Questionnaire sources and rights
The symptom check combines published instruments with questions written for this app. Each publication and instrument retains its own copyright and licensing terms.
RECOVER-Adult Long COVID Research Index
The app asks all 11 symptoms in the 2024 research index. Points and the threshold come from Geng et al., JAMA 2025. Symptom wording comes from the RECOVER questionnaire reported by Thaweethai et al., JAMA 2023.
The app does not administer the separate Neuro-QoL, Seattle Angina Questionnaire-7, or PROMIS severity measures required for three index symptoms. It explains this limitation with the result. The publications and RECOVER materials retain their respective rights.
DePaul Symptom Questionnaire PEM short form
The five frequency and severity items come from Cotler et al., Diagnostics 2018. That article and its questionnaire appendices are distributed under the Creative Commons Attribution 4.0 license.
Post-COVID-19 Functional Status scale
The question and grades are from version 2 of the scale described by Klok et al., European Respiratory Journal 2020. The source article is distributed under the Creative Commons Attribution-NonCommercial 4.0 license.
Condition self-checks
These questions were written for this app from the cited criteria; they are not reproductions of validated questionnaires.
- Long COVID: National Academies 2024 definition.
- ME/CFS: Institute of Medicine 2015 criteria.
- Fibromyalgia: 2016 revised diagnostic criteria.
- Lyme disease: CDC guidance on testing and diagnosis and erythema migrans.
PHQ-9 and GAD-7
The depression check is the Patient Health Questionnaire-9 (PHQ-9) of Kroenke, Spitzer, and Williams, J Gen Intern Med 2001, and the anxiety check is the GAD-7 of Spitzer, Kroenke, Williams, and Löwe, Arch Intern Med 2006. The questions and answer choices are the published forms from phqscreeners.com, which states that no permission is required to reproduce, translate, display, or distribute them. The severity levels follow those papers and the PHQ and GAD-7 instruction manual.
The crisis line details come from the 988 Suicide & Crisis Lifeline.
The introductory history and “What changed” questions were written for this app and are not validated scales. See the linked publications and licenses for authoritative terms and attribution requirements.