COVID-19 Mortality Risk Increased in Solid Organ Transplant Recipients

Mortality risk from COVID-19 was consistently higher in solid organ transplant recipients than the general population over 7 pandemic waves, according to findings from a study published online ahead of print in the American Journal of Transplantation.

“Therefore, solid organ transplant recipients need to undergo protective measures and receive additional booster shots to mitigate the risk of moderate/severe disease and death,” wrote corresponding author Taizo Hibi, MD, PhD, of the Kumamoto University Graduate School of Medical Sciences in Japan and study coauthors.

The study included 1632 solid organ transplant recipients from the Japanese nationwide registry who were diagnosed with COVID-19 between February 1, 2020, and July 31, 2022. Among them, 1170 were kidney recipients, 408 were liver recipients, 25 were lung recipients, 20 were heart recipients, 1 was a small intestine recipient, and 8 were recipients of multiple organs.

Solid organ transplant recipients showed elevated standardized mortality ratios throughout the pandemic compared with the general population, according to the study, although COVID-19 severity and all-cause mortality lessened as variants transitioned.

Standardized mortality ratios for solid organ transplant recipients showed a U-shaped pattern, the study found, with a nadir in the Delta era followed by an increase in the Omicron eras: 6.2 for Waves 1 to 3 (Beta), 4.0 for Wave 4 (Alpha), 3.0 for Wave 5 (Delta), 8.8 (5.3-14.5) for Wave 6 (Omicron BA.1/2), and 21.9 for Wave 7 (Omicron BA.5).

The study did not find significant differences in mortality rates for different transplanted organs. Independent risk factors for moderate/severe COVID-19 or death included age 60 and older, underlying illness, mammalian target of rapamycin inhibitor (mTORi) use, steroid use, and antithymoglobulin use within 3 months of COVID-19.

“The strength of the present study lies in the homogenous population of Japanese solid organ transplant recipients, who generally have universal insurance and immunosuppression regimens and demonstrate strict compliance (87.1%–94.4%) with the safety measures or therapeutics published by the Japan Society for Transplantation COVID-19 guidelines,” researchers wrote. “Consequently, this minimized the possible impact of unexpected confounders.”

Reference

Yamanaga S, Shimata K, Ohfuji S, et al. Excess mortality in COVID-19-affected solid organ transplant recipients across the pandemic. Am J Transplant. Published online March 20, 2024. doi:10.1016/j.ajt.2024.03.016