• Respiratory Medicine, Nottingham University Hospitals NHS Trust, Nottingham, UK.
• Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
• Department of Epidemiology, University of Nottingham School of Medicine, Nottingham, UK.
• Wolfson Institute of Preventive Medicine, Barts and London, London, UK.
• Primary Care Diagnostics, University of Exeter, Exeter, UK.
• Department of Molecular and Clinical Cancer Medicine, Institute of Systems, University of Liverpool, Liverpool, UK.
• Department of Respiratory Medicine, Leeds Teaching Hospitals, Leeds, UK.
• Lungs for Living Research Centre, UCL Respiratory, University College London, London, UK.
• Public Health, Erasmus MC, Rotterdam, The Netherlands.
• European Lung Foundation, Birmingham, UK.

Lung cancer screening is effective if offered to people at increased risk of the disease. Currently, direct contact with potential participants is required for evaluating risk. A way to reduce the number of ineligible people contacted might be to apply risk-prediction models directly to digital primary care data, but model performance in this setting is unknown.

METHOD: The Clinical Practice Research Datalink, a computerised, longitudinal primary care database, was used to evaluate the Liverpool Lung Project V.2 (LLP_v2) and Prostate Lung Colorectal and Ovarian (modified 2012) (PLCO_m2012) models. Lung cancer occurrence over 5-6 years was measured in ever-smokers aged 50-80 years and compared with 5-year (LLP_v2) and 6-year (PLCO_m2012) predicted risk.

RESULTS: Over 5 and 6 years, 7123 and 7876 lung cancers occurred, respectively, from a cohort of 842 109 ever-smokers. After recalibration, LLP_V2 produced a c-statistic of 0.700 (0.694-0.710), but mean predicted risk was over-estimated (predicted: 4.61%, actual: 0.9%). PLCO_m2012 showed similar performance (c-statistic: 0.679 (0.673-0.685), predicted risk: 3.76%. Applying risk-thresholds of 1% (LLP_v2) and 0.15% (PLCO_m2012), would avoid contacting 42.7% and 27.4% of ever-smokers who did not develop lung cancer for screening eligibility assessment, at the cost of missing 15.6% and 11.4% of lung cancers.

CONCLUSION: Risk-prediction models showed only moderate discrimination when applied to routinely collected primary care data, which may be explained by quality and completeness of data. However, they may substantially reduce the number of people for initial evaluation of screening eligibility, at the cost of missing some lung cancers. Further work is needed to establish whether newer models have improved performance in primary care data.