Overview
Respiratory illnesses are a leading cause of morbidity and mortality worldwide, yet their prevalence in the general population remains poorly characterized. Computed tomography (CT) is the most effective diagnostic tool for identifying respiratory illnesses that cause changes to the lung parenchyma, such as pulmonary infections, fibrosis, and nodules. The diagnostic power of CT led the US Preventive Services Task Force (USPSTF) to issue lung cancer screening guidelines. In this prospective, observational cohort study, the study team will recruit 10,000 individuals aged 21 to 85 years, stratified into three cohorts: Cohort 1 (Medical Indication Group), Cohort 2 (Guideline-Based Screening Group), and Cohort 3 (Asymptomatic Research Low-Dose CT \[LDCT\] Group). The primary analysis will estimate the baseline cross-sectional prevalence of LDCT-detectable pulmonary findings in Cohort 3. Secondary analyses will compare baseline LDCT findings across all three cohorts and evaluate baseline associations between risk/exposure variables and CT findings. Exploratory follow-up analyses will use clinical data from the electronic health record (EHR), as available, for up to 5 years after the baseline/index CT. This study has the potential to transform health screening strategies, reduce disease burden, and improve health outcomes across diverse populations.
Eligibility
Inclusion Criteria:
All Cohorts:
•Adults 21 through 85 years of age.
Cohort 1:
•Clinical indication for chest CT, such as suspected lung pathology, abnormal chest imaging, or pulmonary symptoms requiring further evaluation. Cohort 1 activities are routine clinical care; research activity is secondary data use.
Cohort 2:
•Individuals who currently meet USPSTF criteria for LDCT lung cancer screening. Cohort 2 activities are routine clinical care; research activity is secondary data use.
Cohort 3:
- Asymptomatic individuals who:
- Do not have a clinical indication for chest CT
- Do not meet current USPSTF criteria for LDCT lung cancer screening
- Able to provide informed consent
Exclusion Criteria:
All Cohorts:
•Individuals below the age of 21 and above the age of 85.
Cohort 3:
- Meets USPSTF guideline-based indications for LDCT lung cancer screening or has a clinical indication for chest CT.
- Any chest CT within the prior 2 years
- Pregnancy
- In active surveillance or treatment for a current cancer diagnosis, or a recent cancer diagnosis requiring intervention within 5 years of the baseline assessment.
- Unable to provide informed consent or lacks decision-making capacity
- McGaw medical students, residents, and fellows, consistent with NU/FSM policy, to reduce coercion or undue influence. Employees may participate only under the safeguards described in the vulnerable populations section.


