Psychometric Properties under EFA, CFA, Measurement Invariance, and IRT Models for Older Adults' First Aids Knowledge Scale among Iranian Grandparents: The Modified Scale

This research aims to create and evaluate an assessment tool termed Older Adults' First Aid Knowledge Scale, which measures the knowledge and attitude of Iranian grandparents about first aid. In accordance with COSIM guidelines, 485 individuals in southern Iran completed the instrument as part of a psychometric investigation. Rasch partial credit model (PCM), exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and receiver operating characteristic (ROC) analysis were used to analyze the results. The final version of OFAKS consisted of 18 items that were validated through EFA, CFA, and item response theory (IRT) analysis. All items showed measurement invariance and consecutive response groupings in the predictable order, and the instrument had strong internal consistency. Although Rasch's analysis demonstrated the significance of OFAKS, further investigations and testing in different settings are required to confirm the validity of the tool.


Introduction
With the increasing rate of global aging, the population growth of older adults in some developing countries such as Iran and other Middle Eastern and North African (MENA) countries is 3.3 to 4.8 times greater than the developed ones.Te rapid aging of the global population presents a unique challenge in developing countries like Iran, where the older population is growing much faster than in developed nations.Importantly, almost two-thirds of adults live in these developing countries [1].Accidents and injuries are the leading cause of death in young children, making it a signifcant concern in social and health policies [2].Incidents at home account for 35% of unintentional childhood injuries, while for 6-year-old children, this percentage (60-80%) is a signifcant concern [3].Accidents that take place within the household are more widespread compared to other forms of accidents.Tis can be attributed to the continuous presence of potential dangers and the fact that the risk of an accident persists throughout the entire day.Moreover, despite feeling safe and protected at home, it is unfortunate that a signifcant number of children sufer injuries or even lose their lives within the confnes of their own residences [4].Amongst all age groups, children between the ages of 0 and 6 face the greatest vulnerability to such risks [5].
Child safety remains a top concern among parents today.Growing up, children are vulnerable to injuries and accidents due to their limited ability to respond quickly and appropriately in emergency situations.Tey also have little control over their surroundings, which further increases the risk of harm and even death.It is crucial for those around the child, especially family members, to be vigilant and take necessary measures to protect children from domestic accidents.Families should be aware of potential hazards in and around the house [5].To this end, grandparents play a signifcant economic and social role in providing childcare to families, with 58% of grandmothers and 49% of grandfathers in ten European countries taking care of at least one grandchild under the age of 16 in the past year in the absence of parents [6].
In recent years, there has been a signifcant increase in the availability of full-time employment options for women, particularly mothers, in Iran.As a result, the importance of grandparents stepping in to care for their grandchildren in the absence of their mothers has gained prominence. Tis practice has now become deeply ingrained in the child-rearing culture of the Middle East, mirroring similar customs observed in Far Asian countries such as China, Taiwan, South Korea, and Japan.Te prevalence of injuries and accidents for children in Iran may pose a challenge, especially in light of the decreasing size of families (nuclear family).Statistical data reveal that among cases under 5 years of age examined by Iran's forensic medicine, 30.4% of deaths are attributed to domestic accidents, including incidents like drowning, burns, and electrocution, while 21.1% are linked to urban road accidents.Te prevalence of deaths resulting from accidents and mishaps in both urban and suburban areas underscores the signifcance of addressing safety measures to prevent such fatalities.A separate study indicates that nontrafc accidents and incidents constitute 12.5% of the causes of death in this age group, with trafc accidents and incidents contributing to 9.8% of fatalities among children under 5 years of age in Iran.
Preventing home accidents can be achieved through simple interventions such as improving the home environment, providing regular training to parents who spend most of their time with children, and increasing parental awareness [5].Most domestic accidents can be prevented by increasing awareness, improving the home environment and greater safety [7].Notably, nonprofessionals, such as grandparents, can play a vital role in saving children's lives during emergency situations.
Learning life-saving frst aid (LSFA) skills, including frst aid (FA) and cardiopulmonary resuscitation (CPR), should be a part of basic health education for all people starting from the age of 10, according to Bollig et al. [8].Nevertheless, enabling individuals to provide life-saving frst aid in a medical emergency requires training [9].FA is the set of emergency care or treatment given before obtaining regular medical help, and it should be readily available to the general public without hindering professional examination or wound treatment [10].Due to the increasing number of working parents in today's world, grandparents are now more responsible for the care of their grandchildren.Consequently, they should also be introduced to FA measures, including resuscitation.To achieve this, the frst step is to assess the level of knowledge of parents and grandparents in the feld of frst aid using the FA questionnaire for older people.To this end, the Older Adults' First Aid Knowledge Scale has been translated, developed, and validated in the Persian language.
Te OFAKS evaluates middle-aged and older adults' knowledge, attitudes, barriers, and intentions regarding folic acid and its importance.Te OFAKS questionnaire (12items), originally developed in Slovenia, assesses knowledge about frst aid among older adults by Dolenc et al. [11].However, this instrument was only validated in the Slovenian language among 3355 adult inhabitants of Slovenia, and its psychometric properties (i.e., EFA, CFA, and IRT) were not reported in their paper.To address this gap, the current study aimed to develop a Persian version of the OFAKS questionnaire and determine its psychometric properties in Iran.
Te increasing number of older people taking care of their grandchildren, combined with more job opportunities for mothers, highlights the importance of being awareness about frst aid to prevent accidents and injuries at home.It is crucial for families and the healthcare system to have an efective scale to assess the level of frst aid awareness among grandparents.

