Participation in Treatment Decision-Making Scale for Adults with Malocclusion

1. Abstract

The Participation in Treatment Decision-Making Scale for Adults with Malocclusion (PTDMS-AM) is a specialized, multidimensional psychometric instrument developed to assess and quantify the degree to which adult patients actively engage in collaborative clinical decision-making regarding orthodontic and orthognathic interventions. Corrective treatment for adult malocclusion frequently involves high-stakes, preference-sensitive, and irreversible clinical interventions, including surgical-orthodontic combinations, long-term appliance therapy, and significant financial and psychological commitments. Because clinical trajectories carry varying degrees of aesthetic, functional, and psychological uncertainty, active patient engagement is critical to mitigating decisional conflict, post-intervention regret, and therapeutic non-adherence. Developed and psychometrically validated within a tertiary stomatological healthcare setting in China, the PTDMS-AM operationalizes patient involvement beyond unidimensional satisfaction metrics by establishing a triadic factor structure comprising cognitive participation, behavioral participation, and emotional participation.

The scale consists of 21 items scored on a 5-point Likert scale ranging from 1 (Strongly Disagree) to 5 (Strongly Agree), yielding a total score between 21 and 105, with Item 31 being reverse-scored. Psychometric evaluation across two independent clinical samples demonstrated exceptional internal consistency, evidenced by an overall Cronbach’s alpha of α = 0.953 and subscale alphas ranging from 0.860 to 0.909, alongside a split-half reliability of 0.957 and a test-retest reliability coefficient of r = 0.885 over a two-week interval. Content validity was substantiated by an expert panel Scale-Level Content Validity Index (S-CVI) of 0.926. Exploratory factor analysis (EFA) demonstrated an unambiguous three-factor latent structure accounting for 60.98% of the total variance, supported by a Kaiser-Meyer-Olkin (KMO) index of 0.974. Subsequent confirmatory factor analysis (CFA) verified structural adequacy with robust goodness-of-fit parameters, including a Comparative Fit Index (CFI) of 0.968, a Tucker-Lewis Index (TLI) of 0.964, and a Root Mean Square Error of Approximation (RMSEA) of 0.015. Concurrent criterion-related validity was confirmed via moderate-to-strong correlations with the 9-item Shared Decision-Making Questionnaire (SDM-Q-9; r = 0.590–0.650). The PTDMS-AM provides researchers, clinical psychologists, and maxillofacial teams with a robust diagnostic and evaluative tool for fostering patient-centered care and optimizing patient-provider alliance.

2. Keywords

Shared Decision-Making, Malocclusion, Patient Participation, Orthodontics, Orthognathic Surgery, Psychometrics, Scale Development, Health Psychology, Behavioral Medicine, Patient-Centered Care, Decisional Conflict, Tripartite Model

3. Authors

The Participation in Treatment Decision-Making Scale for Adults with Malocclusion was developed and validated by an interdisciplinary team of clinical researchers in nursing science and cranio-maxillofacial surgery at Shanghai Jiao Tong University School of Medicine:

• Xiangying Hu, RN, MSN — Department of Nursing, Shanghai Ninth People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
• Bixia Wang, MD — Department of Oral & Cranio-maxillofacial Surgery, Shanghai Ninth People’s Hospital, College of Stomatology, National Center for Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
• Ting Pan, MD — Department of Oral & Cranio-maxillofacial Surgery, Shanghai Ninth People’s Hospital, College of Stomatology, National Center for Stomatology, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
• Weijun Yuan, RN, MSN (Corresponding Author) — Department of Nursing, Shanghai Ninth People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. Email: [email protected].
• Lili Hou, RN, PhD (Corresponding Author) — Department of Nursing, Shanghai Ninth People’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. Email: [email protected].

