BACKGROUND The EQ-5D, developed in 1990 by the EuroQoL group, is one of the most widely employed generic tools to measure Health-Related Quality of Life (HRQoL) due to its low respondent burden, good psychometric properties and econometric development. In addition, the availability of well-defined requirements for its online administration by multiple devices such as personal computer, tablet or smartphones makes this instrument adequate for monitoring HRQoL in e-Health programmes. To improve

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... s sensitivity the EuroQol Group developed a new EQ-5D version, increasing the number of responses from 3 to 5 levels (EQ-5D-5L). However, to date, there are neither studies assessing the new 5-level version when administered online, nor studies evaluating its metric properties in asthma patients. OBJECTIVE to examine the distribution and construct validity of the new EQ-5D-5L questionnaire administered online to adults with asthma. METHODS Evaluation of asthma patients (18-40 years) from primary care setting in France and England, who self-completed the EQ-5D-5L questionnaire online. Inclusion criteria were: persistent asthmatic patients, with >6 months of prescribed drug of Inhaled Corticosteroids (ICs) and/or LABAs during the 12 months prior to inclusion. The EQ-5D index was obtained by applying the English preference value set for the new EQ-5D-5L and the French 3L-5L crosswalk value set. Both value sets produced single preference-based indices ranging from 1 (best health state) to negative values (health states valued as worse than death), where 0 is equal to death, allowing the calculation of Quality-Adjusted Life-Years (QALYs). Responses to dimensions and index distribution, including ceiling and floor effects, were examined. Construct validity was assessed by comparing means of known groups by analyses of variance and effect sizes (ES). RESULTS Of the 581 patients recruited, 312 filled in the baseline online survey (53.7% online participation rate), but 22 did not complete the EQ-5D-5L questionnaire (7% of questionnaire non-response rate), so 279 patients were finally included in this analysis. Floor effect was null and ceiling effect was 26.5%. Mean EQ-5D-5L index was 0.88 (SD 0.14) with English value set and 0.83 (SD 0.19) with French 3L-5L crosswalk value set. In both indices large ES was observed for known groups defined by Asthma Control Questionnaire (1.06 and 1.04, P<0.001). Differences between extreme groups defined by chronic conditions (P=0.003 and P=0.002), Short-Acting Beta-Agonists (SABA) canisters in the last 12 months (P=0.05), or SABA use during the previous 4 weeks (P=0.034 and P=0.007) were of moderate magnitude with ES around 0.5. CONCLUSIONS High self-completion of the EQ-5D-5L among online respondents (93%) confirms the feasibility of this administration form. The new EQ-5D-5L questionnaire has acceptable ceiling effect, construct validity based on good discriminant ability for distinguishing among health-related known groups, and high measurement accuracy, supporting its adequacy for online administration to asthma patients.