Translation and psychometric evaluation of the dental patient questionnaire (DPQ)

Abstract

BACKGROUND:

Dental patient feedback can elicit concerns about practitioners’ interpersonal skills, such as putting the patient at ease and communicating in a way that the patient understands the nature of the treatment plan offered. Several scales exist to determine the dental practice quality, such as the dental patient questionnaire (DPQ). This scale can detect the specialized relationship between patient and dentist, such as trust, satisfaction, and patient services. The current study was conducted to translate and psychometrically assess DPQ to be employed for the Iranian patients referring to dental clinics.

MATERIALS AND METHODS:

This cross-sectional study was conducted on patients referring to the dentistry offices in Tehran in 2022. After translation and back translation of the original version of the patient-centered care questionnaire, exploratory and confirmatory factor analyses were performed to measure the validity and reliability of the instrument. Validity consisted of face, content, and construct validity, and reliability was calculated by Cronbach’s alpha coefficient and intraclass correlation coefficient. Data analysis was performed in Statistical Package for the Social Sciences version 22 (SPSS, Inc., Chicago, IL, USA) and EQS (version 6.1).

RESULTS:

In this study, 228 respondents were recruited. The content validity results revealed that all items obtained the acceptable required content validity index and content validity ratio scores, and all 23 items were retained and used for later analysis. The Kaiser–Meyer–Olkin index was calculated as 0.913. Measurement of the questionnaire validity by exploratory factor analysis (EFA) revealed three factors (trust, satisfaction, and service) with eigenvalues of >1. The confirmatory factor analysis model were confirmed. The model fit indices were in a good or at least an acceptable level in terms of all goodness of fit indexes. The reliability of the scale was confirmed with a Cronbach’s alpha coefficient >0.6 for all factors and an intra-cluster correlation of 0.7.

CONCLUSION:

The results of the study showed that the Persian version of DPQ had appropriate validity, reliability, and psychometric properties. This tool can be used to measure trust, satisfaction, and quality of service of the patients referring to the dental offices in Iran.

Background

The importance of patient-centered care (PCC) is growing for measuring the performance of dental practices for personal development of practitioners. Use of patient feedback can play an important part for the regulation of dentistry and the standards assumed to be in place in dental practices.[1] In addition, patient feedback can elicit concerns about practitioners’ interpersonal skills, such as putting the patient at ease and communicating in a way that the patient understands the nature of the treatment plan offered.[2] Several ways are recommended for determining dental practice quality, such as the dental patient questionnaire (DPQ).[3] This scale can detect professional relationships between patient and dentist, such as trust, satisfaction, and patient services.

Trust in medical services can be defined based on the patient’s optimistic acceptance of his/her vulnerable health status and the belief in the properness of the health-care services provided by the medical team.[4] Trust is considered as a great social capital[5] and a key component of interpersonal interaction in health-care provider–patient relationship[6] that can affect the outcomes of health-care services.[7] It is clear that the trust between medical service providers and patients is not only dependent on their relationship, but also on factors related to health-care institutions, professional, legal, and political factors, as well as the payment methods of medical care costs.[8] Dentist–patient interactions during a consultation, including cognitive and emotional aspects, have been demonstrated to affect patient compliance with clinical advice and follow-up visits.[9] Despite the paramount importance of the examination of patients’ trust in health-care services, few studies have investigated this issue; there is a wide scientific gap in this domain, especially in dentistry.[10,11] Different tools have been developed to measure patients’ trust in health-care providers. These measures have been translated into different languages and subjected to psychometric assessment across the world.[12,13]

Studies have shown that good communication skills of a clinician can improve patient’s compliance and overall satisfaction. Patients’ satisfaction simultaneously increases with the enhancement of their trust in medical staff.[14,15] Satisfaction in terms of quality relates to what is generally termed “bed-side manner” of the service provider or providers.[16]

Patient satisfaction with dental care is an important aspect of the quality of care[17] and will influence the future utilization of the service. The satisfied patients lead to repeated business, as well as recommendations to family and friends.[3] Therefore, satisfaction evaluation is an essential element in assessing the quality of care. A major issue for careful monitoring of consumer satisfaction is recognition of the complex relationship between patients’ views of the health-care system and their health and illness behavior.[18] While in medical care there are many methods for measurement of satisfaction, only a few dental satisfaction questionnaires have been reported in the literature.[9] A study evaluated dental patients and focused on three aspects of satisfaction: the context of the visit, the content of the visit, and the outcomes of the visit. Later, two additional aspects were surveyed: cost of dental care and satisfaction with facilities.[19] Increasing patient satisfaction requires high quality of health-care services.

