Development and psychometric evaluation of the Patient Safety Culture in Home Health Care Centers Instrument (PSCHCI): a sequential exploratory mixed-methods protocol in Iran

Abstract

Introduction

Patient safety is crucial in healthcare, especially in home-based settings where unregulated environments and limited supervision pose unique challenges. With the expansion of home healthcare due to an ageing population and healthcare workforce shortages, there is a pressing need for tools to assess patient safety culture in this context. Current instruments, developed for hospitals, do not adequately address the specific dynamics of home healthcare, such as patient autonomy and caregiver involvement. This protocol outlines the development and validation of the Patient Safety Culture in Home Health Care Centers Instrument (PSCHCI), using a sequential exploratory mixed-methods approach.

Methods and analysis

This sequential exploratory mixed-methods protocol consists of three phases. Phase 1 fieldwork (semi-structured interviews with 15 participants, 3 participant observations and field notes) has been completed. Qualitative data are currently being analysed using conventional content analysis. The scoping review component of Phase 1 is planned but has not yet been conducted. Phase 2 (instrument development) is planned to include item generation from qualitative results followed by expert panel review. Phase 3 (psychometric evaluation), scheduled for late 2026, will employ a cross-sectional study to assess face, content and construct validity; reliability; interpretability; and feasibility. This phase features pilot testing (n=30–50), face and content validity assessment (n=10 each), test-retest reliability (n=15) and exploratory and confirmatory factor analyses (n=300–400).

Ethics and dissemination

Ethical approval was obtained from the Ethics Committee of Iran University of Medical Sciences. All participants will provide written informed consent. Confidentiality, voluntary participation and withdrawal rights are guaranteed. Findings will be published in peer-reviewed journals, presented at conferences and shared with participating home healthcare centres, policymakers and stakeholders.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• This protocol employs a sequential exploratory mixed-methods design, integrating stakeholder-informed qualitative data with rigorous quantitative validation to develop a reliable, context-specific instrument for evaluating patient safety culture (PSC) in home healthcare centres (HHCs).

• A comprehensive psychometric evaluation, including face, content and construct validity, reliability, interpretability and feasibility, will provide robust evidence on the measurement properties and applicability of the tool in HHCs.

• The study is being conducted in HHCs affiliated with a single university of medical sciences in Iran, which may limit the generalisability of the findings to other regions or healthcare systems.

Introduction

Patient safety is a cornerstone of high-quality healthcare and must be prioritised. Home healthcare settings present distinct challenges, given that services occur in uncontrolled domestic environments with limited professional supervision and substantial involvement of family caregivers.^{1 2}

In Iran, home healthcare centres (HHCs) are private licensed facilities affiliated with universities of medical sciences. These centres employ multidisciplinary teams to deliver physician-prescribed skilled nursing and rehabilitation services directly in patients’ homes. Unlike hospital care, home healthcare is typically provided by a single professional in unpredictable environments, with family members assuming a central caregiving role in the absence of immediate colleague support, standardised equipment or direct supervision.^{1 3 4}

Current evidence indicates that approximately 37.7% of individuals receiving home healthcare experience adverse events. These include infections, falls, pressure injuries and medication errors.^{5 6} Despite the rapid expansion of home healthcare services in Iran, research on patient safety culture (PSC) in this setting remains limited.⁷

Existing instruments, such as the Hospital Survey on Patient Safety Culture (HSOPSC), were developed for controlled hospital environments. In hospitals, teams operate within hierarchical structures, under continuous supervision and with standardised infrastructure. Home healthcare differs fundamentally: care is delivered independently, often by a single professional, across variable home environments and with substantial reliance on untrained family caregivers. Immediate colleague support, standard equipment and direct supervision common in hospitals are largely absent in home settings, making hospital-based tools insufficient to address these unique challenges.^{1 3 4} Qualitative and quantitative methods have long been used separately in instrument development.⁸ However, a sequential exploratory mixed-methods design offers distinct advantages for developing a context-specific tool in an under-researched setting such as Iranian home healthcare. This approach begins with qualitative exploration to identify culturally relevant dimensions of PSC that may not be captured by existing hospital-based instruments. These findings are then used to generate items that are subsequently tested quantitatively. This design enhances content validity and ecological validity by grounding the instrument in the lived experiences of Iranian home healthcare providers, patients and family caregivers.^{9 10}

