Table 1.
Characteristics of literatures included in the meta-analysis.
| Reference | Year | Region | Outcome | No. of metformin users | No. of patients | Adjustment for covariates |
|---|---|---|---|---|---|---|
| Jiang N[20] | 2021 | China | Mortality ARDS |
100 | 328 | age, gender, weight, FBG, severity of COVID-19, Charlson comorbidity index, CHD, metformin therapy prior to hospitalization, DDI, creatinine and site |
| Li W[22] | 2021 | China | Mortality | 37 | 131 | age, BMI, glucose, triglyceride, CRP, D-dimer, and steroid use |
| Bramante CT[18] | 2021 | USA | Mortality | 2333 | 6256 | age, sex, comorbidities, alcohol abuse, HIV, asthma, inflammatory bowel disease, dementia, Charlson comorbidity index, and medications, and state |
| Lally MA[21] | 2021 | USA | Mortality | 127 | 775 | age, body mass index, hemoglobin A1c, estimated glomerular filtration rate, long stay (>90 days), and underlying psychoses |
| Cheng X[35] | 2020 | China | Mortality ARDS DIC Heart failure Acute kidney injury Acute heart injury |
678 | 1213 | age, gender, comorbidities, blood glucose, C-reactive protein, estimated glomerular filtration rate, alanine aminotransferase, and creatinine |
| Ghany R[19] | 2021 | USA | Mortality ARDS |
392 | 1139 | age, gender, Charlson score, diabetes, hypertension and ejection fraction |
| Luo P[40] | 2020 | China | Mortality | 104 | 283 | age, gender, underlying diseases, clinical severity |
| Oh TK[23] | 2021 | Korea | Mortality | 480 | 2047 | age, sex, underlying disability, Charlson Comorbidity Index |
| Li J[41] | 2020 | China | Mortality ventilation |
37 | 131 | age, body weight, BMI, oxygen desaturation, glucose, triglyceride, CRP, and D-dimers |
| Lalau J-D[36] | 2020 | France | Mortality IMV |
1496 | 2449 | sex, age, BMI, arterial hypertension, history of disease, active cancer, treated obstructive sleep apnoea, use of any of anti-diabetes drugs |
| Crouse A[42] | 2020 | USA | Mortality | 76 | 239 | age, race, sex, obesity and hypertension |
| Pérez-Belmonte LM[38] | 2020 | Spain | Mortality ICU admission mechanical ventilation in-hospital death |
825 | 1488 | age; gender; history of smoking, hypertension; dyslipidemia; chronic kidney disease; cerebrovascular disease; chronic obstructive pulmonary disease; atrial fibrillation; coronary artery disease; heart failure; obesity; dementia; Barthel Index score; and Charlson Comorbidity Index score |
| Wargny M[24] | 2021 | France | Mortality | 1553 | 2794 | sex, age, BMI, the patient’s history, routine medication, symptoms on admission, biological features |
| Chen Y[34] | 2020 | China | Mortality Poor prognosis |
43 | 120 | age, albumin, creatinine, glucose, CRP, and usage of a specific medication |
| Goodall JW[39] | 2020 | UK | Mortality | 210 | 981 | age, sex, comorbidities and medication usage |
| Kim MK[37] | 2020 | Korea | Mortality severe disease |
113 | 235 | age, sex, and the presence of underlying diseases |
| Gao Y[44] | 2020 | China | Life threatening complications | 56 | 110 | age, gender, blood glucose and LDH levels |
IMV, tracheal intubation for mechanical ventilation; severe disease, the necessity for the use of a high-flow nasal cannula, mechanical ventilation, CRRT, or ECMO, or admission to an ICU; CRP, C-reactive protein; BMI, body mass index.