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Abstract

Sexual dysfunction has been demonstrated to be related to a poor quality of life. These dysfunctions are especially prevalent among men. This cross-sectional study aimed to investigate the psychometric properties of the Persian translation of the Sexual Quality of Life–Male (SQOL-M), translated and adapted to measure sexual quality of life among Iranian men. Forward–backward procedures were applied in translating the original SQOL-M into Persian, and then the psychometric properties of the Persian translation of the SQOL-M were studied. A total of 181 participants (23-60 years old) were included in the study. Validity was assessed by construct validity using confirmatory factor analysis, convergent validity, and content validity. The international index of erectile function (IIEF) and the work ability index were used to study the convergent validity. Reliability was evaluated through internal consistency and test–retest reliability analyses. The results from confirmatory factor analysis confirmed a one-factor solution for the Persian version of the SQOL-M. Content validity of the translated measure was endorsed by 10 specialists. Pearson correlations indicated that work ability index score, dimensions of the IIEF, and the IIEF total score were positively correlated with the Persian version of the SQOL-M (p < .001). Reliability evaluation indicated a high internal consistency and test–retest reliability. The Cronbach’s alpha coefficient and intraclass correlation coefficients were .96 and .95, respectively. Results indicated that the Persian version of the SQOL-M has good to excellent psychometric properties and can be used to assess the sexual quality of life among Iranian men.

Keywords

reliability validity sexual quality of life men

Introduction

Sexuality as a key aspect of human beings has a fundamental role in the quality of life (QOL) and general well-being (Arrington, Cofrancesco, & Wu, 2004). Sexual dysfunction has been demonstrated to be related to poor QOL (Arrington et al., 2004; Bella, Lee, Carrier, Bénard, & Brock, 2015). Therefore, QOL is an important outcome in clinical sexual research (Litwin, Nied, & Dhanani, 1998). Sexual problems are especially prevalent among men (Kandeel, Koussa, & Swerdloff, 2001). Premature ejaculation (PE) is the most common male sexual dysfunction, with an estimated prevalence of 22% to 38% across all age groups (Laumann et al., 2005; Spector & Carey, 1990). It was reported that approximately 5% to 20% of men have moderate to severe erectile dysfunction (ED; Hatzimouratidis et al., 2010) which increases in older age (Prins, Blanker, Bohnen, Thomas, & Bosch, 2002). In 1995, ED was estimated to have affected over 152 million men worldwide and the ED projections for 2025 were to increase to approximately 322 million men (i.e., an increase of 170 million men; Ayta, McKinlay, & Krane, 1999). A literature review identified that only one study had examined the prevalence of ED among the Iranian male population. The results of that study indicated that the prevalence of ED was 18.8% among a sample aged between 20 and 70 years (Safarinejad, 2003).

With regard to the relatively high prevalence of PE and ED, it is predicted that QOL in many men can be a serious concern (Bella et al., 2015; Rosen, 1998). Attention to the influence of male sexual health on QOL is warranted. Therefore, a valid and reliable measure which can assess the effects of sexual dysfunction on men’s QOL is needed (Abraham, Symonds, & Morris, 2008).

There are some measures to assess the effects of sexual dysfunction on men’s QOL such as the Erectile Dysfunction–Effect on Quality of Life scale, the Sexual Life Quality Questionnaire, and the Self-Esteem and Relationship scale. Erectile Dysfunction–Effect on Quality of Life is a 15-item measure designed to assess the sexual QOL in men suffering from ED (MacDonagh, Porter, Pontin, & Ewings, 2004). Sexual Life Quality Questionnaire is a 16-item questionnaire which assesses sexual QOL and satisfaction with treatment for ED among men and their partners using 10 and 6 items, respectively (Woodward, Hass, & Woodward, 2002). The 14-item Self-Esteem and Relationship scale is another measure assessing the effects of ED on psychosocial well-being through two dimensions: sexual relationships (eight items) and confidence (six items; Cappelleri et al., 2004). Although the main purpose of these instruments is to evaluate the effects of sexual problems on men’s QOL, they cannot be used for assessing changes in sexual QOL among both ED and PE populations (Abraham et al., 2008). Sexual Quality of Life–Male (SQOL-M) is the only measure that can be used for the assessment of QOL among populations affected by both of these dysfunctions. Based on the Sexual Quality of Life–Female (Abraham et al., 2008), which was developed based on Spitzer’s quality of life model (Symonds, Boolell, & Quirk, 2005), SQOL-M is a self-report questionnaire which could be used among male populations with sexual dysfunction. SQOL-M has been reported to have good discriminant and convergent validity. It has also been reported to discriminate men with ED and PE from men without these sexual dysfunctions (Abraham et al., 2008). Good to excellent psychometric properties for the Persian translation of the Sexual Quality of Life–Female has been demonstrated in Iran (Maasoumi et al., 2013) but to the best of our knowledge, there has been no validated Persian translation of the SQOL-M and no research has been conducted using SQOL-M with an Iranian male population. The aim of this study was to examine the psychometric properties of the Persian version of the SQOL-M questionnaire.

