Elevated risk of hospitalization, death after COVID-19 dwindles by six months
A hospitalization for COVID-19 carries higher mortality risk than one for flu for only 90 days, one study found, while another showed that veterans who had COVID-19 actually had lower mortality risk than matched uninfected peers in the subsequent six months to two years.
Two recent studies looked at patients' long-term mortality risk after infection with COVID-19.
One study, published by The BMJ on Aug. 9, compared 883,394 Medicare fee-for-service beneficiaries discharged alive after an admission with COVID-19 in March 1, 2020, to Aug. 31, 2022, with 56,409 historical controls discharged alive after admission with influenza during March 1, 2018, to Aug. 31, 2019. It found that the COVID-19 patients were younger and had a lower comorbidity burden, but after weighting, they had a significantly higher risk of all-cause death at 30 days (10.9% vs. 3.9%; standardized risk difference [RD], 7.0% [95% CI, 6.8% to 7.2%]), 90 days (15.5% vs. 7.1%; RD, 8.4% [95% CI, 8.2% to 8.7%]), and 180 days (19.1% vs. 10.5%; RD, 8.6% [95% CI, 8.3% to 8.9%]). COVID-19 was also associated with higher risk of hospital readmission within 30 days (16.0% vs. 11.2%; RD, 4.9% [95% CI, 4.6% to 5.1%]) and 90 days (24.1% vs. 21.3%; RD, 2.8% [95% CI, 2.5% to 3.2%]) but a similar risk within 180 days (30.6% vs. 30.6%). Over the study period, the 30-day mortality risk after a COVID-19 admission dropped from 17.9% to 7.2%.
The study wasn't able to determine why patients were higher risk after a stay for COVID-19 than for flu, the authors noted, but “the substantial in-hospital and early post-discharge risk of death associated with covid-19 in this sample exclusively of Medicare fee-for-service beneficiaries highlights the need for preventive interventions, particularly in patients at increased long term risk of adverse outcomes.” They called the observed decline in post-discharge death over the study period “encouraging.”
The second study, published by JAMA Internal Medicine on Aug. 21, used prospectively collected health record data from Veterans Affairs hospitals comparing 208,061 patients who had COVID-19 between March 2020 and April 2021 with up to five comparators who had not been infected with COVID-19 at the time of matching. The study found that those with COVID-19 had an unadjusted mortality rate of 8.7% during the two-year period after the initial infection compared with 4.1% among uninfected comparators (adjusted hazard ratio [aHR], 2.01; 95% CI, 1.98 to 2.04). The difference in risk was greatest in the first 90 days after infection (aHR, 6.36; 95% CI, 6.20 to 6.51) but still elevated during days 91 to 180 (aHR, 1.18; 95% CI, 1.12 to 1.23). However, having had COVID-19 was associated with lower mortality during days 181 to 365 (aHR, 0.92; 95% CI, 0.89 to 0.95) and 366 to 730 (aHR, 0.89; 95% CI, 0.85 to 0.92).
There are multiple possible explanations for why COVID-19 survivors might have lower long-term mortality, including closer attention from health care professionals or immunological protection from infection, according to the study authors. The findings “should be reassuring to persons who have survived COVID-19 for at least 180 days,” they said. “These results may suggest that for ongoing care after COVID-19, especially among those not initially hospitalized for COVID-19, efforts that focus on increasing survival may be less relevant than approaches addressing the needs of individual survivors.”
