To evaluate the relative impact of clinical factors and health care environment resources on the expert ratings of appropriateness of preoperative erythropoietin in elective orthopedic surgery, the authors analyzed 6905 individual votes on 496 clinical scenarios from 14 experts, applying a multivariate logistic model. Sixty-six percent of the indications were appropriate when resource constraints (RC) were not considered and 53% when they were, resulting in a drop in the median vote of 2 points on a 9-point scale (P < 0.05). Initial hemoglobin level, expected perioperative blood loss, and RC were by far the most significant contributors to the model (P < 0.01), but other factors (i.e., clinical specialty of the expert, prior history of transfusion reactions, patient age, cardiovascular disease, anemia of chronic disease) also contributed significantly (P< 0.01). For assessing appropriateness of care, this study confirms the need for detailed clinical scenarios and a multidisciplinary panel carefully selected to reflect those involved in the interventions under consideration. [authors]