Method

Design and Study Population

This was a cross-sectional and multicenter study conducted on an available sample of Iranian men during February to June 2014. In psychometric studies, according to Terwee et al. (2007), 4 to 10 subjects per item, with a minimum number of 100 subjects, are needed for a valid sample size. All men (n = 253) who worked in four different work settings including two hospitals, three banks, one industrial factory, and one fire station were invited to participate in the study. After the objectives of the study were explained, individuals who agreed to take part in the study completed the questionnaires. Male workers aged between 18 and 60 years who were married and were able to read and understand Persian questionnaires were included. Workers were selected because the participants were asked to respond to the work ability index (WAI), and married men were included because of cultural taboos in Iran for unmarried respondents, who may not have sufficient sex experience with a partner to allow them to correctly rate the items of SQOL-M and IIEF. Exclusion criteria were having a chronic or severe medical disease and/or mental health disorders which were assessed using a self-report questionnaire. Of the 253 male participants, 52 did not return the questionnaires or more than 50% of data were missing, 17 reported having a chronic or severe medical disease, and 3 reported having a chronic or severe mental disorder. Therefore, data from 181 participants were used in the analyses. For the pilot study, 30 normal men (not in the sample of 181 participants) completed the SQOL-M twice 2 weeks apart. The response rates for the hospitals, the banks, the industrial factory, and the fire station employees were 56 (52.8%), 69 (81.2%), 34 (87.2%), and 22 (95.6%), respectively.

Questionnaires

Sexual Quality of Life–Male

The SQOL-M is a short, self-report questionnaire which was developed by Abraham et al. (2008) to assess sexual QOL in men with sexual dysfunctions. The SQOL-M consists of 11 items with a total score ranging from 11 to 66. Each item is scored using a 6-point Likert-type scale ranging from 1 as completely agree to 6 as completely disagree. Higher scores indicate better male sexual QOL (Abraham et al., 2008).

Translation of the SQOL-M

Using Brislin’s model of translation (Jones, Lee, Phillips, Zhang, & Jaceldo, 2001), the original English version of SQOL-M was used to translate and adapt a Persian version. In the forward translation stage, two independent professional translators translated the questionnaire into Persian. Then, one of the authors along with both translators compared the two Persian translations and produced a single Persian provisional version. In the backward stage, two other expert English translators who were unaware of the original version translated the provisional Persian version back into English (see Table 1, for a sample of forward–backward translation). Afterward, an expert committee consisting of the translators, a sexologist, a urologist, and a social medicine professional compared the back translated English version with the original SQOL-M and after making linguistic and cultural adaptations, the final Persian version of the SQOL-M questionnaire was produced, see the appendix for the final Persian translation.

Table 1.

Sample Forward–Backward Translation Used in the Preparation of the Final Persian SQOL-M.

Original item	Forward translation	Backward translation
When I think about my sexual life, I feel frustrated		When I think about my sexual life, I feel disturbed
When I think about my sexual life, I am embarrassed		When I think about my sexual life, I feel ashamed of it
When I think about my sexual life, I feel guilty		When I think about my sexual life, I feel guilty

Note. SQOL-M = Sexual Quality of Life–Male.