Although some patients do not generally utilize health-care services and are likely to only be seen in a dental office for emergency situations, dental service is a dynamic process between the provider and the recipient, with the goal of improving health.[20] From this perspective, service quality can be defined as the difference between patients’ expectations before the service encounter and their perceptions of the service received.[21] Dental practices traditionally exert a great deal of effort to control the quality of the service outcomes provided to their clients, but devote less attention to patients’ expectations for the entire service delivery process.[22] However, from a services marketing perspective, a patient-centered approach is critical to the delivery of a high-quality dental service.[21] The more important issue is what is best for the patients served by the dental profession.[22] If a patient is to be adequately served, then he or she must have a voice in the process of care.[9] All professions, and especially the health-care professions, are in a constant state of self-assessment aimed at advancing their disciplines in a consistent and measurable fashion.[23] For the health-care professions, the goals are to improve patient health, increase efficiency in the health-care system, and ultimately enhance society as a whole. Although the dental profession is now faced with many challenges and questions, these goals are expressly true for the dental profession.[24] Dental practice is now faced with the introduction of new technologies that will change the delivery of dental care services.[22] The introduction of new technologies and procedures has equipped the profession with more effective and efficient approaches to solving clinical problems and also a concomitant increase in the cost of services.[22]

There is now a growing trend for patient feedback and satisfaction surveys to be conducted in a manner that allows standardization of data collection to ensure that core aspects of PCC are addressed.[25] Surveys conducted by questionnaires are rapidly becoming the dominant method for measuring PCC. The questionnaire must contain core items that can form part of standardization to allow comparison of patient experience across different health-care centers.[26] The questionnaire needs to be demonstrably reliable and valid according to statistical techniques, so that public dissemination of the results can be undertaken with confidence.[3] Accreditation is effective as part of an improvement system because it can verify that actions are being taken, system data and information are being used to inform the analysis of issues and program solutions, and safety and quality improvement are being achieved.[27] Since there is no Persian translated version of DPQ, this study was performed to translate and psychometrically assess the DPQ to be employed for the Iranian patients referring to dental clinic. The initial development of DPQ was based on a tool being implemented across dental practices in the UK. The questionnaire is focused on obtaining information primarily in three core areas: access, interpersonal skills and communication of information, and services provided by the dental practice. DPQ is valid and reliable, and has been shown to be “fit for purpose” in its evaluation. It is a useful tool for supporting dental practices in the practice accreditation scheme.[3] However, to the best of our knowledge, there is no Persian translated version of DPQ that can measure patients’ trust, satisfaction, and service in dental offices yet. The current study was conducted to translate and psychometrically assess the DPQ to be employed for the Iranian patients referring to dental clinic.

Materials and Methods

Study design and setting

This cross-sectional study was conducted among dental patients who referred to three private dental clinics in the west and north of Tehran, Iran, using a consecutive sampling method. Sample enrollment was started on June 20, 2022 and continued till September 2022.

Study participants and sampling

The clinical procedures included general dental treatments and also specialized orthodontic and endodontic treatments. Questionnaires were completed in a private room while patients were waiting for dental services. Each questionnaire was accompanied by a sealable envelope, so patient confidentiality and anonymity were maintained. Exclusion criterion was intellectual and/or physical inability to answer the questionnaire. The sample size was calculated based on the number of DPQ items; in this regard, 10 respondents were selected per item. Therefore, since the questionnaire includes 23 items, the sample size was determined as 230 participants.[28]

