Population and design: Monocentric cohort comparing COVID-19 patients exposed or not exposed to the treatment hydroxychloroquine (HCQ)+azithromycin (AZ) used as a standard of care in our center (Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, Marseille, France). The inclusion period was from 2 March 2020 to 31 December 2021, with a follow-up period of 6 weeks.

Inclusion and exclusion criteria: Data included were those of patients ≥ 18 years of age with PCR-proven COVID-19 disease regardless of symptoms (asymptomatic or symptomatic) and treated in our centre, i.e. having had a medical examination by one of the doctors in our centre (Institut Hospitalo-Universitaire (IHU) Méditerranée Infection, Marseille, France) either as outpatients or as inpatients, i.e. hospitalized on the day of the visit in our outpatient unit following evaluation or directly transferred from another medical ward except intensive care unit. The reasons for exclusion were an erroneous patient identification (identity surveillance and duplicates), lack of available medical data, lack of COVID-19 after checking the medical record (including patients without COVID-19 consulting for a post-COVID-19 syndrome), expression of opposition to the use of their medical data for research purposes (in accordance with European General Data Protection Regulation), and data from patients hospitalized in our center after intensive care. Data from COVID-19 outpatients left without medical advice were excluded.

Data source

For inpatients: Between 03.03.20 and 12.03.2021, i.e. the first year of the epidemic, data were collected using the Electronic Patient Record. The DPI ‘”Dossier Patient Informatisé”) centralized all the medical information of a patient concerning his stays at the Assistance Publique - Hôpitaux de Marseille. During this input, a large amount of medical data concerning the treatment was collected (2799 patients). Between 13.03.21 and 31.12.2021, the data were extracted from the APHM administrative database (PASTEL). PASTEL does not contain medical data but only the following information: IPP (“Identifiant Permanent du Patient”) which is a unique identifier for each patient, age, sex, date of entry, the different services in which the patient may have been hospitalised and the date of discharge (1791 patients).

For the outpatients, the medical cards of the patients who came to the outpatient unit filled in by the medical staff (11,725 patients). The content of these medical forms evolved during the epidemic, particularly with regard to the collection of patients' vaccination status and risk factors. At the outset, they contained information on prescribed treatments (29752 patients).

The fusion of these databases was carried out via the IPP, and made it possible to obtain the total population of patients treated at the IHU with the following information: IPP, age, sex, outpatient care (Y/N), inpatient care (Y/N), date of entry and date of exit. If a patient had more than one episode of SARS-CoV-2 treated at the IHU, only the first stay was taken into account. If a patient was treated as an outpatient and then hospitalized, both pieces of information were kept. In the end, we obtain a database of 30,669 patients

To this merged database were added only for the hospitalized patients the data concerning the treatment from the PHARMA database which is the pharmaceutical prescription file. Similarly, for each patient, the Sars-Cov2 variant was merged with the biology database (NEXLAB Medical Software) which lists all the samples and their associated genotype via an extraction. Finally, the information on death from all causes was obtained via an extraction from the Medical Information Department (DIM). Indeed, if the patient died during his inpatient care, the information system retrieves this information in the discharge mode. For patients discharged alive from the APHM stay, we queried the French National Death Registry (29) to find out whether they died within 42 days of their IHU treatment. All the data were quality controlled, looking for duplicates and aberrant data.

Finally, the construction of the database and the quality controls carried out were verified by a bailiff.