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The World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) is a widespread measure of disability and functional impairment, which is bundled with the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) for use in psychiatry. Administering psychometric scales via the Internet is an effective way to reach respondents and allow for convenient handling of data.
The aim was to study the psychometric properties of the 12-item self-report WHODAS 2.0 when administered online to individuals with anxiety and stress disorders. The WHODAS 2.0 was hypothesized to exhibit high internal consistency and be unidimensional. We also expected the WHODAS 2.0 to show high 2-week test-retest reliability, convergent validity (correlations approximately .50 to .90 with other self-report measures of functional impairment), that it would differentiate between patients with and without exhaustion disorder, and that it would respond to change in primary symptom domain.
We administered the 12-item self-report WHODAS 2.0 online to patients with anxiety and stress disorders (N=160) enrolled in clinical trials of cognitive behavior therapy, and analyzed psychometric properties within a classical test theory framework. Scores were compared with well-established symptom and disability measures, and sensitivity to change was studied from pretreatment to posttreatment assessment.
The 12-item self-report WHODAS 2.0 showed high internal consistency (Cronbach alpha=.83-.92), high 2-week test-retest reliability (intraclass correlation coefficient=.83), adequate construct validity, and was sensitive to change. We found preliminary evidence for a three-factorial structure, but one strong factor accounted for a clear majority of the variance.
We conclude that the 12-item self-report WHODAS 2.0 is a psychometrically sound instrument when administered online to individuals with anxiety and stress disorders, but that it is probably fruitful to also report the three subfactors to facilitate comparisons between studies.
Clinicaltrials.gov NCT02540317; https://clinicaltrials.gov/ct2/show/NCT02540317 (Archived by WebCite at http://www.webcitation.org/6vQEdYAem); Clinicaltrials.gov NCT02314065; https://clinicaltrials.gov/ct2/show/NCT02314065 (Archived by WebCite at http://www.webcitation.org/6vQEjlUU8)
The World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) [
Administering psychometric questionnaires via the Internet is rapidly becoming more common in both research and routine mental care. Compared with conventional pencil-and-paper administration, there are many advantages of this online approach. Respondents can complete the necessary questionnaires wherever an Internet connection is available, and for the clinician or researcher data are quickly and easily stored, scored, analyzed, and interpreted with less risk for human error. Questionnaires are easily integrated with routine care software for evaluation and record keeping, as well as digital monitoring systems and Web-based psychological treatments. Loss of individual item scores may be prevented entirely, time of measurement may be registered and determined by prespecified time schedules, and respondents may be readily contacted via automatic email or text-message reminders. Although it has often been found that well-established scales do well regardless of administration format, online adaptions of validated scales should preferably undergo separate validation [
Based on data from two clinical trials of cognitive behavior therapy (CBT) for anxiety and stress disorders, we aimed to present estimates of test-retest reliability and thoroughly investigate item score distributions, convergent and discriminant validity, as well as the factor structure of the 12-item online WHODAS 2.0 when administered to individuals with anxiety and stress disorders. We expected the scale to be unidimensional, possibly with the six domains of functioning as subfactors (see previous), and with high internal consistency (Cronbach alpha>.80) as seen in previous studies. We expected strong baseline Pearson correlations (approximately .50 to .90) between the WHODAS 2.0 and other measure of disability or functional impairment, as well as substantial, yet slightly weaker, baseline Pearson correlations (approximately .30 to .70) with the measures of depression and general anxiety. We expected the WHODAS 2.0 to discriminate well between chronic stress patients with and without
This was a psychometric study of the WHODAS 2.0 administered online to patients with anxiety and stress disorders. Data were collected from clinical trials of CBT for severe health anxiety (n=60) and stress disorders (n=100) conducted at Karolinska Institutet and Gustavsberg primary care clinic, Stockholm, Sweden. Both trials were approved by the Stockholm regional ethics review board (2015/415-31/5, 2014/1530-31/2), registered at ClinicalTrials.gov (NCT02540317, NCT02314065), and participants provided informed consent. Data used for this study were collected between September 2015 and July 2016.
