Effectiveness of post-COVID-19 primary care attendance in improving survival in very old patients with multimorbidity: a territory-wide target trial emulation.

OBJECTIVES: Older individuals with multimorbidity are at an elevated risk of infection and complications from COVID-19. Effectiveness of post-COVID-19 interventions or care models in reducing subsequent adverse outcomes in these individuals have rarely been examined. This study aims to examine the effectiveness of attending general outpatient within 30 days after discharge from COVID-19 on 1-year survival among older adults aged 85 years or above with multimorbidity. DESIGN: Retrospective cohort study emulating a randomised target trial using electronic health records. SETTING: We used data from the Hospital Authority and the Department of Health in Hong Kong, which provided comprehensive electronic health records, COVID-19 confirmed case data, population-based vaccination records and other individual characteristics for the study. PARTICIPANTS: Adults aged 85 years or above with multimorbidity who were discharged after hospitalisation for COVID-19 between January 2020 and August 2022. INTERVENTIONS: Attending a general outpatient within 30 days of last COVID-19 discharge defined the exposure, compared to no outpatient visit. MAIN OUTCOME MEASURES: Primary outcome was all-cause mortality within one year. Secondary outcomes included mortality from respiratory, cardiovascular and cancer causes. RESULTS: A total of 6183 eligible COVID-19 survivors were included in the analysis. The all-cause mortality rate following COVID-19 hospitalisation was lower in the general outpatient visit group (17.1 deaths per 100 person-year) compared with non-visit group (42.8 deaths per 100 person-year). After adjustment, primary care consultations within 30 days after discharge were associated with a significantly greater 1-year survival (difference in 1-year survival: 11.2%, 95% CI 8.1% to 14.4%). We also observed significantly better survival from respiratory diseases in the general outpatient visit group (difference in 1-year survival: 6.3%, 95% CI 3.5% to 8.9%). In a sensitivity analysis for different grace period lengths, we found that the earlier participants had a general outpatient visit after COVID-19 discharge, the better the survival. CONCLUSIONS: Timely primary care consultations after COVID-19 hospitalisation may improve survival following COVID-19 hospitalisation among older adults aged 85 or above with multimorbidity. Expanding primary care services and implementing follow-up mechanisms are crucial to support this vulnerable population's recovery and well-being.

Real-World Effectiveness and Safety of Tixagevimab-Cilgavimab: A Target Trial Emulation Study.

BACKGROUND: Immunocompromised individuals are at high risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and subsequent severe or fatal coronavirus disease 2019 (COVID-19), yet they have suboptimal responses to mRNA and inactivated COVID-19 vaccines. The efficacy of tixagevimab-cilgavimab in reducing symptomatic SARS-CoV-2 infection was demonstrated in phase III clinical trials. Nevertheless, real-world data on the effectiveness and safety of tixagevimab-cilgavimab remain limited. OBJECTIVE: The aim was to evaluate the effectiveness and safety of tixagevimab-cilgavimab among immunocompromised individuals. METHODS: Adults who were immunocompromised or receiving immunosuppressive therapies were included in this target trial emulation using territory-wide electronic health records in Hong Kong. A sequential trial emulation approach was adopted to compare effectiveness and safety outcomes between individuals who received tixagevimab-cilgavimab and individuals who did not. RESULTS: A total of 746 tixagevimab-cilgavimab recipients and 2980 controls were included from 1 May 2022 to 30 November 2022. Tixagevimab-cilgavimab significantly reduced the risk of COVID-19 infection (hazard ratio [HR] 0.708, 95% confidence interval [CI] 0.527-0.951) during a median follow-up of 60 days. No significant difference was observed in the risk of COVID-19-related hospitalisation. Zero versus eight COVID-19 mortality cases and zero versus two severe COVID-19 cases were observed in tixagevimab-cilgavimab recipients and controls, respectively. Notably, significant risk reduction in COVID-19 infection was also observed among immunocompromised individuals who had been previously vaccinated with three or more doses of COVID-19 vaccine, or had no prior COVID-19 infection history. CONCLUSIONS: Tixagevimab-cilgavimab was effective in reducing COVID-19 infection among immunocompromised patients during the Omicron wave. Findings were consistent among individuals who previously received three or more doses of COVID-19 vaccine, or had no previous history of COVID-19 infection.

Effectiveness of Molnupiravir and Nirmatrelvir-Ritonavir in CKD Patients With COVID-19.