Although instruments such as the HSOPSC have been widely used, they do not adequately reflect the distinct features of PSC in home healthcare. Therefore, developing a new context-specific instrument grounded in the experiences of Iranian stakeholders is essential. This study aims to develop and validate the Patient Safety Culture in Home Health Care Centers Instrument (PSCHCI) using a sequential exploratory mixed-methods approach to address this critical gap.¹¹

Methods and analysis

Study overview

This protocol describes a three-phase sequential exploratory mixed-methods study to design and validate the PSCHCI in Iran. (table 1)

Table 1. Summary of study phases, methods and current status.

Phase	Objective	Key methods	Sample size	Current status (April 2026)
Phase 1 (qualitative)	Conceptualise PSC in HHCs	Semi-structured interviews, participant observation, field notes (scoping review planned but not yet conducted)	15 interviews+3 observations	Data collection completed; analysis ongoing
Phase 2 (instrument development)	Item generation and refinement	Expert panel review	10–12 experts	Planned
Phase 3 (psychometric evaluation)	Validate the PSCHCI	Cross-sectional survey, EFA, CFA, reliability testing	300–400 staff	Scheduled to begin late 2026

CFA, confirmatory factor analysis ; EFA, exploratory factor analysis ; HHC, home healthcare centre; PSC, patient safety culture ; PSCHCI, Patient Safety Culture in Home Health Care Centers Instrument.

Phase 1 (qualitative) involves semi-structured interviews, participant observations, field notes and a scoping review to conceptualise PSC in HHCs.

Phase 2 (instrument development) includes item generation from qualitative findings followed by expert panel review.

Phase 3 (psychometric evaluation) comprises a cross-sectional study assessing face, content and construct validity, reliability, interpretability and feasibility among home healthcare staff.

As of April 2026, the study is in the data analysis stage of Phase 1, with quantitative data collection scheduled to commence in late 2026 and overall study completion anticipated in 2027.

Study design

This study employs a sequential exploratory mixed-methods design. Conducting the research as a single cohesive project ensures seamless integration of qualitative findings into item generation and enables iterative refinement throughout the process.^{11 12} This approach enhances content validity and produces a contextually relevant and methodologically robust instrument. Quality will be assessed using the Mixed Methods Appraisal Tool V.2018¹³ (online supplemental appendix 1).

Timeline and current status

The study was initiated in late 2025. Qualitative data collection (interviews and observations) was completed between late 2025 and early 2026, and analysis is currently underway. The scoping review component of Phase 1 is planned but has not yet been conducted. The quantitative psychometric evaluation is scheduled to commence in late 2026, with overall study completion anticipated in 2027. As this is a protocol for an ongoing study, the methods described reflect the current planned approach and may be subject to minor refinements as the study progresses.

Phase 1: qualitative study

This stage addresses the first goal of the study: ‘explaining the concept of PSC in HHCs.’ The report will be drafted in accordance with the Consolidated Criteria for Reporting Qualitative Studies (COREQ) checklist¹⁴ (online supplemental appendix 2).

Specific objectives

• Explore the experiences and perceptions of staff, patients and family caregivers regarding PSC in HHCs through a fieldwork phase.

• Explain the concept of PSC in HHCs in the literature.

• Finalise the definition of PSC in HHCs by integrating the field findings and scoping review.

Fieldwork phase

Study setting

The study was carried out across home healthcare centres (HHCs) affiliated with Iran University of Medical Sciences in Tehran, Iran, as well as in patients’ actual living environments, including private homes and family residences. In the Iranian healthcare system, HHCs are privately licensed facilities that operate under the supervision of the Ministry of Health and Medical Education and are formally affiliated with medical universities. These facilities are staffed by multidisciplinary teams and deliver physician-prescribed skilled nursing and rehabilitation services directly within patients’ homes throughout Tehran and nearby regions.

