Background
Schizophrenia is a severe mental disorder that affects 1% of the world population [
1,
2] and 600,000 people in France. Schizophrenic patients have excess mortality (their life expectancy is reduced by 20%) and excess morbidity [
3]. Among somatic comorbidities in schizophrenia patients, poor oral health has been reported by many authors and contributes to the overall poor health of these patients [
4,
5]. Generally, schizophrenia leads to disturbances in the progression of thought, errors in contextual analysis and errors of logic. Often patients with schizophrenia do not recognise their health needs and delay seeking advice or treatment [
6].
In dentistry, objective measures of dental diseases do not accurately reflect the patients’ perception of their oral health. Oral Health related Quality Of Life (OHrQOL) questionnaires are interesting tools that evaluate oral health from the patient’s perspective. They take into account the multidimensional aspects of health and consider the functional and psychosocial impacts of dental diseases [
7].
In the general population, these OHrQOL scales are used to assess a patient’s condition or a change in oral status during the course of care, and integrate the perceptions and expectations of the patient. A variety of OHrQOl instruments have been developed. For example, the General Oral Health Assessment Index Questionnaire (GOHAI) developed by Atchison and Dolan [
8] has been widely used to assess oral health in clinical or epidemiological studies. Validated initially in the USA, this questionnaire is available in French [
9]. The GOHAI assesses self-perceived oral health through 12 questions that explore the pain, discomfort, dysfunctions and the psychosocial impacts of dental diseases [
10]. It can be self-administered and is quick and easy to use.
The Oral Health Impact Profile-14 (OHIP-14) is also widely used [
11]. However, the GOHAI identified more oral functional and psychosocial impacts than did the OHIP-14 [
12]. With the OHIP-14 it is more difficult to detect within-subject change [
13]. Finally, OHIP-14 is not available in French.
International studies have reported that the oral health status of mentally ill patients was poor compared with that in the normal population [
14,
15]. They pay less attention to the presence of conditions such as dental caries and periodontal disease [
16]. If left untreated, these conditions can lead to partial or total tooth loss (edentulism), thus compromising nutrition and general physical health. These patients diagnosed with serious mental illness also tend to report perceptions of poor oral health and express important care needs [
17,
18]. The Quality-of-Life Scale (QLS) [
19] and the Schizophrenia quality of life Scale (S- QOL) [
20] have been validated for use in schizophrenic patients, but these tools do not measure OHrQOL. Yet more specific assessments of oral health by caregivers and better management of dental care needs are essential. The implementation of adequate medical or dental care is delayed to the detriment of patients’ health. It is therefore important for caregivers to have access to validated tools to assess the oral health of these patients in order to evaluate accurately their specific needs and to offer appropriate support.
As far as we know, no study has investigated the validity of existing OHrQOL questionnaires in schizophrenic patients.
The aim of this study was to evaluate the psychometric characteristics of the GOHAI scale in a representative sample of patients with schizophrenia.
Discussion
The objective of this study was to evaluate the psychometric characteristics of the GOHAI scale in a French representative sample (Côte d’Or) of patients with schizophrenia.
The GOHAI is widely used in clinical or epidemiological studies worldwide, as it is available for use in different languages [
41]. Nevertheless, the reliability or validity of the existing versions might vary due to cultural, medical or linguistic characteristics of the study population [
42].
In our study, the reliability was confirmed (α = 0.82). Cronbach’s α was slightly lower than that found in a French general population (α = 0.87) but was within the range (0.74-0.87) observed in other validation studies [
8,
9,
41‐
44]. When three questions (X3, X5, X7) were removed, Cronbach’s α increased to 0.87. A rewording of these questions should be considered as in the Chinese version of the GOHAI, where question X3 was reformulated negatively to improve understanding [
43]. In schizophrenic patients, the use of questions worded positively and negatively (X3, X5) and the concept evoked in question X7 may have been particularly misunderstood.
Most participants were unable to clearly distinguish between ‘Always’ and ‘Very often’,‘Seldom’ and ‘Never’. A simple 3-point likert scale was used as cited by Atchison [
45], where the English equivalents of ‘Always’, ‘Very Often’ and ‘Often’ were clubbed together as ‘Always’; ‘Seldom’ and ‘Never’ were clubbed into ‘Never’, thereby giving ‘Always’, ‘Sometimes’ and ‘Never’ as the three options. The resulting mean GOHAI score of their study, according to the new scoring system, was higher than the current study [
45,
46]. The 3-point system should be explored with schizophrenic persons for better understanding.
The predictive and concurrent validity of the GOHAI were confirmed. The GOHAI score was significantly higher for younger patients. In some other studies, no significant relationship was found between age and the GOHAI score [
9,
44]. This can be explained either by age groups that were too narrow [
47] or by an adaptation to poor oral health among older people [
48]. Another potential reason for this difference may be that the relationship between oral health and age may be different in persons with schizophrenia than in the general population.
