Retrospective 193 hospitalized patients in Brazil not finding a significant difference with HCQ.
The control group was composed of patients refusing HCQ or with contraindications. Time based confounding is very likely because HCQ became more controversial in Brazil over the time covered (Mar - Jun 2020), while overall treatment protocols during this period improved dramatically, i.e., more control patients (those refusing HCQ) likely come later in the period when treatment protocols were greatly improved.
The paper does not mention the word "confounding" or make any adjustments.
Lamback et al., 2/19/2021, retrospective, Brazil, South America, peer-reviewed, 10 authors.
risk of death, 8.9% lower, RR 0.91, p = 0.83, treatment 11 of 101 (10.9%), control 11 of 92 (12.0%).
risk of ICU admission, 19.9% higher, RR 1.20, p = 0.61, treatment 25 of 101 (24.8%), control 19 of 92 (20.7%).
hospitalization time, 12.5% lower, relative time 0.88, treatment 101, control 92.
This study is excluded in the after exclusion results of meta analysis: substantial time varying confounding likely due to declining usage over the early period when overall treatment protocols improved dramatically.
Effect extraction follows pre-specified rules
prioritizing more serious outcomes. For an individual study the most serious
outcome may have a smaller number of events and lower statistical signficance,
however this provides the strongest evidence for the most serious outcomes
when combining the results of many trials.