A total of four HHCs affiliated with Iran University of Medical Sciences were selected using purposive sampling. Centres were eligible if they met these requirements¹: official licence from the Ministry of Health and Medical Education,² at least 1 year of active operation providing home healthcare services,⁵ employment of a multidisciplinary team (physicians, nurses, physiotherapists, wound-care specialists and nurse assistants) and⁶ willingness of the centre director to participate. Patients’ homes were selected from these centres based on the following criteria¹: the patient receiving ongoing skilled home healthcare services,² a family caregiver present during visits and⁵ the patient and family caregiver willing to participate in the study and allow observation. This combination of organisational and domestic settings enabled a thorough examination of PSC from both institutional and home-based perspectives.

Participants and sampling methods

Purposive sampling incorporating maximum variation ensured a diverse group of participants for the qualitative phase. Healthcare professionals with at least 1 year of home healthcare experience, a genuine interest in sharing their perspectives and effective communication skills were invited.¹⁵ A total of 15 face-to-face interviews brought together managers, home care nurses, a nurse assistant, a physiotherapist, a wound care specialist, a physician and family caregivers, each offering unique insights into their roles and experiences. Three participatory observation sessions added depth to the research, including two immersive sessions in patients’ homes and one at a HHC. Data saturation was achieved after twelve interviews and three observation sessions, as the final three interviews yielded no novel codes or themes.¹⁶

Data collection method

Following ethical approval and receipt of an official introduction letter from Iran University of Medical Sciences, qualitative data collection and analysis were undertaken. Data were collected and analysed by the first author (AEK), a PhD candidate and nursing student researcher with more than 5 years of qualitative research experience. To address potential bias, AEK maintained a reflexivity journal throughout the study. Participants were informed that AEK was working under the direct supervision of the principal investigator (TNG), who has over 15 years of experience in qualitative research. AEK received structured training and ongoing oversight from TNG, including regular debriefing sessions, transcript review and guidance on reflexive practice.

Recruitment began with the directors’ formal permission from four HHC affiliated with Iran University of Medical Sciences. Directors were asked to provide lists of eligible staff and patients, from which AEK purposively selected participants to ensure maximum diversity. Following consultation with centre managers, selected individuals were contacted, informed about the study and invited to participate. Written informed consent was obtained prior to data collection.

Data were gathered through 15 semi-structured interviews and 3 participant observation sessions (totaling 15 hours), as described above. Interviews lasted 45–90 min and were audio-recorded with consent.¹⁷ Each interview began with an open-ended question: ‘Please describe your experiences and perceptions regarding patient safety in home health care settings?’ Follow-up probes were used based on participant responses, such as ‘Can you share specific incidents where patient safety was compromised or enhanced?’ and ‘What are your thoughts on communication and collaboration among healthcare providers, patients and family members in ensuring safety?’ For unclear responses, clarifying questions such as ‘What do you mean?’, ‘Could you elaborate?’ or ‘Can you give an example?’ were employed. After each interview, participants were invited to provide additional feedback via notes or messages if desired.

In addition, three participatory observation sessions were conducted: two in patients’ homes (lasting 5 and 6 hours) and one at a home healthcare centre (lasting 4 hours). AEK adopted an active participant-observer role, engaging in selected care activities and reviewing relevant clinical documents (with permission) to enable data triangulation. Detailed field notes were recorded to capture interactions, workflows and contextual factors influencing PSC.¹⁸

Data analysis and rigour of qualitative findings

As of January 2026, qualitative data analysis is currently underway. Interview transcripts and field notes are being analysed by AEK using conventional content analysis.¹⁹ Interviews have been transcribed verbatim to ensure participant anonymity. AEK is reviewing the data to identify key themes and patterns, coding meaningful text segments according to the research questions. Similar codes are being grouped into broader categories to form a thematic framework. Throughout the analysis, AEK is maintaining an audit trail to document decisions, interpretations and emerging themes.