For the known-groups validity, there were no significant differences between the mean GOHAI score for out- or in-patients in our sample. The perception of OHrQOL was found to be dependent on the particular psychiatric diagnosis (bi-polar disease, mood disorders or schizophrenia) [
49]. The extent of dental disease was directly associated with the severity of the positive and negative symptoms in patients with severe mental illness (SMI) [
50‐
54]. However, schizophrenia is a complex disease which presents distinctive clinical features that distinguish it from bipolar disease or mood disorders. The treatment can vary in intensity and diversity depending on the stage of the disease, its duration and its severity, and on the patients’ social characteristics and environment [
55,
56].
In our representative sample of schizophrenic persons, the difference in perception of OHrQOl did not differ between out- or in-patients.
Therefore, this known-groups validity needs to be confirmed or invalidated in future studies.
While only one factor emerged in factor analysis in the original English GOHAI version [
8], three factors emerged with schizophenic persons when using the principal components with eigenvalues greater than one. In Swedish [
57] and Chinese [
43] version the factor analysis also revealed three factors. The reason for this may be that the complexity of the OHrQol is refleted in the separate items of GOHAI. It possible means that the participants do not differentiate among psychological, functional, or behavioral impacts and that the perception of the oral health is a global concept.
Our results showed no significant relationship between the duration of mental illness, smoking habits, dental attendance and the GOHAI score. However, the duration of hospitalization (a sign of severe symptoms) or smoking seemed to be associated with poor dental status in patients with schizophrenia [
15,
16]. Moreover, the presence of severe symptoms is associated with poor dental health, indicating a late use of dental care [
41]. It would thus be necessary to explore more thoroughly these relationships in further research using GOHAI scores or other measures of quality of life in schizophrenic patients.
The literature contains examples of high [
8,
43] and low correlations [
13] between GOHAI scores and clinical observations, except for the number of decayed teeth, which is closely related to OHrQOL scores. Furthermore, the level of education or the place of residence often correlates with GOHAI scores [
8,
43,
58], but for schizophrenic patients, we found no significant differences. In our study, several clinical measurements were related to the GOHAI score, indicating that the perception of the patients about their oral health was clearly associated with their objective dental status.
In this study, schizophrenic patients seemed to be less satisfied with the condition of their teeth and to experience a higher impact of their dental health than did the French general population [
9]. These differences can be explained by a worse dental status (namely a higher number of untreated carious lesions) [
30] and a poor oral hygiene as compared with the general population. 50% of patients with schizophrenia never brush their teeth (36% in our sample) while 60% of the control groups brush their teeth once or twice daily [
59]. Another study showed less frequent tooth brushing was associated with a greater DMFT, less frequent tooth brushing was negatively related with dental condition in patients with schizophrenia [
60].
Conversely, compared to the literature, schizophrenic patients described fewer symptoms, such as sensitivity, compared with the general population [
9]. The confusion brought on by mental illness means, for those who are most perturbed by the disease in particular, that the patient does not have a good perception of his or her needs or of pain and can thus postpone dental consultations and seeking treatment [
6]. Dry mouth was the chief complaint among 40% of the psychiatric patients while dental pain was the main complaint among 60% of the control group [
59]. The negligence in self-care of schizophrenic patient seems to be more influenced by symptoms such as lack of concern with personal health, lack of motivation and apathy [
61]. However, in the schizophrenic population, the GOHAI scale is able to express the patients’ perception and subjective evaluation of OHrQOl.
Even though the majority of patients with schizophrenia do not have severe or persistent symptoms all the time or severe side effects of medication, further studies are needed to better understand their perception of OHrQOL. To this end, the relationship with clinical manifestations of the side effects of antipsychotics, like drooling, trismus, facial muscle pain, myasthenia or dyskinesia (tremors), must be investigated in future studies [
62,
63]. Moreover, the impact of the deterioration or rehabilitation of the dental status on self-esteem or on stigma and on social functioning could be evaluated according to modifications of perceived oral health.
A few limitations of the present study must be noticed. First, only 34% of the patients contacted were included. This is a potential selection bias. It was difficult to include schizophrenic persons in the study. Some potential subjects were unable to cooperate due to their psychiatric illness, some were lost to follow-up, others were excluded for diagnostic error (not schizophrenia), and some had died. Furthermore, we can suppose that patients who do not agree to participate in these studies are likely to be unwilling to have a dental check-up because of their poor oral health.
Second, the test-retest reliability was performed with a consecutive rather than random sample.
Third, all of the investigations were conducted by only one investigator.
Fourth, our results are representative of the Côte d’Or department, and the relatively small number of participants limits the robustness of the results. These findings need to be replicated in larger groups of schizophrenic persons.
Therefore, a potential variety bias in our sample cannot be completely excluded.
Acknowledgements
The authors thank the staff and patients of all the hospitals (La Chartreuse Psychiatric Centre, University Hospital of Dijon and Semur and Auxois Hospitals) that participated in the survey. We thank Nicolas Abello for assistance in writing the manuscript and Philip Bastable for his help with English language correction. We are grateful to the Regional Health Agency of Burgundy (Agence Régionale de Santé de Bourgogne) and the University Hospital of Dijon for the financial support given to the study.