New York,   After several studies revealed the side effects of anti-malarial drug hydroxychloroquine (HCQ), new research has found that HCQ did not reduce the risk of ventilation or death in Covid-19 patients and was associated with longer length of hospital stay.

The researchers--from the Columbia VA Health Care System, the University of South Carolina, and the University of Virginia School of Medicine in the US--reported that their study has strengths that earlier studies have not had.

For example, because it employed data from comprehensive electronic medical records (the VA Informatics and Computing Infrastructure, or VINCI), rather than administrative health insurance claims, they were able to apply rigorously identified covariates and outcomes.

Additionally, because the data came from an integrated national healthcare system, the findings were less susceptible to biases that might occur in a single-centre or regional study.

In the study, the research team included data from 807 people hospitalised with Covid-19 at Veterans Affairs medical centres around the country. About half, 395 patients, did not receive HCQ at any time during their hospitalisation. Among those who did, 198 patients were treated with HCQ and 214 were treated with both hydroxychloroquine and azithromycin.

Most of the patient's given hydroxychloroquine, about 86 per cent, received it before being put on a mechanical ventilator.After adjustment for clinical characteristics, the risk of death from any cause was higher in the HCQ group but not in the HCQ + azithromycin group when these were compared with the no-HCQ group.

The researchers also found that the length of hospital stay was 33 per cent longer in the HCQ group and 38 per cent longer in the HCQ + azithromycin group than in the no-HCQ group. Pre-existing conditions such as cardiovascular disease, chronic obstructive pulmonary disease, and diabetes were relatively common and similar across all groups, the study said.

However, the researchers noted that the findings don't provide insight into the use of these drugs in the outpatient setting or as prophylaxis. Meanwhile, on June 4, the World Health Organisation said that HCQ will return to the solidarity trial for the potential treatment of coronavirus disease.

The world health body had temporarily suspended the usage of HCQ from the solidarity trial for coronavirus treatment on May 25 soon after a study published in one of the most reliable medical journals which had suggested that the drug could cause more fatalities among Covid-19 patients.

With 1,897,239 confirmed cases and 109,127 deaths, the US currently accounts for the highest number of infections and fatalities in the world, according to a tally by the Johns Hopkins Univerity.