3.2. 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 significantly 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 stratified 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 significantly different between the two groups.
There are no significant 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 five 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 significantly 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 χ2 test between subgroups three and five showed no statistical difference (p-value = 0.731 and χ2 = 0.393).