ADVANCE DIRECTIVES - CAN PATIENTS STATED TREATMENT CHOICES BE USED TOINFER UNSTATED CHOICES

Advance directives have been widely endorsed as a method to match medi cal interventions to patients' preferences. However, applying advance directives to unspecified future decisions may be problematic. We wond ered how well scenario-based treatment choices in advance directives c an be used to infer other choices specified by the same patients. We a sked 495 out-patients from the Massachusetts General Hospital to state 11 treatment choices in each of four illness scenarios. We calculated likelihood ratios (LRs) to see how well one choice could predict anot her. Predictions within a given scenario were strong and followed a pa ttern that reflected the invasiveness of the treatment. Thus, decline of antibiotics predicted decline of major surgery, in the same scenari o (LR 36.0-108.3). Requests for major surgery strongly predicted reque sts for antibiotics (LR 90.4 - 244.1). Requests for major surgery and decline of antibiotics were the two most predictive preferences; more traditionally considered decisions about cardiopulmonary resuscitation and mechanical ventilation ranged from the third to ninth most predic tive among the 11 interventions. Predictions between scenarios were we aker, but still potentially useful, and followed a pattern that reflec ted the prognoses of the scenarios. Declining treatment in the best pr ognosis scenario (coma-with-a-chance) predicted declining the same tre atment in other scenarios with LRs of 2.5-6.1. Requests for treatment in the worst prognosis scenario (dementia-with-terminal-illness) predi cted the same request in the other scenarios with LRs of 5.2-30.5. The se data suggest that patients' advance scenario-based treatment choice s can provide potentially useful information to apply to unspecified d ecisions if inferences follow considerations of prognosis and treatmen t invasiveness. For maximal predictive power, treatment directives sho uld use a range of illness scenarios and include choices, among severa l others, on antibiotic use and major surgery.