Outcome of Using Intravenous Immunoglobulin (IVIG) in Critically Ill COVID-19 Patients’: A Retrospective, Multi-Centric Cohort Study

To access the effect of Intravenous immunoglobulin (IVIG) in critically ill corona virus disease 2019 (COVID-19) patients. Method: In this retrospective matched cohort study, records of three tertiary centers with large number of COVID-19 admissions were evaluated and used. Based on treatment options, patients were divided into two groups, standard COVID-19 treatment (109 patients) and IVIG treatment (74 patients) patients. Also, the effect of IVIG in different dosages was evaluated. Patients with IVIG treatment were divided into three groups of low (0.25 gr/kg), medium (0.5 gr/kg), and high (1 gr/kg) dose. Data analysis was performed using independent t-test and One-way analysis of variance (ANOVA) to compare the outcomes between two groups, including duration of hospitalization, intensive care unit (ICU) length of stay, and mortality rate. Result: The duration of hospitalization in the IVIG group were signicantly longer than standard treatment (13.74 days vs. 11.10 days, p<0.05). There was not a signicant difference between the two groups in ICU length of stay, number of intubated patients and duration of mechanical ventilation (P>0.05). Also initial outcomes in IVIG subgroups were compared separately with the standard treatment group. The results indicated that only the duration of hospitalization in the IVIG subgroup with medium dose is signicantly longer than the standard treatment group (P<0.01). Conclusion: Using IVIG is not benecial for COVID-19 patients based on no remarkable differences in duration of hospitalization, ICU length of stay, duration of mechanical ventilation and even mortality rate.


Introduction
Novel coronavirus disease 2019 (COVID-19) pandemic has become a global concern since 2019. By August 2021 more than 4,300,000 people have been sacri ced by this disease [1].
No de nitive treatment has been found, so it makes sense to consider the effects of possible treatments on the disease. One of these possible treatments is Intravenous Immunoglobulin (IVIG), which has been reported to have contradictory effects in previous studies [2,3].
The IVIG is a plasma-derived drug that was rst used to treat some immune de ciencies [4]. It has been used as an adjunct therapy in the management of some infections. Among viral infections, this treatment has been used to prevent and treat various viruses such as in uenza, viral hepatitis, rabies, measles and severe acute respiratory syndrome (SARS) [5]. Studies have revealed that IVIG can be effective in the treatment of severe acute viral pneumonia such as in uenza and para-in uenza pneumonia [6,7]. Antigen clearance and immune system modulation are increase by IVIG [8]. Due to the mechanism, safety and e cacy of this treatment in previous viral infections, some centers have utilized it in severe cases of COVID-19 infection. Despite its e cacy, this treatment is expensive and has various side effects [9]. Thus, the effectiveness and safety of this intervention in COVID-19 infection is debatable. Based on several studies IVIG administration in COVID-19 patients is controversial [9,10].
In this study we intend to investigate the e cacy of adding IVIG to the standard regimen of COVID-19 infection in outcome measures such as duration of hospitalization, mechanical ventilation, and intensive care unit (ICU) length of stay and mortality rate.

Materials And Methods
This retrospective study was conducted on COVID-19 patients in Imam Khomeini hospital complex, Rasul-e Akram and Ziaeian hospitals in Tehran, Iran.

Participants
In this study, a total of 202 patients who were admitted to between February 2020 to December 2020 were reviewed. These patients were treated with standard methods or IVIG added to standard care. Inclusion criteria were COVID-19 con rmation with real-time polymerase chain reaction (PCR), signi cant pulmonary ndings compatible with radiographic imaging and critically ill patients in ICU.
Critically ill patients were those with less than 90% oxygen saturation level with Non-rebreather mask, those who needed noninvasive ventilation (NIV) or intubation. Exclusion criteria were age under 18 years old, pregnancy, patients with incomplete data, non-ICU patients, those who participated in other clinical trials or received nonstandard treatment due to national or regional protocol and those who received less than ve grams of IVIG.

Study arms and treatment plans
After carefully reviewing the COVID-19 patients records based on the hospital information database, and nally considering the inclusion and exclusion criteria, 183 patients were divided into two groups; 109 patients have received standard treatment and 74 patients have received IVIG (Fig. 1).
In this study, epidemiological, demographic, clinical, laboratory data, management, and outcomes of patients were obtained. Finally, the outcomes include mortality rate, duration of hospitalization, mechanical ventilation and ICU length of stay were analyzed and compared between two groups.
The standard treatment group regimen was oral Hydroxychloroquine (HCQ) 400 mg daily for 5 days plus Atazanavir/Ritonavir (300/100) daily for ten days. IVIG treatment was divided into three groups of low, medium and high dose (0.25, 0.5 and 1 gr/ kg) during [3][4][5] consecutive days in addition to standard care.

Measurements and statistical analysis
Distribution of age, sex, initial clinical symptoms and on admission vital signs were compared between the two groups. Mortality rate, duration of hospitalization, mechanical ventilation and ICU length of stay were also evaluated.
The results were analyzed using SPSS v.25.0 software. Chi-square tests were performed to evaluate the difference in qualitative data.
Shapiro-Wilk test was performed to assess the normality of data distribution. To compare the differences in the quantitative variables of groups, the independent t-test and One-way analysis of variance (ANOVA) was carried out. Values with p < 0.05 were considered statistically signi cant.

Results
Based on the inclusion and exclusion criteria, 183 ICU admitted COVID-19 patients were included in the study, of which 109 (59.6%) were males and 74 (40.4%) were females, with an average age of 62.71 (± 15.46) years old. The patients were divided between standard treatment (comprising 109 patients) and IVIG treatment groups (comprising 74 patients) based on their treatment method.

