How Covid-19 affects immune-compromised people

A recent study published in the journal PLoS Medicine evaluates outcomes in immunocompromised patients hospitalized with the coronavirus disease 2019 (Covid-19).

Background
Covid-19 disproportionately affects older adults and those with pre-existing health conditions. Early evidence from the Covid-19 pandemic suggested high mortality among immunocompromised subjects.

Several studies have reported conflicting Covid-19 mortality estimates between immunocompromised and other patient groups, with some suggesting more deaths and others reporting no differences.

About the study
In the present study, adults hospitalized with Covid-19 between January 17, 2020, and February 28, 2022, were enrolled in a prospective observational cohort study known as the International Severe Acute Respiratory and Emerging Infection Consortium (ISARIC) Clinical Characterization Protocol (CCP) in the United Kingdom.

Patients were considered immunocompromised if they had active cancer diagnosis/treatment, human immunodeficiency virus (HIV) infection, congenital immune deficiency, underwent solid organ transplant or were using immunosuppressants or steroids before admission. Demographic characteristics, such as sex, age, ethnicity, and comorbidities, were recorded at hospitalization.

Asymptomatic patients were excluded from the analysis. In-hospital interventions were recorded, including respiratory support level and treatments, such as steroids and interleukin 6 (IL-6) receptor inhibitors.

The primary outcome of the study was in-hospital death. Secondary outcomes included oxygen use, non-invasive/invasive ventilation, and admission to critical care.

Multivariable logistic regression was performed to assess in-hospital mortality with adjustments for sex, age, ethnicity, comorbidities, vaccination, and deprivation index. Secondary outcome measures were similarly adjusted for the specified variables.

The researchers also determined whether in-hospital mortality differed between immunocompromised and immunocompetent patients.

Study findings
Overall, data for over 300,000 admissions were collected. Outcome data were available for 156,552 cases, 21,954 of whom were immunocompromised and the remaining were immunocompetent.

The median age of immunocompetent and immunocompromised patients was 69.5 and 71.5, respectively. Cancer patients and those taking immunosuppressants/steroids pre-admission were older than individuals with solid organ transplants, HIV infection, or congenital immune deficiency.

About 95% of immunocompromised patients were comorbid. Chronic pulmonary disease, malignant neoplasm, and hematologic and rheumatologic diseases were more common in immunocompromised patients, while diabetes, chronic cardiac disease, obesity, and hypertension were similar between the two groups.

About 85% of immunocompetent and 81% of immunocompromised individuals were non-vaccinated. Notably, 49% of admissions occurred before Covid-19 vaccines were available.

Disease severity at hospital presentation was similar between the two groups in the early pandemic and reduced over time, albeit to a lesser degree among immunocompromised patients.

Immunocompromised individuals more frequently required critical care admission, as well as invasive and non-invasive ventilation. Of note, cancer patients had a lower frequency of invasive ventilation and critical care admission.

Overall, 29% of immunocompromised and 21% of immunocompetent patients died. The highest mortality rate was observed in cancer patients and pre-hospitalization steroid users.

After adjustment, the odds ratio for mortality was 1.44 in immunocompromised patients. Adjusted odds ratios varied across immunocompromised patients for all outcomes. Patients on steroids/immunosuppressants exhibited consistently higher adjusted odds ratios for critical care admission, invasive/non-invasive ventilation, and mortality.

The mortality risk was the highest in cancer patients and lowest in HIV-infected patients. Mortality rates declined over time in both groups.

After adjustment, the odds ratio for mortality remained higher in immunocompromised patients across Covid-19 waves. The odds ratio for mortality was 0.66 for immunocompromised and 0.38 for immunocompetent patients in the fourth wave.

Conclusions
A higher adjusted mortality rate was observed among immunocompromised as compared to immunocompetent people. Immunocompromised patients had less reduction in severity at presentation and less improvement in mortality than immunocompetent patients. The number of hospitalized patients decreased over time after vaccination as compared to non-vaccinated patients.

Notably, the researchers did not obtain detailed medication histories of patients. As such, there was no information on which drug(s) was/were responsible for the immunocompromised state. Some patients in the first wave also lacked a confirmed Covid-19 diagnosis, as enrollment was based on high clinical suspicion.

Taken together, the researchers noted a smaller reduction in in-hospital deaths among immunocompromised patients in the ISARIC CCP-UK dataset. Cancer patients were at the highest mortality risk than other sub-groups.

Despite vaccination benefits, immunocompromised patients lag behind immunocompetent individuals in improvements in Covid-19 outcomes after hospitalization. Therefore, targeted interventions remain urgently needed in these patients. Medical News