Incorporating new modalities into practice guidelines: platelet growth factors

The outcomes of thrombocytopenia are clinically serious (hemorrhage), costly to prevent and treat (platelet transfusions and hospitalization), and may result in delay of the subsequent cycle of chemotherapy. Oprelvekin, the first commercially available platelet growth factor, has been shown to be safe and effective in reducing the need for platelet transfusions. In placebo-controlled trials of patients with solid tumors receiving dose-intensive chemotherapy, 68% of oprelvekin recipients escaped transfusion altogether, compared with only 41% of those who received a placebo. Side effects are generally mild, reversible, and related to fluid retention. Although clinical trials provide evidence about how many patients, on average, can be expected to benefit from agents such as oprelvekin, the trials provide little information about which patients in the general oncology population will benefit. Guidelines based on clinical trial data are limited by this approach. An alternative approach is to develop a clinical profile or model of patients at high risk of developing serious clinical outcomes and target platelet growth factors to these patients through the use of guidelines. Other important components of the guideline development process include a thorough evaluation of the costs of treatments and side effects as well as a careful evaluation of patient's preferences for alternative treatment strategies. Guidelines limiting growth factor use to only those patients who are most likely to benefit provide an opportunity to use expensive new agents in a cost-effective, evidence-based fashion.