In addition to these nonmodifiable patient characteristics, aspects of our VTE prophylaxis processes likely contributed to the higher than expected rate of VTE. While the electronic medical record at our institution does contain a VTE risk assessment tool based on the Caprini score, we found it often is not used at all or is used incorrectly/incompletely, which likely reflects the fact that physicians are neither prompted nor required to complete the assessment prior to prescribing VTE prophylaxis.
There is a significant body of evidence demonstrating that mandatory computerized VTE risk assessments can effectively reduce VTE rates and that improved outcomes occur shortly after implementation. Cassidy et al demonstrated the benefits of instituting a hospital-wide, mandatory, Caprini-based computerized VTE risk assessment that provides prophylaxis/early ambulation recommendations. Two years after implementing this system, they observed an 84% reduction in DVTs (P < 0.001) and a 55% reduction in PEs (P < 0.001).13 Nimeri et al had similarly impressive success, achieving a reduction in their NSQIP O/E for PE/DVT in general surgery from 6.00 in 2010 to 0.82 (for DVTs) and 0.78 (for PEs) 5 years after implementation of mandatory VTE risk assessment (though they noted that the most dramatic reduction occurred 1 year after implementation).14 Additionally, a recent systematic review and meta-analysis by Borab et al found computerized VTE risk assessments to be associated with a significant decrease in VTE events.15
The risk assessment tool used at our institution is qualitative in nature, and current literature suggests that employing a more quantitative tool may yield improved outcomes. Numerous studies have highlighted the importance of identifying patients at very high risk for VTE, as higher risk may necessitate more careful consideration of their prophylactic regimens. Obi et al found patients with Caprini scores higher than 8 to be at significantly greater risk of developing VTE compared to patients with scores of 7 or 8. Also, patients with scores of 7 or 8 were significantly more likely to have a VTE compared to those with scores of 5 or 6.16 In another study, Lobastov et al identified Caprini scores of 11 or higher as representing an extremely high-risk category for which standard prophylaxis regimens may not be effective.17 Thus, while having mandatory risk assessment has been shown to dramatically decrease VTE incidence, it is important to consider the magnitude of the numerical risk score. This is of particular importance at medical centers with high case-mix indices where patients at the highest risk might need to be managed with different prophylactic guidelines.
Another notable aspect of the process at our hospital was the great variation in the types of prophylactic regimens ordered, and the adherence to what was ordered. Only 25.5% of patients were maintained on a standard prophylactic regimen with no missed doses (heparin 5000 every 8 hours or enoxaparin 40 mg daily). Thus, the vast majority of the patients who went on to develop VTE either were prescribed a nontraditional prophylaxis regimen or missed doses of standard agents. The need for secondary surgical procedures or other invasive interventions may explain many, but not all, of the missed doses.
The timing of prophylaxis initiation for our patients was also found to deviate from accepted standards. Only 16.8% of cases received prophylaxis upon induction of anesthesia, and furthermore, 38% of cases did not receive any anticoagulation within 24 hours of their index operation. While this variability in prophylaxis implementation was acceptable within the SCIP guidelines based on “high risk for bleeding” or other considerations, it likely contributed to our suboptimal outcomes. The variations and interruptions in prophylactic regimens speak to barriers that have previously been reported as contributing factors to noncompliance with VTE prophylaxis.18