Correlation of clinical decision-making with probability of disease: A web-based study among general practitioners

BACKGROUND: Medical decision-making relies partly on the probability of disease. Current recommendations for the management of common diseases are based increasingly on scores that use arbitrary probability thresholds. OBJECTIVE: To assess decision-making in pharyngitis and appendicitis using a set of clinical vignettes, and the extent to which management is congruent with the true probability of having the disease. DESIGN: We developed twenty-four clinical vignettes with clinical presentations corresponding to specific probabilities of having disease defined by McIsaac (pharyngitis) or Alvarado (appendicitis) scores. Each participant answered four randomly selected web-based vignettes. PARTICIPANTS: General practitioners (GP) working in primary care structures in Switzerland and the USA. MAIN MEASURES: A comparison between the GP’s management decision according to the true probability of having the disease and to the GP’s estimated probability, investigating the GP’s ability to estimate probability of disease. KEY RESULTS: The mean age of the GPs was 48 years (SD 12) and 66% were men. The correlation between the GP’s clinical management decision based on the vignette and the recommendations was stronger for appendicitis than pharyngitis (k(w) = 0.74, 95% CI 0.70–0.78 vs. k(w) = 0.66, 95% CI 0.62–0.71). On the other hand, the association between the clinical management decision and the probability of disease estimated by GPs was more congruent with recommendations for pharyngitis than appendicitis (k(w) = 0.70, 95% CI 0.66–0.73 vs. 0.61, 95% CI 0.56–0.66). Only a minority of GPs correctly estimated the probability of disease (29% for appendicitis and 39% for pharyngitis). CONCLUSIONS: Despite the fact that general practitioners often misestimate the probability of disease, their management decisions are usually in line with recommendations. This means that they use other approaches, perhaps more subjective, to make decisions, such as clinical judgment or reasoning that integrate factors other than just the risk of the disease.