Data collection tools and techniques

DPQ includes 23 performance evaluation questions.[3] The first 20 questions use a 5-point Likert scale and the final three questions use three categories: “Yes,” “No,” and “Not applicable.” The Likert scale values are evaluative: 1 = poor, 2 = fair, 3 = good, 4 = very good, 5 = excellent. Finally, there are four questions asking for supplementary information concerning the rater: age (three categories), gender (two categories), whether the visit was to the usual dentist (two categories), and how many years the rater had attended the practice (three categories). The 23 performance evaluation questions are divided into three sections:

• Seven questions about access to the practice (Q1–Q7, Likert);

• 13 questions about the interpersonal and communication skills of the dentist (Q8–Q20, Likert); and

• Three questions about the services provided by the practice (Q21–Q23, categorical).

The four supplementary questions adopt the following categories:

Q24: How old are you in years? 1 = Under 25; 2 = 25–59; 3 = 60+

Q25: Are you: 1 = Female; 2 = Male?

Q26: Was this a visit with your usual dentist? 1 = Yes; 2 = No

Q27: How many years have you been attending this practice? 1 = Less than 5 years; 2 = 5–10 years; 3 = More than 10 years

After evaluating the questionnaire and acquiring permission from the Client Focused Evaluations Programme (CFEP) Surveys[29] as the copyright holder of DPQ, the original English version of the questionnaire was subjected to translation by two individuals having a good command of English and Persian using forward and backward translations. Then, the translations were compared; in this regard, the items were examined in terms of meaning and concept, and the best options were selected to develop a Persian questionnaire.

Statistical analysis

Face validity: To examine quantitative face validity, the opinions regarding the importance of each item in measuring the issue under investigation were collected in the form of a 5-point Likert scale (i.e. very important, somewhat important, moderately important, of little importance, and not important at all). Subsequently, the impact factor was calculated for each item; an impact score above 1.5 means that the item was suitable for later analysis and was retained in the questionnaire.

Content validity: To examine the content validity of the questionnaire, the opinions of 10 professors and experts in dental fields regarding each item were obtained in a written form. Content validity index (CVI) was calculated based on clarity, simplicity, and relatedness. CVI was developed by Waltz and Bassel. After calculating CVI by summing up the scores of each item, the items with CVIs greater than 0.78 were regarded as appropriate and were consequently accepted.[30] Furthermore, the content validity ratio (CVR) was calculated based on three parts of necessary, useful but not necessary, and unnecessary. The minimum acceptable CVR for the Lawshe table was calculated as 0.75.[30,31]

Construct validity: Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were run in two steps for evaluation of construct validity. In EFA, the validity of DPQ was evaluated to extract the latent factors. EFA involved estimation of the eigenvalues of all items. In this regard, if an eigenvalue was higher than 1, it was retained in the questionnaire. The extraction of the factors was accomplished using maximum likelihood estimation. Given the lack of a significant correlation between the factors, varimax rotation was used. Sampling adequacy was calculated using Kaiser–Meyer–Olkin (KMO) and Bartlett’s tests. Correlation between one item and related factor is indicated through factor loading. A factor loading of 0.3 is conventionally indicative of a weak relationship between the factor and the item. It is better to remove such an item because it cannot well clarify the variable. A factor loading of 0.3–0.6 is acceptable, while a factor loading of >0.6 is considered desirable.[32]

CFA was used to determine the construct validity of the instrument. To examine the construct validity, the average variance extracted (AVE) and the maximum shared squared variance were employed. In addition, to examine the fit index of the questionnaire final model, goodness of fit test on χ²/degree of freedom, parsimony normed fit index, goodness of fit index (GFI), adjusted goodness of fit index, parsimony goodness of fit index, incremental fit index, relative fit index, root mean square error of approximation, and normed fit index were calculated.

Reliability: The reliability of the instrument was measured using Cronbach’s alpha coefficient for the whole questionnaire and each factor separately.[33] Determination of test–retest reliability (time stability) was performed within an interval of 2 weeks to 1 month. In the current study, the questionnaires were handed to the women in an interval of 1 month to calculate intraclass correlation coefficient (ICC). If the ICC is higher than 0.8, the questionnaire is considered to have an appropriate reliability.[34] Data analysis was performed in Statistical Package for the Social Sciences version 22 (SPSS, Inc., Chicago, IL, USA) and EQS (version 6.1).

