Materials and Methods:
This study was reviewed and approved by the Institutional Review Board at Nationwide Children’s Hospital prior to any data collection. Using the International Classification of Diseases (ICD-9)diagnosis codes for DKA (250.1x), billing database records were reviewed for children aged less than five years old between January 2002 and December 2011 with a DKA admission to Nationwide Children’s Hospital in Columbus, OH. DKA diagnosis was confirmed after chart review by laboratory results: venous pH <7.3, hyperglycemia (blood glucose >200mg/Dl), and ketonuria, as described by Woldorf et al [16]. This patient group was then cross-referenced for CVC placement (ICD-9 code 38.93 and 38.97) as well as VTE (ICD-9 code 453.2, 453.4x, 453.8x, and 453.9) diagnoses. All VTE codes were confirmed after chart review established that each case was diagnosed by Doppler ultrasonography and was CVC-associated.
Data were recorded for two patient groups: “DKA with CVC” and “DKA with CVC and VTE.” Demographic and hospital course information was noted. Details of the CVC, including hospital day of placement, duration of use, type, size, location, continuous fluid infusion, and anticoagulation prophylaxis, were elucidated and compared between the two groups. Laboratory findings at DKA presentation were also reviewed to evaluate for predictive indicators for VTE in the setting of DKA with CVC. White blood cell count (WBC), hemoglobin, hematocrit, platelet count, blood urea nitrogen (BUN), creatinine, urine pH, venous blood pH, and hemoglobin A1C were among those evaluated.
The patients that developed a VTE also had baseline coagulation studies (Prothrombin Time (PT), activated Partial Thromboplastin Time (aPTT)) and thrombophilia testing performed at the time of VTE diagnosis. Protein C activity, protein S activity, antithrombin activity, Prothrombin G20210A mutation, Factor V Leiden mutation, anticardiolipin antibodies, homocysteine levels, and quantitative D-dimer studies were investigated at the discretion of the hematologist.
Billing database records were also searched using the same ICD-9 codes for patients aged two months to five years of age for all CVC placements during our study period for any reason other than DKA. We elected to use two months as our lower age limit since our youngest patient with DKA and a CVC was two months old. This patient group was subsequently cross-referenced for VTE diagnoses up to three months after line placement and was compared to the DKA group for the incidence of CVC-associated VTE.
Descriptive statistics for patients with DKA and CVC are provided for all variables. Reported demographic and laboratory variables between groups were compared using Mann-Whitney rank sum tests. Fisher’s exact test was used to compare the prevalence of CVC-associated VTEs between children with DKA and those without DKA. Statistical significance was determined by p < 0.05. Statistical analyses were performed using Statistical Analysis System software 9.3 (SAS Institute Inc., Cary, NC, USA).