Ahlstrom 2021.

Study characteristics
Notes	English title The Swedish Covid‐19 intensive care cohort: risk factors of ICU admission and ICU mortality Study setting Start of study recruitment (MM/YYYY): NR End of study recruitment (MM/YYYY): 05/2020 Study design: Case‐control Study centre(s): Multiple centres/clinics/areas within a country Number of centres, clinics or areas: NR Study setting: Inpatient Number of participants recruited: 1981 Sampling method: Consecutive participants Participants Female participants (absolute number): 516 Age measure, value: Median (IQR), 61 (52‐69) Inclusion criteria: The study population was defined by at least one COVID‐19 registration in the SIRI until data acquisition on 27 May 2020. From RTB, four age‐ and sex‐matched controls per patient were drawn. Age matching was performed as close to ICU admission as possible, on the age at 31 January 2020. Cases could not become controls and controls could not be selected twice. Exclusion criteria: Exclusion criteria were aged < 18 years or the absence of a Swedish personal identification number (PIN) Smoking frequency: NR Diabetes frequency: 522 Hypertension frequency: 982 Cardiovascular disease frequency: 317 Asthma frequency: 133 Chronic obstructive pulmonary disease frequency: 75 Other pulmonary disease frequency: NR Immunosuppression frequency: 236 Chronic kidney disease frequency: 75 Cancer frequency: 94 Steroid administration frequency: NR Supplemental oxygen administration frequency: NR Other treatments (frequency): NR Prognostic factor(s) Study’s definition for obesity: Obesity was defined based on ICD‐10 coding E66 The time when obesity has been measured: Before disease or right at presentation Main variable used for determination of obesity: BMI Threshold used for definition: 30 Obesity frequency (absolute number): 123 Prognostic factor(s): BMI > 30 kg/m2 Outcome(s) Mortality Outcome (prognostic factor) Mortality (BMI > 30 kg/m2) Follow‐up Number of patients followed completely for the outcome: 1981 Number of obese patients followed completely for the outcome: 123 Number of non‐obese patients followed completely for the outcome: 1858 Univariable unadjusted analysis for obesity Effect measure for obesity: NR Effect measure value (95% CI), P value: NR Multivariable analysis for obesity Modelling method: Cox regression The set of prognostic factors used for adjustment: Age, gender, simplified acute physiology score 3 (SAPS3) Effect measure for obesity: Hazard ratio Effect measure value (95% CI), P value: 0.87 (0.51, 1.48), 0.61
Item	Authors' judgement	Support for judgement
Study Participation	Yes	Appendix 3
Study Attrition Mortality	Yes	Appendix 3
Prognostic Factor Measurement	Yes	Appendix 3
Outcome Measurement Mortality	Yes	Appendix 3
Confounding Bias Mortality	Unclear	Appendix 3
Statistical Analysis Bias	Yes	Appendix 3