International Index of Erectile Function

International index of erectile function (IIEF) is a 15-item, self-administered, and cross-culturally validated measure to assess erectile function designed by Rosen et al. (1997). Ten items of the IIEF are scored on a 6-point Likert-type scale ranging from 0 to 5 and the other five items are scored on a 5-point Likert-type scale ranging from 1 to 5, with higher scores indicating better sexual functioning. This measure can assess male sexual functioning along five dimensions: erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction (Rosen et al., 1997). Intercultural validation and generalizability of IIEF was demonstrated in Iran with satisfactory psychometric properties (Pakpour, Zeidi, Yekaninejad, & Burri, 2014).

Work Ability Index

WAI is among the important self-report instruments to assess ability to work and was originally developed by the Finnish Institute of Occupational Health (de Zwart, Frings-Dresen, & van Duivenbooden, 2002). This index consists of seven dimensions including “current work ability compared with lifetime best, work ability in relation to the demands of the job, number of current diseases diagnosed by a physician, estimated work impairment due to diseases, sick leave during the past 12 months, personal prognosis of work ability 2 years from now, and mental resources.” Reliability and validity of the Persian version of WAI was described by Abdolalizadeh et al. (2012).

Methods Used for Validity and Reliability Study

Construct validity using confirmatory factor analysis (CFA), convergent validity, and content validity of the Persian translation of the SQOL-M questionnaire were investigated as follows:

Construct Validity

Two methods were used to investigate the construct validity of the Persian version of the SQOL-M: exploratory factor analysis (EFA) using the principal component analysis (PCA) method and CFA using the weighted least squares. In the CFA, goodness-of-fit was investigated based on the root mean square error of approximation (RMSEA), the root mean square residuals (RMR), the goodness-of-fit Index (GFI), the adjusted goodness-of-fit index (AGFI), the comparative fit index (CFI), and the chi-square/degrees of freedom ratio (χ²/df; Munro, 2005). Values of RMSEA less than .05 were considered a close fit, less than .08 a reasonable fit, and greater than .1 a poor fit (Browne & Cudeck, 1992). Values of the RMR close to 0 were considered an acceptable fit. Values of GFI, greater than .9 or .8, and when this index is close to 1, indicate the best goodness-of-fit (Bentler, 1990; Hsu et al., 2012). Values of AGFI greater than .9 or .8 were considered as a good fit (Hsu et al., 2012). Also, values of the CFI greater than .9 were considered a good fit (Bentler, 1990). Finally, values of the χ²/df ratio greater than 2 were considered a good fit (Tabachnick & Fidell, 2007).

Convergent Validity

To assess the degree of convergent validity, all participants completed the SQOL-M, the IIEF, and the WAI. Pearson’s correlation coefficients were used to examine the correlations between the SQOL-M, the IIEF, and the WAI.

Content Validity

To study the content validity, two quantitative indicators were used: the content validity index (CVI) and the content validity ratio (CVR). Ten specialists (urologists and sexologist) rated each item of the Persian version of the SQOL-M. To calculate CVI, the specialists rated each items of the Persian version of the SQOL-M on a 4-point Likert-type scale from 1 (not relevant, not simple, and not clear) to 4 (very relevant, very simple, and very clear). Similarly, to calculate CVR, experts rated each item on a 3-point scale (1 = essential, 2 = useful but not essential, 3 = not essential).

Reliability

Internal Consistency

Cronbach’s alpha was used to assess the internal consistency of the Persian version of the SQOL-M. Values equal or greater than .7 were considered satisfactory (Munro, 2005).

Test–Retest Reliability

Thirty participants (not included in the sample of 181 participants) completed the SQOL-M questionnaire twice in 2 weeks. Reproducibility of the Persian version of the SQOL-M was analyzed using IBM SPSS 21 (USA, SPSS Inc.) to compute the intraclass correlation coefficient (ICC; using a two-factor mixed-effects model and type consistency with 95% confidence intervals).

Ethics

The ethics committees of both Birjand University of Medical Sciences and Sabzevar University of Medical Sciences reviewed and approved the study procedures. All the study centers also approved the study procedures. All participants were informed about the objectives of the study and were assured data would be confidential. All participants read and signed the written informed consent documents.

Statistical Analysis

The statistical analyses were performed using IBM SPSS 21 (USA, SPSS Inc.) and LISREL 8.80 (Scientific Software International, Inc., Lincolnwood, IL, USA).

