Structural validity and reliability of the “Oral Health Assessment Tool” applied by speech-language therapists in a population of older Chilean people

Oral health is defined as the ability to speak, smile, smell, taste, touch, chew and swallow, as well as to transmit emotions through facial expressions with confidence, without pain, discomfort and/or craniofacial disorders [1]. It allows people to communicate and feed themselves effectively [2]. This construct is particularly important given its implication and close relationship with overall health [3]; for this reason, poor oral health (usually expressed by the presence of caries, periodontal diseases, oral pain or cancer) affects the self-perception of a person both in terms of self-esteem and self-confidence [4].

The progressive understanding of the consequences associated with this construct has given rise to the implementation of oral health promotion plans and programs at a local and international level. At the end of the twentieth century, modest reductions in the prevalence of dental caries were achieved in children [5, 6]; however, focus on older people is still incipient. Considering current demographic changes at a global level, promotion and prevention efforts vis-à-vis this latter group has become increasingly relevant. As people reach older age, their needs, including oral health issues, require continual attention. The aging process and associated changes affecting the population pose major challenges to maintain an optimal state of health throughout the lives of individuals and populations [5, 7]. In this context, several research efforts have sounded the alarm regarding the risks that poor oral health and mouth diseases have on general health, particularly in older people [3, 8, 9]. The literature describes a link between oral health and systemic diseases. For example, an association between the number of missing teeth with heart disease has been reported; periodontal disorders have been related to cardiovascular disease, atherosclerosis, subclinical lower artery disease, strokes, metabolic and lipid disorders and obesity [3, 10]. Additionally, pathologies such as diabetes and respiratory ailments can be related to poor oral health conditions [11]; Chalmers [10], reported that state of dental health, loss of teeth and temporomandibular disorders are associated with auditory impairment. These various relationships acquire greater relevance because older people seem prone to present oral health problems [12]. The data indicate that the elderly population tends to have poor oral health largely due to dental care deficiencies during their entire lifetime. Elderly people with some degree of dependence or limited autonomy tend to present worse oral conditions [13]. Therefore, the risk of developing these problems in older people with attention needs is high, particularly for those with severe dependence problems living in nursing homes or who are hospitalized. This risk is also related to social patterns in the older population, such as income level, knowledge regarding oral health care or access to health facilities [14], and therefore its prevalence varies depending on these variables. Although several studies have tried to look into and establish oral health intervention programs for older people, this is still described as insufficient or jeopardized [3, 14].

Although the detection of alterations or their oversight are carried out through clinical examinations performed by dentists, these methods are increasingly more difficult to use due to the high cost and scarcity of human resources, even in high-income countries [4, 15]. Therefore, alternative and less resource-demanding approaches are needed. In this context, it is important to mention the existence of self-report questionnaires, associated mainly with the oral health dimension in relation to quality of life. However, because it is based on the ability of a person to report any adverse dental symptom, it increases the risk of bias, especially in people with some kind of cognitive impairment [16]. Moreover, the majority of clinical instruments or oral health indices are designed to be used by dentists and dental hygienists, but they are not suitable for use by non-dental professionals [17, 18], even though, given their disciplinary similarity, speech-language therapists would be suitable for this purpose. Therefore, the availability of valid and reliable instruments enabling the evaluation of oral health through the observation of structures by trained professionals would be especially relevant.

In this sense, at an international level there are tools available to evaluate and detect oral health problems, such as the Oral Health Assessment developed by the World Health Organization (WHO) [19] in its version for adults; the Geriatric Oral Health Assessment Index (GOHAI) [20] specifically targeted at older people, and the Oral Health Impact Profile (OHIP) [5]. However, these last two measure the perception of individuals regarding their own oral health [21], with their respective limitations.

Conversely, reports in the literature point to the Oral Health Assessment Tool (OHAT) as an instrument that measures oral health intended as an interdisciplinary valuation of this condition. That is to say, its application by other professionals, specifically nurses and speech-language therapists has been signaled as feasible [17, 18], making it possible for this tool not to be linked solely to dentists. The OHAT consists of eight categories aimed at identifying oral health impairments as well as pinpointing the need for prevention actions or referrals for dental intervention, making it a useful instrument for the detection of possible disorders and their early management in elderly adults, whether or not dependent. On the basis of the original (Australian) instrument, validation studies of similar instruments have been conducted in Germany, Japan, Brazil, Indonesia, the Netherlands and Turkey [22‐27]. At present, the OHAT has not been translated or validated in the Spanish language in any country, including Chile.

Given the relevance and usefulness that this instrument represents for health policies and clinical approaches regarding oral health of the older adult population in different contexts, the objective of this study is to determine the structural validity and reliability of the OHAT instrument in the Chilean older adult population. We hypothesize the OHAT correctly adjust to a one-factor model, consistent with the “Disease and condition status” sub-dimension of the oral health framework proposed by the World Dental Federation (FDI), defined as the threshold of severity or level of progression of a possible oral health pathology, which also includes pain or discomfort [1]. Moreover, we hypothesize that the instrument has adequate internal consistency and test–retest reliability.

The translated and adapted Chilean version of the Oral Health Assessment Tool is presented initially as a tool that is easy to understand and apply. In general terms, the main goal was to achieve conceptual equivalence with the original instrument, safeguarding that any modification made of terms that were difficult to understand or not appropriate for implementation in the Chilean context in general, and more specifically in older adults, was as close as possible to the original meaning. Following this precept, the only concept that differed from the original text was the presence (or absence) of dentures marked with the name of the users, a usual practice in geriatric residences of other countries but currently not applicable to the Chilean reality. Thus, the general valuation of the instrument was not limited solely to the situation of institutionalized older people but to any evaluation context.

