The robustness of the relative recall method depends on the quality of the searches within each systematic review. Despite passing a quality checklist, some of the systematic reviews employed less than optimal search methods, which may have negatively affected study identification.

Also, a larger quasi-gold standard set may have improved the generalizability of the study findings. During filter development, several terms (utility loss, disutility, short form, SF-12) were removed to increase precision. However, during final validation, it was found that inclusion of these search terms would have retrieved an additional three records, revealing the difficulty in making filter decisions based on a small number of relevant records. These removed terms could be added to the filters to maximize sensitivity. Similarly, some terms added to the filters resulted from an analysis of a very small number of records. These revisions were made to increase sensitivity, but the missed records retrieved through these additions were outliers, and less likely to be representative of the wider body of relevant results. The addition of these terms may increase search result size, but potentially have minimal impact on the total number of relevant results retrieved.

The initial filters created by YHEC were developed through pragmatic and traditional subjective methods, rather than using objective filter design methods. Despite the pragmatic development, these strategies performed well in testing.

The final filters are designed to find reviews, cost-utility analyses and utility elicitation studies that report HSUVs, as well utility mapping studies. Since the filters do not distinguish between these different types of research, precision for research seeking only utility elicitation studies, for example, will be lower than the results reported in the article.