Prognosis of patients with long COVID symptoms: a protocol for a longitudinal cohort study at a primary care referred outpatient clinic in Helsinki, Finland

INTRODUCTION: After COVID-19, many continue to experience persistent debilitating symptoms, that is, long COVID. Its most prevalent symptoms are chest pain, difficulties with breathing, painful muscles, ageusia or anosmia, tingling extremities and general tiredness. This paper describes the protocol of the Long COVID Cohort Study to assess the prognosis and prognostic determinants of patients with long COVID by implementing patient-reported outcome measures (PROMs), patient-reported experience measures (PREMs) and clinical examinations during a 1-year follow-up. METHODS AND ANALYSIS: This is a prospective, single-site cohort study consisting of administering questionnaires and clinical examinations to adult patients referred to the Clinic for Long-Term Effects of COVID-19 at Helsinki University Hospital (Hospital district of Helsinki and Uusimaa). The referrals are from all healthcare units within HUS and other hospital districts during years 2021–2023. All admitted patients have had laboratory-confirmed COVID-19. The targeted study sample size is 500 participants. The questionnaires are administered at 0, 3, 6 and 12 months. The main outcome variables are the changes in self-reported functional abilities and quality of life. In addition, we will evaluate functional abilities at baseline using neurocognitive evaluation, a 6MWT and a measurement of hand grip strength. The Long COVID Cohort Study will form a quality register for the clinic and characterise the first systematic collection of PROMs, PREMs, questionnaire and clinical examinations related to long COVID in Finland. The Study belongs to a study consortium Long COVID—HORIZON-HLTH-2021-DISEASE-04 that aims to reveal the biomechanisms of long COVID. ETHICS AND DISSEMINATION: This study has been approved by the Helsinki University Hospital research ethics committee board, ID HUS/1493/2021 on 6 March 2021. All study participants sign written informed consent for participation. The study findings will be reported for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT05699512; Pre-results.