Materials and Methods
To validate and modify the OFAKS questionnaire, a crosssectional psychometric study was conducted at the Farzangan Daily Care Foundation (FDCF), a residence for over 17,500 individuals aged 60 and above located in southern Iran.Based on these parameters, the sample size was calculated to be 485 people.To select the participants for the study, the names of eligible seniors were entered into Excel software, and eligible participants were classifed using the inclusion criteria.Each person was assigned a membership ID, and the sample was randomly selected using the random numbers table.
Te study's inclusion criteria were individuals aged 60 years or older who desired and provided informed consent to participate, had literacy skills, had grandchildren under fve years of age, and took care of their grandchildren in the absence of their parents.Exclusion criteria included failing to answer the questionnaire, sufering from an illness that afected their ability to provide care for the child, unwillingness to continue cooperation, failing to answer more than three questions of OFAKS, and failure to take care of the grandchild.Demographic information such as age, gender, number of hours spent caring for grandchildren in 24 hours, and number of grandchildren was collected for each participant.

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Te Scientifc World Journal 2.1.Instrumentation.Te published version of the OFAKS in English in 2021 includes 12 items, six of which are related to FA knowledge and six of which are related to attitude towards FA.Tis tool helps measure and identify the knowledge and attitude of older adults towards FA.Te main language of the OFAKS was Slovenian in the study by Dolenc et al. [11], whose English version is included in the appendix of the current paper.Te original version of OFAKS was created by a team at the University of Ljubljana in Slovenia in 2021 and was administered over the phone to 3355 Slovenian citizens, 35% of whom were over 60 years old (1174 individuals) [11].Te questionnaire was analyzed with pre-and post-tests and an expert panel, and all items, except for the emergency medical phone number question, had three answer options.Te instrument's scoring range was from 0 to 10, with a low score indicating limited knowledge of frst aid.While the English version of this tool is available, no validation was found in other languages, and classical EFA and CFA validation and modern IRT models are not reported for this instrument.