Both clinical trials employed patient self-referral via the Internet, and advertised in newspapers as well as on online social media networks. Study applicants completed a series of online screening symptom questionnaires before a diagnostic interview with a licensed psychologist. This interview primarily served to survey eligibility criteria and lead up to a decision regarding inclusion or exclusion (ie, this decision was based on the psychiatric interview), but also served to collect important clinical data (eg, comorbid diagnoses). After the pretreatment assessment, which was conducted online, patients underwent randomization and subsequent treatment. All included patients were at least 18 years of age. The severe health anxiety sample had a principal diagnosis of
All questionnaires were completed through a simple Web-based interface with white background, radio buttons, and checkboxes. All 60 patients in the severe health anxiety sample and 50 patients in the stress disorders trial received CBT (12 weeks, disorder-specific) for their principal disorder. The WHODAS 2.0 was administered before and after CBT. In addition, patients with severe health anxiety completed the WHODAS 2.0 at screening, thus allowing for estimates of test-retest reliability. Other measures used to validate the WHODAS 2.0 were also administered before and after treatment.
Both
The self-report 12-item WHODAS 2.0 [
The Sheehan Disability Scale (SDS) is a well-established three-item measure of psychiatric symptom-related functional impairment with a sum score range from 0 to 30, with a higher score indicating a higher degree of functional impairment [
The Health Anxiety Inventory (HAI) is a 64-item questionnaire that measures health anxiety on a scale from 0 to 192, with a higher score indicating more health anxiety [
The self-reported Montgomery-Åsberg Depression Rating Scale (MADRS-S) is a widely used nine-item questionnaire that measures depressive symptoms on a scale from 0 to 54, with higher scores indicating more symptoms of depression [
Analyses were done in SPSS version 23.0.0.2 (IBM Corp, Armonk, NY, USA) and R 3.3.2 [
Internal consistency was investigated in terms of Cronbach alpha, complemented by adjusted item-total correlations (ITCs), which are not as strongly affected by the number of scale items. For instruments of typical length, Cronbach alpha≥.9 is usually regarded as excellent, ≥8 as good, and ≥7 as acceptable. Test-retest reliability was estimated based on a two-way mixed-effects model absolute agreement intraclass correlation coefficient (ICC) and data from a subsample (n=25) from the severe health anxiety trial that had completed the screening and pretreatment assessments within 14 days (mean 6.8, SD 3.2, range 1-13).
We used an independent samples
To evaluate sensitivity to change, we compared pretreatment and posttreatment mean scores using paired samples
The WHODAS 2.0 response rate was 100% for the screening and pretreatment assessments. Because there was a small proportion of missing posttreatment data (for the WHODAS 2.0: 3%, 3/100 in the stress sample; 5%, 3/60 in the severe health anxiety sample), and we did not aim to investigate treatment effects but rather the responsiveness of the scale, data were used on a complete case (not intention-to-treat) basis.
Sample characteristics for the severe health anxiety sample, the stress disorders sample, and the pooled sample are presented in
Neither the one-factor model endorsed by the WHO (χ254=1699.1,
Sample characteristics.
Measure | Severe health anxiety (n=60) | Stress disorders (n=100) | Total (N=160) | ||
Age (years), mean (SDa), range | 36.4 (11.9), 18-78 | 46.2 (8.8), 26-65 | 42.5 (11.1), 18-78 | ||
Gender (female), n (%) | 40 (67) | 85 (85) | 125 (78) | ||
HAI, mean (SD), range | 105.6 (24.7), 51-164 | — | — | ||
PSS, mean (SD), range | — | 36.8 (7.1), 17-52 | — | ||
MADRS-S, mean (SD), range | 13.9 (7.4), 1-34 | 19.7 (7.5), 3-40 | 17.5 (7.9), 1-40 | ||
GAD-7, mean (SD), range | 12.0 (5.3), 2-21c | 10.8 (4.8), 2-21 | 11.2 (5.0), 2-21c | ||
MDD, n (%) | 11 (18) | 13 (13) | 24 (15) | ||
≥1 anxiety disorder/OCDd, n (%) | 34 (57) | 19 (19) | 53 (33) | ||
WHODAS 2.0, mean (SD), range | 21.1 (6.3), 12-36 | 24.7 (8.5), 12-51 | 23.4 (7.9), 12-51 | ||
SDS, mean (SD), range | 10.4 (6.7), 0-26 | — | — | ||
WAI, mean (SD), range | — | 33.0 (8.4), 13.0-47.0 | — | ||
On sick leave, n (%) | 3 (5) | 14 (14) | 17 (11) |
aSD: standard deviation.
bHAI: Health Anxiety Inventory; PSS: Perceived Stress Scale; MADRS-S: Montgomery-Åsberg Depression Rating Scale self-report version; GAD-7: Generalized Anxiety Disorder 7-item scale; MDD: major depressive disorder; OCD: obsessive compulsive disorder;.
cGAD-7 data only available from a subsample of the severe health anxiety sample (n=43).
dAt least one anxiety or obsessive compulsive disorder that is not severe health anxiety.
eWHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0; SDS: Sheehan Disability Scale; WAI: Work Ability Index.
