Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus is associated with a plethora of long-lasting symptoms (long-COVID). The presence of long-COVID symptoms causes decreased functionality. This study described the psychometric properties of the Functional Impairment Checklist (FIC), a disease-specific patient-reported outcome measure (PROM) used for evaluating the functional consequences of SARS in previously hospitalized COVID-19 survivors with long-COVID symptoms. The LONG-COVID-EXP-CM is a multicenter cohort study including patients hospitalized with COVID-19 during the first wave of the pandemic in five hospitals in Madrid. A total of 1969 (age: 61 ± 16 years, 46.4% women) COVID-19 survivors with long-COVID completed the FIC at a long-term follow-up after hospitalization (mean: 8.4 ± 1.5 months). Internal consistency (Cronbach alpha value), reliability (item-internal consistency, item-discriminant validity), construct validity (exploratory factor analysis), floor effect and ceiling effect were calculated. The mean time for fulfilling the FIC was 62 ± 11 s. The Cronbach's alpha values reflecting the internal consistency reliability were 0.864 for FIC-symptoms and 0.845 for FIC-disability. The correlation coefficient between the FIC-symptoms and FIC-disability scale was good (r: 0.676). The ceiling effect ranged from 2.29% to 9.02%, whereas the floor effect ranged from 38.56% to 80.19%. The exploratory factor analysis showed factor loadings from 0.514 to 0.866, supporting good construct validity. Women exhibited greater limitations in all physical symptoms and disability-related domains of the FIC compared with men (all, p < 0.001). Further, younger patients (those aged <45 years) self-reported lower physical symptoms and disability-related domains than older patients. In conclusion, this study indicates that the FIC has good psychometric properties to be used as a specific-disease PROM to measure function and disability in COVID-19 survivors with long-COVID.