To ensure the credibility and trustworthiness of the findings, several strategies are being employed in accordance with established qualitative research standards.¹⁹ Credibility is strengthened through prolonged engagement, triangulation (interviews, participant observations, field notes and scoping review findings), member checking and peer debriefing. Member checking is being conducted by sharing preliminary summaries of themes and categories with 5–10 purposively selected participants representing diverse perspectives. Peer debriefing is carried out through regular discussions with TNG (principal investigator) and HS-N, who review selected transcripts and emerging themes to identify potential biases. Dependability and confirmability are ensured through systematic documentation, including a reflexivity journal, decision memos and timestamped logs. To support transferability, a comprehensive description of the research context, participants and methodological procedures is provided.

Additionally, 20% of the transcripts are being independently coded by a second researcher (external to the core team), and inter-coder reliability is being assessed to minimise subjective bias.²⁰

Theoretical phase

As detailed in our previously published scoping review protocol,³ a scoping review methodology will be employed to summarise the results of various studies and provide a comprehensive overview of PSC in HHCs. This approach was selected because scoping reviews are well-suited for mapping the breadth of literature on emerging topics, identifying key concepts and knowledge gaps, without requiring formal quality assessment. This aligns with the exploratory aim of conceptualising PSC in HHCs.^{21 22} This review will follow the framework developed by Arksey and O'Malley, as updated by the Joanna Briggs Institute, which comprises five stages: identifying the research question, finding relevant studies, selecting studies, charting the data and summarising the results. The review will adhere to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) for reporting.²³ The inclusion criteria will follow the Population, Concept and Context framework. A comprehensive search of PubMed, Embase, Scopus, ProQuest, Web of Science, Cochrane and grey literature will be conducted without date restriction and supported by a qualified research librarian. The search will be updated until the study is completed, and the reference lists of included studies will be reviewed for further relevant research. Studies that are duplicates or not written in Persian or English will be excluded. Two independent reviewers will screen titles, abstracts and full texts according to the eligibility criteria. Data extraction will be performed by the same reviewers using a pre-prepared form, with discrepancies resolved through discussion and, if necessary, the involvement of a third reviewer. The extracted data will include study characteristics (author, publication year, study design, aim/purpose, population, sample size, key findings and identified gaps or limitations). The results will be presented in tables, diagrams and a narrative synthesis.

Integration of qualitative data with literature review

The integration of qualitative findings with the scoping review involves a systematic comparison and contrast of emergent themes with existing literature on PSC in HHCs. This collaborative process, conducted by the research team (including the principal investigator and experts in qualitative analysis and patient safety), features independent reviews followed by iterative discussions to identify alignments, discrepancies and patterns. Merging decisions such as pinpointing overlaps, resolving conflicts through evidence weighting (prioritising field data for contextual relevance), and synthesising novel dimensions will rely on majority vote (≥80% agreement), with unresolved issues escalated to two independent qualitative researchers for impartial adjudication. By presenting a standard display table and detailing the characteristics and resulting dimensions of the concept under study in two parts (field and theoretical), the final definition of PSC in HHCs will be presented. This integration will use a joint display matrix to visually map qualitative themes against scoping review findings, facilitating meta-inferences and ensuring methodological congruence.¹¹

Phase II: instrument development

In this phase, an initial item pool will be generated directly from the codes, subcategories and main categories identified in the qualitative phase. Each meaningful code will be rephrased into a clear and concise item aligned with the construct of PSC in HHCs. Items will be selected based on relevance, clarity and measurability. The research team will collaboratively draft two to three items per subcategory. Preliminary drafts will undergo iterative internal review until 80% team consensus is reached.

This initial pool will then be refined through expert panel review. The panel comprises 10–12 members, including clinicians, managers, researchers, patients and family caregivers. This panel is used solely for item refinement in Phase II and is distinct from the samples that will later assess face and content validity in Phase III.

