In several populations, such as the general population and youth, intervals between data collection may extend to 4-6 years, while in populations with higher HIV incidence, shorter intervals and more flexibility are needed.
Thus, it is important to emphasize that our data do not exclude an association between increased activity of systemic coagulation pathways and increased decline in lung function, and that larger population-based studies of change in lung function with shorter intervals between data collection will be required to clarify this important question.
18– 20 This may be due to extended intervals between data collection.
The time intervals between data collection occasions varied across couples depending on their vacations or other planned activities.
However, the intervals between data collection, blood sampling, and diagnosis differ substantially between the three different study populations, something that might be considered a limitation of the study.
Nevertheless, letters and reminders are part of the research process and play a role in participant engagement especially if there is little face-to-face contact or in trials with long intervals between data collection time points.
More thorough desk-based tracking before issuing addresses to fieldworkers would improve the cost-effectiveness of the fieldwork, particularly for a mobile cohort such as the ALSPAC YPs, and for other cohorts with a similarly long interval between data collection exercises.
The average time period between data collection in the first cohort was four years and two months, with a minimal interval of 3 years and 2 months.
