant S. aureus rate, and occurrence of intensive care. Awareness of for the characteristics of DVT among children with osteomyelitis will reduce delay to diagnostic ultrasound and improve anticoagulation management which must be carefully coordinated given the high rate of surgery of these children. LEVEL OF EVIDENCE: Level II-prognostic, retrospective cohort comparison.

The impact of Staphylococcus aureus genomic variation on clinical phenotype of children with acute hematogenous osteomyelitis.

BACKGROUND: Children with acute hematogenous osteomyelitis (AHO) have a broad spectrum of illness ranging from mild to severe. The purpose of this study is to evaluate the impact of genomic variation of Staphylococcus aureus on clinical phenotype of affected children and determine which virulence genes correlate with severity of illness. METHODS: De novo whole genome sequencing was conducted for a strain of Community Acquired Methicillin Resistant Staphylococcus aureus (CA-MRSA), using PacBio Hierarchical Genome Assembly Process (HGAP) from 6 Single Molecule Real Time (SMRT) Cells, as a reference for DNA library assembly of 71 Staphylococcus aureus isolates from children with AHO. Virulence gene annotation was based on exhaustive literature review and genomic data in NCBI for Staphylococcus aureus. Clinical phenotype was assessed using a validated severity score. Kruskal-Wallis rank sum test determined association between clinical severity and virulence gene presence using False Discovery Rate (FDR), significance <0.01. RESULTS: PacBio produced an assembled genome of 2,898,306 bp and 2054 Open Reading Frames (ORFs). Annotation confirmed 201 virulence genes. Statistical analysis of gene presence by clinical severity found 40 genes significantly associated with severity of illness (FDR ≤0.009). MRSA isolates encoded a significantly greater number of virulence genes than did MSSA (p < 0.0001). Phylogenetic analysis by maximum likelihood (PAML) demonstrated the relatedness of genomic distance to clinical phenotype. CONCLUSIONS: The Staphylococcus aureus genome contains virulence genes which are significantly associated with severity of illness in children with osteomyelitis. This study introduces a novel reference strain and detailed annotation of Staphylococcus aureus virulence genes. While this study does not address bacterial gene expression, a platform is created for future transcriptome investigations to elucidate the complex mechanisms involved in childhood osteomyelitis.

Spatiotemporal multivariate mixture models for Bayesian model selection in disease mapping.

It is often the case that researchers wish to simultaneously explore the behavior of and estimate overall risk for multiple, related diseases with varying rarity while accounting for potential spatial and/or temporal correlation. In this paper, we propose a flexible class of multivariate spatio-temporal mixture models to fill this role. Further, these models offer flexibility with the potential for model selection as well as the ability to accommodate lifestyle, socio-economic, and physical environmental variables with spatial, temporal, or both structures. Here, we explore the capability of this approach via a large scale simulation study and examine a motivating data example involving three cancers in South Carolina. The results which are focused on four model variants suggest that all models possess the ability to recover simulation ground truth and display improved model fit over two baseline Knorr-Held spatio-temporal interaction model variants in a real data application.

Acute Hematogenous Osteomyelitis in Children: Pathogenesis, Diagnosis, and Treatment.

Acute hematogenous osteomyelitis (AHO) in children is an ideal condition to study due to its representation of a wide spectrum of disorders that comprise pediatric musculoskeletal infection. Proper care for children with AHO is multidisciplinary and collaborative. AHO continues to present a significant clinical challenge due to evolving epidemiology and complex pathogenesis. A guideline-driven, multidisciplinary approach has been introduced and shown to effectively reduce hospital stay, improve the timing and selection of empirical antibiotic administration, reduce delay to initial MRI, reduce the rate of readmission, and shorten antibiotic duration.

Sequential Parenteral to Oral Clindamycin Dosing in Pediatric Musculoskeletal Infection: A Retrospective Review of 30 mg/kg/d Versus 40 mg/kg/d.