Introduction: Even with effective vaccines, patients with CKD have a higher risk of hospitalization and death subsequent to COVID-19 infection than those without CKD. Molnupiravir and nirmatrelvir-ritonavir have been approved for emergency use, but their effectiveness for the CKD population is still unknown. This study was conducted to determine the effectiveness of these drugs in reducing mortality and severe COVID-19 in the CKD population. Methods: This was a target trial emulation study using electronic health databases in Hong Kong. Patients with CKD aged 18 years or older who were hospitalized with COVID-19 were included. The per-protocol average treatment effect among COVID-19 oral antiviral initiators, including all-cause mortality, intensive care unit (ICU) admission, and ventilatory support within 28 days, were compared to noninitiators. Results: Antivirals have been found to lower the risk of all-cause mortality, with Molnupiravir at a hazard ratio (HR) of 0.85 (95% confidence interval [CI], 0.77 to 0.95] and nirmatrelvir-ritonavir at an HR of 0.78 [95% CI, 0.60 to 1.00]. However, they do not significantly reduce the risk of ICU admission (molnupiravir: HR, 0.88 [95% CI, 0.59 to 1.30]; nirmatrelvir-ritonavir: HR, 0.86 [95% CI, 0.56 to 1.32]) or ventilatory support (molnupiravir: HR, 1.00 [95% CI, 0.76 to 1.33]; nirmatrelvir-ritonavir: HR, 1.01 [95% CI, 0.74 to 1.37]). There was a greater risk reduction in males and those with higher Charlson Comorbidity Index (CCI). The nirmatrelvir-ritonavir trial also showed reduced risk for those who had antiviral treatment and received 3 or more vaccine doses. Conclusion: Both molnupiravir and nirmatrelvir-ritonavir reduced mortality rates for hospitalized COVID-19 patients with CKD.

COVID-19 vaccine effectiveness against the Omicron variant of SARS-CoV-2 in multimorbidity: A territory-wide case-control study.

Multimorbidity entails a higher risk of SARS-CoV-2 infection and COVID-19 complications. We examined vaccine effectiveness (VE) stratified by multimorbidity using a case-control study of territory-wide electronic health records in Hong Kong. Cases of infection (testing positive), hospitalization, and mortality were identified from January to March 2022. Controls were matched by age, sex, outpatient attendance/hospitalization date, and Charlson Comorbidity Index. We demonstrated a consistently good VE among people with increased multimorbidity burden; even more so than among those with minimal such burden. There was also a significantly greater VE after a third dose of BNT162b2 or CoronaVac against infection. The difference in VE between those with multimorbidity and those without was less pronounced for hospitalization, and such difference for COVID-19-related mortality was negligible. In conclusion, VE of both examined vaccines against SARS-CoV-2 infection among people with more complex multimorbidity burden is significant. Further vaccine roll-out should prioritize people with multimorbidity.

Vaccine Effectiveness of BNT162b2 and CoronaVac against SARS-CoV-2 Omicron BA.2 in CKD.

BACKGROUND: The ongoing coronavirus disease 2019 (COVID-19) pandemic has posed increased risks of hospitalization and mortality in patients with underlying CKD. Current data on vaccine effectiveness of COVID-19 vaccines are limited to patients with CKD on dialysis and seroconversion in the non-dialysis population. METHODS: A case-control study was conducted of adults with CKD using data extracted from the electronic health record database in Hong Kong. Adults with CKD and COVID-19 confirmed by PCR were included in the study. Each case was matched with up to ten controls attending Hospital Authority services without a diagnosis of COVID-19 on the basis of age, sex, and index date (within three calendar days). The vaccine effectiveness of BNT162b2 and CoronaVac in preventing COVID-19 infection, hospitalizations, and all-cause mortality was estimated using conditional logistic regression adjusted by patients' comorbidities and medication history during the outbreak from January to March 2022. RESULTS: A total of 20,570 COVID-19 cases, 6604 COVID-19-related hospitalizations, and 2267 all-cause mortality were matched to 81,092, 62,803, and 21,348 controls, respectively. Compared with the unvaccinated group, three doses of BNT162b2 or CoronaVac were associated with a reduced risk of infection (BNT162b2: 64% [95% confidence interval (CI), 60 to 67], CoronaVac: 42% [95% CI, 38 to 47]), hospitalization (BNT162b2: 82% [95% CI, 77 to 85], CoronaVac: 80% [95% CI, 76 to 84]), and mortality (BNT162b2: 94% [95% CI, 88 to 97], CoronaVac: 93% [95% CI, 88 to 96]). Vaccines were less effective in preventing infection and hospitalization in the eGFR <15 and 15-29 ml/min per 1.73 m 2 subgroups as compared with higher GFR subgroups. However, receipt of vaccine, even for one dose, was effective in preventing all-cause mortality, with estimates similar to the higher eGFR subgroups, as compared with unvaccinated. CONCLUSIONS: A dose-response relationship was observed between the number of BNT162b2 or CoronaVac doses and the effectiveness against COVID-19 infection and related comorbidity in the CKD population.