4. Purpose

The primary purpose of the Participation in Treatment Decision-Making Scale for Adults with Malocclusion (PTDMS-AM) is to systematically measure, evaluate, and interpret the active involvement of adult patients presenting with dentofacial disharmony and malocclusion during the formulation of their clinical treatment regimens. In modern dental medicine, health psychology, and behavioral science, patient-provider communication has evolved from traditional paternalistic paradigms toward egalitarian, patient-centered models. When addressing adult malocclusion, clinical decision-making is extraordinarily complex, preference-sensitive, and inherently discretionary. Unlike pediatric or adolescent orthodontics, where parental guidance often predominates, adult malocclusion management requires individuals to independently weigh substantial trade-offs involving invasive surgical interventions (such as bilateral sagittal split osteotomy or Le Fort I osteotomies), multi-year fixed orthodontic appliances, clear aligner mechanics, potential tooth extractions, substantial out-of-pocket financial commitments, and potential risks of neurosensory deficits or root resorption.

From a theoretical and psychometric standpoint, generic shared decision-making instruments—such as the 9-item Shared Decision-Making Questionnaire (SDM-Q-9) or the CollaboRATE measure—often fail to capture condition-specific nuances inherent in craniofacial interventions. Generic scales frequently display ceiling effects in specialized surgical environments, overlooking the precise cognitive, behavioral, and emotional investments required when patients must align subjective facial aesthetic desires with objective cephalometric and occlusal goals. The PTDMS-AM was engineered specifically to fill this methodological void, providing an empirical framework sensitive to the sociodemographic, psychological, and clinical idiosyncrasies of adult orthodontic cohorts.

In clinical practice, the PTDMS-AM serves multiple crucial functions:

• Screening for Decisional Passivity: It enables maxillofacial surgeons, orthodontists, and specialized nursing personnel to identify patients exhibiting low decision-making participation prior to the finalization of irreversible treatment plans, flagging individuals who may require targeted educational interventions, visual digital simulations (e.g., three-dimensional virtual surgical planning), or psychological counseling.
• Mitigating Decisional Regret and Conflict: Adult orthodontic-surgical treatment pathways frequently span two to four years, during which physical discomfort, altered dietary habits, and aesthetic transformations can induce emotional distress. High decision-making engagement has been empirically linked to reduced post-treatment regret, superior coping strategies, and higher adherence to post-operative elastic wear and oral hygiene protocols.
• Evaluating Communication Quality: Health systems and clinical departments can administer the instrument to audit the quality of patient-centered communication and shared decision-making protocols delivered by surgical and dental teams, serving as a standardized quality indicator.
• Facilitating Health Psychology Research: The scale enables empirical investigations exploring the associations between patient personality traits (e.g., health locus of control, neuroticism, self-efficacy), communicative dynamics, and long-term oral health-related quality of life (OHRQoL).

5. Psychological Construct

The psychological construct operationalized by the PTDMS-AM is patient participation in treatment decision-making, conceptualized as a dynamic, interactive, and multidimensional cognitive-behavioral-affective process. Rather than viewing participation as a passive or binary event (i.e., whether the patient signed an informed consent document), the instrument conceptualizes participation as an active empowerment process wherein the patient mobilizes personal agency, interacts with clinical knowledge, and shares responsibility for healthcare outcomes. The construct comprises three distinct, highly integrated dimensions:

1. Cognitive Participation (Items 1, 4, 5, 6, 7)

Cognitive participation refers to the internal intellectual processes through which the patient receives, comprehends, retains, and critically evaluates medical information regarding their dentofacial pathology and corresponding therapeutic alternatives. Within the context of adult malocclusion, this involves:

• Comprehension of Diagnostic Realities: Grasping complex anatomical, cephalometric, and occlusal concepts explained by the clinician, including skeletal discrepancies (e.g., Class III skeletal prognathism, open bite) versus dental compensations.
• Information Processing and Retention: Actively processing the procedural steps, timelines, and biological limitations of combined orthognathic-orthodontic treatments.
• Comparative Risk-Benefit Appraisal: Weighing the pros and cons of divergent intervention strategies, such as surgical correction versus orthodontic camouflage, or extraction versus non-extraction approaches, while considering potential complications such as relapse, inferior alveolar nerve paresthesia, or periodontal compromise.

