AnalytiCare provided data for all residents who had available MDS and pharmacy data and who had been identified as having either DVT (“DVT” checkbox in Section I1 or ICD-9-CM codes of 451.1x, 451.2, 453.2, or 453.4x in Section I3) or PE (415.1x in Section I3) in any MDS assessment over the study period. To estimate the number of admissions and selleck screening library days at risk of the total resident population, AnalytiCare separately provided a simple random sample of 1350 residents from the universe of residents (n = 74,019) who had available MDS and pharmacy

data over the study period (reference sample). Residents in both groups (census of those with VTE and reference sample) were considered eligible for analysis if they had 1 or more admission (or readmission) MDS assessment(s) over the study period; the earliest MDS admission (or readmission) over the study period was identified as the admission index date.

Eligible residents were followed longitudinally from the admission index date until the end of follow-up (ie, censoring). Follow-up ended on the earliest occurrence of (1) an MDS assessment coded for VTE (follow-up equaled zero if VTE was coded on admission); (2) a postindex discharge that occurred wherein the resident was not readmitted to Selleck Ruxolitinib the facility within 30 days following discharge; (3) 90 days following the earliest MDS assessment for which a gap of 120 days or more occurred between successive MDS assessments; (4) date of death; or (5) the end of the data collection period. Cases (eligible residents in the VTE census) were exclusively defined as either VTE on admission or VTE during residence depending on whether the date of the earliest VTE-coded MDS assessment occurred on or after the admission index date, respectively. Counts of cases were

used to supply numerators for the rate of admissions coded for VTE and Casein kinase 1 the incidence of postadmission VTE cases. The respective denominators—the total number of initial admissions and resident days at risk (sum of elapsed days from admission index date to end of follow-up)—were estimated from the reference sample. Data for demographics were derived from the AnalytiCare resident characteristic data file. A set of 20 VTE risk factors was obtained from the risk stratification tool developed by Zarowitz et al15 (5 other risk factors from this tool lacked available data for the current study: surgical resection of abdominal or pelvic cancer, central vein catheter, history of VTE, having first-degree relative with VTE, and treatment with erythroid-stimulating agents to hemoglobin greater than 12 g/dL).