2.2.
Procedure.Te research instrument was translated and validated according to the protocol of the World Health Organization (WHO) after obtaining permission from the designers of the OFAKS.Initially, the questionnaire was translated from English to Persian by two independent translators, and a common version of the initial questionnaire was obtained in a meeting attended by the translators.Ten literate older adults possessing at least a bachelor's degree were interviewed to evaluate the face validity of the questionnaire.Tey were asked to check the level of difculty, appropriateness, and ambiguity of the items and ofer their suggestions to determine the comprehensibility of the questionnaire.After confrming the face validity, the content validity was evaluated using the content validity ratio (CVR) and then the content validity index (CVI).According to the Lawshe table, if ten evaluators are used, the acceptable limit of CVR is 0.62.
During the study, it was found that the validity ratio for certain items, such as 3 and 7, was less than 0.6.In the second session for developing the OFAKS, the test was reviewed with an expert panel.Te panel consisted of eight clinical experts and PhD holders in Emergency Medicine, Health In Emergencies and Disaster, Pediatrics, Geriatrics, and Gerontology.Tey had at least eight years of work experience.Te expert panel provided their opinions, and through a semistructured interview and brainstorming, new themes were extracted.Finally, with face and content validity, the OFAKS was developed to include 20 questions with three answer options (0, 1, and 2) and was classifed into four subscales: Knowledge (items 1 to 8), Attitude (items 9 to 13), Obstacles/Barriers (items 14 to 19), and Intention (items 19 and 20).Te scoring range for each of the subscales includes 0 to 9, 0 to 10, 0 to 10, and 0 to 4, respectively, and the total score range of OFAKS includes 0 to 33.A higher score indicates a better and more accurate measure of FA.Te overall CVI was determined to be higher than 0.71.After confrming the validity of the form and content, this version of the questionnaire was presented to 5 literate older adults for reading comprehension.Teir feedback was subsequently collected and used to improve the questionnaire.
In the next step, 285 older men and women completed the 20-item version of the OFAKS questionnaire, which was then entered into SPSS software (v.28).To determine OFAKS' construct validity, EFA with the Maximum Likelihood model, Varimax rotation method, and Scree-Plot were used to identify its factors.Presuppositions related to the adequacy of the samples were checked using the Kaiser-Meir-Olkin (KMO) test and Bartlett sphericity test, which confrmed these assumptions [12].During the following step, the results of the EFA were calculated on the second group population (n � 200) using the confrmatory factor analysis method (CFA) in JAMOVI 2.4.8 software (2023), and the ft indices were measured [13].Finally, the internal homogeneity of the OFAKS was tested using McDonald's omega coefcient, Cronbach's alpha, and Pearson's correlation [14,15].
Te study utilized the JAMOVI 2.4.8 software to conduct an IRT analysis, specifcally using the partial credit model (PCM) and rating scale model (RSM) [16,17].Te analysis also included measuring the measurement invariance (MI) for good ft estimates across the groups, as well as checking the internal stability of the tool by examining the intracluster correlation index (ICC).Unfortunately, we were unable to determine the cutof points of OFAKS using receiver operating characteristics (ROC) curve analysis due to the lack of a criterion questionnaire in the Persian language.Te study adhered to the Helsinki Convention, the COSMIN checklist, and the STROBE guide and was approved by the Ethics Committee of Shiraz University of Medical Sciences (IR.SUMS.SCHEANUT.REC.1402.009 on March 5, 2023).All participants provided verbal and written informed consent, and data were collected between March and June 2023.

Participants' Characteristics.
Te research involved almost 485 older adults, with 56.7% males and 43.3% females.Among them, 93% live with their spouses and 84.7% of them have taken care of at least one grandchild in the past year.Teir average age was 63.4 (with an SD of 8.57).Te mean score of the OFAKS 20-item scale was 12.91 for all participants, with a range of 0-33, an SD of 4.65, a median score of 12, and an interquartile range of 6.75.For men, the mean score was 13.33 (SD � 4.77, IQR � 7), and for women, it was 12.37 (SD � 4.47, IQR � 6).Te reliability coefcient (McDonald's Omega) was 0.645 (Cronbach's α � 0.655).Moreover, there were no signifcant diferences between male and female participants in the total score of OFAKS (t � 1.255, Cohen's d � −0.11 [95% CI � −0.1182-0.5307],df � 483, P > 0.05).Based on the table above, it can be observed that Factor 1 (Knowledge) includes items 1, 2, 4, 5, 6, and 8, while Factor 2 (Attitude) contains items 9 to 13. Factor 3 (Barriers) comprises items 14 to 18, and Factor 4 (Intention) consists of items 19 and 20.Te most commonly used ft indices (RMSEA � 0.44, SRMR � 0.072, CFI � 0.951, GFI � 0.958, and TLI � 0.942) demonstrate that there is an acceptable ft between the hypothetical model and the data.All comparative ft indices showed good model ftness of OFAKS 18item, P < 0.05 [20].However, items 3 and 7 were removed from the OFAKS' items as they did not meet the criteria of the CFA due to less measure of uniqueness (Psi) (<0.2), as evident in table (P > 0.05).

