117 per 100 person-years (PY). The

incidence of DVT appears Bioactive Compound Library in vitro to increase markedly with age.12 Heit et al13 found that institutionalization (current or recent hospitalization or nursing home residence) was independently associated with 21.72 odds (among those with recent surgery) and 7.98 odds (without recent surgery) of having VTE. In another study, Heit et al14 found that 59% of VTE cases in the community could be attributed to institutionalization: hospitalization for surgery accounted for 24%; hospitalization for medical illness 22%; and nursing home residence 13%. To facilitate risk assessment for the unique characteristics of nursing home residents, a literature-based long term care (LTC) risk stratification tool for VTE has recently been developed by Zarowitz et al.15 In the nursing home setting, 3 studies evaluated the incidence of VTE diagnosed during facility residence,16, 17 and 18 and 1 study evaluated prevalence of asymptomatic disease.19 Using Minnesota Case Mix Review Program (MCMRP) data for the period 1988 to 1994, Liebson et al16 found a crude incidence rate of 1.2 (95% confidence interval [CI]:

0.9–1.5) to 1.5 (95% CI: 1.1–1.9) cases per 100 PY. In the same study, analysis of a second database (Rochester Epidemiology Project of Olmstead County, MN, 1998–1994) revealed a crude incidence rate of 3.6 (95% CI: 3.0–4.2) cases per 100 PY.16 Gomes C59 wnt et al,17 compiling Minimum Data Set (MDS) and Medicare records for residents in Kansas for the period

1997 to 1998, found a crude VTE incidence rate of 1.30 events per 100 PY (95% CI: 1.10–1.51) when excluding warfarin users. Gatt et al18 evaluated VTE incidence for residents with a length of stay (LOS) of 3 months or longer in a nursing home in Jerusalem, Israel, during the period 1991 to 2001. The crude incidence rate of VTE was similar in both chronically immobilized and mobile cohorts: 1.39 and 1.58 per 100 PY, respectively (P = .77). 18 Arpaia et al19 recently concluded that “[d]ata on the frequency of VTE among nonacute patients nursed at home or in long term care residential homes are still scarce.” The FER current study updates earlier US research regarding the incidence of VTE events that occur during nursing home residence16 and 17 and introduces an analysis of the proportion of nursing home admissions that were coded for VTE. Data for this study were extracted for the data collection period January 1, 2007, to June 30, 2009, from the AnalytiCare longitudinal LTC database (www.analyticare.com). This database included MDS 2.0 assessments, pharmacy dispensing records, and resident characteristics from 181 nursing home facilities across 19 states (29% of facilities had 0–100 beds, 70% 101–200 beds, 1% >200 beds).