How do anesthesiologists select patients when introducing a new drug into practice?

As part of the marketing strategy for the anesthetic drug propofol (Diprivan®), Stuart Pharmaceuticals began a Phase IV postmarketing study soon after the drug received Food and Drug Administration approval in 1989. We used data from this study to test the hypothesis that anesthesiologists would initially use propofol for young, relatively healthy patients and then, with experience, for older, sicker patients. The Phase IV study involved 1722 institutions, 1819 anesthesiologists, and 25,981 patients. The study incorporated three sequential steps, each to be tested in five patients. In Step 1, propofol was used for induction only; in Step 2, for induction and maintenance of anesthesia by intermittent injection; and, in Step 3, for induction and maintenance by continuous infusion. Inclusion criteria were age 18-80 yr and ASA physical status I-III. Exclusion criteria were continuing pregnancy and a previous adverse anesthetic experience. Physicians used standardized data collection forms to voluntarily compile detailed demographic, perioperative, and outcome variables for patients. Data were then evaluated by an independent, multicenter team of seven anesthesiologists and three epidemiologists to determine whether the first two patients selected to participate in each step (Patients 1 and 2, 6 and 7, and 11 and 12) were less sick, younger, or undergoing less invasive or shorter procedures than patients enrolled later in the same steps (Patients 4 and 5, 9 and 10, and 14 and 15). Physicians gave propofol first to patients with fewer concurrent diseases than are found in the general population (10% were hypertensive versus 16%; 3% were diabetic versus 10%). As the study progressed to Steps 2 and 3, slightly, but only slightly, sicker and older patients were enrolled. Although this pattern pertained to the group as a whole, not all physicians followed it. Of the three most serious adverse events (one death and two cardiac arrests), two occurred in patients older than 90 yr of age. Institutions at which one or more physicians began Step 3 before completing Step 2 were labeled 'innovative.' Comparison revealed that physicians at innovative institutions introduced the drug in slightly older, sicker patients than did physicians at noninnovative institutions. This study suggests that anesthesiologists are conservative in the selection of patients for the introduction of a new drug.