For the longitudinal studies, we added two items to the quality assessment, namely a response at main moment of follow-up ≥80%, and data collection for ≥1 year.
This rests upon a lack of data collection for many years and a strong need to do so, but it means that real solutions will take years to be researched, studied and proven.
Following the first year, insufficient matched questionnaires were received, and it was necessary to continue data collection for a second year.
Noticing the change over time, we then extended the data collection for a further year and observed the change in case fatality in the two districts.
Formal follow-up using designed data collection for up to 3.5 years after randomisation and routine data for 10 years.
After continuous data collection for more than 5 years, P Q became stable.
While we utilized a systematic and rigorous approach to collecting data, due to the urgency to develop solutions that could be implemented at the beginning of the next academic year, data collection for this case occurred in the summer months.
The results of our paired t-test identified a mean difference of 3.1 years (95% CI: 2.6 to 3.6) between the year of publication and the year of data collection, for studies with both values present.
Monthly data collection for 6 months at 7-year follow-up of participants in a prospective cohort study.
We applied this time lag to estimate the year of data collection for studies missing this value.
