Paxlovid reduced hospitalizations and deaths during Omicron

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Nirmatrelvir-ritonavirsold under the brand name Paxlovid, significantly reduces the likelihood of hospitalization or death in patients with COVID-19 and at high risk of severe disease, the data shows.

For 62 people treated with nirmatrelvir-ritonavir, the drug prevented one case of severe COVID-19.

Doctor Kevin Schwartz

“A number of studies now support the effectiveness of Paxlovid for use in patients at risk for severe COVID-19. It is important that those at risk have access to testing and a Paxlovid prescriber so they can start medication within 5 days of onset of symptoms to prevent serious consequences,” said lead author Kevin Schwartz, MD, infectious disease physician at Public Health Ontario and associate scientist at ICES. Medscape Medical News.

In many regions, pharmacists can prescribe nirmatrelvir-ritonavir directly to patients, which could improve access to treatment, he added. “Prescribers should consider individual patient risk factors, particularly advanced age, immunocompromised status, and other comorbidities, to balance drug-related risks, including drug interactions. Many drug interactions can be mitigated, and it is important to assess these in all patients.”

The study has been published on February 13 in the Journal of the Canadian Medical Association.

Significant clinical benefit

Although nirmatrelvir-ritonavir was shown to be effective in a randomized controlled trial conducted in 2021, the trial only included unvaccinated patients, excluded patients with potentially important drug interactions, and was conducted before the emergence of the disease. Omicron variant, Schwartz said. In 2022, however, many patients who received this drug combination were often vaccinated and had potential drug interactions. Additionally, the Omicron variant was circulating at the time.

Schwartz and colleagues conducted a population-based cohort study in Ontario that included adults with mild illness who tested positive for COVID-19 with a polymerase chain reaction test between April 4 and August 31, 2022. They compared patients who were taking nirmatrelvir-ritonavir with patients who were not treated with this combination and measured hospital admission due to COVID-19 or death from all causes at 30 days, as well as overall all-cause mortality.

Among 177,545 patients, 8,876 (5%) were treated with nirmatrelvir-ritonavir and 168,669 (95%) did not receive the treatment. Most of the patients who received nirmatrelvir-ritonavir were over the age of 70, had received three or more doses of the COVID-19 vaccine, and had potential drug interactions.

Patients who received nirmatrelvir-ritonavir had a 2.1% risk of hospitalization or death, compared with a 3.7% risk in those who did not receive the treatment. The weighted odds ratio (OR) of hospital admission or death within 30 days was 0.56 (P < 0.001), and the weighted OR of death alone was 0.49 (P < .001).

Overall, results were similar across age, vaccination status, comorbidities, potential drug interactions, and risk status.

The research team observed a potential decrease in effectiveness over time, with a weighted OR of 0.43 for hospital admission or death between April and June 2022 and a weighted OR of 0, 67 between July and August 2022. There was a similar trend for death alone.

Additionally, the researchers found that the number needed to treat (NNT) to prevent hospitalization or death was 62. They found substantial variability in the absolute risk reductions: the NNT ranged from 28 in those not vaccinated at 181 among those under 70 years old. years.

“For example, we need to treat about 30 under-vaccinated patients to prevent one severe case of COVID-19. This number needed to treat increases to about 80 for patients with three or more vaccine doses and 180 for those under 70. years,” says Schwartz. “Prescribers should consider the balance of risks and benefits for their patients when prescribing Paxlovid and consider prescribing it to their patients who have risk factors for severe COVID-19, weighed against side effects. potentials and drug interactions.”

The researchers noted significant clinical benefit from the use of nirmatrelvir-ritonavir, although the benefit was lower than that seen in the 2021 randomized controlled trial. This discrepancy could be the result of differences in patient populations, underlying immunity, differences between circulating variants or study designs.

Efficiency may change

Further research should examine differences by age and risk factors, the study authors wrote. Advanced age remains the strongest risk factor, they noted, followed by obesitythe underlying conditions and the time elapsed since vaccination.

“It will be important to continue monitoring the effectiveness of Paxlovid,” Schwartz said. “As new variants emerge and population immunity changes, the risk-benefit assessment of Paxlovid may change over time.”

Based on the data sources used in this study, the authors could not confirm whether patients were taking any drugs that may interact with nirmatrelvir-ritonavir or whether potential drug interactions were mitigated during the prescribing process. . Additionally, Schwartz and colleagues are continuing their research on the equity of nirmatrelvir-ritonavir prescribing in Ontario.

“Evidence suggests that some populations are less likely to have access to Paxlovid, which we hope can improve,” he said. “Prescribers should consider social determinants of health when evaluating patients for Paxlovid.”

Ongoing assessments needed

Dr Edward Mills

Commenting on the study for Medscape, Edward Mills, PhD, professor of health research methods, evidence and impact at McMaster University in Hamilton, Ont., said, “This observational study is important because Recent randomized trials conducted by industry sponsor, Pfizer, have failed to demonstrate a significant role for Paxlovid in low-risk patients and with the newer, less severe variants.”

Mills, who was not involved in this study, has researched several COVID-19 therapies during the pandemic, including lopinavir–ritonavir (Kaletra), ivermectin (Stromectol), and molnupiravir (Lagevrio). He noted that observational studies provide a weaker form of evidence for effectiveness and may have spurious precision due to large sample sizes in the control population.

“Continued evaluations of antiviral therapies are desperately needed,” he said. “Perhaps further randomized evaluations of Paxlovid will determine its continued usefulness.”

The study was funded by Public Health Ontario. Schwartz and Mills report no relevant financial relationship.

CMY. Published on February 13, 2023. Full Text

Carolyn Crist is a health and medical journalist who reports on the latest studies for Medscape, MDedge, and WebMD.

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