Prospective evaluation of ondansetron for undifferentiated nausea and vomiting in the prehospital setting

Objective. To evaluate the change in nausea scales and incidence of vomiting with the use of ondansetron in the treatment of nausea and vomiting in the prehospital setting. Methods. Data were prospectively collected on all emergency medical service patients who received ondansetron for undifferentiated nausea and vomiting during a 6-month study period. Added outcome measures for this study were verbal quantitative (scale of 1-10) and qualitative "nausea scales," incidence of vomiting prior to and after administration of ondansetron, and adverse events. Patients who had this additional data collected and ones who did not were compared. Changes in the "nausea scales" and incidence of vomiting before and after administration and correlation among these measures were also compared. There was no control or placebo group. Results. Ondansetron was administered to 952 patients of 20,054 patients transported during this time period (5%); of these 472 had at least some of the outcome measures documented. There were minimal differences in the two cohorts; 198 patients had paired before and after quantitative "nausea scales" documented: 7.6 ± 2.4 and 4.6 ± 3.1, respectively (Δ = 2.9, 95% CI: 2.5-3.4); 447 patients had a qualitative change in nausea level documented: 0.4% "a lot worse," 1.3% "a little worse," 34% "unchanged," 40% "a little better," and 25% "a lot better"; 187 patients had all three measures documented with a Pearson correlation coefficient of 0.63 between the change in the quantitative scale and the qualitative scale (95% CI: 0.14-0.20, R2 0.39). In 462 patients, vomiting decreased from 60% to 30% (Wilcoxon signed ranks test p < 0.001). The Pearson correlation coefficients for the change in vomiting incidence with the qualitative and quantitative "nausea scales" were poor: 0.012 (95% CI: -0.015 to 0.039, R2 0.00014) and 0.051 (95% CI: -0.032 to 0.118, R2 0.00026), respectively. There were no reported adverse events. Conclusions. Ondansetron appears to be moderately effective in decreasing nausea and vomiting in undifferentiated prehospital patients. Additional controlled trials may be needed to compare it with other antiemetics.