The review process will be conducted over two to three rounds via secure online survey platforms (eg, Google Forms or Porsline) to gather feedback and achieve consensus. In Round 1, panellists will independently rate each item on relevance (four-point scale), clarity and overall suitability. A predefined reduction strategy will be applied¹: eliminate items with an average relevance score below 3.0²; merge or delete redundant items (content similarity >80% as rated by ≥70% of panellists); and⁵ cap the final pool at 40–50 items. Consensus is defined as 80% of panellists rating an item as ‘Quite Relevant’ or ‘Highly Relevant.’ Revised items will be recirculated across rounds until the consensus threshold is met or no further changes are proposed. This structured process will yield a concise, patient-centred, and robust preliminary version of the PSCHCI.^{24 25}

Phase III: psychometric evaluation of the PSCHCI

This phase is a methodological study involving a cross-sectional survey to evaluate the psychometric properties of the PSCHCI,²⁶ which will conduct a cross-sectional study to evaluate the psychometric properties of the PSCHCI developed in the qualitative phase.

Specific objectives

• Determining the face validity (qualitative and quantitative) of the tool.

• Determining the content validity (qualitative and quantitative) of the tool.

• Determining the construct validity (exploratory and confirmatory factor analysis (CFA)) of the tool.

• Evaluating the reliability of the tool.

• Evaluating the interpretability of the tool.

• Evaluating the feasibility of the tool.

• Scoring the tool.

Determining face validity

Qualitative assessment of face validity

Cognitive interviewing using the think-aloud technique will be employed to assess the qualitative face validity of the draft tool. A purposive sample of at least 10 home healthcare providers, distinct from both the expert panel and the content validity sample, will be recruited from the target population. Interviews will be conducted either in person or virtually (via Skype or WhatsApp), according to participant preference.

During the interviews, participants will be asked to read each item aloud and verbalise their thoughts and interpretations in real time (think-aloud technique). This approach will allow exploration of the cognitive processes involved in responding to the items, including comprehension, information retrieval, judgement and response formulation.²⁷ In addition, participants will be prompted to evaluate each item for: difficulty (identifying items that are hard to understand), incongruence (assessing how well items align with the intended dimensions of the tool) and ambiguity (detecting potential misinterpretations or incomplete meanings).

All interviews will be audio-recorded with consent, and detailed notes will be taken to document participants’ comments, hesitations and suggested revisions. Findings from the cognitive interviews will be used to refine item wording, improve clarity and enhance the overall comprehensibility of the tool.²⁸

Quantitative assessment of face validity

Following participant feedback from the qualitative section, we will use quantitative face validity to revise items based on their impact scores. At least 10 home healthcare providers will assess each item and choose one option, rating importance on a 5-point Likert scale from ‘very important’⁷ to ‘not important at all’.¹ The impact score for each item is calculated as: impact score=frequency (%)×importance. Items with an impact score of 1.5 or higher will be deemed appropriate for further analysis.²⁹

Determining content validity

Qualitative assessment of content validity

For content validity, another separate group of at least 10 experts (managers, staff and researchers experienced in home care, patient safety or instrument development) will be recruited. These experts may be a subset of the Phase II expert panel or newly recruited, but they are distinct from the face validity sample. Through purposive sampling, those who have provided informed consent will be interviewed in-person sessions or virtually (eg, Skype or WhatsApp) based on their preference. Following the iterative refinement of items based on expert feedback concerning grammar, vocabulary appropriateness, item placement, range suitability and scoring accuracy, the expert panel will rigorously evaluate the revised instrument, focusing on the relevance of each item to the construct of PSC in HHCs.³⁰