Ethical consideration

Approval from the Ethics Committee by Shahid Beheshti University of Medical Sciences was obtained before conducting the study (ethical code: IR.SBMU.DRC.REC.1401.003). Participants were informed about the study objectives and ensured about the confidentiality of their information. In addition, written informed consent was obtained from all subjects.

Results

In this study, 228 respondents were recruited. Age of 50% of the participants was 25–59 years, and the majority of participants (68%) were females.

All the items received an impact factor above 1.5, so the face validity of the questionnaire was approved. The content validity results revealed that all items obtained the acceptable CVI and CVR score, and all 23 items were retained and used for later analysis [Table 1]. The KMO index was calculated as 0.913 regarding the sample size, which was within the favorable level, and the results of Bartlett’s test were statistically significant (P < 0.001). In explanatory factor analysis, initially, the number of factors was determined to be 4 using Eigenvalues greater than 1. In the next step, the items were analyzed by the method of maximum likelihood and varimax rotation. Finally, three factors were found to be appropriate based on the following: (a) each factor was required to correspond to at least three items, (b) each item was highly correlated (>0.5), and (c) each factor explained at least 5% of the total variance. The scree plot confirms the three-factor solution for the questionnaire [Figure 1].

Table 1.

Factor loadings of the extracted factors in the exploratory factor analysis and content analysis of the questionnaire including CVI and CVR

Factor loadings								Content validity
		Factor 1a		Factor 2b		Factor 3c		CVI		CVR
q1 Contact		0.120		0.744		0.133		0.91		0.87
q2 Making appointment		0.229		0.781		0.084		0.93		0.99
q3 Duration of wait		0.216		0.732		0.096		0.98		0.88
q4 Emergency appointment		0.081		0.556		0.131		0.94		0.89
q5 Reception staff		0.320		0.654		0.322		0.90		0.89
q6 Waiting area		0.038		0.615		0.031		0.99		0.89
q7 Satisfaction from appointment process		0.286		0.736		0.296		0.98		0.86
q8 Satisfaction from visit		0.498		0.667		0.272		0.80		0.81
q9 Dentists greeting		0.790		0.252		0.206		0.91		0.85
q10 Dentists listening		0.748		0.234		0.064		0.88		0.92
q11 Dentist’s explanation		0.724		0.355		0.261		0.82		0.83
q12 Patient’s concern		0.686		0.247		0.113		0.89		0.90
q13 Involvement in treatment options		0.698		0.180		0.085		0.87		0.76
q14 Sensitivity of dentists		0.788		0.224		0.600		0.81		0.79
q15 Respect of dentists		0.758		0.006		0.370		0.83		0.88
q16 Patient’s confidence		0.580		0.152		0.325		0.86		0.78
q17 Health information		0.620		0.237		0.446		0.84		0.90
q18 Confidentiality		0.669		0.143		0.416		0.79		0.82
q19 Dentist/staff communication		0.361		0.099		0.649		0.92		0.87
q20 Patient’s recommendation		0.225		0.169		0.589		0.88		0.90
q21 Emergency treatmentd		0.189		0.022		0.312		0.85		0.83
q22 Cost		0.220		0.163		0.690		0.80		0.84
q23 Overall satisfaction		0.066		0.099		0.778		0.79		0.98
Eigenvalue		9.034		2.069		1.773		-		-
Impact score		0.701		0.160		0.138		-		-
Explained variance		26.30		19.38		10.30		-		-
Extraction method: principal component analysis; rotation method: varimax with Kaiser normalization. Total explained variance=55.98%.

^aPatient service (eight items). ^bTrust (10 items). ^cSatisfaction (four items). ^dThis question was deleted from statistical analysis. CVI=content validity index, CVR=content validity ratio

Figure 1.

Scree plot of eigenvalue from exploratory factor analysis

As indicated in Table 1 (which presents the results of EFA), factor loadings were above 0.5 for all items except one question (q21), which was omitted from CFA. The three factors were related to patient service, trust, and satisfaction, each of which entailed eight, 10, and four items, respectively.

