Development and validation of a simple 11-item long COVID burden index (LCBI)

Existing patient-reported outcome measures for long COVID are comprehensive; however, they are time-consuming and burdensome for some patients in daily practice.

This study aimed to develop and validate a simple patient-reported outcome measure to assess the burden associated with frequently occurring symptoms in patients with long COVID.

Following an extensive literature review, a questionnaire consisting of 11 items was developed based on the modified Delphi method with an expert panel. Its face validity was assessed in three individuals with COVID-19 history. The study subjects were Japanese residents who responded to the online QoLCoVE (Quality of Life in the COVID-19 Era) study between March 8 and April 1, 2024. The known-groups and concurrent validity were assessed after exploratory factor analysis. The internal consistency was evaluated using Cronbach's alpha.

A total of 1014 participants were included in the analysis, all at least two months after their last COVID-19 infection. The factor analysis results showed unidimensionality. Internal consistency reliability assessed using Cronbach's alpha was 0.89. For known-groups validity, the total score decreased with time since the acute COVID-19 infection, as well as with more frequent vaccinations, and increased with an increasing previous history of COVID-19. A dose-dependent relationship was observed between EQ-5D-5L and the scale's total score, categorized according to quartiles.

We successfully developed the Long COVID Burden Index, a simple 11-item scale to easily quantify symptoms frequently experienced by patients with long COVID, which may interfere with their daily lives.