A new study has found that the use of weight-adjusted hydroxychloroquine (HCQ) and azithromycin (AZM) improved the survival of ventilated COVID-19 patients by nearly 200 percent.

The observational study, which hasn't yet been peer-reviewed, was based on a re-analysis of 255 patients on invasive mechanical ventilation (IMV) during the first two months of the pandemic in the United States.

The researchers found that when the HCQ–AZM combination was given at lower dosages to treat ventilated COVID-19 patients, the risk of death was more than three times higher.

"We found that when the cumulative doses of two drugs, HCQ and AZM, were above a certain level, patients had a survival rate 2.9 times the other patients," the authors of the study noted.

"By using causal analysis and considering of weight-adjusted cumulative dose, we prove the combined therapy, >3 g HCQ and > 1g AZM greatly increases survival in COVID patients on IMV and that HCQ cumulative dose > 80 mg/kg works substantially better."

While the authors acknowledged that patients with higher doses of HCQ had higher doses of AZM, they "cannot solely attribute the causal effect to HCQ/AZM combination therapy."

"However, it is likely AZM does contribute significantly to this increase in survival rate. Since higher dose HCQ/AZM therapy improves survival by nearly 200 [percent] in this population, the safety data are moot," they added.