Effects of Random Measurement Error on Lung Cancer Screening Decisions: A Retrospective Cohort-Based Microsimulation Study

Chest. 2021 Feb;159(2):853-861. doi: 10.1016/j.chest.2020.08.2112. Epub 2020 Sep 14.


Background: Self-reported tobacco pack-year history plays a large role in decisions about low-dose CT screening for lung cancer, yet is challenging to measure accurately.

Research question: To what extent does random measurement error in pack-year information impact screening decisions and screening effectiveness?

Study design and methods: Retrospective cohort study of 10,449 patients with pack-year history documented at least twice between October 2013 and July 2017 across 8 academic Veterans Affairs sites. Outcome measures included (1) observed reliability of pack-year information based on all repeat measures for the study population and (2) each person's statistically "true" pack-year information based on best linear unbiased predictor from a multilevel linear random effects model. To examine how unreliability leads to misclassification of screening eligibility and inaccuracy in estimating lung cancer risk, we simulated pack-year observations for each person, first comparing simulated pack-year and lung cancer risk values with true values, then comparing outcomes when basing screening decisions on unreliable pack-year information vs true information.

Results: Reliability of assessing pack-year information in routine practice varied across sites. Thus, we examined the clinical impact of two different levels of reliability, based on the range of intraclass correlation coefficients observed. Using a ≥ 30-pack-year threshold led to a high rate of eligibility misclassifications (48.1% misclassified with higher reliability pack-year information and 60.7% misclassified with lower reliability information). However, using a lung cancer risk threshold leads to fewer misclassifications (47.3%-49.7% misclassified when using lower reliability pack-year information) and maintains screening effectiveness better when using unreliable pack-year information.

Interpretation: Random error in real-world pack-year assessments leads to a substantial rate of misclassifying who should be offered CT screening if a ≥ 30-pack-year criterion is used. However, using a lung cancer risk threshold mitigates the impact of unreliable pack-year information. Decision-makers concerned about the impact of unreliable pack-year information should consider using risk-based approaches to CT screening.

Keywords: lung cancer screening; measurement error; self-reported smoking history.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Decision Making*
  • Early Detection of Cancer
  • Female
  • Hospitals, Veterans
  • Humans
  • Lung Neoplasms / diagnostic imaging*
  • Male
  • Mass Screening / methods*
  • Middle Aged
  • Reproducibility of Results
  • Retrospective Studies
  • Risk Assessment
  • Smokers*
  • Tomography, X-Ray Computed*
  • United States