Efficacy of Polyspecific Intravenous Immunoglobulin Therapy in Streptococcal Toxic Shock Syndrome

TO THE EDITOR—With interest we read the publication by Linner et al [1] demonstrating an effect of intravenous immunoglobulin (IVIG) therapy in patients with streptococcal toxic shock syndrome (STSS). However, as several questions remain unanswered, we believe that the data should be interpreted with caution. First, the use and timing of antibiotics was well documented and described in the article. However, the timing of IVIG administration between the fasciitis necroticans and non–fasciitis necroticans groups is lacking. Can the difference in mortality between the groups be attributed to this possible difference? Another point we would like to raise is the difference in baseline patient characteristics. The authors rightly address several imbalances between the IVIG-treated and not-treated groups. However, it should be noted that in percentages, there is also a difference with respect to previous health, alcohol use, and diabetes in favor of the IVIG-treated group. Although not statistically significant in this article, the small number of patients per arm might be caused by a type 1 error (α error). Therefore, the lower mortality in the IVIG-treated group might in part be explained by the more favorable baseline characteristics. Last, we noted when looking at Figure 1 [1], that 697 patients who were initially diagnosed with invasive group A Streptococcus in the database (we assume based on the case definition according to the Centers for Disease Control and Prevention [2]), were later excluded. We wonder why so many possible patients were excluded. In conclusion, we agree with Linner et al that IVIG therapy is save and that, because large randomized studies are difficult to achieve, observational data are a valuable contribution to the field. However, caution in interpreting the effect of IVIG treatment on mortality in STSS patients should still be taken.