Heparin-induced thrombocytopenia (HIT) is a prothrombotic adverse reaction to heparin that may result in limb- or life-threatening thromboembolism. Traditionally viewed as an inevitable and inexorable complication of treatment with heparin, the primary focus of investigation and management in HIT has been on diagnosis and treatment, and little attention has been given to its prevention. Recently, investigators at Sunnybrook Health Sciences Centre in Toronto sought to change that.
Capitalizing on the observation that low molecular weight heparin (LMWH) is associated with a five- to 10-fold lower risk of HIT than unfractionated heparin (UFH),1 they implemented the “Avoid-Heparin Initiative” at their institution in 2006 with the lofty goal of preventing HIT. The protocol included four elements: 1) replacement of most prophylactic and therapeutic intensity UFH with LMWH (UFH was retained for hemodialysis and intraoperative anticoagulation during cardiac surgery), 2) replacement of heparinized saline flushes with saline flushes, 3) modification of order sets to exclude UFH, and 4) removal of UFH from most nursing units. Outcomes were compared in the preintervention (2003-2005) and postimplementation (2007-2012) phases.
The avoid-heparin protocol was successful in replacing UFH with LMWH. Overall use of LMWH increased fourfold during the study period. The relative risk reductions (RRRs) in HIT-associated outcomes were dramatic. Compared with the pre-intervention phase, the avoid-heparin protocol was associated with a decreased incidence of suspected HIT (85.5 vs. 49.0 cases per 10,000 admissions; p<0.001; 41.7% RRR), adjudicated HIT (10.7 vs. 2.2 cases per 10,000 admissions; p<0.001; 79.0% RRR), and HIT complicated by thrombosis (4.6 vs. 0.4 cases per 10,000 admissions; p<0.001; 90.7% RRR). The average annual estimated cost (in 2007 Canadian dollars) of HIT-associated care fell 82.8 percent from $322,321 to $55,383 after implementation of the avoid-heparin initiative. Benefits were observed across patient populations. The incidence of HIT was reduced 77 percent in cardiovascular surgery patients, 77 percent in other surgery patients, 75 percent in cardiology patients, and 62 percent in medical patients.
Table. Relative Risk Reductions Associated With Selected Interventions to Prevent Nosocomial Diseases.
| Nosocomial disease . | Intervention . | Relative Risk Reduction . |
|---|---|---|
| Deep vein thrombosis3 | Prophylactic intensity LMWH | 44%* |
| Ventilator-associated pneumonia4 | Aspiration of subglottic secretions | 45% |
| Central venous catheter-associated bloodstream infection5 | Chlorhexidine bathing | 55% |
| Pressure ulcers6 | Alternative foam mattress | 60% |
| Heparin-induced thrombocytopenia | Avoid heparin protocol | 79% |
| Nosocomial disease . | Intervention . | Relative Risk Reduction . |
|---|---|---|
| Deep vein thrombosis3 | Prophylactic intensity LMWH | 44%* |
| Ventilator-associated pneumonia4 | Aspiration of subglottic secretions | 45% |
| Central venous catheter-associated bloodstream infection5 | Chlorhexidine bathing | 55% |
| Pressure ulcers6 | Alternative foam mattress | 60% |
| Heparin-induced thrombocytopenia | Avoid heparin protocol | 79% |
*In medical patients
In Brief
In this elegant quality-improvement study, institutionwide replacement of UFH with LMWH effected dramatic reductions in the incidence of HIT and HIT-associated thrombosis. Several limitations of the study deserve mention. It was carried out in a single center. Only a minority of patients underwent testing with the serotonin release assay (considered the gold standard for diagnosis of HIT). The approximately eightfold greater price tag for LMWH compared with UFH was not accounted for in the cost analysis.2 Despite these limitations, the study provides valuable proof-of-principle that HIT is, indeed, a preventable disease.
Quality metrics and reimbursement are increasingly linked to the incidence of preventable nosocomial diseases. Interventions to forestall selected nosocomial illnesses such as deep vein thrombosis, ventilator-associated pneumonia, central venous catheter–associated bloodstream infections, and pressure ulcers are listed in the Table.3-6 The RRR of the avoid-heparin protocol compares favorably with these widely used interventions, spurring the question as to whether institutions should be doing more to prevent HIT.
The analogy between HIT and the other nosocomial diseases in the Table is imperfect. HIT is probably less common. Therefore any intervention to prevent HIT, no matter how effective, may result in lower reductions in absolute risk and a greater number needed to treat. Moreover, a wholesale switch from UFH to LMWH may be more costly than targeted, less-expensive interventions (e.g., aspiration of subglottic secretions in mechanically ventilated patients). Nevertheless, the message from the study by Dr. Kelly McGowan and colleagues is clear: Institutional adoption of an avoid-heparin protocol is feasible and reduces the incidence of HIT. It may be time for clinicians, administrators, policymakers, and payers to re-envisage HIT, not as an unavoidable iatrogenic disorder, but as a preventable nosocomial disease.
References
Competing Interests
Dr. Cuker indicated no relevant conflicts of interest.
