et al., Clinical Microbiology and Infection (Peer Reviewed) (meta analysis - not included in study count)
Meta analysis of late stage studies (and one early treatment study with only 2 deaths), showing HC
Q RR 0.83 [0.65-1.06], before exclusions RR 0.80 [0.65-1.0].
Authors claim "HC
Q alone is not effective", but the result directly contradicts this, RR 0.83 [0.65-1.06], i.e., inconclusive but much more likely to be effective than not.
There are many errors in this meta analysis which introduce critical bias, for example:
- Very biased sample of studies, including <4% of early treatment studies (only 1), and <30% of late treatment studies, focused on negative studies.
- Arshad et al. (propensity matched HR 0.49, p=0.009) was excluded because the authors claim a "critical" risk of confounding bias due to steroid use, however steroids were controlled for in the multivariate and propensity analyses .
- For Skipper et al., authors use an RR of 1.01, however the study had one hospitalized control death and one non-hospitalized HC
Q death. Since the HC
Q death was non-hospitalized, it may not be caused by COVID-19, or the patient did not receive standard care, therefore this should not be treated as equal to the control death. Further, medication adherence was only 77%, the HC
Q patient may not have taken the medication (Skipper et al. neglects to answer this question). In any case, including a trial with only 1-2 deaths is likely to increase bias.
- Cavalcanti et al. received the lowest bias rating, despite having treatment delayed up to 14 days after symptoms, randomizing 14% of patients in the ICU, having significant protocol deviations, unusually low medication adherence, randomization that resulted in 64.3% male patients (HC
Q) vs. 54.2% (control), and excluding patients already receiving longer and potentially therapeutic doses of the study treatments.
- Sbidian el al. received the lowest bias rating, however many more control patients are still in hospital at 28 days suggesting there will be a significant improvement when extending past 28 days.
- The RECOVERY trial received the lowest bias rating, despite using a very high dose likely responsible for the increased mortality. Results of this trial are not relevant to use at normal dosages.
- Inclusion criteria required RT-PCR confirmed cases, but this was disregarded when including Horby et al. (very negative, excessive dose) and Skipper et al.
- Authors do not consider different treatment delays, risk level of patients, differences in dosage, or usage of Zinc.
Also see  indicating that this study is fatally flawed. For other problems, see: [3, 4]. This analysis is also missing several recent studies, for a more up-to-date analysis see .