Prediction models for covid-19 outcomes: Reasons to be cautious

Robust models that predict the prognosis of coronavirus 2019 (covid-19) are urgently needed to support decisions about shielding, hospital admission, treatment, and population level interventions. With cases increasing in the UK and elsewhere, and winter approaching, such models could have a rapid clinical impact. Two linked articles report on two newly developed covid-19 prediction
models. QCOVID is a risk prediction model for covid-19 related mortality for use in the general population (doi:10.1136/bmj.m3731), whereas the 4C mortality score is for use on admission to hospital (doi:10.1136/bmj.m3339). Notably, these models are of higher quality than others published to date, having been developed using ample sample sizes, with generally appropriate modelling choices, and suitably internally validated and reported. Nevertheless, we sound a note of caution in their use.