Psychometric properties and diagnostic performance of three dry eye questionnaires in Italian: OSDI, OSDI-6, and SPEED

SIGNIFICANCEPsychometric questionnaires are highly valuable instruments in clinical practice as they make subjective symptoms easier to measure. Recently, a short version of the Ocular Surface Disease Index (OSDI) questionnaire was developed, named OSDI-6.PURPOSEThis study aimed to assess the psychometric properties and compare the diagnostic criteria of three questionnaires, available in the Italian language, designed for assessing dry eye disease: Standard Patient Evaluation of Eye Dryness (SPEED), OSDI-12, and specifically the new shortened version, OSDI-6.METHODSPsychometric evaluations were conducted on 250 adult participants aged 20 to 83 years. Classic and Rasch psychometric analyses were performed on the three questionnaires. The repeatability of the questionnaires was assessed by retesting 120 participants.RESULTSThe exploratory factor analysis of OSDI-6 indicated saturation on two factors. Repeatability was optimal for all three questionnaires. Based on the reference OSDI-12, the cutoff for OSDI-6 was 5 points and 7 for SPEED. Rasch analysis showed that OSDI-6 and OSDI-12 present disordered response categories and thresholds. Conversely, the SPEED questionnaire shows the optimal item characteristic curve.CONCLUSIONSThe OSDI-12 is a reference questionnaire used in dry eye disease studies and clinics, but OSDI-6 does not represent a perfect shortened version, primarily for the absence of one factor measured and secondarily for the same problem of category response order and thresholds. Conversely, SPEED focusing only on symptoms showed better psychometric properties.