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. 2023 May 24;2023(5):CD015201. doi: 10.1002/14651858.CD015201

Wu 2021.

Study characteristics
Notes English title
Association of body mass index with severity and mortality of COVID‐19 pneumonia: a two‐center, retrospective cohort study from Wuhan, China
Study setting
Start of study recruitment (MM/YYYY)
01/2020
End of study recruitment (MM/YYYY)
03/2020
Study design
retrospective cohort
Study centre(s)
multiple centres/clinics/areas within a country
Number of centres/clinics/areas
2
Study setting
inpatient
Number of participants recruited
1091
Sampling method
consecutive participants
Participants
Female participants
(absolute number), 582
Age measure, value
median (interquartile range), 59 (49, 67)
Inclusion criteria
The cohort consisted of 1171 adult patients aged 21 to 93 years old with confirmed COVID‐19 pneumonia who were admitted between January 1 to March 1, 2020 and who died or were discharged before March 30, 2020.
Exclusion criteria
missing data on BMI, missing data on the outcomes
Smoking
NR
Diabetes
(absolute number), 137
Hypertension
(absolute number), 288
Cardiovascular diseases
(absolute number), 82
Please indicate if additional information is available 
NR
Asthma
(unspecified), NR
Chronic obstructive pulmonary disease
NR
Other pulmonary diseases
(absolute number), 57
Please indicate if additional information is available 
chronic lung disease
Immunosupression
(unspecified), NR
Please indicate if additional information is available
NR
Chronic kidney disease
(unspecified), NR
Cancer
(absolute number), 40
Steroid administration
(unspecified), NR
Supplemental oxygen
(absolute number), 901
Differential values for various oxygenation methods (if indicated)
Nasal cannula, 607 (57.3)
NPPV, 176 (16.2)
HFNC, 87 (8.0)
IMV, 31 (2.8)
Other treatment
not reported
Dose if applicable
not reported
Duration if applicable
not reported
Percentage received this treatment
not reported
Prognostic factor(s)
Study’s definition for obesity
BMI was categorised by the definitions as follows: 1) underweight (BMI < 18.5 kg/m2); 2) normal weight (BMI 18.5–23 kg/m2); 3) overweight (BMI 23–25 kg/m2); 4) obesity (BMI ≥ 25 kg/m2) according to the World Health Organization recommendations for Asian populations. The validity of this definition has been confirmed previously.
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 of obesity 
25
Measure of frequency
absolute number
Frequency value
285
How many eligible outcomes reported?
4
How many eligible outcomes reported?
4
Outcome(s)
mortality, ICU admission, mechanical ventilation, severe COVID
Outcome (prognostic factor)
mortality (BMI < 18.5)
Outcome
mortality
Prognostic factor (category): 
BMI < 18.5
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
3.71 (1.27, 10.79)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
3.85 (1.26, 11.76)
Outcome (prognostic factor)
mortality (BMI 23 to 25)
Outcome
mortality
Prognostic factor (category): 
BMI 23 to 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.57 (0.15, 2.10)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.53 (0.14, 2.00)
Outcome (prognostic factor)
mortality (BMI > 25)
Outcome
mortality
Prognostic factor (category): 
BMI > 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
2.50 (1.08, 5.79)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
1.74 (0.73, 4.21)
Outcome (prognostic factor)
ICU admission (BMI < 18.5)
Outcome
ICU admission
Prognostic factor (category): 
BMI < 18.5
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
1.94 (0.95, 3.97)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
2.17 (0.94, 5.05)
Outcome (prognostic factor)
ICU admission (BMI 23 to 25)
Outcome
ICU admission
Prognostic factor (category)
BMI 23 to 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.93 (0.51, 1.70)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.84 (0.42, 1.68)
Outcome (prognostic factor)
ICU admission (BMI > 25)
Outcome
ICU admission
Prognostic factor (category): 
BMI > 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
2.78 (1.78, 4.34)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
2.62 (1.52, 4.49)
Outcome (prognostic factor)
mechanical ventilation (BMI < 18.5)
Outcome
mechanical ventilation
Prognostic factor (category): 
BMI < 18.5
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
NA
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
NA
Outcome (prognostic factor)
mechanical ventilation (BMI 23 to 25)
Outcome
mechanical ventilation
Prognostic factor (category): 
BMI 23 to 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.88 (0.27, 2.83)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.85 (0.24, 2.98)
Outcome (prognostic factor)
mechanical ventilation (BMI > 25)
Outcome
mechanical ventilation
Prognostic factor (category): 
BMI > 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
3.11 (1.40, 6.88)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
2.85 (1.15, 7.05)
Outcome (prognostic factor)
severe COVID (ARDS) (BMI < 18.5)
Outcome
severe COVID (ARDS)
Prognostic factor (category): 
BMI < 18.5
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.28 (0.04, 2.07)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.23 (0.03, 1.85)
Outcome (prognostic factor)
Severe COVID (ARDS) (BMI 23 to 25)
Outcome
Severe COVID (ARDS)
Prognostic factor (category): 
BMI 23 to 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.80 (0.35, 1.82)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
0.70 (0.29, 1.73)
Outcome (prognostic factor)
severe COVID (BMI > 25)
Outcome
severe COVID
Prognostic factor (category): 
BMI > 25
Follow‐up
Number of patients followed completely for this outcome 
1091
Number of obese patients followed completely for this outcome 
285
Number of non‐obese patients followed completely for this outcome 
806
Univariable (unadjusted) analysis for obesity
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
3.44 (2.00, 5.94)
Multivariable (adjusted) analysis for obesity
Modelling method
Cox regression
The set of prognostic factors used for adjustment
age, sex, neutrophil counts, lymphocyte counts, platelet counts, high‐sensitivity C‐reactive protein (hs‐CRP), and cancer (yes/no)
Effect measure for obesity
hazard ratio
Effect measure value (95% CI)
3.16 (1.69, 5.88)
 
Item Authors' judgement Support for judgement
Study Participation Yes Appendix 3
Study Attrition
Mortality Unclear Appendix 3
Study Attrition
Mechanical ventilation Unclear Appendix 3
Study Attrition
ICU admission Unclear Appendix 3
Study Attrition
Severe COVID Unclear Appendix 3
Prognostic Factor Measurement Yes Appendix 3
Outcome Measurement
Mortality Yes Appendix 3
Outcome Measurement
Mechanical ventilation Yes Appendix 3
Outcome Measurement
ICU admission Yes Appendix 3
Outcome Measurement
Severe COVID Yes Appendix 3
Confounding Bias
Mortality Unclear Appendix 3
Confounding Bias
Mechanical ventilation Unclear Appendix 3
Confounding Bias
ICU admission Unclear Appendix 3
Confounding Bias
Severe COVID Unclear Appendix 3
Statistical Analysis Bias Yes Appendix 3