OBJECTIVES: Using data from a prospective, randomized, double blind clinical trial comparing olopatadine to levocabastine in patients with Seasonal Allergic Conjunctivitis (SAC), two synthetic scores, summarizing recorded effectiveness information one being a single-dimensional symptoms score and the other a quality-of-life (QOL) measure were derived. We then compared the two measures in various national contexts. METHODS: Correspondence analysis was used to analyze the study results. Coordinates on the first factorial axis were transformed into an aggregate symptom score and averaged across patients at each visit. At the same time, 32 experts from 6 European countries were asked to quantify the impact of each level of each symptom on QOL from a patient’s perspective. They were also asked to weigh on each symptom. An aggregated QOL score was thus derived and averaged across patients in both arms. RESULTS: At baseline, aggregated symptoms scores were identical across both groups of patients (p=0.798). At day 42, the score in the olopatadine branch was significantly better than that in the levocabastine arm (p=0.032). QOL life scores exhibited the same pattern of improvement. Comparisons between scores show that QOL score is positively, but not linearly, correlated to the symptom score. For high levels of symptom severity, a clinical improvement, measured in terms of a reduction of symptoms intensity, offers little QOL improvement, while the same improvement, starting from a lower level of symptom score, offers an important QOL improvement. CONCLUSION: The indicators constructed from the study data exhibit several interesting properties. Although they have strong clinical significance, they do not describe the same phenomenon. The analysis allows a better understanding of how symptom improvements are reflected in patients’ well-being. It also enables meaningful health economic analysis in situations using clinical data sources to be conducted.