Development and validation of the long covid symptom and impact tools, a set of patient-reported instruments constructed from patients’ lived experience

Tran, Viet-Thi; Riveros, Caroline; Clepier, Bérangère; Desvarieux, Moïse; Collet, Camille; Yordanov, Youri; Ravaud, Philippe

OBJECTIVES: To develop and validate patient-reported instruments, based on patients' lived experiences, for monitoring the symptoms and impact of long covid. DESIGN: The long covid Symptom and Impact Tools (ST and IT) were constructed from the answers to a survey with open-ended questions to 492 patients with long COVID. Validation of the tools involved adult patients with suspected or confirmed COVID-19 and symptoms extending over three weeks after onset. Construct validity was assessed by examining the relations of the ST and IT scores with health related quality of life (EQ-5D-5L), function (PCFS, post-COVID functional scale), and perceived health (MYMOP2). Reliability was determined by a test-retest. The "patient acceptable symptomatic state" (PASS) was determined by the percentile method. RESULTS: Validation involved 1022 participants (55% with confirmed COVID-19, 79% female, and 12.5% hospitalized for COVID-19). The long COVID ST and IT scores were strongly correlated with the EQ-5D-5L (r(s) = -0.45 and r(s) = -0.59 respectively), the PCFS (r(s) = -0.39 and r(s) = -0.55), and the MYMOP2 (r(s) = -0.40 and r(s) = -0.59). Reproducibility was excellent with an interclass correlation coefficient of 0.83 (95% confidence interval 0.80 to 0.86) for the ST score and 0.84 (0.80 to 0.87) for the IT score. In total, 793 (77.5%) patients reported an unacceptable symptomatic state, thereby setting the PASS for the long covid IT score at 30 (28 to 33). CONCLUSIONS: The long covid ST and IT tools, constructed from patients’ lived experiences, provide the first validated and reliable instruments for monitoring the symptoms and impact of long covid.