Research Article: Validation of a Portuguese version of the Oral Health Impact Profile adapted to people with mild intellectual disabilities (OHIP-14-MID-PT)

Date Published: June 14, 2018

Publisher: Public Library of Science

Author(s): Patrícia Couto, Paulo Almeida Pereira, Manuel Nunes, Rui Amaral Mendes, Peter M. Milgrom.


The purpose of this study is to develop a Portuguese version of the Oral Health Impact Profile (OHIP-14) and validate it for people with mild intellectual disability (OHIP-14-MID-PT).

The Portuguese version of the questionnaire was drawn up from the original English version, following internationally defined guidelines. Interviews were conducted with 240 individuals living in (or attending) institutions of the central region of Portugal that are affiliated with Humanitas (Portuguese Federation for Intellectual Disability) to measure oral health related quality of life (OHRQoL). The interview also included a sociodemographic and oral health questionnaire followed by an intraoral examination. Two types of reliability were analyzed: test-retest (ICC) and internal consistency (Cronbach´s α, inter-item and item-total correlations). Convergent and divergent validities were also assessed, and a confirmatory factor analysis was performed using the maximum likelihood method.

The OHIP-14-MID-PT presented high reliability (ICC = 0.999; Cronbach’s α = 0.922). The inter-item correlation coefficient ranged from 0.277 to 0.749, and the item-total correlation coefficient varied between 0.529 and 0.718. Lower OHIP-14-MID-PT total scores were significantly associated with: a self-perception of better oral health status (r = -0.545, p<0,001) and reduced need for dental treatment (U = 2366.5, p<0,001), more natural teeth (χ2 = 29.74, p<0,001) and better results in the clinical oral health index (COHI) (χ 2 = 18.50, p<0,001); the results support the convergent and divergent validities of the questionnaire. OHIP-14-MID-PT has proved to be a consistent, valid and reliable instrument with good psychometric properties to determine the impact of oral health on quality of life in adults with mild intellectual disabilities in Portugal.

Partial Text

There are several definitions of intellectual disability. In this study, we opted to use the American Association on Intellectual and Developmental Disabilities (AAIDD) definition, which is the one most widely used in the literature. In the definition, intellectual disability is characterized by “significant limitations both in intellectual functioning (reasoning, learning, problem solving) and in adaptive behavior, which covers a range of everyday social and practical skills. This disability originates before the age of 18” [1].

The development of a Portuguese version of the OHIP-14-MID-PT adapted to people with mild intellectual disabilities included a cross-cultural adaptation and the subsequent exploration of the psychometric properties of the scale.

This study aimed to create and evaluate the Portuguese version of the OHIP-14, in terms of validity and reliability, for use among adult population with mild intellectual disabilities. To this effect, the original English version of the OHIP-14 was translated using the forward-backward technique, pre-tested in a convenience sample and then applied to a group of the Portuguese population with mild intellectual disabilities in order to test its reliability and validity. In fact, most versions of the OHIP-14, as in our case, are based on the translation and linguistic adaptation of the original English version [15–17].




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