2. Behavioral Participation (Items 8, 10, 11, 13, 14, 15, 19, 20, 21, 23)

Behavioral participation encapsulates the tangible, observable actions executed by the patient to actively influence their treatment trajectory. This represents the behavioral manifestation of patient activation and information-seeking, including:

• Self-Directed Information Acquisition: Independently conducting research prior to and between clinical consultations using reliable scientific literature, digital health platforms, and multimedia orthodontic simulations.
• Inquisitive Consultation Behavior: Preparing structured questions, seeking clarification regarding ambiguous clinical terms, and challenging clinical assumptions where necessary.
• Explicit Articulation of Goals and Preferences: Proactively communicating personal aesthetic standards, lifestyle constraints, social expectations, and personal priorities (e.g., soft tissue profile preferences, timeline urgency) to the dental team.
• Collaborative Negotiation: Actively discussing treatment milestones, evaluating appliance choices (e.g., labial braces, lingual appliances, skeletal anchorage devices), and jointly finalizing the comprehensive treatment strategy with the attending surgeon and orthodontist.

3. Emotional Participation (Items 24, 25, 26, 29, 30, 31)

Emotional participation reflects the affective domain of the consultation encounter, encompassing the patient’s subjective emotional resonance, therapeutic alliance, and emotional investment in the collaborative process. This dimension captures:

• Therapeutic Alliance and Trust: The affective experience of mutual trust, psychological safety, and respect established between the patient and the healthcare team.
• Affective Empowerment and Excitement: Feelings of optimism, excitement, fulfillment, and psychological satisfaction derived from having one’s voice validated and actively contributing to life-altering facial and dental modifications.
• Mitigation of Vulnerability and Alienation: The reduction of feelings of helplessness, intimidation, or emotional detachment during high-stress medical encounters. Notably, this dimension includes Item 31, which is reverse-scored to capture negative emotional disconnection or passive surrender to paternalistic directives.

6. Theoretical Framework

The conceptual architecture of the PTDMS-AM is grounded in several convergent theories within health psychology, medical sociology, and patient-centered communication:

The Shared Decision-Making (SDM) Framework

The primary theoretical foundation is the Shared Decision-Making model pioneered by Charles, Gafni, and Whelan (1997, 1999). This paradigm posits that medical encounters exist along a continuum ranging from paternalistic decision-making (where the physician acts as the sole authoritative decision-maker) to informed decision-making (where the patient is provided information and left to decide independently). SDM represents the optimal middle ground, characterized by four essential tenets:

1. At least two participants (clinician and patient) are involved.
2. Both parties share information reciprocally (the clinician contributes biomedical evidence; the patient contributes personal values, goals, and lifestyle preferences).
3. Both parties take steps to build a consensus regarding the preferred treatment.
4. An agreement is reached on the treatment to implement.

The PTDMS-AM expands this model by asserting that within complex stomatological interventions, shared decision-making is not merely an external consultation format, but an internal developmental process within the patient that demands cognitive synthesis, behavioral initiative, and emotional engagement.

Self-Determination Theory (SDT)

The instrument also integrates Ryan and Deci’s Self-Determination Theory, specifically its emphasis on the universal psychological needs for autonomy, competence, and relatedness. In the context of the PTDMS-AM:

• Autonomy is reflected in behavioral participation, where patients assert control over decisions impacting their physical appearance and masticatory function.
• Competence corresponds to cognitive participation, wherein patients acquire sufficient knowledge and health literacy to understand orthodontic biomechanics and surgical consequences.
• Relatedness aligns with emotional participation, reflecting the empathetic, collaborative connection formed between the patient and the stomatological care team.