IRT Psychometric Analysis for OFAKS. Te Rasch Rating
Scale Model (RSM), also known as the polytomous Rasch model, developed by Andrich in 1978, and the Partial Credit Model (PCM) are both models of IRT analysis used for instruments with polytomous items.Tese models were extracted for the scale (see Table 2).Te Inft (informationweighted mean square statistic), Outft (outlier-sensitive mean square statistic), Delta-tau, and Turstone thresholds of the PCM all indicate the well and unique distribution of items' threshold in difculty, person's ability, and discriminant, which are the same across items in the OFAKS (P < 0.001) [21].Tis indicates that the scales are well designed for respondents (Person Reliability � 0.676, MADaQ3 > 0.882, n � 485, P < 0.001).Additionally, some ft indices in IRT analysis were satisfactory, such as the item separation index (8.32,suggested cutof >2), person separation reliability (0.84, suggested cutof >0.7), item separation reliability (0.91, suggested cutof >0.7), and person separation index (2.32,suggested cutof >2) [16,17].However, items 3 and 7 of OFAKS, due to high measures in difculty and a person's ability, seem to be deleted (delta-tau >0.9).In the OFAKS, 18 items confrmed satisfactory ft statistics (ranging from 0.45 to 1.8), not including items 3 and 7, which showed undesirable ones (equal to 3.211 and 2.113).
Te results of PCM and RSM models are shown in Figures 1 and 2, which illustrate the inft and outft plots.Tese fgures also illustrate the intersections of the category probability curves (CPC), also known as theta for measuring      Te Scientifc World Journal ability parameters in the IRTcontext, for two misftted items, i.e., 3 and 7, as samples, with the remaining items [16,17].

Measurement Invariance Results
. Table 3 displays the results of the MI analyses for older men and women.Te results show that the goodness-of-ft was excellent for all MI models, there were minimal diferences between the descriptive ft parameters, and the likelihood ratio tests indicate that there were no signifcant diferences in model ft between MI models (with and without menopausal spouse).Terefore, an equal ft across all MI models was obtained for the OFAKS among both samples (ΔSRMR and ΔRMSEA ≤0.05) [22,23].
3.5.OFAKSs (Short-Version) Reliability.Te internal consistency of the tool was assessed using Cronbach's alpha, McDonald's omega coefcients, and the intraclass correlation coefcient (ICC).Te results of the ICC calculation indicated that the internal consistency of the tool was good, with a value of ICC � 0.71 (n � 485, P < 0.002, 95% CI � 0.69-0.78).Cronbach's alpha and McDonald's omega were also found to be above 0.65, which is considered an acceptable level of internal consistency.Additionally, Fleiss's kappa coefcient (1981) was calculated as 0.74 in this study, indicating the high reliability of the tool (P < 0.002, 95% � 0.68-0.79).Furthermore, Table 4 shows the results of the Pearson correlation coefcient (PCC) between the OFAKS sum score and its domains.Te r-value of four domains and the total score of OFAKS are signifcantly high (rp ≥ 0.4, P < 0.01 and 0.05, n � 485).However, it was not possible to establish the cutof points of the OAKS using ROC analysis due to the lack of alternative and equivalent questionnaires (criterion-related validity) in the Persian language and golden standard.

