Clinical decision-making on lung cancer investigations in primary care: a vignette study

Objectives: To investigate the role of comorbid chronic obstructive pulmonary disease (COPD) and symptom type on general practitioners' (GP's) symptom attribution and clinical decision-making in relation to lung cancer diagnosis. Design: Vignette survey with a 2×2 mixed factorial design. Setting: A nationwide online survey exploring clinical decision-making in primary care. Participants: 109 GPs based in the United Kingdom (UK) who were registered as responders on Dynata (an online survey platform). Interventions: GPs were presented with four vignettes which described a patient aged 75 with a smoking history presenting with worsening symptoms (either general or respiratory) and with or without a pre-existing diagnosis of COPD. Primary and secondary outcome measures: GPs indicated the three most likely diagnoses (free-text) and selected four management approaches (20 pre-coded options). Attribution of symptoms to lung cancer and referral for urgent chest X-ray were primary outcomes. Alternative diagnoses and management approaches were explored as secondary outcomes. Multivariable mixed-effects logistic regression was used, including random intercepts for individual GPs. Results: 422 vignettes were completed. There was no evidence for COPD status as a predictor of lung cancer attribution (OR=1.1, 95% CI=0.5-2.4, p=0.914). There was no evidence for COPD status as a predictor of urgent chest X-ray referral (OR=0.6, 95% CI=0.3-1.2, p=0.12) or as a predictor when in combination with symptom type (OR=0.9, 95% CI=0.5-1.8, p=0.767). Conclusions: Lung cancer was identified as a possible diagnosis for persistent respiratory by only one out of five GPs, irrespective of the patients' COPD status. Increasing awareness among GPs of the link between COPD and lung cancer may increase the propensity for performing chest X-rays and referral for diagnostic testing for symptomatic patients.