Design of the Arizona CoVHORT: A Population-Based COVID-19 Cohort

Abstract

This study is a prospective, population-based cohort of individuals with a history of SARS-CoV-2 infection and those without past infection through multiple recruitment sources. The main study goal is to track health status over time, within the diverse populations of Arizona and to identify the long-term consequences of COVID-19 on health and well-being. A total of 2,881 study participants (16.2% with a confirmed SARS-CoV-2 infection) have been enrolled as of December 22, 2020, with a target enrollment of 10,000 participants and a planned follow-up of at least 2 years. This manuscript describes a scalable study design that utilizes a wide range of recruitment sources, leveraging electronic data collection to capture and link longitudinal participant data on the current and emerging issues associated with the COVID-19 pandemic. The cohort is built within a collaborative infrastructure that includes new and established partnerships with multiple stakeholders, including the state's public universities, local health departments, tribes, and tribal organizations. Challenges remain for ensuring recruitment of diverse participants and participant retention, although the electronic data management system and timing of participant contact can help to mitigate these problems.

Keywords: COVID-19; SARS-CoV-2; cohort study [or longitudinal study]; epidemiology; long-term follow up.

Figure 1

Primary recruitment methods and number of participants enrolled into the Arizona CoVHORT as of December 22, 2020. ^*Total includes participants also recruited through other methods and by word of mouth.

Figure 2

Current classification of participants based on verification of SARS-CoV-2 infection status. ¹Verified through case investigations conducted by SAFER for state and local health departments. ²Verified through partnerships with the State of Arizona Antibody Testing Initiative. ³All self-reported test results regardless of tests (PCR, antigen, or antibody) are determined to be suspected due to inability to verify each participant's results.

Figure 3

Frequency of on-cycle surveys administered to uninfected and infected participants, and the frequency of off-cycle surveys administered to only infected participants over the course of the follow-up period of the Arizona CoVHORT. (Top and Middle panel) Participants who were uninfected that self-report a COVID-19 illness or a positive test during follow up are shifted to the infected participants survey timeline including the additional “off-cycle” surveys. (Bottom panel) Infected participants that report they are no longer experiencing symptoms over the course of two “off-cycle” surveys are shifted to the uninfected participant survey timeline without the additional “off-cycle” surveys.