IQoL-32: a new ichthyosis-specific measure of quality of life

Background: Inherited ichthyoses are associated with impaired quality of life (QoL).

Objectives: The aim of this study was to create and validate a QoL questionnaire specifically dedicated to patients with ichthyosis.

Methods: A prequestionnaire was drawn after selecting items from a verbatim transcript. It was then subjected to a cognitive debriefing. During the validation step, this questionnaire was sent to patients with the Dermatology Life Quality Index, Short Form-12 health-related questionnaire, and severity scores (global severity: mild/moderate/severe/very severe; clinical severity evaluated by 6 visual analog scales). A shortened version of the questionnaire was designed. The validity of the tool was confirmed: for its structure and 1-dimensional nature (Cronbach α), convergent (Spearman correlation) and discriminating (Tukey test) validity; α risk was fixed at 5%.

Results: The initial questionnaire included 60 items. During the validation phase, 59 subjects were tested. The shortened version included 32 items (IQoL-32) and 7 dimensions (Cronbach α: 0.94). The higher the score, the more impacted the QoL. IQoL-32 was positively correlated to Dermatology Life Quality Index (P < .0001) and negatively to Short Form-12 health-related questionnaire (P < .0001). IQoL-32 was highly correlated to clinical severity: overall analysis (Spearman ranking: 0.72; P < .0001) or analysis per dimension (highest correlations: discomfort, pain, interpersonal relations). IQoL-32 demonstrated a higher correlation with visual analog scale compared with Dermatology Life Quality Index and Short Form-12 health-related questionnaire. It also showed a good discriminating power (P < .0001) according to overall severity levels.

Limitations: Only patients residing in France were included.

Conclusion: IQoL-32 is a specific and validated questionnaire for inherited ichthyosis. It will be very useful for patient care and research.