Figure 1.

Temporal windows for machine learning model inclusion

We searched for health-care visits, medical conditions, and prescription medication orders before and after each patient's COVID-19 index date, up to a maximum of 365 days post-index. We ignored all data occurring in a buffer period of 45 days before and after the COVID-19 index date to differentiate pre-COVID-19 and post-COVID-19 from acute COVID-19. For patients who attended a long COVID clinic, we ignored all data occurring on or after their first visit to such a clinic to avoid influencing the model with clinical observations occurring as a result of the patient's long COVID assessment.