The Tripartite Model of Attitudes and Engagement

By dissecting participation into cognitive, behavioral, and affective components, the scale reflects the classic ABC (Affect, Behavior, Cognition) model of social psychology (Eagly & Chaiken, 1993). In healthcare communication, patient activation is incomplete if any of these components is absent. For instance, a patient may possess high cognitive understanding (comprehending the surgical protocol) but display low behavioral participation (failing to ask questions or state preferences) due to cultural deference, or low emotional participation (feeling alienated or anxious). By measuring all three dimensions simultaneously, the PTDMS-AM provides a comprehensive assessment of patient engagement.

7. Validity

The psychometric validation of the PTDMS-AM followed rigorous scale development guidelines (DeVellis, 2017) and involved a sequential, multi-phase methodological protocol evaluating content, construct, and criterion-related validity.

Content Validity

An initial pool of items was generated via comprehensive literature reviews, qualitative patient interviews, and clinical expert consultations. To evaluate content relevance, clarity, and representativeness, an expert panel consisting of senior maxillofacial surgeons, orthodontists, dental nursing specialists, and health psychometricians was assembled. Content validity was quantified utilizing the Content Validity Index (CVI) framework (Lynn, 1986; Davis, 1992):

• Item-Level Content Validity Index (I-CVI): Evaluated across all retained items, with values exceeding standard acceptability criteria (≥ 0.83).
• Scale-Level Content Validity Index (S-CVI): The overall S-CVI achieved an outstanding 0.926, well above the recommended psychometric threshold of 0.80, confirming that the 21 items accurately represent the construct of treatment decision-making participation in malocclusion.

Criterion-Related and Concurrent Validity

Criterion-related validity was established by comparing the PTDMS-AM against the validated Chinese version of the 9-item Shared Decision-Making Questionnaire (SDM-Q-9) (Kriston et al., 2010; Luo & Xiao, 2019). Bivariate Pearson correlation analyses demonstrated moderate-to-strong positive correlations between the PTDMS-AM total/subscale scores and the SDM-Q-9, ranging between r = 0.590 and 0.650 (p < 0.001).

From a psychometric perspective, correlation coefficients within this range provide compelling evidence of convergent validity while confirming discriminant utility. A correlation exceeding 0.85 would suggest construct redundancy, whereas values between 0.590 and 0.650 demonstrate that while the PTDMS-AM measures the overarching construct of shared decision-making, it accounts for substantial unique variance specific to the cognitive, behavioral, and emotional realities of orthodontic-orthognathic patients that generic instruments miss.

8. Reliability

The reliability of the PTDMS-AM was evaluated through multiple complementary indices of internal consistency, split-half dependability, and temporal stability across two independent clinical cohorts.

Internal Consistency

Internal consistency analyses demonstrated exceptional homogeneity among the scale items:

• Total Scale: The overall 21-item instrument demonstrated an exceptional Cronbach’s alpha of α = 0.953.
• Cognitive Participation Subscale: Cronbach’s α = 0.860.
• Behavioral Participation Subscale: Cronbach’s α = 0.909.
• Emotional Participation Subscale: Cronbach’s α = 0.887.

All calculated alpha coefficients substantially exceeded the standard psychometric threshold of 0.70 for research instruments and the 0.85 threshold recommended for individual clinical diagnostic tools (Nunnally & Bernstein, 1994). Furthermore, item-total correlations across all 21 items remained high, demonstrating that each item contributed meaningfully to its latent dimension without redundancy.

Split-Half Reliability

To further examine the structural dependability and internal coherence of the instrument without relying solely on Cronbach’s alpha, a split-half reliability analysis was conducted. The calculated Guttman split-half coefficient was 0.957, confirming strong equivalence across parallel halves of the scale.

Test-Retest Reliability (Temporal Stability)

To establish the stability of the PTDMS-AM over time in patients whose clinical condition had not changed, a subsample of participants was re-administered the scale after a two-week interval. The test-retest intraclass correlation coefficient was r = 0.885 (p < 0.001), demonstrating high temporal stability while remaining sensitive to genuine clinical changes resulting from decision-aid interventions.