Factor loadings of the WHODAS 2.0a.
Factor 1: psychosocialb | Factor 2: self-careb | Factor 3: mobilityb | A priori dimensionc | |
1. Standing long periods | –.008 | –.097 | .877 | Mobility |
2. Household responsibilities | .540 | –.027 | .264 | Household |
3. Learning new tasks | .740 | –.002 | .035 | Cognitive |
4. Joining community activities | .848 | –.046 | .042 | Society |
5. Emotionally affected | .652 | –.087 | .074 | Society |
6. Concentrating | .683 | –.010 | –.040 | Cognitive |
7. Walking long distance | –.003 | .329 | .597 | Mobility |
8. Washing whole body | –.068 | .893 | .132 | Self-care |
9. Getting dressed | .078 | .909 | –.126 | Self-care |
10. Dealing with strangers | .704 | .167 | –.164 | Social |
11. Maintaining friendships | .618 | .128 | –.101 | Social |
12. Work/school activities | .814 | –.059 | .037 | Household |
aWHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0.
bFactor loadings (regression coefficients) based on principal axis factoring with promax rotation.
cCognitive: understanding and communicating; household: life activities; mobility: getting around; social: getting along with others; society: participation in society.
Post hoc exploratory factor analysis (Kaiser-Meyer-Olkin test=0.85, Barlett test<.001) was suggestive of a three-factor solution, with one very strong factor (eigenvalue=5.4, 45.0% of variance explained) and two weak factors (eigenvalues=1.1-1.7, 9.3%-14.2% of variance explained).
After rotation (
Parameters related to item score distributions are presented in
Adjusted baseline ITCs are presented in
The test-retest reliability of the WHODAS 2.0, based on the severe health anxiety sample data (n=25), was estimated at ICC=0.83 (95% CI 0.62-0.92) and the correlation between the measurements was
In the stress disorders sample, patients with a principal diagnosis of exhaustion disorder had a significantly higher WHODAS 2.0 mean score than those who had a principal diagnosis of adjustment disorder (mean difference 8.84, 95% CI 5.96-11.72;
Effect sizes and tests pertaining to responsiveness are presented in
Web-based self-report 12-item WHODAS 2.0 item scoresa.
Mean (SDb) | ITCc | |||||||
1. Standing long periods | 1.54 (0.89) | 1 (1-4) | 66% | 0% | 1.58 | 1.47 | 0.44 | |
2. Household responsibilities | 2.07 (1.02) | 2 (1-4) | 38% | 0% | 0.47 | –1.00 | 0.64 | |
3. Learning new tasks | 1.87 (1.02) | 2 (1-5) | 49% | 1% | 0.85 | –0.37 | 0.70 | |
4. Joining community activities | 2.23 (1.19) | 2 (1-5) | 38% | 4% | 0.55 | –0.77 | 0.78 | |
5. Emotionally affected | 3.21 (1.14) | 4 (1-5) | 13% | 6% | –0.69 | –0.60 | 0.59 | |
6. Concentrating | 2.37 (1.05) | 2 (1-5) | 26% | 1% | 0.17 | –0.90 | 0.61 | |
7. Walking long distance | 1.51 (0.82) | 1 (1-5) | 66% | 1% | 1.63 | 2.29 | 0.52 | |
8. Washing whole body | 1.20 (0.55) | 1 (1-4) | 86% | 0% | 3.12 | 10.22 | 0.48 | |
9. Getting dressed | 1.16 (0.47) | 1 (1-4) | 88% | 0% | 3.44 | 12.87 | 0.48 | |
10. Dealing with strangers | 1.83 (1.01) | 2 (1-5) | 49% | 1% | 1.10 | 0.43 | 0.66 | |
11. Maintaining friendships | 1.85 (1.07) | 1 (1-5) | 53% | 1% | 0.97 | –0.17 | 0.59 | |
12. Work/school activities | 2.54 (1.20) | 3 (1-5) | 25% | 6% | 0.27 | –0.88 | 0.75 | |
Total score | 23.37 (7.91) | 23 (12-51) | 8% | 0% | 0.68 | 0.52 | — | |
Psychosocial | 12.60 (4.70) | 12.76 (5.60-24.84) | 8% | 0% | 0.31 | –0.49 | — | |
Self-care | 2.12 (0.86) | 1.80 (1.80-7.21) | 84% | 0% | 3.20 | 11.23 | — | |
Mobility | 2.25 (1.15) | 1.47 (1.47-6.49) | 56% | 0% | 1.56 | 1.76 | — |
aWHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0. Based on baseline data from two clinical trials of severe health anxiety and stress disorders (total N=160, items scored from 1 to 5).
bSD: standard deviation.
cITC: adjusted item-total correlation.
