Avoiding Heparin: The First Step to Preventing HIT and HITT

Use of an “Avoid-Heparin Initiative” resulted in a dramatic reduction in the burden of heparin-induced thrombocytopenia (HIT) and associated costs, according to a report by Kelly E. McGowan, MD, from the Department of Medicine at the University of Toronto in Ontario, Canada, and colleagues.

“Heparin-induced thrombocytopenia is a serious complication of heparin, occurring in up to 5 percent of patients exposed to unfractionated heparin (UFH),” Dr. McGowan and colleagues wrote. Its treatment involves discontinuing all forms of heparin and the administration of a non-heparin anticoagulant, though the recognition and evaluation of suspected HIT is often delayed. Even with prompt cessation of heparin, complications occur in 20 to 50 percent of patients, and death or limb amputation occurs in approximately 5 to 10 percent of patients.

“This study questions the safety of continuing to expose patients to UFH except in situations where there is no better alternative,” William Geerts, MD, the corresponding author of the study, told ASH Clinical News.

To potentially lower the incidence of HIT, HIT with thrombosis (HITT), and HIT-related costs, the authors developed a hospital-wide strategy of replacing UFH with low-molecular-weight heparin (LMWH) for prophylactic and therapeutic indications, including:

  • Systematic replacement of most intravenous and subcutaneous UFH with subcutaneous LMWH for prophylactic or therapeutic indications
  • The remaining use of UFH was for hemodialysis, intraoperatively for cardiovascular surgery and in some patients with acute coronary syndrome
  • Replacement of heparinized saline in arterial and central venous lines with saline flushes
  • Modification of order sets to exclude UFH options
  • Removal of UFH stores from most nursing units

The researchers chose LMWH as replacement therapy because it is associated with a five- to 10-fold lower risk of HIT than UFH and thrombosis is less likely to occur when HIT is triggered by LMWH than by UFH.

The Avoid-Heparin Initiative was implemented at Sunnybrook Health Sciences Centre, a tertiary-care hospital in Toronto, Canada, starting in 2006. Consecutive cases with suspected HIT from 2003 through 2012 were reviewed. Rates of suspected HIT, adjudicated HIT, HITT, and HIT-related expenditures were compared in the pre-intervention (2003-2005) and the Avoid-Heparin (2007-2012) phases.

Most health-care providers in the facility were not aware that heparin was being replaced by LMWH, per the Avoid-Heparin Initiative. “We wanted this to be as close to a natural history experiment as possible,” Dr. Geerts explained. “The Avoid-Heparin intervention was not complex and is highly feasible for any hospital.”

From 2003 to 2012, there were 1,118 cases of suspected HIT, defined as a clinical suspicion of HIT with a HIT ELISA performed. Sixteen percent of these patients (n=175) had a positive HIT ELISA; 51 percent (n=89) were adjudicated HIT positive and 48 percent (n=84) were adjudicated HIT negative. The HIT status remained uncertain after adjudication in two cases.

Over the 10-year period, 31 patients (35%) with adjudicated HIT developed HIT and HITT. In 10 of these patients, the thromboembolic event occurred within five days before the diagnosis of HIT. Four patients were diagnosed with thromboembolism and HIT on the same day. Notably, more than half of the HITT cases (17/31) had their thromboembolic event diagnosed after the diagnosis of HIT and while on HIT-safe anticoagulation, “emphasizing not only the need for early recognition and treatment, but also the need to prevent HIT,” the authors observed.

There was a 42 percent decrease in the annual rate of suspected HIT in the pre-intervention and Avoid Heparin phases, respectively (85.5 per 10,000 admissions in the pre-intervention phase to 49.0 per 10,000 admissions in the intervention group; p<0.001).

Following the intervention phase, the annual rates of patients with a positive HIT assay, adjudicated HIT, and HITT also decreased:

  • Positive HIT assay: a 62.9% decrease, from 16.5 to 6.1 per 10,000 admissions (p<0.001)
  • Adjudicated HIT: a 79% decrease, from 10.7 to 2.2 per 10,000 admissions (p<0.001)
  • HITT: a 91% decrease, from 4.6 to 0.4 per 10,000 admissions (p<0.001)

“Although the greatest overall impact of the program was in cardiac surgery, the HIT burden was also reduced in other surgical and medical patients,” Dr. McGowan and co-authors noted.

The median hospital stay length from date of suspected HIT to discharge among patients with HITT was 22 days, compared with eight days for those with HIT without thrombosis (p<0.001). The additional costs for suspected HIT, adjudicated HIT, and HITT were based on a published cost-analysis performed at the Sunnybrook Health Sciences Centre and the observed events in the present study. Avoiding heparin led to a $266,938 decrease in HIT-related expenditures from the pre-intervention to the intervention phase (TABLE).

One limitation of the study is its location at a single tertiary care hospital, “whose HIT-related practices may differ from other centers,” the authors wrote. “Since there is no reference standard for the diagnosis of HIT, the observations in this study were based on a review of all cases with suspected HIT and therefore reflect routine clinical practice.” In addition, this was not a prospective, randomized, blinded intervention, so it is possible that some practices may have been altered with awareness that the intervention had been made.

The authors stressed that the study’s findings did not result in an overall reduction in the number of admissions or length of stay during the study period. “In fact, total patient admissions increased 21 percent while the mean length of stay decreased only 9 percent over the study period,” noted the authors.

“We were able to successfully decrease the patient burden and costs of HIT over a prolonged period of time,” Dr. Geerts concluded. “We recommend that all hospitals carefully consider the findings of this study and determine if they should also implement ‘avoid-heparin strategies’ to improve patient safety and reduce costs.”


McGowan KE, Makari J, Diamantouros A, et al. Reducing the hospital burden of heparin-induced thrombocytopenia: impact of an avoid-heparin program. Blood. 2016 January 27. [Epub ahead of print]

TABLE. Estimated Costs Associated with HIT Care in the Pre-Intervention and Avoid-Heparin Phases
Additional Costs per Case Pre-Intervention, 2003-2005 Avoid-Heparin, 2007-2012
Cases per year Cost per year Cases per year Cost per year
HIT-Negative $119 123.7 $14,716 91.7 $10,908
HIT without thrombosis $4,575 10.0 $45,750 3.5 $16,012
HITT $34,155 7.7 $261,855 0.8 $28,462
Total $322,321 $55,383