Clinical and laboratory ndings
The clinical characteristics of patients (case and control group) are shown in Table I. Based on the results there were no signi cant differences between the two groups in demographic data, vital sign on admission, clinical features, laboratory tests and even risk factors. (P > 0.05).

Primary and secondary outcome
Primary outcomes including mortality rate, duration of hospitalization, ICU length of stay and duration of mechanical ventilation were compared in the two groups (Table II).
According to the primary outcomes the duration of hospitalization was longer in the IVIG group (P < 0.05). Two groups were not signi cantly different in ICU length of stay, number of intubated patients, duration of mechanical ventilation and mortality rate (P > 0.05).
Patients in the IVIG treatment group were divided into three groups; low, medium and high dose of IVIG (0.25, 0.5 and 1 gr/kg). Accordingly, 33.8% of the cases received low dose, 43.2% medium dose and 23% high doses (Table III). In these groups, mortality rate, duration of hospitalization, ICU length of stay and duration of mechanical ventilation were compared using analysis of variance (ANOVA) for Continuous scores and chi-square (χ2) for strati ed scores. The LSD post hoc test was also used to determine the location of the discrepancy. ANOVA test results are listed in Table III along with the results which are signi cantly different between the two groups.
There are no signi cant differences among three groups of IVIG treatment in primary outcomes as indicated in Table III. (P ≥ 0.05). The comparison between IVIG groups and standard treatment is summarized in Table IV. Based on the results, the duration of hospitalization was longer in the medium dose IVIG group (p < 0.01).
Finally, 165 patients were divided into ve subgroups based on intubation as shown in Table V. Eighteen out of 183 patients were excluded due to the lack of data.
Mortality rate was not signi cantly different between IVIG and standard treatment groups in both intubated and non-intubated subgroups.
Mortality rate in subgroups one and four was 0% and the result of χ 2 test between subgroups three and ve showed no statistical difference (p-value = 0.731 and χ 2 = 0.393).

Discussion
There have been different studies so far with different results about effect of IVIG on COVID-19 patients. But clear results have not been obtained [2,3,11]. Hence in this study, the therapeutic effects of IVIG on the con rmed COVID-19 cases were examined and the previous valuable results of related articles were reviewed.
Based on a randomized clinical trial on 84 patients, 52 patients received a treatment regimen including hydroxychloroquine, lopinavir / ritonavir and supportive care, plus 400 mg/kg IVIG daily for three days, but 32 patients received the same regimen without IVIG. Addition of IVIG to the standard treatment of critically ill COVID-19 patients could not decrease the duration of hospitalization, mechanical ventilation or mortality rate. In this study Tabarsi et al. found that duration of hospitalization was signi cantly longer in IVIG treatment group [2]. In our study we also found that the duration of hospitalization in the medium dose subgroup of IVIG was longer than control group and no positive effects were obtained on duration of mechanical ventilation and mortality of patients. Many studies have shown that IVIG administration reduces mortality in patients with COVID-19, but increases hospitalization time instead of standard COVID-19 treatment [12,13].
In a multicenter retrospective cohort study on 325 patients (174 patients in the case group who received IVIG and 151 patients in the control group), 28-day and 60-day mortality were the primary outcomes. Subgroup analysis showed that 28-day mortality in patients with critical type was improved compared to the control group and in these critically ill patients, IVIG reduced the in ammatory response and improved some organ functions, but the length of hospital stay and overall duration of the disease was increased [11].
In another study, IVIG administration in the rst 48 hours of hospitalization reduced mortality, length of stay, length of stay in the ICU, and duration of mechanical ventilation compared to IVIG administration after 48 hours of hospital admission [9]. Herth et al. retrospectively evaluated the clinical courses of 12 COVID-19 patients who received IVIG at various stages of their disease, including within the rst 72 h of clinical presentation, after initiation of mechanical ventilation, and after prolonged ventilation and ICU stay. Patients in this study received 0.2 or 0.5 g/kg/d of IVIG for 1 to 4 days. Early IVIG administration in viral phase of COVID-19 infection can decrease the duration of hospitalization, ICU length of stay, duration of mechanical ventilation and even mortality rate rather than late administration [9,14,15].
In our retrospective matched cohort study, we examined 183 patients with severe covid-19 infection who were admitted to the ICU. Seventyfour (40/4 %) patients were included in the case group and received IVIG in addition to the standard treatment, but 109 (59/6 %) patients in the control group received only standard treatment. On admission vital signs, clinical signs, laboratory data, and risk factors did not differ signi cantly between the two groups. Primary outcomes in our study were, duration of hospitalization, ICU length of stay, duration of mechanical ventilation and mortality rate. The results showed that the duration of hospitalization in the IVIG group (13.74 days) was signi cantly longer than the standard treatment group (11.10 days) (p-value = 0.041), But there were no signi cant differences between the other primary outcomes (P > 0.05).
Another question that was examined in this study was the impact of the time, dose and period of IVIG prescription on its effectiveness. For this purpose, patients with IVIG treatment were divided into three subgroups of low, medium and high dose. Then the primary outcomes of mortality rate, duration of hospitalization, ICU length of stay and mechanical ventilation were compared between these subgroups, but no signi cant differences were obtained. Also, initial outcomes were compared separately with the standard treatment group. The results indicated that only the duration of hospitalization in the IVIG subgroup with medium dose is signi cantly longer than standard group, and in other cases these differences were non-signi cant. These ndings were consistent with the results of Tabarsi et al [2]. So, in this study, it can be concluded that, the use of IVIG method in COVID-19 treatment, is not preferable to its standard treatment.
Di culty in patient matching and the difference timing in IVIG administration were the limitations in our study which should be overcome by conducting RCT studies with a large statistical population.