Web-based self-report 12-item WHODAS 2.0a internal consistency.
Sample | Screening | Pretreatment | Posttreatment | ||||
Cronbach alpha | n | Cronbach alpha | n | Cronbach alpha | n | ||
Severe health anxiety | .83 | 60 | .86 | 60 | .87 | 56 | |
Stress disorder | — | — | .90 | 100 | .92 | 97 | |
Severe health anxiety | .82 | 60 | .88 | 60 | .87 | 56 | |
Stress disorder | — | — | .89 | 100 | .91 | 97 |
aWHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0.
bPsychosocial subscale with regression weights applied.
WHODAS 2.0 associations (bivariate Pearson correlations) with other self-rated questionnairesa.
WHODAS 2.0b | MADRS-Sb | GAD-7b | SDSb | |||
WHODAS 2.0 | — | .96c | .60c | .58c,d | .66c | |
Psychosocial subscale | .97e | — | .65c | .54c,d | .67c | |
MADRS-S | .65e | .64e | — | .54c,d | .59c | |
GAD-7 | .45e | .45e | .71e | — | .40c | |
WAI | –.71e | –.71e | –.55e | –.28e | — |
aAll bivariate Pearson correlations significant at α=.05.
bWHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0; MADRS-S: Montgomery-Åsberg Depression Rating Scale-self-report version; GAD-7: Generalized Anxiety Disorder 7-item scale; SDS: Sheehan Disability Scale; WAI: Work Ability Index.
cSevere health anxiety sample (n=60).
dGAD-7 data only available from a subsample of the severe health anxiety sample (n=43).
eStress disorder sample (n=100).
Responsiveness stratified by change in primary symptom domaina.
Change in primary symptom domainb | ESc | |||||
32 (5) | ||||||
WHODAS 2.0 | 1.21 | 7.19 (5.17, 9.22) | <.001 | |||
SDS | 1.00 | 7.28 (4.59, 9.98) | <.001 | |||
8 (14) | ||||||
WHODAS 2.0 | 0.52 | 2.75 (–0.85, 6.35) | .11 | |||
SDS | 0.53 | 1.88 (–1.07, 4.82) | .18 | |||
18 (31) | ||||||
WHODAS 2.0 | 0.29 | 2.00 (–0.13, 4.13) | .06 | |||
SDS | 0.22 | 1.39 (–0.59, 3.37) | .16 | |||
33 (34) | ||||||
WHODAS 2.0 | 0.80 | 6.42 (4.27, 8.58) | <.001 | |||
WAI | –0.49 | –4.14 (–5.75, –2.52) | <.001 | |||
12 (12) | ||||||
WHODAS 2.0 | 0.39 | 2.83 (0.09, 5.58) | .04 | |||
WAI | –0.25 | –2.29 (–5.10, 0.51) | .10 | |||
52 (54) | ||||||
WHODAS 2.0 | 0.19 | 1.75 (-0.10, 3.60) | .06 | |||
WAI | –0.13 | –0.96 (–2.66, 0.73) | .26 |
aAll estimates based on data from patients that completed the posttreatment assessment. Status as improved or not improved based on the Jacobson and Truax reliable change index [
bHAI: Health Anxiety Inventory; WHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0; SDS: Sheehan Disability Scale; PSS: Perceived Stress Scale; WAI: Work Ability Index.
cStandardized effect sizes (ES) are calculated with the stratum-specific pretreatment standard deviation as nominator.
d
eSD: standard deviation.
To our knowledge, this was the first in-depth analysis of the reliability and validity of the self-rated 12-item WHODAS 2.0 when administered online to patients with anxiety and stress disorders. In line with our hypotheses, the WHODAS 2.0 exhibited high internal consistency, acceptable test-retest reliability, and was demonstrated to identify cases of exhaustion disorder. As expected, the WHODAS 2.0 also showed substantial associations with other measures of functioning, as well as slightly weaker but yet substantial associations with primary symptom measures. The instrument was sensitive to change in the primary psychiatric symptom domain, as illustrated by a convincing gradient in change effect size over the nonimproved versus slightly improved versus much improved strata (
Regarding factor structure, we could neither confirm the expected one-factor WHO solution nor the second-order model put forward by previous investigators [
On an item level, the most striking aspect of the score distribution was that both items 8 and 9 (ie, the “self-care” items) had a mode score of 1 and appeared to pick up on very little variance in the two samples. This may suggest that individuals with a principal diagnosis of severe health anxiety or a stress disorder are typically not much impaired in terms of ability to carry out everyday self-care tasks such as washing oneself or getting dressed.