Figure 2 displays the CFA model, in which the factors extracted from EFA were confirmed. Standardized factor loadings (T-values) for the structural equation model are shown in Figure 3.

Figure 2.

A confirmatory factor model for dental patient questionnaire with standard factor loadings

Figure 3.

Loading of T-values for dental patient questionnaire

Table 2 shows the indices related to the goodness of fit. The results revealed that the model fit indices were in a good or at least an acceptable level in terms of all GFI. After assuring the fitness of the model, the results indicated that the construct reliability (CR) of the instrument was higher than 0.7 [Table 3]. Furthermore, all standard factor loadings were greater than 0.5 and therefore significant (P < 0.05). Consequently, the presence of all items in each construct was confirmed. In addition, given that the AVE value was higher than 0.5 and the CR value was greater than AVE, it could be concluded that the convergent validity conditions were satisfied.

Table 2.

Goodness of fit indices for confirmatory factor analysis

GFI		Index range for acceptable fitness		Index range for good fitness		Observed GFI		Result
χ2 (DF)		-				421.44 (206)		-
P of χ2 testa		>0.05				<0.05		-
χ2/DF		<3.0		Closer to 0		2.05		Good fitness
RMSEA		<0.08		<0.05		0.070		Good fitness
SRMR		<0.10		<0.08		0.081		Good fitness
CFI		>0.90		>0.95		0.98		Good fitness
PNFI		>0.50		>0.50		0.86		Good fitness
GFI		>0.90		>0.95		0.98		Good fitness
AGFI		>0.90		>0.95		0.98		Good fitness

^aP-value of Chi-square test depends on the sample size, and it is a weak index for evaluation of model fitness. AGFI=adjusted goodness of fit index, CFI=comparative fit index, DF=degree of freedom, GFI=goodness of fit index, PNFI=parsimony normed fit index, RMSEA=root mean square error of approximation, SRMR=standardized root mean square residual

Table 3.

Reliability and validity of DPQ constructs

Factor		Mean±SD		Alpha		ICC (95% CI)		SEM		CR		AVE		MSV
Patient services		24.35±5.57		0.87		0.72 (0.27–0.89)		2.00		0.90		0.54		0.66
Trust		35.14±5.50		0.91		0.75 (0.41–0.90)		1.65		0.95		0.67		0.59
Satisfaction		11.03±1.61		0.68		0.82 (0.55–0.93)		0.91		0.87		0.55		0.66
Total		70.51±10.83		0.92		0.75 (0.39–0.90)		3.00		0.97		0.60		-

alpha: Cronbach’s alpha. AVE=average variance extracted, CI=confidence interval, CR=composite reliability, DPQ=dental patient questionnaire, ICC=intraclass correlation coefficient, MSV=maximum shared squared variance, SD=standard deviation, SEM=standard error of measurement

Cronbach’s alpha for all factors was greater than 0.6 and indicates an acceptable level of reliability. ICC (internal consistency of the constructs) was greater than 0.7 for all factors, which is indicative of a high consensus among the respondents.

Discussion

Attention to the three skill areas obtained in the current study can be considered a big step toward the enhancement of dental PCC. The overall aim of this investigation was to evaluate the psychometric properties of the Persian version of DPQ. Evidence was found to support a three-factor structure for the Persian DPQ. Our developed Persian version consisted of three factors related to different skill areas, including service (n = 8), trust (n = 10), and satisfaction (n = 4). Some patients may have difficulty in evaluating the technical quality of the dental service they had received and would base their judgment on other factors, such as physical and environmental settings and also the ability to solve problems.[35] One study found that dentists who have previously worked with or currently employ expanded function dental hygienists or assistants in their practices view them more positively and are more likely to delegate procedures to these providers. In addition, they have more positive views of dental therapists and believe they have the potential to increase access to care. Effective use of expanded function allied dental personnel has the potential to expand the capacity of general dental practices to treat more patients, yet these providers are underutilized.[36]