Quantitative assessment of content validity

The same 10 content validity experts (described above) will independently assess each item for content validity ratio (CVR) and content validity index (CVI). They are not the same individuals as those participating in face validity. To ensure the selection of the most essential and precise content, the CVR and CVI are employed to validate that the instrument’s items effectively measure the intended construct.³¹ For the PSCHCI, 10 experts in home healthcare, patient safety and instrument development will independently assess each item using a standardised three-point scale: ‘Not Necessary’, ‘Useful but Not Essential’ and ‘Essential’. The CVR for each item is computed via the formula: CVR=(Ne–N/2)/(N/2), where Ne represents the number of experts rating the item as ‘Essential’ and N is the total number of experts. Per Lawshe’s table, items achieving a CVR of 0.62 or higher (the critical value for significance at p<0.05 with 10 experts) will be retained for further analysis.³²

The CVI is evaluated through item-level and scale-level approaches. At the item level, experts rate each PSCHCI item on a four-point scale of relevance to PSC in HHCs (1=not relevant, 2=somewhat relevant, 3=quite relevant, 4=highly relevant), yielding the item-level CVI as the proportion of experts assigning ratings of 3 or 4. Items with an item-level CVI≥0.79 are deemed acceptable. The scale-level CVI, calculated as the average of all item-level CVIs, requires a value≥0.90 to indicate strong content validity.³³

Item analysis

This stage involves the initial assessment of the instrument within the target population, conducted before testing for construct validity. During this phase, each item will be evaluated based on its mean, SD, correlation with other items, and the overall internal consistency of the instrument. Items with a corrected item-total correlation below 0.32 will be removed. Additionally, the reliability coefficient for all items will be calculated at this stage. If the removal of an item leads to a decrease in the reliability coefficient, it indicates that the item effectively contributes to the alignment with other items and should be retained.^{24 26}

Pilot testing

After the final draft of the PSCHCI has been developed (following face and content validity assessments), a pilot test will be conducted with a separate, convenience sample of home healthcare staff. The purpose of pilot testing is to evaluate the feasibility, clarity and initial performance of the instrument in a real-world setting before proceeding to full psychometric analysis.

Sample: A minimum of 30 and a maximum of 50 staff (nurses, physicians, physiotherapists, wound care specialists and nurse assistants) will be recruited from two to three home healthcare centres affiliated with Iran University of Medical Sciences. These centres will be different from those used in the qualitative phase and the main factor analysis cohort.

Procedure: Participants will complete the draft PSCHCI and a brief demographic form. After completion, they will be asked to provide feedback on the time required to finish the questionnaire, any unclear items and overall ease of completion. The research team will also monitor missing response rates and any technical issues with electronic or paper formats.

Data use: Pilot data will be used to conduct the Item Analysis, including corrected item-total correlations and initial reliability estimates. Based on pilot results, problematic items may be revised or removed before the main psychometric evaluation (exploratory factor analysis (EFA), CFA, etc). The pilot sample will not be included in the main factor analysis sample.

Determining construct validity

Construct validity, defined as the degree to which a test or tool measures its intended construct, will be evaluated through exploratory and CFA, together with convergent and discriminant validity.

Research environment

This phase will be conducted in HHCs affiliated with Iran University of Medical Sciences in Tehran and its surrounding areas. These centres are private licensed facilities that provide physician-prescribed skilled nursing and rehabilitation services directly in patients’ homes.

Research samples

The target population consists of all healthcare professionals (nurses, physicians, physiotherapists, wound care specialists and nurse assistants) currently employed in the participating HHCs affiliated with Iran University of Medical Sciences.

Inclusion criteria

Having at least 1 year of work experience in HHCs¹⁵ and a willingness to participate in the study.

Exclusion criteria

Incomplete or invalid questionnaire responses.

Research tools

A demographic information form and the final version of the PSCHCI will be used. The demographic form will collect data on age, gender, education level, job title and years of experience in home healthcare. The PSCHCI, which will be refined through face and content validity assessments, will be administered to evaluate PSC in HHCs.

Sample size

The sample size required for factor analysis depends on several factors, including the number of variables, the number of factors and the desired level of statistical power. A rule of thumb suggests that a sample size of 3 to 10 participants per item is considered adequate.^{26 34} EFA samples will differ from those used in CFA.³⁴ A target range of 300–400 participants is planned to ensure robust and stable psychometric estimates.

