Methods
Study design A single-center retrospective follow up study was conducted in which 2 separate databases; the MST clinical database which contains electronic health records of COVID-19 hospitalized patients and the Post-COVID cohort database which contains patient follow-up data were combined. Using the merged database, it is possible to determine the association between patient pharmacotherapy during the hospital stay and the development of post-COVID-19 syndrome 6 months after hospital discharge (figure 1 ). Three drugs of interest were identified and analyzed, i.e., antibiotics, anticoagulants, and corticosteroids. Separate regression models were made to analyze each individual drug treatment. Drug class effects were measured without taking into account the dose variations or length of use as patients were treated according to the hospital protocol from which physicians rarely deviated.
SettingThe first database consists of retrospectively sourced patient data (March 2020 – September 2021) of 995 COVID-19 hospitalized patients from Medisch Spectrum Twente (MST), Enschede, the Netherlands. Patient data was collected from the time of the first admission with COVID-19 until the last discharge. This database was set up in line with the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) rapid COVID-19 case report form (Annex 2) and will hereinafter be referred to as the MST clinical database. The second database is a separate post-COVID database that consists of 274 patients. This database was originally set up to follow COVID-19 patients’ overall health and well-being after hospital discharge (September 2020 - present) using the short form Health survey 36 (SF-36), the EuroQol 5-dimension 5 level descriptive system (EQ-5D-5L), the Medical research council dyspnoe (MRC) survey and the short fatigue survey. Thereby this database will hereinafter be referred to as the Post COVID database.