BACKGROUND: Children with musculoskeletal infection in methicillin-resistant Staphylococcus aureus (MRSA) prevalent communities are often treated with oral clindamycin. Current guidelines recommend approximately 40 mg/kg/d for MRSA infections. This study investigates the clinical practice of using 30 mg/kg/d of clindamycin as an alternative for outpatient dosing. METHODS: Children with musculoskeletal infection treated with outpatient clindamycin from 2009 to 2014 were studied by retrospective review. The amount of clindamycin administered was determined from dose, interval and duration of outpatient treatment. Hospital readmission, surgeries and sequelae were assessed. Severity of illness was determined for children with osteomyelitis. The readmission rate of 25 children treated with 40 mg/kg/d was compared with that of 190 children treated with 30 mg/kg/d. The reason for readmission was evaluated to consider whether antibiotic dosing strategy was a potential factor. RESULTS: Among 215 children studied, the average outpatient duration of treatment was 32.8 days. There was no significant difference in the rate of readmission between dosing cohorts. Severity of illness scores (0-10 scale) was significantly higher among readmitted children with osteomyelitis (mean 9.8 ± 0.4) than among those with osteomyelitis who were not readmitted (mean 2.9 ± 3.2), P = 0.001. Sequelae were more common in the high-dose group and were noted in 3 children (12%) in that cohort compared with 6 children (3.2%) in the low-dose cohort (P > 0.05). CONCLUSION: Oral dosing of 30 mg/kg/d was effective for musculoskeletal infection in children in an MRSA prevalent community. Illness severity appeared to have greater impact on readmission and sequelae than did antibiotic dosing.

Spatio-temporal Bayesian model selection for disease mapping.

Spatio-temporal analysis of small area health data often involves choosing a fixed set of predictors prior to the final model fit. In this paper, we propose a spatio-temporal approach of Bayesian model selection to implement model selection for certain areas of the study region as well as certain years in the study time line. Here, we examine the usefulness of this approach by way of a large-scale simulation study accompanied by a case study. Our results suggest that a special case of the model selection methods, a mixture model allowing a weight parameter to indicate if the appropriate linear predictor is spatial, spatio-temporal, or a mixture of the two, offers the best option to fitting these spatio-temporal models. In addition, the case study illustrates the effectiveness of this mixture model within the model selection setting by easily accommodating lifestyle, socio-economic, and physical environmental variables to select a predominantly spatio-temporal linear predictor.

The Clinical Usefulness of Polymerase Chain Reaction as a Supplemental Diagnostic Tool in the Evaluation and the Treatment of Children With Septic Arthritis.

INTRODUCTION: Culture-negative septic arthritis occurs frequently in children. The supplemental use of polymerase chain reaction (PCR) techniques improves the detection of bacteria in the joint fluid. This study evaluates the clinical utility of PCR at a tertiary pediatric medical center. METHODS: Children with septic arthritis were studied prospectively from 2012 to 2014. Culture results and clinical infection parameters were recorded. PCR was performed whenever sufficient fluid was available from the joint aspiration. A statistical comparison was made for the rates of identification of the causative organism by these methods. A subgroup analysis was performed to assess the correspondence of clinical and laboratory parameters with the results of joint fluid culture and PCR. RESULTS: Ninety-nine children with septic arthritis were enrolled consecutively. A broad range of parameter results was identified among these children with an average of 3.6 of 6 parameters per child that met thresholds of infection. Joint fluid cultures were positive in 34 of 97 (35.1%) children from whom they were sent. Among the 68 children from whom the material was sent for PCR, the result was positive in 32 (47.1%). The combination of blood culture, joint fluid culture, and PCR resulted in bacterial detection in 49 of 97 (50.5%) children. PCR improved the rate of detection of Kingella kingae markedly when compared with joint fluid culture. PCR results were available at an average of 14.6 days after the acquisition of joint fluid. 16S PCR results were reported at an average of 17.5 days, whereas Kingella PCR took 5.1 days. DISCUSSION: PCR provides supplemental information for diagnostic confirmation through an increased rate of detection of bacteria. The timing of results and the inability to provide antibiotic sensitivity are factors that limit its clinical usefulness currently.

Improved Magnetic Resonance Imaging Utilization for Children with Musculoskeletal Infection.

BACKGROUND: Magnetic resonance imaging (MRI) with sedation is an important resource used to evaluate children with musculoskeletal infection. This study assesses the impact of multidisciplinary guidelines and continuous process improvement on MRI utilization at a tertiary pediatric medical center. METHODS: A multidisciplinary team developed a guideline for MRI with sedation, and it was implemented at our institution. Scan duration, anatomic regions imaged, sequences performed, timing of surgical intervention, length of hospital stay, and readmissions for these children were compared with these measures among a cohort of similar children who had been treated prior to guideline implementation. Comparative data were gathered for the subsequent cohort to determine any impact of the continued process improvement program on MRI utilization. Statistical comparison was performed to determine significant differences between groups. RESULTS: Children evaluated prior to the guideline implementation had 9.0 MRI sequences per scan, an MRI scan duration of 111.6 minutes, and a hospital stay of 7.5 days. In comparison, children in the initial MRI guideline cohort had 7.5 sequences per scan, a scan duration of 76.1 minutes, and a hospital stay of 5.4 days. Children in the subsequent guideline cohort had 6.5 sequences per scan, a scan duration of 56.3 minutes, and a hospital stay of 5.0 days. The rate of immediate surgical procedure under continued anesthesia was 16.7% prior to the guideline, 50.5% among children in the initial guideline cohort, and 64% among children in the subsequent guideline cohort. Differences between cohorts were significant (p < 0.0001). In aggregate, 264 hours of MRI scan time and 809 hospital bed-days were conserved for more than thirty months. CONCLUSIONS: This initiative promoted improvement in diagnostic efficiency, therapeutic consistency, and patient safety for children with musculoskeletal infection. CLINICAL RELEVANCE: The findings of this study illustrate the beneficial impact of interdisciplinary coordination of care on clinical outcomes for children with musculoskeletal infection. Tangible improvements occurred for both length of stay and resource utilization.

