Study Exclusion reasons Remarks Reference(s)
HYDRA, 2020 randomized controlled trial Initially found in Axfors et al. meta-analysis results published by Hernadez et al  
CloroCOVID19, 2020 randomized controlled trial inadequate or absent control group This paper reports partial results from an unplanned interim analysis.Efficacy and safety criteria do not appear to have ever been assessed on the same number of patients (denominators are different for almost every criterion and are less than the number of patients randomized). Compared to the registration record, the patient eligibility criteria were changed.

Borba JAMA Netw Open 2020; 3:e208857 10.1001/jamanetworkopen.2020.8857

Mayla Borba for CloroCovid-19 Team medRxiv 2020.04.07.20056424

ChiCTR2000029975, 0 single-arm not relevant study design  
ChiCTR2000029826 (Cancelled by the investigator), 0 randomized controlled trial cancelled by investigator  
Duke university (Hydroxychloroquine), 2020 randomized controlled trial cancelled by investigator  
Thakar, 2021 randomized controlled trial no clinically relevant endpoint

Thakar A Indian J Med Res 2021 Jan 21. 10.4103/ijmr.IJMR_3665_20

Barbosa, 2020 retrospective cohort other the only document variable for this study is a copy of a submission to NEJM. It is impossible to verify the veracity of this document. The paper was submitted apr 4th and since this date ther is no publication in NEJM or in other media (included preprint server).  
Mallat, 2020 retrospective cohort other inapropriate statistical analysis. Time to events analyszed with means without taken into account the censure due to death or lost to follow-up

Jihad Mallat, Fadi Hamed, Maher Balkis, Mohamed A Mohamed, Mohamad Mooty, Asim Malik, Ahmad Nusair, Fernanda Bonilla medRxiv 2020.04.27.20082180 10.1101/2020.04.27.20082180

Mehra, 2020 retrospective cohort other the paper was retracted by 3 authors on June 4, 2020

Mehra MR Lancet 2020 May 22;S0140-6736(20)31180-6. 10.1016/S0140-6736(20)31180-6

Mehra MR Lancet 2020 Jun 13;395(10240):1820. 10.1016/S0140-6736(20)31324-6