Retrospective 283 patients in the USA showing higher mortality with all treatments (not statistically significant). Confounding by indication
is likely. In the supplementary appendix, authors note that the treatments were usually given for patients that required oxygen therapy. Oxygen therapy and ICU admission (possibly, the paper includes ICU admission for model 2 in some places but not others) were the only variables indicating severity used in adjustments. Time based confounding is likely because HCQ became increasingly controversial and less used over the time covered (March 1 to May 31, 2020), while overall treatment protocols during this period improved dramatically, i.e., more control patients likely come later in the period when treatment protocols were greatly improved.
risk of death, 4.8% higher, RR 1.05, p = 0.89, treatment 22 of 55 (40.0%), control 33 of 216 (15.3%), adjusted per study, odds ratio converted to relative risk, multivariate logistic regression.
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This study is excluded in the after exclusion results of meta
substantial confounding by time
likely due to declining usage over the early stages of the pandemic when overall treatment protocols improved dramatically; substantial unadjusted confounding by indication
Gadhiya et al., 8 Apr 2021, retrospective, USA, peer-reviewed, 4 authors.