Need for developing a standardized case definition and guidelines for swelling at or near injection site as an adverse events following immunization:
Swelling at injection site is the most frequent adverse event following immunization (AEFI) reported to the U.S. Vaccine Adverse Event Reporting System (VAERS), and is also a frequently reported AEFI in vaccine clinical trials [1], [2], [3]. However, because of a current lack of standardization of the assessment of swelling at injection site, comparability of data across different studies and settings is at best difficult. In more than 100 articles reviewed, we identified 11 different measured cut offs to describe the size of swelling, and no standardized criteria for defining the reaction [4], [5], [6], [7], [8], [9], [10], [11], [12], [13].
Sections 2 and 3 of this paper provide the case definition and guidelines for data collection, analysis and presentation that the Brighton Collaboration Local Reactions Working Group has developed for the standardized collection and assessment of information about swelling at or near injection site. Widespread use of this definition with its guidelines will improve data comparability and allow a better understanding of the adverse event. The case definition and guidelines are intended to be applicable in diverse geographic, administrative and cultural regions, regardless of differences in the availability of health care resources.
1.2. Methods for the development of the case definition and guidelines for swelling at or near injection site as an adverse events following immunization
Following the process described in the overview paper [14], a Brighton Collaboration Local Reactions Working Group was formed in December 2001 comprised of 12 members with public health, regulatory, clinical and academic, and industry backgrounds. The Working Group identified several injection site reactions chosen on the basis of their frequency or severity. The Working Group has previously published its case definition with guidelines for nodule at injection site [15]. The Working Group, whose composition is slightly different for each of the definitions depending on availability and interest in a particular topic by working group members, has since developed four additional case definitions with guidelines published in this volume. The member composition and results of the web-based surveys completed by the reference group and subsequent discussions in the Working Group can be viewed at: http://brightoncollaboration.org/internet/en/index/working_groups.html.
To guide the decision-making for the case definition and guidelines, a literature search identified English and non-English citations of local reactions overall including swelling in the context of immunization (MEDLINE 1976–2001; search terms included amongst others “swelling”, “edema” or “local reaction” or “inflammation” and “injection site” and “immunization”); the search also included reviews of textbooks and study protocols. Based on a review of the title and abstract of the >970 references identified, we identified more than 120 potentially relevant articles, of which we summarized 102 articles in detail. As mentioned above, structured work on the evaluation or development of a definition for swelling at or near the injection site was not found in the literature reviewed.