Results

The sociodemographic characteristics of the participants are reported in Table 2. The mean age of the participants was 35.32 ± 6.97 years with a range from 23 to 60 years. The highest proportion of workers were bank employees (38.12%) and the educational level of a majority of the participants was high school (55.68%). The mean scores and standard deviations on the Persian SQOL-M, the IIEF and the WAI were 53.8 (12), 48.2 (14.4), and 37.7 (6.8), respectively. The descriptive results for the IIEF and WAI subscales are reported in Table 3. Interitem correlations and the mean (SD) of all the 11 items on the Persian translation of the SQOL-M are reported in Table 4.

Table 2.

Demographic Characteristics of the Participants (N = 181).

Characteristics	N	%
Age (years)
≤29	32	17.7
30-39	99	54.7
40-49	40	22.1
≥50	10	5.5
Educational level
High school	98	55.7
Bachelor	26	14.8
Master	42	23.9
Degree of philosophy	10	5.7
Working sector
Industrial workers	34	18.8
Bank	69	38.1
Fire station	22	12.2
Health care works	56	30.9
Length of marriage (years)
≤5	37	20.5
6-10	77	42.5
11-16	32	17.7
≥17	35	19.3

Table 3.

Descriptive Statistics for the Persian SQOL-M, IIEF, and WAI Among the Participants (N = 181).

Variables	Dimensions	M (SD)	Range
SQOL-M	Total score	53.8 (12.0)	12-66
IIEF	Erection Function	20.2 (6.9)	1-30
	Orgasmic Function	7.1 (2.6)	0-12
	Sexual Desire	5.2 (1.7)	1-10
	Intercourse Satisfaction	9.6 (3.5)	0-15
	Overall Satisfaction	6.0 (2.0)	0-10
	Total score	48.2 (14.4)	3-75
WAI	Current work ability compared with lifetime best	7.7 (2.0)	3-10
	Work ability in relation to demands of the job	7.8 (1.7)	2-10
	Number of current diseases diagnosed by physician	4.7 (2.3)	1-7
	Estimated work impairment due to diseases	4.9 (1.2)	2-6
	Sick leave during past year (12 months)	4.3 (1.1)	1-5
	Own prognosis of work ability 2 years from now	5.7 (1.7)	1-7
	Mental resources	2.6 (0.9)	1-4
	Total score	37.7 (6.8)	18-49

Note. SQOL-M = Sexual Quality of Life–Male; IIEF = international index of erectile function; WAI = work ability index.

Table 4.

Interitem Correlations and Mean (SD) for Items of the Persian Translation of SQOL-M.

	M (SD)	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	Q9	Q10	Q11
Q1	4.53 (1.48)	1	.825**	.681**	.720**	.738**	.685**	.610**	.696**	.660**	.630**	.664**
Q2	4.73 (1.37)		1	.690**	.765**	.776**	.743**	.629**	.721**	.725**	.592**	.697**
Q3	4.93 (1.26)			1	.736**	.699**	.568**	.565**	.692**	.648**	.598**	.631**
Q4	5.05 (1.13)				1	.739**	.658**	.630**	.697**	.644**	.685**	.609**
Q5	4.9 (1.25)					1	.782**	.706**	.754**	.699**	.665**	.781**
Q6	4.98 (1.21)						1	.689**	.688**	.715**	.683**	.713**
Q7	4.66 (1.44)							1	.680**	.649**	.650**	.718**
Q8	5.04 (1.21)								1	.851**	.757**	.729**
Q9	5.1 (1.23)									1	.659**	.687**
Q10	4.9 (1.27)										1	.701**
Q11	4.99 (1.3)											1

Note. SQOL-M = Sexual Quality of Life–Male.

p < .01.

Validity

Construct Validity

EFA using the PCA method was conducted on the 11 items of the Persian version of the SQOL-M without rotation, because only one factor was identified. The Kaiser–Meyer–Olkin measure of sampling adequacy was 0.93, which was above the acceptable value of 0.5 (Field, 2009). Bartlett’s test of sphericity was significant (p = .001), indicating sufficient correlation between the items to proceed with PCA. Only one component identified had an eigenvalue over Kaiser’s criterion of 1. This single factor was the sexual QOL among men (eigenvalue = 7.918) and had 11 items, accounting for 71.99% of the total variance. Corrected item–total correlations ranged from .76 to .87, and Cronbach’s alpha was .96. Table 5 contains the 11 Persian items of the translated SQOL-M, the factor loadings, the communality estimates, the item–total correlations, and Cronbach’s alpha if an item was deleted from the Persian version of the SQOL-M.

