COVID-19 Patient Outcomes and Hospital Readmissions

Hospitalisation for COVID-19 carries substantial risk of both in-hospital mortality and subsequent readmission, with long-term outcomes influenced by age, underlying health status and previous patterns of healthcare use. Early studies reported 30-day readmission rates of around 4–8% and one-year cumulative readmission approaching one-third of survivors, alongside one-year mortality rates near 30%. Key drivers of poor outcome include advanced age, multimorbidity, frailty and markers of acute disease severity. Patterns of pre-index hospital use and comorbidity burden have emerged as independent predictors of both post-discharge mortality and emergency readmission, underscoring the need for tailored discharge planning. Predictive models have been developed to estimate individual readmission risk, incorporating clinical stability criteria and reversible physiological abnormalities. Globally, these insights have informed strategies to optimise discharge timing, allocate post-acute support and target high-risk groups for monitoring, thereby reducing avoidable rehospitalisation and alleviating pressure on healthcare systems.

Research from Nature Portfolio

Large multicentre analyses have shown that 4–5% of patients discharged after COVID-19 are readmitted within 30 days, with higher risk in older individuals and those with chronic respiratory conditions. Factors independently associated with readmission include elevated comorbidity scores, chronic obstructive pulmonary disease and asthma, whereas acute oxygen requirement at discharge was not predictive. A separate cohort study reported a 9% readmission rate over a median of seven days post-discharge, identifying solid organ transplantation and higher baseline comorbidity index as the strongest predictors. Post-discharge mortality was concentrated among very elderly patients with cognitive impairment or dependency in daily living activities. Together, these studies highlight that non-modifiable patient factors outweigh in-hospital treatment variables in predicting short-term readmission and mortality.

COVID-19 Patient Outcomes and Hospital Readmissions publication trend

The graph below shows the total number of articles in covid-19 patient outcomes and hospital readmissions across all publications each year (not limited to Nature Index journals).

Technical terms

Readmission: Hospital admission occurring within a defined period after discharge from an initial stay for the same or related condition.

Comorbidity: Co-existence of additional diseases or disorders alongside a primary condition, influencing prognosis and management.

Charlson Comorbidity Index: Validated scoring system that assigns weights to comorbid conditions to predict mortality risk.

Hazard Ratio: Statistical measure comparing the hazard rates between two groups over time, indicating relative risk.

Risk Prediction Model: Algorithmic tool that combines patient characteristics and clinical variables to estimate the probability of future outcomes.

References

1. Patient emergency health-care use before hospital admission for COVID-19 and long-term outcomes in Scotland: a national cohort study. The Lancet Digital Health (2023).
2. Analysis of Clinical Criteria for Discharge Among Patients Hospitalized for COVID-19: Development and Validation of a Risk Prediction Model. Journal of General Internal Medicine (2024).
3. Frequency, risk factors, and outcomes of hospital readmissions of COVID-19 patients. Scientific Reports (2021).
4. Risk-factors for re-admission and outcome of patients hospitalized with confirmed COVID-19. Scientific Reports (2021).