McMonnies Questionnaire: Enhancing screening for Dry Eye Syndromes using Rasch Analysis.
Invest Ophthalmol Vis Sci. 2009 Nov 5.
Gothwal VK, Pesudovs K, Wright T, McMonnies C.
NH&MRC Centre for Clinical Eye Research, Department of Ophthalmology, Flinders Medical Centre and Flinders University of South Australia, Adelaide, Australia.

PURPOSE: To determine, using Rasch analysis, if the McMonnies questionnaire satisfied the properties of a measure and whether screening for dry eye syndromes (DES) could be enhanced using different scoring approaches.

METHODS: The questionnaire was self-administered by 43 female Sjögren syndrome patients (>45 years) recruited from a specialized rheumatology clinic and 140 age-matched controls. Data were scaled using Rasch analysis and assessed for response category behavior and ability to reliably discriminate between severity of participant's dry eye symptoms (i.e. person separation reliability; minimum acceptable value 0.80). Standard summary statistics of screening performance were calculated for raw and Rasch-scaled scores from Receiver-Operating Characteristic analysis including area under the curve (AUC). Best predictors (i.e. questions) from a discriminant analysis were used to calculate a discriminant function for both Rasch-scaled and raw scores.

RESULTS: Response categories were not used as intended, necessitating collapse of categories. Person separation reliability was inadequate (0.75). Rasch-scaled discriminant cut-off score of -2.29 logits from 7 items provided an AUC of 0.99 with 95% sensitivity. However, discriminant raw score from modification in the scoring of a question, i.e. use of medications (used singly rather than individual questions) provided AUC (0.97) not significantly different (z = 1.11, p = 0.27) with 98% sensitivity and required only 2 questions.

CONCLUSIONS: In this population, the McMonnies questionnaire does not function as a measure. However, various scoring methods can be used to efficiently screen for DES.