Introduction
Stroke ranks as the second leading cause of death and one of the primary causes of disability worldwide [1-3]. Many stroke survivors face limitations in their activities and participation [4, 5]. Common issues include diminished interpersonal relationships, daily immobility, an inability to resume previous social activities or engage in new ones, mood disturbances, and a subsequent decrease in quality of life (QOL) [6]. The ultimate goal of clinical rehabilitation for stroke patients is to mitigate these consequences, enhance independence, and improve social participation [7, 8]. Participation is a multidimensional concept that should be measured both objectively (observable and measurable aspects) and subjectively (personal experiences) [9, 10, 11]. Gathering information on participation from both perspectives provides a comprehensive overview of the quantity and quality of a patient’s participation, assisting therapists in establishing clearer treatment goals and better evaluating the effectiveness of interventions [6]. Chang and Custer proposed a conceptual model of “participation” based on the ICF, defining participation as “active involvement in activities that are intrinsically social and occur within a societally defined context.” [12]. The areas of participation were categorized into three domains, productivity, social, and community, with dimensions defined by subjective factors (such as perceived difficulty and desire for change) and objective factors (like frequency and variety) [12]. Based on this concept, the participation measure–3 domains, 4 dimensions (PM-3D4D) questionnaire was developed by Chang et al in Taiwan to assess adult participation in outpatient rehabilitation services [13]. This questionnaire consists of 24 items that evaluate individuals’ participation over the past three months, encompassing productivity (6 items), social (6 items) and community (12 items) domains across four dimensions, diversity, frequency, perceived difficulty, and desire for change. The questionnaire scores reflect the activities individuals engaged in during the last three months, the frequency of participation in the past week, month, or quarter, the difficulties encountered while performing these activities, and their desire to modify their participation. Previous studies in Taiwan have reported strong psychometric properties for this questionnaire, including good content validity, high internal consistency (Cronbach’s α=0.89~0.93 for each domain), and strong test re-test reliability exceeding 0.7 [13-16]. In the current research, the Persian translation, face, and content validity of the test were conducted and studied.

Materials and Methods
The inclusion criteria for participants included adults with a stroke diagnosis, at least six months post-onset, at least a middle school education, and proficiency in Farsi. The exclusion criteria included cognitive impairment (MoCA ≤23) [17], severe depression or anxiety (hospital anxiety and depression scale [HADS] ≥11) [18] and significant pain (visual analogue scale [VAS] ≥7) [19]. The inclusion criteria for experts included occupational therapists and physiotherapists with 5 or more years of experience in the rehabilitation of stroke patients. Non-random convenience sampling was conducted from the occupational therapy and physiotherapy departments in hospitals and rehabilitation clinics in Tehran and Alborz Province, Iran.

Questionnaire
The original PM-3D4D test was developed in Chinese to measure participation in adults using outpatient rehabilitation services in Taiwan, addressing neurological deficits (such as stroke), musculoskeletal issues (such as chronic back pain) and other chronic conditions (such as cancer) [13]. The latest version includes 24 items assessing participation across three domains, productivity (6 items), social (6 items), and community (12 items), evaluated through the dimensions of variety, frequency, difficulty, and desire for change. Respondents answer “yes/no” for the diversity dimension, report activity frequency over the last week, month, or quarter, rate difficulty from 1 (very difficult) to 4 (no difficulty) and indicate their desire for change participation levels with “yes/no” answer options. It is essential to mention that the questionnaire was translated from Chinese to English by test developers.

Translation
Following permission from the test developer, the translation of the questionnaire was conducted about the international QOL assessment (IQOLA) protocol, ensuring cultural and linguistic equivalence for the Iranian context [20]. The process of translating was forward-backward. At first, permission was taken from the test developer. The original questionnaire was translated from English to Farsi by two translators fluent in native Farsi—one with a medical background and the other with a non-medical background. The translators focused on conceptual equivalence rather than a literal translation, ensuring that the choice of phrases, wording, and writing style was appropriate for a middle school education level. Subsequently, they assessed the difficulty and ease of each item in the translation using a linear analog scale assessment rating scale from 0 (not at all difficult) to 100 (very difficult) and provided comments when necessary. The preliminary translation was then given to two translators whose native language was either American or British English, depending on availability and who had extensive knowledge of Farsi. These translators translated the questionnaire back into English. The backward translations were reviewed by researchers for conceptual equivalence with the original version. Item-to-item and response option-to-response option translations were discussed in researchers’ meetings, and corrections were made to some translations [21]: 
In the forward translation of item 14 (“playing sports [e.g. playing badminton, basketball, table tennis, or baseball]”), “baseball” was replaced with “volleyball” since it is not a common sport in Iran. 
For item 15 (“participating in non-physical group entertaining activities [e.g. playing cards, chess, mahjong, or online games]”), “mahjong” was omitted due to a lack of familiarity among Iranians and replaced with “mental games.” 
In item 16 (participating in religious or spiritual activities [e.g. go to a church, temple, or meditation group]”), “church” and “temple” were substituted with “mosque” and “shrine” because the former are not common spiritual activities in Iran.
For item 21 (“receiving school education or taking courses for personal skills development [e.g. taking courses, such as languages, computer, music, art, or finance in a community college]”), “community college” was replaced with “vocational school” because this term is more familiar in Iran. 
In item 24 (“getting involved in investment activities [e.g. buy and sell stocks, buy lottery tickets, and collect rent from tenants]”), the mention of buying lottery tickets was updated to reflect current practices in Iran, and the phrase “participation in lotteries” was included in the examples.
The developer reviewed and approved these changes during the backward translation process. After addressing their comments, the revised version was emailed to the developer for final approval. The approved Persian version was used to assess face and content validity.

