Both sub-scales of the “Keratoconus End-Points Assessment Questionnaire” (KEPAQ) are unidimensional and reliable

Standardizing the measurement and classification of quality of life using the Keratoconus End-Points Assessment Questionnaire (KEPAQ): the ABCDEF keratoconus classification

“…The problem of using such non-specific scales in different populations from what they were initially designed for, is that results are not necessarily reliable or trustable. So far only two instruments have been specifically created and validated in keratoconus subjects: the KORQ [ 2 , 17 – 19 ] and the KEPAQ [ 1 , 3 , 6 ]. Although both scales measure subjective functional compromise by the disease, the main difference between them is the fact that the KEPAQ also has a sub-scale for measuring emotional distress secondary to keratoconus [ 1 ].…”

“…All patients are also given the choice to select “Not applicable” if they feel the question does not correlate with any situation in their daily lives. Early tables for converting the total sum score into a non-transformed Rasch-derived score were previously published by our group [ 1 , 6 ], with a greater KEPAQ score meaning less disability by disease [ 3 ]. A complete description and explanation on the origin and philosophy behind the development of the KEPAQ is available here [ 1 ].…”

“…A complete description and explanation on the origin and philosophy behind the development of the KEPAQ is available here [ 1 ]. Our group has previously demonstrated the KEPAQ to comply adequately to the Rasch model [ 1 ], to be unidimensional and reliable [ 6 ] and to correlate well with the Belin ABCD classification [ 3 ].…”

Diseño, desarrollo y validación de un cuestionario para evaluar el compromiso visual y emocional en pacientes con queratocono

“…Questionnaire' (KEPAQ) are unidimensional and reliable']. [172] En este artículo se evaluó la unidimensionalidad del KEPAQ mediante una metodología de análisis de componentes principales, similar a la utilizada en el Artículo 1. [170] Para llevarlo a cabo, se incluyeron 249 sujetos con diagnóstico confirmado de QC, que fueron sometidos a la versión final del KEPAQ, y sus respuestas fueron evaluadas primero por medio de un nuevo análisis de Rasch y, finalmente, por medio de un análisis de componentes principales.…”

“…El KEPAQ puede ser usado con confianza para medir la calidad de vida en pacientes con queratocono, tanto con objetivos clínicos como de investigación. [172] Sin embargo, a pesar de los datos anteriores, hasta ese momento sólo se habían publicado datos respecto a una realización única del KEPAQ. No existía evidencia de que los datos obtenidos por este se mantenían estables ante una nueva realización del cuestionario cuando ningún elemento clínico hubiese cambiado, característica conocida como "fiabilidad test-retest".…”