9. Factor Analysis

The factorial structure and construct validity of the PTDMS-AM were determined using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) across two independent, non-overlapping patient samples recruited from tertiary stomatological hospitals.

Exploratory Factor Analysis (EFA)

EFA was executed on the first calibration sample (n = 257 adult patients with malocclusion). Sampling adequacy and data factorability were confirmed through standard diagnostic metrics:

• Kaiser-Meyer-Olkin (KMO) Measure: 0.974, indicating outstanding sampling adequacy for factor extraction (well above the conventional threshold of 0.60).
• Bartlett’s Test of Sphericity: Highly statistically significant (χ² = 4398.21, p < 0.001), rejecting the null hypothesis that the correlation matrix was an identity matrix.

Principal Axis Factoring with Promax (oblique) rotation was conducted, aligning with the theoretical expectation that cognitive, behavioral, and emotional dimensions of patient participation are intercorrelated. The analysis extracted three distinct latent factors with eigenvalues greater than 1.0, aligning with the theoretical model:

• Factor 1: Behavioral Participation (10 items: 8, 10, 11, 13, 14, 15, 19, 20, 21, 23).
• Factor 2: Emotional Participation (6 items: 24, 25, 26, 29, 30, 31).
• Factor 3: Cognitive Participation (5 items: 1, 4, 5, 6, 7).

Together, these three latent factors accounted for 60.98% of the total variance. Factor loadings for individual items across their designated latent factors ranged from 0.452 to 0.884, with minimal cross-loadings (< 0.30).

Confirmatory Factor Analysis (CFA)

To cross-validate the three-factor structure identified in the EFA, a Confirmatory Factor Analysis using Maximum Likelihood estimation was conducted on the second independent validation sample (n = 269 adult patients with malocclusion). The structural model demonstrated strong overall fit:

• Root Mean Square Error of Approximation (RMSEA): 0.015 (90% CI [0.000, 0.032]), well below the strict threshold of ≤ 0.05, demonstrating exceptional parsimonious fit.
• Comparative Fit Index (CFI): 0.968, exceeding the standard ≥ 0.95 criterion for excellent fit.
• Tucker-Lewis Index (TLI): 0.964, confirming robust model fit adjusting for model complexity.
• Normed Fit Index (NFI): 0.641. Although NFI fell below conventional benchmarks (an outcome often observed in complex multidimensional models where cross-loadings are strictly constrained to zero and sample sizes are moderate), the superior CFI, TLI, and RMSEA indices confirmed the structural viability of the three-factor specification.

Standardized factor loadings in the CFA remained statistically significant (p < 0.001), confirming that the 21 items serve as reliable indicators of their respective latent constructs.

10. Instrument / Measurement Tool

• Tool Name: Participation in Treatment Decision-Making Scale for Adults with Malocclusion (PTDMS-AM)
• Test Type: Patient-Reported Outcome Measure (PROM) / Self-report psychometric questionnaire
• Target Population: Adult clinical patients diagnosed with dental or skeletal malocclusion facing orthodontic and/or orthognathic surgical decisions
• Applicable Age Range: Adults aged 18 to 43 years
• Item Count: 21 items
• Dimensional Structure: Multidimensional (3 latent subscales):
  • Cognitive Participation: 5 items (Items 1, 4, 5, 6, 7)
  • Behavioral Participation: 10 items (Items 8, 10, 11, 13, 14, 15, 19, 20, 21, 23)
  • Emotional Participation: 6 items (Items 24, 25, 26, 29, 30, 31)
• Response Format: 21 items, 5-point Likert scale:
  • 1 = Strongly Disagree
  • 2 = Disagree
  • 3 = Neutral (Neither Agree nor Disagree)
  • 4 = Agree
  • 5 = Strongly Agree
• Administration Format: Paper-and-pencil questionnaire or computerized self-administered survey (typical completion time: 5–8 minutes)
• Scoring Instructions:
  • Reverse Scoring: Item 31 must be reverse-scored prior to calculating subscale and total scores (i.e., 1 → 5, 2 → 4, 3 → 3, 4 → 2, 5 → 1).
  • Total Score Calculation: Sum the scores of all 21 items (after reversing Item 31).
  • Subscale Scores: Sum the respective item responses for each subscale:
    • Cognitive Subscale Score: Sum of Items 1, 4, 5, 6, 7 (Score range: 5 to 25)
    • Behavioral Subscale Score: Sum of Items 8, 10, 11, 13, 14, 15, 19, 20, 21, 23 (Score range: 10 to 50)
    • Emotional Subscale Score: Sum of Items 24, 25, 26, 29, 30, and reversed 31 (Score range: 6 to 30)
  • Score Range: Theoretical total score ranges from 21 to 105.
  • Score Interpretation: Higher cumulative scores represent greater active patient participation, empowerment, and collaborative engagement in treatment decision-making.