Face validity
The questionnaire was administered to 20 participants (10 men and 10 women) with chronic stroke, aged between 54 to 73 years, to assess qualitative face validity. This group included 5 individuals with under-diploma education, 6 with a diploma, and 9 with academic degrees. Additionally, 15 rehabilitation specialists (8 occupational therapists and 7 physiotherapists) with 5 to 30 years of experience in stroke rehabilitation were included. Face-to-face interviews were conducted with the participants to evaluate the meaning of the questions from their perspectives. During this process, any misunderstandings regarding the questions were noted and clarified. Subsequently, quantitative face validity was assessed. The same 20 chronic stroke patients rated the importance of each questionnaire item on a 5-point Likert scale (5=completely crucial; 4=crucial; 3=moderately crucial; 2=slightly crucial; and 1=not crucial at all). An impact score >1.5 for each item was required for it to be considered appropriate and retained (Equations 1, 2 and 3) [22, 23].

1. Impact Score=Frequency(%)×Importance

Content validity
The questionnaire was administered to 15 occupational and physical therapists who had 5 or more years of experience in the rehabilitation of stroke patients. Based on their feedback, two indicators were calculated, the content validity index (CVI) and content validity ratio (CVR). The CVR assessed the necessity of each item’s inclusion in the questionnaire. The expert panel rated each item using a three-point scale: 1=the item is necessary, 2=the item is useful but not necessary, and 3=the item is not necessary. The CVR was then calculated to ensure that the items effectively measured the intended concepts. The expert panel evaluated each item using a four-point Likert scale based on three criteria, simplicity and fluency, relevance and clarity. For the simplicity criterion, the options were as follows: 1=not simple; 2=relatively simple; 3=simple; and 4=completely simple. Given that 15 experts existed, the minimum acceptable score for CVR, according to Lawshe’s table [24], is 0.49. Furthermore, the acceptance criteria for each item based on CVI are as follows: A score above 0.79 is deemed appropriate, scores between 0.7 and 0.79 require revision, and scores below 0.7 are considered unacceptable [24].



Results
Face validity
In terms of qualitative face validity, the patients’ opinions regarding the items and questions of the questionnaire were acceptable. Consequently, the PM-3D4D questionnaire was deemed clear, appropriate, and satisfactory in both structure and concept. The assessment of quantitative face validity revealed that the impact scores of the items ranged from 4.36 to 6.88 (>1.5), indicating that all items had acceptable importance and were retained (Table 1).



Content validity
The CVR for the items ranged from 0.6 to 0.87. Additionally, the CVI for all items across the three sections was >0.83. Based on these results, all items demonstrated necessity, simplicity, relevance to the concept, and sufficient clarity (Tables 2 and 3).






Discussion
Participation is the ultimate goal of rehabilitation programs and a key determinant of an individual’s health and well-being. Given the multidimensional nature of participation, encompassing both subjective and objective aspects, and its various domains, including social, community, and productivity, it is essential to employ a comprehensive test that addresses these areas. This study was conducted to translate and evaluate the face and content validity of the PM-3D4D questionnaire. Recognizing the importance of accurately conveying the concepts and examples in the questionnaire, cultural adaptation was performed during the translation process to account for the differences between Chinese and Iranian cultures. For instance, due to the unfamiliarity of Iranians with “Mahjong,” this example was removed and substituted with “mental games.” Face validity was assessed qualitatively through feedback from rehabilitation specialists and chronic stroke patients, and quantitatively based solely on the opinions of stroke patients. The results indicated that all items were clear and understandable, with acceptable importance, resulting in no deletions. The CVR and CVI were evaluated through ratings by rehabilitation experts, demonstrating that all items met acceptable levels of necessity, relevance, clarity, and simplicity. Consistent with the results of Chang et al. who reported good model fit and item fit through confirmatory factor analysis, the PM-3D4D questionnaire exhibits strong construct validity [13]. Therefore, the Persian version of the PM-3D4D questionnaire is poised to be a valuable test for future research in the field of instrument psychometrics, specifically to measure participation among adults with chronic stroke.

Conclusion
The Persian adaptation of the PM-3D4D questionnaire shows strong face and content validity, indicating that it deserves more research in the field of psychometrics as a means to assess participation in adults who have experienced chronic stroke.
Limitations and suggestions
The Persian version of the PM-3D4D questionnaire has been designed exclusively for Persian speakers in Iran, while various ethnic groups, including Azari and Arabic speakers, also reside in the country. Literacy programs in Iran are conducted in Persian. It is recommended that future studies focus on the psychometrics of the Persian version of PM-3D4D and the cultural adaptation of this questionnaire for the languages of other ethnic groups present in Iran. 

Ethical Considerations
Compliance with ethical guidelines
The study was approved by the Ethics Committee of Iran University of Medical Sciences (Code: IR.IUMS.REC.1400.12.42). All participants read the consent form and agreed.

Funding
This paper was extracted from the master’s thesis of Diba Sharifi Khajehdehi, approved by the Department of Occupational Therapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran.

Authors' contributions
Methodology: Ghorban Taghizadeh and Laleh Lajevardi; Investigation: Diba Sharifi Khajehdehi; Conceptualization, writing, review & editing: All authors.

Conflict of interest
The authors declared no conflict of interest.

Acknowledgments
The authors appreciate the kind assistance and support provided by the Occupational Therapy Department, the Vice Chancellor for Research at the Iran University of Medical Sciences, the test developer and to all the patients and experts who participated in this study.



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