The effectiveness of implementing the weight-based heparin nomogram as a practice guideline

Objective: To determine the effectiveness of the nomogram in a community hospital that implemented it as a practice guideline. Design: A nonexperimental, retrospective time series. Setting: A 600-bed community teaching hospital and regional referral center in Phoenix, Ariz. Patients: The study population included 591 consecutive patients with venous thromboembolism, treated over a 5-year study period. Methods: During this period, the weight-based heparin nomogram was adapted into a preprinted order sheet and distributed to the hospital wards. The main outcome variables were the time to achieve a therapeutic activated partial thromboplastin time and the rate of bleeding complications. Results: Voluntary implementation of the nomogram steadily increased, reaching 94%. Comparison of the periods before and after 50% implementation demonstrated an increase in initial heparin dose (1185 vs 1420 U/h, P<.001), a decrease in time to achieve therapeutic activated partial thromboplastin time (19.6 vs 11.8 hours), a decrease in the variance of this parameter (25 vs 4 hours, P<.001), and no change in bleeding rates. The proportion of patients achieving a therapeutic activated partial thromboplastin time within 24 hours decreased from 97% to 86% when the results from our previous randomized controlled trial (efficacy) are compared with the present results (effectiveness). Conclusions: The weight-based heparin nomogram was well accepted by clinicians at our institution and led to more aggressive heparin dosing and improvements in intermediate outcomes, without increasing bleeding. Mitigation of benefit is likely to occur when practice guidelines are moved from the realm of efficacy research into clinical practice. Therefore, the effectiveness of such measures requires monitoring.