Purpose Chronic hypoxic and hypercapnic respiratory failure and obstructive sleep apnoea (OSA) are chronic diseases associated with decreased quality of life and increased mortality. The rationale behind the set up the retrospective nationwide DISCOVERY cohort was to study several questions including disease course and risk factors for incident disease, impaired quality of life, hospitalisation risk and mortality in patients with chronic respiratory failure with long-term oxygen therapy (LTOT), long-term mechanical ventilation (LTMV) and obstructive sleep apnoea (OSA) on treatment with continuous positive airway pressure (CPAP).
Participants and settings Data from the national quality registry for respiratory insufficiency and sleep apnoea (Swedevox) and a population-based control group from Statistics Sweden were merged with governmental registries, the Swedish Cancer Registry, the Swedish Cause of Death Registry, the Swedish Drug registry, the Swedish National Patient Registry and the Swedish Dental Health Registry and with national quality registries for diabetes, rheumatic diseases (Swedish Rheumatology Quality Registry), stroke (RiksStroke), heart failure (RiksSvikt), acute heart infarction care (SwedeHeart) and intensive care (SIR) and with socioeconomic data from Statistics Sweden (SCB).
Findings to date The cohort comprises 25 804 unique patients with LTOT since 1987 (54.1% females, age 73.3±9.8 years, body mass index (BMI) 26.6±6.5 kg/m2), 8111 with LTMV since 1996 (48.6% women, age 60.6±16.9 years, BMI 32.9±10.8 kg/m2), 65 809 with OSA on CPAP since 2010 (29.5% women, age 57.2±12.5 years, BMI 31.9±6.2 kg/m2) and 145 224 persons in a population-based control group from same time span up to March 2018 (51.7% women, age 49.9±20.4 year, BMI 24.9±4.0 years).
Future plans In patients with chronic respiratory failure and sleep apnoea important questions regarding comorbidity burden, hospitalisation rate, mortality and treatment outcomes are still unexplored to a large extent. The DISCOVERY cohort will provide unique opportunities by its size and comprehensiveness to fill this clinically relevant gap of knowledge.
- adult thoracic medicine
- sleep medicine
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Contributors Project administration: AP and MPE (principal investigator). Data analysis: AP and KÅ. First manuscript draft: AP. Contribution to the study design, critical revision for important intellectual content and approval of final version to be published: AP, LG, ML, BM, JS, JT-H, MPE.
Funding The work was supported by the Swedish Society for Sleep Research and Sleep Medicine, Uppsala-Örebro Regional Research Council (Log Nos RFR-931234), Centre for Research and Development, Uppsala University/Region Gävleborg (Log Nos CFUG-925881), Bror Hjerpstedt′s Foundation and the Fagerström foundation. ME was supported by unrestricted grants from the Swedish Society for Medical Research and the Swedish Research Council (Dnr 2019-02081).
Competing interests LG reports no conflicts of interest related to the submitted work but outside the submitted work: grants from Bayer, Resmed, Respironics/Philips, Desitin, the European Respiratory Society and non-financial support from Itamar Medical and Resmed; speakers bureau for Resmed, Philips, AstraZeneca and Fisher and Paykel; patent on sleep apnoea therapy issued. No conflicts of interest are declared for any of the other authors.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. The DISCOVERY data are not freely available as they are subject to secrecy in accordance with the Swedish Public Access to Information and Secrecy Act. Data are available after approval from the Swedish Ethical Review Authority (https://etikprovningsmyndigheten.se) for researchers who meet the criteria for access to confidential data.
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