Change in visual analog scale score in a pragmatic randomized cluster trial of allergic rhinitis

BackgroundMost patients with allergic rhinitis consult in primary care. A simple test is needed to evaluate globally the severity of allergic rhinitis to assess the efficacy of treatment.ObjectiveThis study compared the responsiveness of visual analog scale (VAS) scores between baseline and treatment with the 2 gold-standard outcomes (symptom score and quality of life). Five hundred eighty-six subjects were included, all with allergic rhinitis caused by grass pollens and all seen in primary care.MethodsA randomized, multicenter, open-label parallel study was designed to compare 2 therapeutic strategies in patients with allergic rhinitis. The disease-specific Rhinoconjunctivitis Quality of Life Questionnaire total score, the symptom score, and the VAS score (0-10 cm) were all self-assessed by the patient before and after 2 weeks of treatment. Receiver operating characteristic curves and cost function were used to assess VAS cutoff scores and to distinguish between patients with no clinical improvement and patients with improvement in symptoms, quality of life, or both.ResultsThe optimal cutoff in VAS score change separating the patients without improvement from those with improvement is 0.30 cm. By using the cost of false-positive and false-negative results, a difference of more than 1 cm is significant. However, when patients show an improvement in both symptoms and Rhinoconjunctivitis Quality of Life Questionnaire scores, the median improvement on the VAS is 7 cm.ConclusionsA VAS, when used for a global evaluation of rhinitis, is highly responsive to change during the treatment of a large number of patients in a cluster randomized pragmatic trial.