Some psychometric properties of the Chinese version of the Modified Dental Anxiety Scale with cross validation

Health and Quality of Life Outcomes BioMed Central Open Access Research Some psychometric properties of the Chinese version of the Modified Dental Anxiety Scale with cross validation Siyang Yuan1, Ruth Freeman1, Satu Lahti2,3, Ffion Lloyd-Williams4 and Gerry Humphris*5 Address: 1Dental Health Research Unit, Mackenzie Building, Ninewells Hospital, University of Dundee, UK, 2Department of Community Dentistry, University of Oulu, Finland, 3Oral and Maxillo-facial Department, Oulu University Hospital, Oulu, Finland, 4Department of Public Health, University of Liverpool, UK and 5Health Psychology, Bute Medical School, University of St-Andrews, UK Email: Siyang Yuan - ; Ruth Freeman - ; Satu Lahti - ; Ffion LloydWilliams - ; Gerry Humphris* - * Corresponding author Published: 25 March 2008 Health and Quality of Life Outcomes 2008, 6:22 doi:10.1186/1477-7525-6-22 Received: 19 November 2007 Accepted: 25 March 2008 This article is available from: http://www.hqlo.com/content/6/1/22 © 2008 Yuan et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Objective: To assess the factorial structure and construct validity for the Chinese version of the Modified Dental Anxiety Scale (MDAS). Materials and methods: A cross-sectional survey was conducted in March 2006 from adults in the Beijing area. The questionnaire consisted of sections to assess for participants' demographic profile and dental attendance patterns, the Chinese MDAS and the anxiety items from the Hospital Anxiety and Depression Scale (HADS). The analysis was conducted in two stages using confirmatory factor analysis and structural equation modelling. Cross validation was tested with a North West of England comparison sample. Results: 783 questionnaires were successfully completed from Beijing, 468 from England. The Chinese MDAS consisted of two factors: anticipatory dental anxiety (ADA) and treatment dental anxiety (TDA). Internal consistency coefficients (tau non-equivalent) were 0.74 and 0.86 respectively. Measurement properties were virtually identical for male and female respondents. Relationships of the Chinese MDAS with gender, age and dental attendance supported predictions. Significant structural parameters between the two sub-scales (negative affectivity and autonomic anxiety) of the HADS anxiety items and the two newly identified factors of the MDAS were confirmed and duplicated in the comparison sample. Conclusion: The Chinese version of the MDAS has good psychometric properties and has the ability to assess, briefly, overall dental anxiety and two correlated but distinct aspects. Background The assessment of dental anxiety is becoming increasingly relevant with the stronger emphasis on evidence based methods for improving patient oral health care [1,2]. In particular, recording self-reported dental anxiety in those patients who report psychological difficulties in receiving dental treatment enables planners of dental services to make informed decisions about suitable interventions [1,3]. This is especially important in countries like China that are experiencing rapid economic development. Page 1 of 11 (page number not for citation purposes) Health and Quality of Life Outcomes 2008, 6:22 China's health services are receiving close attention as its population is drawn into utilizing a mix of traditional and western influenced primary care provision. Dental services are expanding and little evidence is currently available on the factors responsible for uptake, of which dental anxiety is a likely candidate for explaining utilisation. Issues that govern the choice and the use of dental anxiety measures in clinical practice and epidemiological surveys are: number of question items, complexity, validity and useability [4]. There are a number of self-reported measures of dental anxiety that vary in length, theoretical background and psychometric evidence [5]. Some scales are available in a variety of languages e.g. [6-8]. A popular measure of dental anxiety was the four item Corah's dental anxiety scale [9], however this scale omits assessing respondents' views to dental anaesthesia and has a complex answering scheme. The 5 item modified dental anxiety scale (MDAS) was constructed to satisfy both problems by introducing a new item about local anaesthesia and simplifying the response format [10]. Conversion tables are available [11]. A clinical cut-off score of 19 and above has been determined to identify highly dentally anxious individuals who require specialist care (e.g. behavioural management and/or anaesthesia) [10]. A diagnostic classification for dental phobia has been devised based upon international criteria [12]. There are issues of usability that concern, first, how long the questionnaire takes to complete and, second the effect of instrumentation. An example of the first issue is the 36 item questionnaire (Dental Anxiety Inventory, DAI) designed to assess 3 'facets' of dental anxiety [13]. Although highly reliable it was found to be impractical in clinical settings because of the relatively long completion time [14]. A shorter 8 item version has been devised [15]. The second issue of instrumentation has received little interest hitherto. There is some evidence that dental personnel are concerned about the possibility of raising dental anxiety by inviting patients to report their feelings associated with a dental visit [16]. The design and subsequent development work with the Modified Dental Anxiety Scale has attempted to address this concern. The MDAS is brief and requires just 2–3 minutes to complete [10]. Moreover, and crucially, the scale does not raise anxiety in respondents, regardless of their initial level of dental anxiety [17,18] and rather than be detrimental its completion can be beneficial to patients when incorporated into managed care procedures within a practice setting [19]. The MDAS has been validated in the UK [10,20,21] and a number of other countries with native translations: Finnish, Arabic, Hindi [20] Turkish [22,23], Norwegian [24], German, Portuguese and Rumanian [25]. A previous http://www.hqlo.com/content/6/1/22 report has demonstrated the validity of the Mandarin version of the short DAI [14], however the scale consists of 8 items and for clinical purposes, and inclusion in large epidemiological surveys, the shorter MDAS may be considered more suitable. The current study was motivated to develop the Chinese version of the MDAS that would be reliable and valid. Reliability was to be tested employing methods that reduce the number of assumptions used by traditional tests (explained below), and the scale's construct validity was checked by reference to the predicted relationships of the scale with a number o (...truncated)