In terms of the validity of the instrument and as we hypothesized, the CFA of the OHAT confirmed the one-dimension solution. This is the first study that considered the structural validity of the instrument through confirmatory factor analysis. The factor loadings of the instrument were all greater or equal to 0.4 demonstrating adequate correlation between item and latent variable [39], as well as the previously reported model fit indices. In other validation research such as the Dutch study [23], the number of dimensions extracted did not concur with the dimension hypothesized in the model of the World Dental Federation (FDI) [1], but it is important to stress that the latent variables or constructs to be evaluated tend to differ from culture to culture and thus some variation is to be expected considering the modifications and contexts to which the instrument has been subject [29]. In addition, it is important to mention that these studies used the exploratory factor analysis procedure and that the sample size used was smaller than that recommended by the literature [29, 40].

As mentioned above, the OHAT measures a sub-dimension of oral health (disease and condition status). However, the concept of oral health is complex and multidimensional and not only involves identifying affected structures or functions but also the perceptions of the individuals themselves regarding their health status, or the context that favors or obstructs maintaining their health [1]. In this sense the OHAT is an instrument whose clinical usefulness lies in the observation of structures or consequences in oral functioning that increase risk or detect possible alterations that can lead to disease as a more objective measure than just self-perception or self-report. Consequently, the results obtained in the present research are sufficient to consider that the OHAT has structural validity.

In terms of internal consistency reliability, the reported ordinal Cronbach’s alpha and Mcdonald’s Omega coefficient were good (α = 0.82; ω = 0.87) for the entire one-dimension instrument, similar results than obtained by Kuwamura et al. [41] but differing from the values obtained by Mello et al. [26], who evaluated the internal consistency of the instrument applied by a group of nurses and dentists to 50 older people, obtaining alpha values considered to be low. In this respect, the following should be considered: first of all, it is important to note the definition of this measure, which is frequently considered to refer to the degree in which all elements of a test or instrument measure the same attribute or dimension [42]. In this sense, according to Bonett [43] and Charter [44], sample sizes of more than 250 subjects are required to obtain appropriate and precise values with this coefficient, both for determining the coefficient of the instrument and to validate any comparisons. In this study, the calculation of the coefficient was carried out in compliance with this condition.

In the same vein, another objective of the study was to determine the test–retest reliability or reproducibility of the instrument. This provides an indicator of the stability of the test measurements as a function of a specific interval between two evaluations taken in different time periods [45], which is also of clinical interest. In this study the intraclass correlation coefficient value was 0.81 (IC95% 0.74 – 0.87), considered to be good. Similar values were obtained in the original validation [17] of the OHAT and the English validation directed at evaluators who were speech-language therapists by profession [18].

Another limitation has to do with the process itself. International guidelines on the validation of instruments contemplate other types of validation that are useful when considering whether or not an instrument is valid (and also reliable) [46, 47]. In this sense, it would be useful to develop other studies that would make it possible to compare performance in terms of detecting the OHAT using a previously established criterion (such as, for example, the considered opinion or valuation of a professional dentist), its concurrent and discriminant validity, or likewise its predictive validity. From a methodological viewpoint, a prospective (cohort) study would be useful to test these hypotheses. Notwithstanding the above, previous systematic reviews have reported that for general geriatric assessment, screening or triage carried out by non-dentist professionals, the OHAT is suggested [48]. In this sense, one of the strengths of this research is that it contributes with antecedents regarding the construct to be assessed at the time of evaluation, adding to the existing evidence of content and criterion validity [48].

Although there is evidence available regarding the clinical usefulness of the OHAT in other contexts, especially in terms of its application by speech-language therapists and nurses, no certainty exists regarding the feasibility of its use by the latter professionals given that the training and application of this study was carried out solely by the former. It would be a mistake to assume that the formative processes or conceptual contents of nurses are identical to their similar counterparts in other countries or contexts. It is therefore considered relevant to undertake additional research efforts that will evaluate the feasibility of the use of the OHAT by these evaluators.

Similarly, given variable conditions for assessment, it is necessary to consider future validation studies contemplating more assessment contexts. Currently, the resources of tele-assessment or tele-care associated with the virtualization of oral health care are of interest and growing acceptability given the evidence of its benefits, especially in terms of promotion and prevention related to access to dental or oral health professionals (shortening distances, facilitating access to care) [49, 50], so, having an instrument such as the OHAT adapted for remote application could be an interesting projection regarding these new trends.

In light of the foregoing, it is considered that the Oral Health Assessment Tool has structural validity and possesses adequate properties of internal consistency and test–retest reliability for the population under study. Its orientation is initially clinical, aimed at favoring the detection of possible oral health problems in Chilean older people and referring them in a timely fashion to a professional dentist for their optimal care. The information provided could be useful also in possible actions of health promotion and disease prevention, not only directed at older adults but also their caretakers and treatment team, and could have an impact on indicators of oral health and particularly in the quality of life of older people. In turn, it is considered as an alternative or complement to the valuation of speech and language structures, and even the valuation of the swallowing process by the speech-language therapists, who could use the instrument in future lines of research to determine its contribution to the diagnostic or decision-making process regarding the treatment of swallowing disorders in the elderly.

Finally, it is important to undertake further studies of different types of validity and reliability in order to collect more information about the psychometric properties of the instrument and extend or project its usefulness into the future. By the same token, it is useful to stress that no instrument is definitive in terms of its psychometric properties, thus making it advisable to review and enrich the instrument over time in order to improve its characteristics.