Adapting epidemiological research through unexpected environmental events: COVID-19 and bushfires impacts on the administration of the PATH cohort study.

Background: At the outbreak of the pandemic in Australia, which directly followed unprecedented bushfires, the PATH Through Life Study had just commenced data collection of its 5th wave for the 40s age cohort. Continuation of fieldwork required dynamic transition from an in-person structured assessment protocol, to remote assessment methods with adaptation of established measures. We aim to describe the methods used to adapt the longitudinal study to these events, and the implications of data collection methodology for analysis. Reflections on these experiences are essential for transparent reporting of protocol change, and for informing future study design.

Methods: Evaluation of the data collection process for the fifth follow-up assessment of the PATH Through Life Study, a population-based cohort of Australians aged 58-64 years (n = 2530). Evaluation metrics include response rates for interviews done in-person and remotely, observations from data collection modifications, and participant feedback. Additional online survey items measuring the impact of exposure to bushfires and COVID-19 were developed and deployed as part of the study.

Results: Of 2147 contacted for follow-up, 1558 participants completed wave 5 (data collection commenced September 2019). By November 2019 (onset of the bushfires), 585 (37%) participants had completed face-to-face interviews and by March 2020, a further 1057 (68%) participants had completed their interviews at the onset of government restrictions relating to COVID-19. The shift to remote assessments resulted in 30% of assessments being completed by telephone. Challenges of the data protocol approach are discussed including the impact of multiple data collection pathways on analysis, and limitations of telephone interviews. Participant completion rates for the additional bushfire and COVID-19 surveys for the wave were 60% and 69% respectively; anecdotal participant feedback was positive regarding the inclusion of these measures.

Conclusions: Dynamic capture of exposure to unexpected events within the context of an established longitudinal study requires rapid design and protocol adaptations, and careful documentation of participation timing and pathways. Given the heightened public interest, participant response was encouraging, and the data captured not only enhances the value of the whole dataset, but is uniquely placed to address questions on population-level vulnerabilities and ongoing impacts of the exposures.