11. Permissions & Fee and Test Year

• Test Year: 2025
• Original Publication: BMC Oral Health (Springer Nature)
• Licensing: The developmental and validation study is published open access under the terms of the Creative Commons Attribution 4.0 International License (CC BY 4.0).
• Permitted Use: The publication permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are appropriately credited.
• Fee: Free of charge for academic, non-commercial research, and non-profit clinical evaluation purposes.
• Item Access Protocol: Although the overarching psychometric structure, validation parameters, and scoring rules are published open access, individual full-text questionnaire items in their standardized phrasing are not displayed verbatim in the open publication tables. Researchers and clinicians wishing to utilize the official instrument must contact the corresponding authors directly (Weijun Yuan: [email protected]; Lili Hou: [email protected]) to obtain the complete scale materials and administration guidelines.

12. References

Ballesteros, J., Moral, E., Brieva, L., Ruiz-Beato, E., Prefasi, D., & Maurino, J. (2017). Psychometric properties of the SDM-Q-9 questionnaire for shared decision-making in multiple sclerosis: Item response theory modelling and confirmatory factor analysis. Health and Quality of Life Outcomes, 15, Article 79. https://doi.org/10.1186/s12955-017-0656-2

Barone, S., Morice, A., Picard, A., & Giudice, A. (2021). Surgery-first orthognathic approach vs conventional orthognathic approach: A systematic review of systematic reviews. Journal of Stomatology, Oral and Maxillofacial Surgery, 122(2), 162–172. https://doi.org/10.1016/j.jormas.2020.08.008

Byrne, B. M. (2016). Structural equation modeling with AMOS: Basic concepts, applications, and programming (3rd ed.). Routledge. https://doi.org/10.4324/9781315757421

Charles, C., Gafni, A., & Whelan, T. (1997). Shared decision-making in the medical encounter: What does it mean? (Or it takes at least two to tango). Social Science & Medicine, 44(5), 681–692. https://doi.org/10.1016/S0277-9536(96)00221-3

Charles, C., Gafni, A., & Whelan, T. (1999). Decision-making in the physician-patient encounter: Revisiting the shared treatment decision-making model. Social Science & Medicine, 49(5), 651–661. https://doi.org/10.1016/S0277-9536(99)00145-8

Costello, A. B., & Osborne, J. W. (2005). Best practices in exploratory factor analysis: Four recommendations for getting the most from your analysis. Practical Assessment, Research, and Evaluation, 10, Article 7. https://doi.org/10.7275/jyj1-4868

Davis, L. L. (1992). Instrument review: Getting the most from a panel of experts. Applied Nursing Research, 5(4), 194–197. https://doi.org/10.1016/S0897-1897(05)80008-4

DeVellis, R. F. (2017). Scale development: Theory and applications (4th ed.). SAGE Publications.

