Factors associated with the use of over-the-counter medications in cases of acute gastroenteritis in Hamilton, Ontario

Background: Monitoring over-the-counter (OTC) medication sales may provide an accurate, reliable way to observe trends and detect aberrations in community health status. This study assessed demographic and symptomatic factors associated with the use of OTC anti-nauseants (AN), anti-diarrheals (AD), and rehydration therapies (RT) in cases of acute gastroenteritis (GE). Methods: Data on 351 cases of self-reported, acute GE obtained from a population-based telephone survey were analyzed. The four outcomes of interest were use of an OTC 1) AD, 2) AN, 3) RT, and 4) use of at least one of the three. The association between each factor of interest and the use of OTC treatments was assessed. Results: Of the 351 cases, 110 (31%) used at least one OTC AD, AN, or RT for their illness. The most significantly associated factor was primary symptom group: cases with both vomiting and diarrhea were 3.6 times more likely to use at least one of the three OTC medications than cases with either vomiting or diarrhea only. Other factors associated with the use of at least one OTC were being female (OR=1.97), being 10-14 years of age (OR=11.22), and use of antacids in the 28 days prior to illness (OR=2.31). Conclusion: This study provides the first published assessment of factors associated with the use of OTC medications by community cases of GE. Those who use OTC medications for their illness appear to differ from those who do not. This information can inform health officials, and aid development of pharmacy-based syndromic surveillance.