Numeracy and Interpretation of Prognostic Estimates in Intracerebral Hemorrhage Among Surrogate Decision Makers in the Neurologic ICU

Abstract

OBJECTIVE Clinicians caring for patients with intracerebral hemorrhage (ICH) must often discuss prognosis and goals of care with their patients’ surrogate decision makers, and may make numeric estimates of likelihood of survival and functional independence, informed by validated prediction models. Surrogates’ prognostic estimates are often discordant with physicians’, suggesting that physicians’ numeric statements may not be accurately interpreted. We sought to assess the relationship between numeracy and interpretation of prognostic estimates in ICH among surrogate decision makers. We also assessed surrogates’ application of prognostic estimates to decisions regarding goals of care. DESIGN Single-center, survey-based, cross-sectional study SETTING 22-bed neurologic intensive care unit (ICU) at an urban, academic hospital SUBJECTS Surrogate decision makers for patients admitted to the neurologic ICU INTERVENTIONS Participants completed a survey containing 5 clinical vignettes describing patients with non-traumatic ICH. For each patient, numerical estimates of survival and functional independence were explicitly provided, based on the validated ICH score, and the Prediction of Functional Outcome in Patients with Primary Intracerebral Hemorrhage (FUNC) score. MEASUREMENTS AND MAIN RESULTS Participants were asked to make their own prognostic estimates, as well as to describe their preferred goals of care for each hypothetical patient. Respondent demographics were collected, and numeracy was assessed using a modified Lipkus 11-item scale. Poor numeracy was common (42 out of 96 subjects) in this relatively highly educated population. Most prognostic estimates (55%) made by surrogates were discordant with the provided estimates. High numeracy correlated with better concordance (OR 23.9 [5.57–97.64], p<0.001), independent of several factors, including level of education and religion. Numeracy also affected goals-of-care decisions made by surrogates. CONCLUSIONS Poor numeracy, resulting in impaired understanding of statistics and risk magnitudes, is common among surrogate decision makers in an intensive care setting, and poses a barrier to communication between surrogates and clinicians regarding prognosis and goals of care.

Age differences in COVID-19 risk-taking, and the relationship with risk attitude and numerical ability

“…Numerical abilities were a significant predictor of COVID-19 related risk-taking, with those having higher numerical abilities less likely to adopt preventative behaviours, thus taking more risk. This finding was the opposite of what we expected, as prior research has found that low numeracy was related to poorer health outcomes and decisions [29][30][31][32]. When looking at numeracy and COVID-19 health behaviours specifically, other studies found that numeracy was not significantly related to adopting preventative measures [56,59].…”

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“…Several common surrogate biases warrant discussion. First, in experimental settings, surrogates' interpretations of clinician prognostications were affected by numeracy skills ( 81 ) and were often overly optimistic ( 82 ). Second, surrogates may be subject to recall bias, remembering patients as more independent than they really were prior to illness ( 83 ).…”

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“…A study of decisionmakers in a critical care environment demonstrated that even college-educated people possessed low numeracy (the ability to understand numbers), which led to discordant surrogate prognostic estimates. 37 There are established strategies for making decisions in the setting of prognostic uncertainty, including describing the best case/worst case scenario, and most likely functional outcomes, for a particular illness, and gauging the acceptability of each of these outcomes based on a patient's known wishes. 38,39 It is also helpful to frame predictions of longevity in time intervals (hours to days, days to weeks, weeks to months, months to years, or many years), rather than more specific time frames, to enhance accuracy and flexibility.…”