Research Reports - Wide variation and systematic bias in expert clinicians' perceptions of prognosis following brain injury
Br J Neurosurg. 2013 Jun;27(3):340-3
Moore NA, Brennan PM, Baillie JK
BACKGROUND: The heterogeneous nature of traumatic brain injury (TBI) makes
outcome prediction difficult. Although a considerable evidence base exists in the
form of well-validated predictive models, these models are not widely used. We
hypothesised that this prognostic gap, between the availability and use of
prognostic data, leads to inaccurate perceptions of patient outcome. We
investigated whether outcome predictions in TBI made by expert clinicians were
consistent and accurate when compared to a well-validated prognostic model
METHODS: Neurosurgeons and neurointensivists were asked to predict probability of
death at 6 months for 12 case vignettes describing patients with isolated TBI.
Predictions were compared to IMPACT prognosis for each vignette. To interrogate
potential sources of bias in clinical predictions, respondents were given one of
two sets of vignettes (A or B) identical apart from one critical factor known to
make a large difference to outcome.
RESULTS: 27 of 33 questionnaires were returned. Clinicians were consistently more
pessimistic about outcomes than the IMPACT model, predicting a significantly
greater probability of death (mean difference + 16.3%, 95% CI 13.3-19.4, p <
0.001). There was wide variation between clinicians predicting outcomes for any
given vignette (mean range 68.3%), and within the predictions made by each
individual: 30% of clinicians were both the most pessimistic respondent, and the
most optimistic, for at least one vignette. Clinicians modified their predictions
appropriately for most of the factors altered between corresponding vignettes.
However when the reported blood glucose was changed, clinicians' predictions
deviated widely from IMPACT predictions, indicating that clinicians
systematically overlooked the prognostic relevance of this information.
CONCLUSION: Clinical experts' predictions of outcome in TBI are widely variable
and systematically pessimistic compared to IMPACT. Clinicians overlook important
factors in formulating these predictions. Use of well-validated outcome models
may add value and consistency to prognostication.