Indications in the adult and pediatric data were grouped into the following categories: ‘appropriate use’, ‘future research’ (defined as additional research is required to determine whether this is an appropriate or inappropriate indication for IVIG use) and, lastly, ‘inappropriate use’. Appropriate use designation as described above was assigned based on the recommendations from two published Canadian Healthcare guidelines that assessed both specialist expertise and the medical literature for off-label use of IVIG and whether sufficient published evidence existed to establish IVIG treatment recommendations in these individual indications.
Due to the lack of standardization of terminology of indications across institutions, each local term for an indication was grouped by Coding Symbols for Thesaurus of Adverse Reaction Terms (COSTART), which is an internationally recognized system of grouping medical conditions by indication and body system (Department of Health and Human Services, United States Food and Drug Administration, 1995). Analysis of data was separated by adult and pediatric populations. Analysis of the data is based on known indications, unless specifically stated otherwise. Furthermore, the analysis used frequency counts and percentages by indications (grouped primarily by COSTART), appropriateness codes, physician specialties and amount of IVIG prescribed. Use was totaled by indication. Percentage use per indication per year was calculated based on total IVIG use both with and without unknown use included in the calculation. No formal statistical analysis was performed on the data.