Because stringent exclusion criteria that minimized use of pharmacologic thromboprophylaxis in patients at risk for bleeding were applied, a higher rate of use was expected. This difference between expected and actual rates likely occurred because patient care is individualized and not all factors can be readily assessed in an observational study using retrospective data.
Additionally, for patients who remain ambulatory or have an invasive procedure, thromboprophylaxis may be appropriately delayed past the first 24-hour window of therapy or even temporarily interrupted. Subsequently, the measure of thromboprophylaxis initiation within the first 24 to 48 hours of admission was not elected. Instead, an alternative endpoint of VTE protected time period on thromboprophylaxis was selected. When thromboprophylaxis was used, the median period of protection was 83% of the time period hospitalized for this subgroup. Standardizing to a 7-day period, a VTE protected time period of 83% is coverage for 5.81 days. This would support the Joint Commission ORYX measure that allows for the receipt of thromboprophylaxis within 48 hours of admission to be counted as a success.6
Unfortunately, the authors did not assess whether mechanical thromboprophylaxis was provided to the remaining one-third of patients not receiving pharmacologic thromboprophylaxis. As a result, the complete data set is lacking, which would document whether the Joint Commission measure of ≥ 95% of the time was achieved. Therefore, the claim that TVHS is a top performing hospital for this ORYX measure cannot be made.
Although this study demonstrated a low mortality rate, this rate was not selected as a measure of interest, since one meta-analysis has demonstrated no mortality benefit from VTE thromboprophylaxis.4 Although in-hospital mortality may be an appropriate measure for critical care patients, most of the study patients did not meet this criterion.21 Last, mortality should be assessed no earlier than 30 days from admission.17 Subsequently, statistical assessment and conclusions from this measure are not relevant.
Limitations
A number of limitations hindered the generalizability of the results. This was an observational study using retrospectively collected data. The sample was narrowed to those with chronic respiratory disease, which has been less studied and typically examined in concert with acute processes, such as pneumonia. The demographic was primarily white males. The BMI of subjects enrolled in this study (26 kg/m2) was lower than the BMI of nonveteran subjects with COPD (28.6 kg/m2), nonveteran subjects with COPD and VTE (29 kg/m2), or veteran nonsurgical patients receiving thromboprophylaxis (29 kg/m2).18,34,35
The exclusion criteria resulted in a 73% reduction in the cohort and severely limited the number of medical critical care patients included. However, the problem of a small cohort was anticipated.
Other researchers conducting a prospective VHA thromboprophylaxis study found only 7.6% of veterans screened were eligible for enrollment, although 25% of subjects were anticipated by chart review. Two of the 3 primary reasons for trial exclusion were indication for therapeutic anticoagulation and contraindications to heparin (other than thrombocytopenia), and these were also primary reasons for exclusion in this study.30 Subsequently, the cohort appropriate for thromboprophylaxis in VHA seems relatively small.
Additionally, mobility is difficult to judge in a chart review. Day-to-day clinical assessments of mobility lead to individualization of care, including delayed initiation and timely termination of thromboprophylaxis. It is also possible that a significant portion of the patients had mechanical thromboprophylaxis, because they may have had an unrecognized risk factor for bleeding or patient preferences were considered. Last, some veterans may have classified as palliative care, and VTE prophylaxis may have been omitted for comfort care purposes.32
This study was not designed to evaluate the Padua Prediction Score, which categorizes risk and ration-alizes use of thromboprophylaxis for nonsurgical patients.3 This tool eliminates many of the established risk factors for VTE, including COPD, which was a qualifying diagnosis for inclusion in this study.1 It is not clear how the Padua Prediction Score would categorize the inpatient veteran population. Veterans clearly have poorer health status, more medical conditions, and higher medical resource use compared with the general patient population.25
Veterans with COPD have a higher comorbid illness burden than that of veterans without COPD.36 Chronic obstructive pulmonary disease is associated with VTE development, and when VTE develops in patients with COPD, mortality is greater than that of patients without COPD.37,38 VTE mortality may be related to an increased likelihood of fatal pulmonary embolism.39 Therefore, the authors recommend that VHA conduct studies to examine the Padua Prediction Score and potentially other RAMs that include COPD subjects, to determine what tool should be used in VHA.32
The authors also recommend that VHA evaluate how to improve thromboprophylaxis care with time-based studies. Since manual extraction to determine study inclusion was a time-consuming process, this time frame likely was a barrier to physician implementation of pharmacologic thromboprophylaxis. Therefore an electronic tool that serves as a daily reminder for subjects calculated as high risk for VTE but low risk for bleeding may improve clinical outcomes.