Table 5.

SQOL-M Items and Factor Loadings for the Persian Items^a From PCA.

SQOL-M items	Factor loadings	Communality	Corrected item–total correlation	Cronbach’s alpha if item deleted
1. When I think about my sexual life, I feel frustrated	.848	.72	.813	.956
2. When I think about my sexual life, I feel depressed	.877	.769	.847	.955
3. When I think about my sexual life, I feel like less of a man	.804	.646	.761	.958
4. I have lost confidence in myself as a sexual partner	.844	.713	.811	.956
5. When I think about my sexual life, I feel anxious	.896	.802	.869	.954
6. When I think about my sexual life, I feel angry	.85	.722	.816	.956
7. I worry about the future of my sexual life	.805	.648	.763	.958
8. When I think about my sexual life, I am embarrassed	.887	.787	.858	.955
9. When I think about my sexual life, I feel guilty	.852	.725	.816	.956
10. When I think about my sexual life, I worry that my partner feels hurt or rejected	.815	.664	.774	.957
11. When I think about my sexual life, I feel like I have lost something	.850	.723	.817	.956

Note. SQOL-M = Sexual Quality of Life–Male; PCA = principal component analysis.

Although the original English items of the SQOL-M are written in the table, all the data are for the Persian items.

Similarly, examination of the underlying constructs of the Persian version of the SQOL-M using CFA indicated that a one-factor model for the questionnaire had the best goodness-of-fit (see Figure 1). The results of the CFA indicated a relatively acceptable goodness-of-fit obtained from responses to the Persian version of the SQOL-M. The goodness-of-fit indices were as follows: RMSEA = .063; RMR = .04; GFI = .94; AGFI = .89; CFI = .99; and χ² = 63.59 (p < .0043, df = 37), χ²/df = 1.719. Almost all these indices, except for χ²/df, suggested an acceptable goodness-of-fit.

Figure 1.

The one-factor model of the Persian translation of SQOL-M obtained by confirmatory factor analysis.

Convergent Validity

The results from Pearson correlations analysis indicated that the WAI, the IIEF’s dimensions, and total score were positively correlated with the Persian SQOL-M (all ps < .001; see Table 6). Correlations ranged from .27 to .56 with the highest correlation found between the IIEF’s overall satisfaction scale and the Persian SQOL-M’s total score (r = .56, p < .001).

Table 6.

Correlations Between the Persian Translation of SQOL-M With WAI, IIEF’s Dimensions, and Total Scores (N = 181).

Variables		Pearson correlation	p
The Persian SQOL-M’s total score	Erection Function	.37	<.001
	Orgasmic Function	.43	<.001
	Sexual Desire	.41	<.001
	Intercourse Satisfaction	.44	<.001
	Overall Satisfaction	.56	<.001
	Total score of IIEF	.50	<.001
	Total score of WAI	.27	<.001

Note. SQOL-M = Sexual Quality of Life–Male; IIEF = international index of erectile function; WAI = work ability index.

Content Validity

As noted earlier, to study the content validity of the Persian version of the SQOL-M, two indices were calculated using the ratings from 10 specialists: CVI and CVR. CVI was .9 and CVR was .82, indicating excellent content validity from the experts’ points of view.

Reliability

Internal Consistency

Results indicated that the Persian translation of the SQOL-M had a high internal consistency. The Cronbach’s alpha for the total scale was .96 (see Table 5, for more details about corrected item–total correlations).

Test–Retest Reliability

Conducting ICC using a two-factor mixed-effects model and type consistency (McGraw & Wong, 1996; Shrout & Fleiss, 1979), excellent reliability was found between the first and the second administration of the Persian version of the SQOL-M. The response rate for the second assessment was 100% and the single measure ICC was .995 with a 95% confidence interval from .99 to .998. The within-person analysis of variance was not significant (F_{(1, 29)} = 3.002, p = .094).