Comparing INLA and OpenBUGS for hierarchical Poisson modeling in disease mapping.

The recently developed R package INLA (Integrated Nested Laplace Approximation) is becoming a more widely used package for Bayesian inference. The INLA software has been promoted as a fast alternative to MCMC for disease mapping applications. Here, we compare the INLA package to the MCMC approach by way of the BRugs package in R, which calls OpenBUGS. We focus on the Poisson data model commonly used for disease mapping. Ultimately, INLA is a computationally efficient way of implementing Bayesian methods and returns nearly identical estimates for fixed parameters in comparison to OpenBUGS, but falls short in recovering the true estimates for the random effects, their precisions, and model goodness of fit measures under the default settings. We assumed default settings for ground truth parameters, and through altering these default settings in our simulation study, we were able to recover estimates comparable to those produced in OpenBUGS under the same assumptions.

Microbiological culture methods for pediatric musculoskeletal infection: a guideline for optimal use.

BACKGROUND: Culture results affect the diagnosis and treatment of children with musculoskeletal infection. To our knowledge, no previous large-scale study has assessed the relative value of culture methods employed during the evaluation of these conditions. The purpose of this study was to identify an optimal culture strategy for pediatric musculoskeletal infection. METHODS: Children with musculoskeletal infection were retrospectively studied to assess culture results from the infection site or blood; culture type, including aerobic, anaerobic, fungal, and acid-fast bacteria (AFB); antibiotic exposure history; and clinical history of children with positive culture results. RESULTS: We studied 869 children, including 353 with osteomyelitis, 199 with septic arthritis, forty-two with pyomyositis, and 275 with abscess. The 4537 cultures processed included 1303 aerobic, 903 anaerobic, 340 fungal, 289 AFB, and 1702 blood. Of 3004 specimens sent during initial work-up, positive results occurred in 677 of 1049 aerobic cultures (64.5%), 140 of 763 blood cultures (18.3%), eighteen of 722 anaerobic cultures (2.5%), five of 251 fungal cultures (2.0%), and two of 219 AFB cultures (0.9%). Staphylococcus aureus was the most common pathogen isolated, from 428 (50.7%) of 844 children for whom blood or infection-site culture material was sent (methicillin-resistant S. aureus, 252; and oxacillin-sensitive S. aureus, 176). Cultures were negative in 206 (29.0%) of the 710 children for whom culture material from the site of infection was sent. Children with true-positive anaerobic, fungal, or AFB cultures had a history of immunocompromise, penetrating inoculation, or failed primary treatment. Antibiotic exposure prior to culture-sample acquisition did not interfere with aerobic culture results from the site of infection. CONCLUSIONS: Our findings suggest that anaerobic, fungal, and AFB cultures should not be routinely performed during the initial evaluation of children with hematogenous musculoskeletal infection. These cultures should be performed for children with immunocompromise, clinical suspicion of penetrating inoculation, or failed primary treatment.

Space-Time Areal Mixture Model: Relabeling Algorithm and Model Selection Issues.

With the growing popularity of spatial mixture models in cluster analysis, model selection criteria have become an established tool in the search for parsimony. However, the label-switching problem is often inherent in Bayesian implementation of mixture models and a variety of relabeling algorithms have been proposed. We use a space-time mixture of Poisson regression models with homogeneous covariate effects to illustrate that the best model selected by using model selection criteria does not always support the model that is chosen by the optimal relabeling algorithm. The results are illustrated for real and simulated datasets. The objective is to make the reader aware that if the purpose of statistical modeling is to identify clusters, applying a relabeling algorithm to the model with the best fit may not generate the optimal relabeling.