Donaldson, C. D., Manisali, M., & Naini, F. B. (2021). Three-dimensional virtual surgical planning (3D-VSP) in orthognathic surgery: Advantages, disadvantages and pitfalls. Journal of Orthodontics, 48(1), 52–63. https://doi.org/10.1177/1465312520954871

Eagly, A. H., & Chaiken, S. (1993). The psychology of attitudes. Harcourt Brace Jovanovich College Publishers.

Elnagar, M. H., Aronovich, S., & Kusnoto, B. (2020). Digital workflow for combined orthodontics and orthognathic surgery. Oral and Maxillofacial Surgery Clinics of North America, 32(1), 1–14. https://doi.org/10.1016/j.coms.2019.08.004

Elwyn, G., Barr, P. J., Grande, S. W., Thompson, R., Walsh, T., & Ozanne, E. M. (2013). Developing CollaboRATE: A fast and frugal patient-reported measure of shared decision making in clinical encounters. Patient Education and Counseling, 93(1), 102–107. https://doi.org/10.1016/j.pec.2013.05.009

Hair, J. F., Black, W. C., Babin, B. J., & Anderson, R. E. (2019). Multivariate data analysis (8th ed.). Cengage Learning.

Hinkin, T. R. (1998). A brief tutorial on the development of measures for use in survey questionnaires. Organizational Research Methods, 1(1), 104–121. https://doi.org/10.1177/109442819800100106

Hu, X., Wang, B., Pan, T., Yuan, W., & Hou, L. (2025). Participation in treatment decision-making scale for adults with malocclusion: Development and psychometric evaluation. BMC Oral Health, 25, Article 6825. https://doi.org/10.1186/s12903-025-06825-2

Kriston, L., Scholl, I., Hölzel, L., Simon, D., Loh, A., & Härter, M. (2010). The 9-item Shared Decision Making Questionnaire (SDM-Q-9): Development and psychometric properties in a primary care sample. Patient Education and Counseling, 80(1), 94–99. https://doi.org/10.1016/j.pec.2009.09.034

Lerman, C. E., Brody, D. S., Caputo, G. C., Smith, D. G., Lazaro, C. G., & Wolfson, H. G. (1990). Patients’ Perceived Involvement in Care Scale: Relationship to attitudes about illness and medical care. Journal of General Internal Medicine, 5(1), 29–33. https://doi.org/10.1007/BF02602306

Luo, B. H., & Xiao, S. H. (2019). Reliability and validity of Chinese version for the 9-item shared decision making questionnaire. Journal of Central South University (Medical Science), 44(7), 823–829. https://doi.org/10.11817/j.issn.1672-7347.2019.180630

Lynn, M. R. (1986). Determination and quantification of content validity. Nursing Research, 35(6), 382–385. https://doi.org/10.1097/00006199-198611000-00017

Murdoch, A. I. K., Blum, J., Chen, J., Baziotis-Kalfas, D., Dao, A., Bai, K., & Sadr, A. (2023). Determinants of clinical decision making under uncertainty in dentistry: A scoping review. Diagnostics, 13(6), Article 1076. https://doi.org/10.3390/diagnostics13061076

Nunnally, J. C., & Bernstein, I. H. (1994). Psychometric theory (3rd ed.). McGraw-Hill.

Ryan, R. M., & Deci, E. L. (2000). Self-determination theory and the facilitation of intrinsic motivation, social development, and well-being. American Psychologist, 55(1), 68–78. https://doi.org/10.1037/0003-066X.55.1.68

Sahlsten, M. J. M., Larsson, I. E., Sjöström, B., & Plos, K. A. E. (2008). An analysis of the concept of patient participation. Nursing Forum, 43(1), 2–11. https://doi.org/10.1111/j.1744-6198.2008.00090.x

Song, M., & Kim, M. (2023). Development and validation of a patient participation scale. Journal of Advanced Nursing, 79(6), 2393–2403. https://doi.org/10.1111/jan.15593

13. Items of the Scale