Data source and study period
We used FEDRA, the Spanish Pharmacovigilance database, to identify all
the ADR cases related to HCQ. This database includes all ADRs reported
to the Spanish Pharmacovigilance System (SEFV-H). Health professionals,
pharmaceutical industry and the public submit spontaneous reports of
suspected ADRs. Then, ad hoc committees evaluate reports using an
algorithm [9] to determine whether a causal relationship exists.
Nevertheless, information coming from the reports is included in the
database regardless of causality and severity. ADRs are coded according
to the Medical Dictionary for Regulatory Activities dictionary (MedDRA)
[10].
The study period was defined from 1 January 1982 to 19 February 2021.
Likewise, we considered a pre-pandemic period the period before 1 March
2020 and a pandemic period from 1 March 2020 on.