Unintended Consequences of a Standard Admission Order Set on Venous Thromboembolism Prophylaxis and Patient Outcomes

BACKGROUND: Standard order sets often increase the use of desirable interventions for patients likely to benefit from them. Whether such order sets also increase misuse of these interventions in patients potentially harmed by them is unknown. We measured the association between a paper-based standard admission order set with a venous thromboembolism pharmacoprophylaxis (VTEP) module and use of VTEP for patients likely to benefit from it as well as patients with unclear benefit or potential harm from it. METHODS: We conducted a retrospective cohort study using administrative and pharmacy charge data of patients admitted between 1 July 2005 and 31 December 2008 to two medical and three surgical services that implemented a standard admission order set in August 2006. The primary outcome was use of VTEP in patients with likely benefit, unclear benefit, and potential harm from VTEP prior to and following order set implementation. KEY RESULTS: A total of 8,429 patients (32%) were admitted prior to and 17,635 (68%) following order set implementation. There was a small unadjusted rise in overall VTEP use after implementation (51% to 58%, p<0.001). In multivariable models with interrupted time series analysis, patients with potential harm from VTEP had the largest increase in VTEP use at the time of implementation [adjusted odds ratio = 1.58; 95% confidence interval (CI), 1.12-2.22]. The increased likelihood of receiving VTEP in this subgroup gradually returned to baseline (adjusted odds ratio per month=0.98; 95% CI, 0.96-0.99). CONCLUSIONS: Implementation of a standard admission order set transiently increased VTEP in patients with potential harm from it. Order set and guideline success should be judged based on the degree to which they successfully target patients likely to benefit from the intervention without inadvertently targeting patients potentially harmed.