Validation of the 'Post-COVID-19 Functional Status Scale (PCSF)' in patients with COVID-19 infection.

<bold>Objective:</bold> The purpose of the study was the cross-cultural adaptation of the Post-COVID-19 Functional Status Scale (PCSF) as an instrument to assess functional limitation and quality of life in a population of subjects diagnosed with SARS-CoV- 2. <bold>Methods:</bold> Scale validation study, through the assembly of a prospective cohort with 6-month follow-up. The study was carried out in a fourth level University Hospital in two sequential phases: first linguistic validation followed by psychometric validation. A total of 120 subjects aged 18 years and older diagnosed with SARS-CoV-2 infection were included in the study, in which the PCSF instrument was administered. Internal consistency, instrument stability and correlation with SF-36 V2 were evaluated. <bold>Outcomes:</bold> Spanish version of the PCFS scale was obtained with semantic and conceptual equivalence with respect to the original version in English. The internal consistency, evaluated using Cronbach's alpha coefficient, was >0.7. The scale's stability, assessed through test-retest, showed a high intra-subject agreement of 0.96 (95% CI: 0.93-0.97). A correlation of -0.79 (95% CI: -1.0 to -0.51) was found with the SF-36 V2 scale, with a stronger correlation observed in the domains of physical functioning, physical role limitation, and social functioning of the SF-36 V2 scale. <bold>Conclusions:</bold> The validated Spanish version of the PCFS scale shows semantic, conceptual, and technical equivalence with respect to the original version in English and presents adequate psychometric characteristics. Keywords: SARS-CoV-2, severe acute respiratory syndrome, quality of life