Measurement and Monitoring of Nausea Severity in Emergency Department Patients: A Comparison of Scales and Exploration of Treatment Efficacy Outcome Measures

Abstract

Objectives: The objective was to investigate the correlation of the visual analog scale (VAS) and numeric rating scale (NRS) for nausea severity measurement and to explore options for improved reporting of antiemetic efficacy trial results.Methods: This was a multicenter observational study of adult emergency department (ED) patients with nausea. Participants rated severity at enrollment and 30 minutes posttreatment using an adjectival scale, a VAS, and an NRS. Posttreatment, patients described symptom change and rated satisfaction.Results: Ratings were performed by 258 patients. Both the VAS (0 to 100 mm) and the NRS (0 to 10) discriminated between adjectival severity categories. Median ratings with interquartile ranges (IQRs) were "severe" VAS 90.5 (IQR = 79 to 97) and NRS 9 (IQR = 8 to 9), "moderate" VAS 59 (IQR = 48 to 71) and NRS 6 (IQR = 5 to 7), "mild" VAS 34 (IQR = 25 to 49) and NRS 4 (IQR = 3 to 5), and "none" VAS 5 (IQR = 0 to 9) and NRS 0 (IQR = 0 to 1). Correlation between the VAS and NRS was high (0.83, Spearman). For the VAS, median mm (IQR) reductions for posttreatment change were "a lot less" -42 (IQR = -26 to -58.5), "a little less" -20.5 (IQR = -11 to -33), "the same" -2 (IQR = -8 to 3.5), "a little more" 14 (IQR = -2 to 22), and "a lot more" 17 (IQR = 6 to 23) and for satisfaction were "very satisfied" -45 (IQR = -27 to 63), "satisfied" -27 (IQR = -13 to 46), "unsure" -15 (IQR = -3 to -24), "dissatisfied" 4.5 (IQR = -5.5 to 13.5), and "very dissatisfied" 8.5 (IQR = 0 to 23). A VAS cutoff of ≥-5 mm detected symptom improvement with sensitivity 91.6% (95% CI = 86.7% to 95.1%), specificity 72.1% (95% CI = 59.9% to 82.3%), and positive predictive value 90.2% (95% CI = 85.1% to 94.0%). Conclusions:The VAS and NRS correlate highly. A VAS cutoff level of ≥-5 mm was a good predictor of symptom improvement, suggesting that its inclusion as an outcome measure would enhance reporting in antiemetic efficacy trials.ACADEMIC EMERGENCY MEDICINE 2015;22:685-693

Antiemetic treatment in the emergency department: Patient opinions and expectations

“…Our findings support the usual approach taken in recent studies, of excluding patients with mild nausea and timing the outcome measure at 30 min . Current approaches equate clinical significance with symptoms becoming ‘a little less’, or no longer being ‘the same’ . This degree of change meets the definition for efficacy being a ‘beneficial’ effect, but efficacy may equally be defined as a ‘desired’ effect .…”

“…Patient satisfaction has been used as a secondary outcome measure in some ED‐based antiemetic drug trials, but its utility has been questioned . We found the overall responses regarding satisfaction, and expectations being met, to be similar.…”

“…In contrast, when expectations were met versus not, median VAS changes were −44 mm and −20 mm, respectively. Nausea measurement studies have shown that these levels of VAS change reliably correlate with symptoms being ‘a lot less’ and ‘a little less’, respectively . It was not possible to specifically explore reasons for this possible inconsistency between the ordinal scale and the VAS in this population.…”

“…Students did not keep details of eligible patients they were unable to approach for whatever reason, or those who were approached and declined participation. However, the recruited population did represent all severity subgroups, with VAS ranges for these being consistent with previous reports . Potential interviewer bias was minimised by having multiple people deliver the questionnaire at different times.…”

“…The MCSD is defined as the mean VAS change reported when symptoms have become ‘a little less’ . This approach has recently been criticised because the mean VAS change yields no information on number of patients per group who are improved …”