RESUMO
OBJECTIVE: Many patients with advanced illness are unrealistically optimistic about their prognosis. We test for the presence of several cognitive biases, including optimism bias, illusion of superiority, self-deception, misattribution, and optimistic update bias, that could explain unrealistically optimistic prognostic beliefs among advanced cancer patients and quantifies the extent to which hope exacerbates these biases. METHODS: A cross-sectional survey was administered to 200 advanced cancer patients with physician-estimated prognoses of one year or less. Hope was measured using the Herth Hope Index (HHI). Hypotheses were tested using linear and logistic regressions and a structural-equation model. RESULTS: Results are consistent with the presence of optimism bias, illusion of superiority, self-deception, and misattribution. All of these biases are amplified by higher levels of hope. Each 1-point higher HHI is associated with a 6% (OR: 1.06; 95% CI: 1.01-1.11) greater odds of believing their illness is curable, a 0.33-year (95% CI: 0.17-0.49) longer expected survival, a 6% (OR: 1.06; 95% CI: 1.02-1.11) higher probability of believing that survival outcomes are better than the average patient, a 5% higher odds of believing primary intent of treatment is curative (OR: 1.05; 95% CI: 1.00-1.10), and a 12% (OR: 1.12; 95% CI: 1.05-1.17) higher odds of believing they are well-informed. Mediation analyses revealed that hope significantly mediates the effect of mental-well-being and loneliness on expected survival. CONCLUSIONS: Results suggest advanced cancer patients succumb to several cognitive biases which are exacerbated by greater levels of hope. As a result, they are susceptible to possible over-treatment and regret.