In this study, some items, such as making appointments, duration of wait to visit, and waiting environment, were categorized as service factors. Dental service is always fully booked, and the usual waiting time to get an appointment for treatment depends on each patient’s case and on the dentists’ schedule for their clinics. However, patients with acute problems can make an emergency appointment and are seen on the same day.[9] In one research, the problems identified in this audit were addressed and strategies formulated to improve the waiting time were carried out, including increasing the number of staff at the registration counter, enforcing staggered appointment system for follow-up of patients, and improving the queuing system.[37]

In this study, the individual skills of the dentist, such as greeting, listening, respecting, and speaking, were categorized as satisfaction factors. Results of another study showed that dentist–patient interaction was influenced by the characteristics of the dentists.[38]

In this study, some items, such as patient concern and confidence with information about treatment options, were categorized as satisfaction factors. Providing the patient with further explanation of their treatment options is necessary to achieve a high level of satisfaction with the service provided.[9] One of the “challenges” faced by researchers in DPQ is the continual high levels of satisfaction reported, especially in the dental domain,[17] with patients being genuinely happy with their dental practices, not feeling confident about their ability to evaluate, and unwillingness to criticize cited as possible reasons. Some studies have shown a relationship between patient satisfaction with ethnicity and education levels.[9,39,40,41] Patients who visited the dentist only when having a problem tended to be more satisfied than those who visited the dentist regularly. This may be because those patients with problems get immediate relief after treatment compared to those who come for a check-up only.[9]

In this study patient, recommendation was categorized as a trust factor. High levels of trust have been associated with many benefits, including a perception of better care, greater acceptance, and treatment recommendation.[42] Financial issues can have a huge impact on patient trust,[43] and in this study, the cost of dental care was categorized as a trust factor. In addition, financial management is a skill that is used at all levels of health-care services to choose the therapeutic options.[11] Tuominen and Tuominen[44] declared that for a considerable number of patients, the ultimate goal of the treatment is “the cure” and the rest of the items in the process contributing to this curing appear to be disregarded by these patients. Thus, they prefer to see the end result to express their satisfaction, ignoring the efforts of oral diagnosticians and radiologists, and any other dental personnel along the way.[44] Douglas et al.[45] reported that the patients responded more positively to female dentists than to male dentists, even when they assumed noninteractive behavior.[45] Two issues cited by patients as most important in evaluating dental care were the dentist’s awareness of discomfort and explanation of treatment.[46]

Based on the results of studies, it can be concluded that factors such as satisfaction and trust are very important and intertwined items that can determine the quality of service of a dental office. With regard to the skill areas obtained in the current study, it can be concluded that the empowerment of dentists is important not only in the professional skill area, but also in the improvement of coordination and financial management skills. To this end, the universities of medical sciences and Ministry of Health and Care Services should implement specialized training and retraining programs. Moreover, it is recommended that dentists use psychometric instruments in the local language, such as the DPQ in their offices, and find useful solutions to eliminate the problems ahead.

One of the limitations of the present study is that the scale study has not been used in the countries other than the research community of the original developer. Consequently, it was not possible to find similar studies to compare the psychometric results of the scale in different communities. The other limitation of the study is that its results cannot be generalized to other settings due to the limitations of the study location. Therefore, it is required to investigate more varied environments using a higher confidence level and a larger sample size.

Conclusion

The results of the study showed that the Persian version of DPQ, which had appropriate validity and reliability, was an appropriate, suitable psychometric properties tool to measure the trust, satisfaction, and quality of service of the patients referring to the dental offices in Iran.

List of abbreviations

• PCC: patient-centered care

• DPQ: dental patient questionnaire

• KMO: Kaiser–Meyer–Olkin

• ICC: intraclass correlation coefficient

• CVI: content validity index

• CVR: content validity ratio

• EFA: exploratory factor analysis

• CFA: Confirmatory factor analysis

• AVE: average variance extracted

• CR: construct reliability

• MSV: maximum shared squared variance

• DF: degree of freedom

• PNFI: parsimony normed fit index

• GFI: goodness of fit index

• IFI: incremental fit index

• RMSEA: root mean square error of approximation

• NFI: normed fit index.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.