Discussion and Conclusion
Te main fndings of the current research are as follows: (1) classic factor analysis (EFA & CFA) confrmed that OFAKS consists of 18 items with a 4-factor structure.(2) OFAKS is found to be more reliable when used with Iranian samples.
(3) Te IRT analysis models (PCM & RSM) also confrmed the 18-item structure of OFAKS.(4) Te OFAKS is a practical tool for assessing the frst aid knowledge of older adults.( 5) Te research also evaluated the attitudes and barriers towards participating in frst aid education.(6) Te OFAKS is used in community-based settings to inform health policy making.Tis study assessed the reliability of the 18-item OFAKS scale by using Cronbach's alpha, McDonald's omega coefcients, convergent validity, and ICC.Te results mirrored fndings from other samples, but all items exhibited misft in a unidimensional model.1.Four factors were identifed through EFA and CFA.Yet, items 3 and 7 were deemed misftting in Rasch PCM and RSM analysis.Consequently, these items were excluded from the original 20-item scale.Te initial evaluation of person fts revealed that the lack of unidimensionality assumption led to the misft.However, eliminating respondents with diverse patterns did not enhance the overall ft indices.To sum up, all aforementioned items displayed misft in a unidimensional population.Additionally, unidimensionality assumes the scale measures a single underlying construct.Unidimensionality refers to the ability to measure a single concept, trait, or attribute.For instance, a personality scale, attitude scale, or any other scale that is unidimensional would consist of items that are solely related to the specifc concept being measured.
Moreover, out of the 20 items, two had category ft statistics greater than 1.5, despite the fact that the average measures and step calibrations for all fve response categories were consistently increasing.According to Linacre, achieving a minimum of 1.0 logits between step calibrations is crucial for a three-category scale to have the optimal number of response categories [14].In addition, there were no signifcant diferences between older men and women in the sum score of OFAKS and its four domains (P ≤ 0.05).
Te results revealed that the satisfactory model for the scale has a 4-factor structure that accounts for 73.51% of the variance, based on exploratory and confrmatory factor analyses.Further, McDonald's omega and Cronbach's alpha were both higher than 0.7 for the 18-item scale and four factors.Te study also indicated that the 18-item version of OFAKS has improved in convergent rationality and internal consistency with the new 4-factor structure.Te number of response categories requires evaluating all versions, according to Rasch's analysis results, though the PCM and RSM designated that all the items contributed satisfactorily to their domain [21].Based on the results of the likelihood ratio tests, there were no signifcant diferences in model ft between MI models [22,23].Tis indicates that the OFAKS version was equally efective for both men and women.Additionally, as an ofcial language of Iran, the Persian version of the OFAKS questionnaire was administered to the adult participants who shared a similar ethnicity.Based on the psychometric properties and IRT characteristics, it can be concluded that the 18-item version of OFAKS is superior, although further research is required.

Limitations and Suggestions
Tis study had some limitations, such as difculty reaching inhabitants in certain areas of the south and southwest of Iran due to geographic dispersion.Te survey was conducted by native questioners from the same areas.Bilingualism was also a concern, as the Qashqai Turks and Lors have their own languages.Terefore, questioners were selected who were familiar with the local language of the area.Additionally, since the data collected were from aged couples who were caring for their grandchildren, further investigation is required on single grandfathers or grandmothers.
Due to its cultural sensitivity, the 18-item OFAKS is recommended as a reliable and valid multidimensional instrument to be used among middle-aged grandparents in Iran and other societies with similar cultures in the MENA region.Future research should focus on examining the expressive aspects of various psychological constructs and 8 Te Scientifc World Journal develop culturally sensitive items to represent them.Since there is no criterion scale available as a golden standard for criterion-related validity, ROC analysis was not conducted in this study, and the cutof point for the OFAKS could not be determined.It is also suggested that future validation studies evaluate the OFAKS's versions and response categories, particularly among never-married and widowed men and women who care for their siblings' children.In Iran, there is a need to take into account the gender and cultural aspects when considering the awareness of frst aid among grandparents.Grandparents have a signifcant impact on the growth and emotional well-being of young children, as they introduce them to family history and provide support for their development.Studies indicate that grandmothers who actively care for their grandchildren experience better physical and mental health compared to those who do not.Consequently, the presence of grandchildren with grandparents is crucial, necessitating the availability of emergency supplies such as a frst aid kit in case of unforeseen incidents.

Figure 1 :
Figure 1: Items 3 and 7 of OFAKS with the lowest ftting among all items.

Table 1 .
Validity.Te results of the EFA (n � 285) and CFA (n � 200) performed on the OFAKS are presented in Construct validity was tested using Maximum Te Scientifc World Journal

Table 2 :
IRT psychiatric analysis in the polytomous Rasch model for the OFAKS 18 items (RSM and PCM models).
Results of measurement invariance for the OFAKS (18 items) between older women and men (n � 485).