Background Pediatric venous thromboembolism (VTE) is an increasingly common difficult to

Background Pediatric venous thromboembolism (VTE) is an increasingly common difficult to diagnose problem. 12 weeks localized tenderness along the course of a deep vein entire leg swelling calf swelling Rifaximin (Xifaxan) pitting edema confined to a symptomatic leg collateral superficial veins previous DVT and documentation of a suspected alternative diagnosis (15). In some situations special considerations for pediatric application of these adult signs/symptoms were needed. For instance infants are physiologically non-ambulatory. Thus bedridden paralysis and paresis was defined as pathologically limited activity. Iatrogenic pharmacologically induced paralysis which is commonly employed in critically ill ventilated children was counted as paralysis. A non-ambulatory infant without any pathologic limitation or medical restraint was not ‘bedridden’. Assigning the presence or absence of an alternative diagnosis is particularly challenging in a retrospective study. Thus an alternative diagnosis was considered present only if a documenting practitioner listed one or more differential diagnoses in addition to VTE. These parameters were supplemented with pediatric-specific VTE variables: presence of a central venous access device (CVAD) in the symptomatic venous system (currently or within the past year) loss of CVAD patency congenital heart disease kidney disease prematurity sepsis systemic lupus erythematosus sickle cell disease pain in the symptomatic extremity chest pain dusky discoloration (plethora) of the symptomatic extremity head or neck swelling suggestive of superior vena cava syndrome and Rifaximin (Xifaxan) respiratory compromise (respiratory distress and/or a new or increasing oxygen requirement) (4 6 Additional parameters of general interest including age gender ethnicity/race BMI (for children ≥2 years of age) and hormonal contraceptive within 3 months of assessment (for adolescent females) were also considered. Documentation of all variables was only considered prior to the day and time of the imaging study that qualified the subject for the study. To validate the collected data five percent of the charts were also reviewed by an additional research assistant or an investigator (BAK) in a blinded fashion which yielded >95% raw agreement. For the validation cohort only ECSCR those parameters included in the final model were abstracted from the medical records. Statistics Demographics and characteristics of suspected VTE cases were compared between patients with VTE and those without VTE. Wilcoxon rank-sum tests were used to compare continuous variables and Chi-square tests or Fisher’s exact tests were used for categorical variables. Backward stepwise modeling methods were used to estimate the relative significance of potential predictors for Rifaximin (Xifaxan) VTE for this group of subjects. Model fit was determined by the Hosmer-Lemeshow test and discrimination by the AUC for the ROC curve. These analyses were performed using SAS version 9.2 (SAS Institute Inc Cary NC) and Stata/SE 10.0 (StataCorp College Station TX). Subjects with missing variables were excluded from the univariate analyses utilized to determine which parameters to include in the multivariate analysis. The pilot CPT algorithm generated from the multivariate analysis was applied to the validation cohort without excluding subjects with missing data in an ‘intention to diagnose’ fashion. ROC curves were generated to compare the performance of the pilot CPT in the training and validation cohorts using SPSS Statistics version 21 (IBM Rifaximin (Xifaxan) Armonk NY). Acknowledgments The authors are indebted to Ms. Dawn Fowler for performing the radiology records keyword searches as well as Ms. Marlene Wears Ms. Corinna Bowers and Ms. Susan Cunningham for diligently executing the chart abstractions. Financial Support: This project was supported by the George & Elizabeth Kelly Foundation and grants 239409 and 285712 from The Research Institute at Nationwide Children’s Columbus Ohio USA both to B. A. Kerlin and Award Numbers UL1TR001070 and UL1TR000090 from the National Center for Advancing Translational Sciences National Institutes of Health USA. Footnotes Disclosure of Conflict of Interests: The.