Data collection method

A convenience sampling method will be used to recruit participants for the quantitative phase. Staff working in HHCs affiliated with Iran University of Medical Sciences will be invited to participate through direct contact by the research team during centre visits or via official communication channels of the centres.

The purpose of the study, the voluntary nature of participation and the confidentiality of responses will be clearly explained to all potential participants. Written informed consent will be obtained prior to data collection. Participants will complete the demographic form and the final version of the PSCHCI on a self-reported basis. The questionnaires will be distributed in both electronic and paper formats according to participant preference. The research team will provide clear instructions on how to complete the instruments and will be available to answer any questions during the data collection period. To ensure anonymity and confidentiality, no personally identifiable information will be collected, and all responses will be kept strictly confidential.

Data analysis method

Data analysis will be performed using SPSS software V.25. The data will first be screened for missing values and outliers, and appropriate methods will be employed to address any issues identified. Descriptive statistics, including means, SD, frequencies and percentages, will be calculated to summarise the sample’s characteristics and the distribution of scores on the PSCHCI. EFA will identify the PSCHCI underlying factor structure, while CFA will verify it.³⁵

Multivariate normality and outliers

Before advanced statistical analysis, it is crucial to assess multivariate normality and identify outliers to ensure the models’ assumptions are met and avoid biased results. In this study, we will use Mardia’s coefficients to check normality and the Mahalanobis distance to detect extreme outliers. These measures will enhance the reliability of EFA and CFA for evaluating the psychometric properties of the PSCHCI.

Exploratory factor analysis

EFA is a statistical method designed to identify the hidden patterns or structure within a group of variables. Before performing EFA, we will check if the data are appropriate for factor analysis by using the Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy and Bartlett’s test of sphericity. The KMO test evaluates how well the sample size suits each item in the questionnaire. Bartlett’s test checks the idea that the correlation matrix is an identity matrix, which would mean the variables are not related and thus not suitable for factor analysis. If the KMO value is above 0.6 and Bartlett’s test shows a significant result, the data will be considered ready for factor analysis. We will apply Principal Components Analysis as the method to extract factors and use Varimax rotation to make the factors easier to interpret. The number of factors to keep will be decided based on the Kaiser criterion and the scree plot. Only items with factor loadings of 0.40 or higher will be viewed as important and kept in the instrument.^{24 36}

Confirmatory factor analysis

CFA is a statistical technique used to assess the proposed factor structure of a measurement scale. It is typically employed during the later stages of scale development to validate the factor structure that was previously established through EFA. In this study, CFA will be performed using AMOS software to determine how effectively the proposed factor structure corresponds with the collected data. Model fit will be assessed using various indices, including the χ² statistic, comparative fit index (CFI), Tucker Lewis’s index (TLI) and root mean square error of approximation (RMSEA). A model will be considered to fit well if it demonstrates a non-significant chi square value, CFI and TLI scores exceeding 0.90 and RMSEA values below 0.08.^{24 37}

Convergent and discriminant validity

In this method, to determine convergent and discriminant validity, the correlation between variables is first calculated using SPSS/AMOS software, followed by the establishment of a standardised regression weighting table. Finally, convergent and discriminant validity will be obtained using the Excel coding tool provided by Gaskin.³⁸ The convergent and discriminant validity of the identified factors will be assessed using the Fornell-Larcker criteria in JASP V.15.0.0, based on the following metrics: (a) average variance extracted (AVE), (b) maximum shared squared variance (MSV) and (c) composite reliability (CR). For convergent validity, AVE must exceed 0.5 and CR must be greater than AVE. For discriminant validity, MSV should be less than AVE for each construct.³⁹ Additionally, discriminant validity will be evaluated using the Heterotrait-Monotrait Ratio (HTMT) matrix, as proposed by Henseler. To confirm discriminant validity, all HTMT values must be below 0.85.⁴⁰

Reliability

To evaluate the reliability of the instrument, we will assess internal consistency, stability and absolute reliability using JASP V.15.0.0. Internal consistency will be measured through Cronbach’s alpha, McDonald’s omega and the average inter-item correlation (AIC), with acceptable thresholds set at α and ω greater than 0.7 and AIC ranging from 0.2 to 0.4. Additionally, CR and maximum reliability, both exceeding 0.7, will be used to evaluate construct reliability within the structural equation model.

