Objective Health information retrieval (HIR) on the Internet has become an important practice for millions of people, many of whom have problems forming effective queries. We have developed and evaluated a tool to assist people in health-related query formation.

Design We developed the Health Information Query Assistant (HIQuA) system. The system suggests alternative/additional query terms related to the user's initial query, which can be used as building blocks to construct a better, more specific, query. The recommended terms are selected according to their semantic distance from the original query, which is calculated on the basis of concept co-occurrences in medical literature and log data as well as semantic relations in medical vocabularies.

Measurements An evaluation of the HIQuA system was conducted and a total of 213 subjects participated in the study. The subjects were randomized into two groups. One group was given query recommendations and the other was not. Each subject performed HIR for both a pre-defined and a self-defined task.

Results The study demonstrated that providing HIQuA recommendations resulted in statistically significantly higher rates of successful queries (odds ratio: 1.66, 95% CI: 1.16 - 2.38), although no statistically significant impact on user satisfaction or the users' ability to accomplish the pre-defined retrieval task was found.

Conclusion Providing semantic-distance based query recommendations can help consumers with query formation during HIR.