Time-Varying Risk of Death After SARS-CoV-2-Infection in Long-Term Care Facility Residents: A Matched Cohort Study
Authors: Ballin Marcel , Ioannidis John P.A. , Bergman Jonathan , Kivipelto Miia , Nordström Anna , Nordström Peter 
Published: March 2022

Background

SARS-CoV-2 confers high risk of short-term death in residents of long-term care (LTC) facilities, but longer-term risk among survivors is unclear.

Methods

We extended the follow-up period of a previous, propensity score-matched retrospective cohort study based on the Swedish Senior Alert register. N=3731 LTC residents with documented SARS-CoV-2 until 15 September 2020 were matched to 3731 uninfected controls using time-dependent propensity scores on age, sex, health status, comorbidities, and prescription medications. In a sensitivity analysis, matching included also geographical region and Senior Alert registration time. The outcome was all-cause mortality over 8 months (until October 24, 2020). The absolute risk of death was examined using Kaplan-Meier plots. Hazard ratios (HR) for death over time were estimated using flexible parametric models with restricted cubic splines. Cox regression was used to estimate HRs and 95% confidence intervals (CIs) in 30-day intervals of follow-up until 210 days.

Results

The median age was 87 years and 65% were women. Excess mortality was highest 5 days after documented infection (HR 19.1, 95% CI, 14.6-24.8), after which excess mortality decreased. From the second month onwards, mortality rate became lower in infected residents than controls. The HR for death during days 61-210 of follow-up was 0.41 in the main analysis (95% CI, 0.34-0.50) and 0.76 (95% CI, 0.62-0.93) in the sensitivity analysis. Median survival of uninfected controls was 1.6 years, which was much lower than the national life expectancy in Sweden at age 87 (5.05 years in men, 6.07 years in women).

Conclusions

No excess mortality was observed in LTC residents who survived the acute SARS-CoV-2 infection. Life expectancy of uninfected residents was much lower than that of the general population of the same age and sex. This suggests that LTC resident status should be accounted for in years-of-life-lost estimates for COVID-19 burden of disease calculations.

Impact statement

We certify that this work is novel. This research adds to the literature by showing there was no excess mortality observed in long-term care facility residents who survived the acute SARS-CoV-2 infection, and that life expectancy of uninfected residents was much lower than that of the general population of same age and sex. This has major repercussions for estimation of years of life lost in infected long term care facility residents.

Key points

SARS-CoV-2 infection sharply increased mortality risk among residents of long-term care (LTC) facilities in the first month.

After the first month, the mortality risk in infected residents rapidly returned to baseline and dropped below the mortality risk of uninfected controls, where it remained lower for 8 months of follow-up.

Median survival of uninfected controls was 1.6 years, which was much lower than national life expectancy in Sweden at age 87.

Why does this matter?

Whereas LTC residents who recover from SARS-CoV-2 infection may be concerned about having residual debilitation caused by the infection, we found no excess mortality was in those who survived the acute infection.

Because life expectancy of uninfected residents was much lower than that of the general population of same age and sex, LTC resident status should be accounted for in estimations of years of life lost.