To compare the accuracy of oncologists’ estimates of expected survival time with estimates made by patients themselves.
Patients and Methods
25 oncologists estimated the “median survival of a group of identical patients” for 163 individuals with advanced cancer at the time of enrolment in an advanced care planning trial. At enrolment each patient was asked to record “your understanding of how long you may have to live”. We hypothesized that oncologists’ estimates of survival time (EST) would be: unbiased (~50% longer or shorter than the observed survival time [OST]); imprecise (<33% within 0.67 to 1.33 times OST); independently predictive of OST; and accurate for deriving ranges for scenarios, with 5-10% of patients dying within a quarter of their EST (worst-case scenario), 50% living within half to double their EST (most-likely scenario), and 5-10% living ≥3 times their EST (best-case scenario).
Oncologists’ EST were unbiased (56% longer than OST), imprecise (27% within 0.67 to 1.33 times OST), moderately discriminative (Harrell’s C-statistic 0.65, p<0.01) and significantly associated with OST (HR=0.88, 95% CI 0.82 to 0.93, p<0.01). Only 40 patients (22%) estimated their own survival. Patient estimates were: less precise (17% within 0.67 to 1.33 times OST); more likely to overestimate (85% longer than OST); similarly discriminative (Harrell’s C-statistic 0.64, 95% CI; 0.53 to 0.75; p<0.01); and not associated with OST (HR 0.98, 95% CI 0.96 to 1, p=0.08). Scenarios for survival derived from oncologists’ estimates were accurate with 7.5% of patients dying within a quarter of their EST, 63.7% living within half to double their EST, and 4.5% living ≥3 times their EST.
Few patients estimated their own survival and those that did were more likely to overestimate compared to oncologists. Oncologists’ estimates provide a reasonable basis for estimating ranges for worst-case, most-likely, and best-case scenarios for survival.