Do potential patients prefer tissue plasminogen activator (TPA) over streptokinase (SK)? An evaluation of the risks and benefits of TPA from the patient's perspective

BACKGROUND: In patients with acute myocardial infarction, TPA (compared to SK), has been shown to reduce the 30-day mortality rate at the expense of an increased rate of stroke. The assumption in the literature is that were it not for cost issues, all patients presenting with a myocardial infarction would choose TPA. Our hypothesis is that, for many informed individuals, regardless of cost, the increased risk of stroke may deter them from selecting TPA over SK. OBJECTIVE: To assess which thrombolytic drug informed patients would prefer and to explore the clinical and economic implications of such preferences. DESIGN: Prospective survey. SETTING: Tertiary care hospital. PATIENTS: 120 hospitalized patients with cardiac disease who would be "at risk" for a myocardial infarction. INTERVENTIONS: Face-to-face interviews utilizing a decision instrument. MEASUREMENTS: To minimize bias in soliciting patients' preferences and to standardize the presentation of information we developed a decision instrument which portrays a case scenario of a myocardial infarction, describes treatment outcomes (survival and stroke rate), and displays the likelihood of these outcomes with SK and TPA using three scenarios: a base stroke risk (all patients data), a lower stroke risk (<75 years old data), a higher stroke risk (>75 years old data). Outcome data were derived from the published literature (GUSTO study). RESULTS: When presented the overall results of the GUSTO study, 60/120 (50%) expressed a preference for SK. When presented the outcome data for the subgroups of patients <75 years old (lower stroke rate), 37/120 (31%) preferred SK. When presented the subgroup data for patients >75 years old (higher stroke risk), 67/120 (56%) preferred SK. CONCLUSIONS: Regardless of the scenario that individuals were presented with, a substantial proportion of individuals (31-56%) who could potentially require thrombolytic therapy chose SK over TPA. This study should be repeated in other settings to establish the generalizability of our results. Assuming that these results will be consistent, considering the patient's perspective has significant implications on clinical decision making as well as from an economic perspective.