The accuracy of probabilistic versus temporal clinician prediction of survival for patients with advanced cancer: a preliminary report

Abstract

Clinicians have limited accuracy in the prediction of patient survival. We assessed the accuracy of probabilistic clinician prediction of survival (CPS) and temporal CPS for advanced cancer patients admitted to our acute palliative care unit, and identified factors associated with CPS accuracy. Eight physicians and 20 nurses provided their estimation of survival on admission by (a) the temporal approach, "What is the approximate survival for this patient (in days)?" and (b) the probabilistic approach, "What is the approximate probability that this patient will be alive (0%-100%)?" for ≥24 hours, 48 hours, 1 week, 2 weeks, 1 month, 3 months, and 6 months. We also collected patient and clinician demographics. Among 151 patients, the median age was 58 years, 95 (63%) were female, and 138 (81%) had solid tumors. The median overall survival time was 12 days. The median temporal CPS was 14 days for physicians and 20 days for nurses. Physicians were more accurate than nurses. A higher accuracy of temporal physician CPS was associated with older patient age. Probabilistic CPS was significantly more accurate than temporal CPS for both physicians and nurses, although this analysis was limited by the different criteria for determining accuracy. With the probabilistic approach, nurses were significantly more accurate at predicting survival at 24 hours and 48 hours, whereas physicians were significantly more accurate at predicting survival at 6 months. The probabilistic approach was associated with high accuracy and has practical implications.

Figure 1.

Predicted survival versus actual survival by physicians and nurses for 127 patients who died. The diagonal line depicts perfect concordance, with dots above suggesting overestimation and dots below suggesting underestimation. This plot shows that nurses (♦) were more optimistic than physicians (■) in estimating survival. A logarithmic scale is used for both x-axis and y-axis.

Figure 2.

Accuracy of clinician prediction of survival (CPS) by the traditional and probabilistic approaches. Probabilistic CPS was significantly more accurate than temporal CPS (p < .001 for all paired comparisons between the temporal approach and each probabilistic time frame; i.e., column 1 versus column 3, 4, 5, 6,7, 8, and 9 for physicians; column 2 versus column 10, 11, 12, 13, 14, 15, and 16 for nurses; McNemar test). We also compared between physicians and nurses for each prognostication question, and the significant p-values are indicated with paired asterisks.

Figure 3.

Accuracy of temporal clinician prediction of survival (CPS) by clinician and patient age. The y-axis represents the predicted values from a multivariate logistic regression examining temporal accuracy of CPS as a function of clinician and patient age. The x-axis represents the actual patient age (in years) for each observation. Patient age was a significant predictor of clinician accuracy (p = .019). On average, a significantly more accurate temporal CPS was provided for older patients than for younger patients, regardless of which clinician provided the estimate.