Stability will be assessed using intraclass correlation coefficients (ICC) based on a two-way random effects model. A test-retest approach, conducted with a 2-week interval among 15 home healthcare providers, will be employed, with an ICC greater than 0.8 considered acceptable.^{41 42} A sample size of 15 was selected based on recommendations for minimum sample sizes in test-retest reliability studies during instrument development, where 15–30 participants are typically sufficient for initial estimation of ICC.^{26 42} Absolute reliability will be determined by calculating the SE of measurement (SEM) and minimal detectable change (MDC). The SEM will be computed as SD×√(1−ICC), and the MDC as 1.96×SEM×√2. The MDC represents the smallest change in score that exceeds measurement error, indicating an actual change in performance.⁴³

Interpretability

To evaluate interpretability, we will compute the MDC, investigate ceiling and floor effects, conduct a descriptive analysis of the total score distribution across study samples and assess the frequency of missing responses.^{42 44}

Ceiling effect and floor effect

These effects manifest when more than 15% of respondents achieve the highest or lowest possible scores. The presence of ceiling and floor effects (defined as more than 15% of respondents achieving the highest or lowest possible scores) implies that the questionnaire may lack items capturing the extreme intensities of the measured phenomenon, thereby indicating potential deficiencies in content validity.⁴²

Frequency of unanswered items

High rates of missing responses may indicate issues with item clarity, relevance or respondent burden, potentially compromising data quality and the instrument’s psychometric properties. These rates can highlight specific items requiring revision or removal due to poor understanding or sensitivity. Analysing patterns in missing data can help determine which items to retain or modify. Generally, missing rates between 10% and 20% are considered acceptable.⁴⁴

Determining feasibility

The feasibility of a questionnaire is typically evaluated by ensuring that its items are concise and easily comprehensible, while also minimising the time required for completion. In this study, two primary indicators will be computed to gauge feasibility: the mean duration for respondents to complete the instrument and the proportion of missing responses for each item. To mitigate the risk of an overly lengthy questionnaire, a comprehensive item analysis will be conducted alongside rigorous validation processes. The anticipated completion time will be calculated and documented, with an optimal threshold not exceeding 30 min to enhance participant engagement and response quality.²⁶

Scoring method

The instrument uses a Likert-type scale for scoring, and its final version will incorporate a standardisation method to yield a normalised scale from 0 to 100. This approach was preferred over raw sum scoring because the latter depends on the number of items and response options, leading to inconsistent ranges that hinder straightforward interpretation and inter-study comparisons. In contrast, the 0–100 normalized scale provides an intuitive, percentage-based metric that is independent of item count, thereby improving result interpretability, enabling consistent benchmarking, and supporting statistical analyses across diverse.^{45 46}

Integration of qualitative and quantitative data

Following the guidelines for mixed-methods research,¹¹ we will use a joint display matrix to integrate findings from the qualitative phase with item development and quantitative results. Qualitative themes and subcategories will be mapped against the generated items and factor structure to examine convergence, complementarity and expansion. Meta-inferences will be drawn to explain how the qualitative insights informed the final instrument and its psychometric properties. This integration process will enhance the content validity and contextual relevance of the PSCHCI.

Ethics approval and consent to participate

Ethical approval has been obtained from the Ethics Committee of Iran University of Medical Sciences (approval number: IR.IUMS.REC.1401.553). All participants will provide written informed consent prior to involvement, with detailed information provided on study aims, voluntary participation, confidentiality and the right to withdraw at any time without repercussion. Data will be stored securely on password-protected servers, accessible only to the research team, and anonymised during analysis to protect participant privacy. Any adverse events or ethical concerns will be reported immediately to the ethics committee.