Discussion

Findings reported show excellent internal consistency (Cronbach’s alpha = .96) and test–retest reliability (single measure ICC = .995) for the Persian translation of the SQOL-M; these findings were consistent with those of Abraham et al. (2008) which indicated that the original SQOL-M had excellent internal consistency among those with PE and with a normal population (Cronbach’s alpha = .93 and .82, respectively) as well as excellent test–retest reliability (ICC = .9) among normal men (Abraham et al., 2008). Corrected item–total correlations ranging from .76 to .87 (see Table 5) suggest a high degree of consistency among the items of the Persian version of the SQOL-M.

Both the EFA and the CFA findings indicated that a one-factor solution is a good fit for the 11-item Persian version of the SQOL-M. In the EFA using the PCA method, only one factor with 11 items was identified with an eigenvalue as large as 7.92 accounting for 71.99% of the variance. This interesting finding encouraged us to hypothesize a one-factor solution for the Persian version of the SQOL-M in the CFA. As noted earlier, almost all goodness-of-fit indices, except for χ²/df, which approached Tabachnick and Fidell’s (2007) criterion of 2 (see the Results section), demonstrated an acceptable goodness-of-fit for the one-factor solution. These findings were consistent with those of Abraham et al. (2008) using the original English version of the SQOL-M which also showed a one-factor solution.

The Persian version of the SQOL-M was positively correlated with all the dimensions as well as the total score of IIEF indicating good convergent validity for the Persian version of the SQOL-M. Of the IIEF dimensions, overall satisfaction had the highest correlation with the total score of Persian version of the SQOL-M. Consistent with these results, Abraham et al. (2008) reported a positive correlation between the SQOL-M and dimensions of the IIEF. One possible interpretation of these findings is that a gratifying sexual relationship not only is related to better sexual performance, especially erection and reflex genic orgasm, but also can affect the quality of sexual relationships and the occurrence of psychogenic orgasm. The WAI was also significantly correlated to the Persian version of the SQOL-M. The positive correlation between the WAI and the QOL has been previously well documented (Chiu et al., 2007; Rostamabadi, Mazloumi, & Rahimi Foroushani, 2014; Tuomi, Huuhtanen, Nykyri, & Ilmarinen, 2001). Since sexuality is an important aspect of the QOL (Robinson & Molzahn, 2007), perhaps sexual QOL can also positively affect the WAI.

To the best of our knowledge, Abraham et al.’s (2008) study is the only psychometric study of the SQOL-M so the findings of this study provide support for the generalizability of the SQOL-M, especially the intercultural generalization and the applicability of SQOL-M to Iranian men who speak Persian. The study also may facilitate further research on the sexual QOL among Iranian men.

Limitations

This study has several limitations: It did not test the known-group (discriminant) validity of the Persian version of the SQOL-M although the original validation study did report that the SQOL-M had satisfactory known-group validity (Abraham et al., 2008). Examining these and other psychometric properties such as the diagnostic power of the original and the Persian version of the SQOL-M to identify sexual dysfunctions in men could be worthwhile for further research. The sample might be biased because only men who were workers, younger than 60 years, and married were included, limiting the external validity (generalizability) of the findings. Finally, the χ²/df index results did not support a one-factor solution. Therefore, caution should be exercised when interpreting the findings.

Conclusion

Altogether, findings indicated that the Persian version of the SQOL-M is a reliable and valid instrument for the assessment of sexual QOL among Iranian men. These findings could extend the intercultural generalizability of the original SQOL-M and could facilitate further research on sexual QOL among Iranian Men.

Footnotes

Appendix

Acknowledgements

We would like to gratefully acknowledge the participants in this study. In addition, we are grateful to Lucy Abraham for her kind permission to translate and validate the Persian version of the SQOL-M questionnaire and all Iranian specialists for their cooperation in the translation process.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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Psychometric Properties of the Persian Translation of the Sexual Quality of Life–Male Questionnaire

Abstract

Keywords

Introduction

Method

Design and Study Population

Questionnaires

Sexual Quality of Life–Male

Translation of the SQOL-M

International Index of Erectile Function

Work Ability Index

Methods Used for Validity and Reliability Study

Construct Validity

Convergent Validity

Content Validity

Reliability

Internal Consistency

Test–Retest Reliability

Ethics

Statistical Analysis

Results

Validity

Construct Validity

Convergent Validity

Content Validity

Reliability

Internal Consistency

Test–Retest Reliability

Discussion

Limitations

Conclusion

Footnotes

Appendix

Acknowledgements

Declaration of Conflicting Interests

Funding

References