Although the internal consistency and test-retest reliability estimates were in line with our expectations, and also fulfilled commonly accepted quality criteria for health status questionnaires [
In this study, correlations with other measures of psychiatric symptoms and functional impairment corroborate the construct validity of the self-rated 12-item WHODAS 2.0. As this study was based on data from two clinical trials, we do not find it unfit or surprising that the WHODAS 2.0 was highly correlated with measures of anxiety and depression which were likely to be the primary reasons for functional impairment.
Due to the limited sample size and variability in the size of substrata (nonchanged vs minimally changed vs much changed) we wish to emphasize that the significance tests pertaining to change (
The primary limitation of this study is that over and above clinical diagnoses we did not have access to “hard” measures of functional impairment, collected by other means than self-assessment (eg, register data on disability status) that could be used to validate the WHODAS 2.0. One consequence of this is that all indexes of change were to some degree susceptible to social desirability bias or the possibility that patients reported change so as to please their therapist rather than as a consequence of real change in symptoms or disability. However, it has been demonstrated that Web-based survey administration is relatively robust to desirability bias [
We also had no control over what equipment the patients used to access the Web-based WHODAS 2.0, meaning we could not determine the significance of filling in the questionnaire via a mobile phone app rather than a conventional browser on a desktop computer, for example. The results showing good psychometric properties of the WHODAS 2.0 also suggest that there was no substantial measurement error related to the type of device used. Another threat to the generalizability of our findings is that the two samples were relatively homogenous due to the eligibility criteria for the two clinical trials, which were not primarily designed to study the psychometric properties of the WHODAS 2.0. Therefore, it is preferable to validate the findings of this study, particularly with regard to factor structure, in anxiety and stress disorder samples recruited through other means.
The item mean score profile seen in this study—with substantial functional impairment in the “understanding and communicating,” “life activities,” and “getting along with others” domains but very low functional impairment in the “self-care” domain—is highly similar to the item mean score profile seen in studies of interview and pencil-and-paper versions of the WHODAS 2.0 administered to individuals with common mental disorders [
Before this study, the 12-item WHODAS 2.0 had also been administered online to individuals with common anxiety, stress, and mood disorders in several clinical trials (
Previous studies that have administered the 12-item self-report WHODAS 2.0 online to respondents with common mental disordersa.
Diagnosisb | |||||||
12-60 scaled | 0-48 scaled | 0-100 scaled | |||||
Allen et al (2016) [ |
63 | PD | 26.0 | 14.0 | 29.2 | .89 | Yes |
Andrews et al (2011) [ |
37 | SAD | 26.6 | 14.6 | 30.4 | — | Yes |
Mason & Andrews (2014) [ |
173e | Mixed CMD | 25.0 | 13.0 | 27.1 | — | Yes |
Mewton et al (2012) [ |
588 | GAD | 25.7 | 13.7 | 28.5 | .90 | Yes |
Newby et al (2016a) [ |
2109 | Mixed CMD | 26.3 | 14.3 | 29.8 | >.88 | Yes |
Newby et al (2016b) [ |
16 | SHA | 20.3 | 8.3 | 17.3 | .83 | Yes |
Perini et al (2008) [ |
13 | MDD | —f | —f | —f | — | Yes |
Spence et al (2011) [ |
244 | PTSD | 32.1 | 20.1 | 41.9 | .92 | — |
Titov et al (2008a) [ |
105 | SAD | 26.3 | 14.3 | 29.8 | — | Yes |
Titov et al (2008b) [ |
88 | SAD | 25.0 | 13.0 | 27.1 | — | Yes |
Williams et al (2013) [ |
69 | MDD | 41.2 | 29.2 | 60.8 | — | Yes |
Williams et al (2014) [ |
560 | SAD | 39.3 | 27.3 | 56.9 | — | Yes |
Williams et al (2015) [ |
75 | MDD | 44.8 | 32.8 | 68.3 | .83 | Yes |
Wootton et al (2011) [ |
118 | OCD | 30.4 | 18.4 | 38.3 | .91 | — |
aInformation from articles complemented by personal communication via email.
bPD: panic disorder; SAD: social anxiety disorder; CMD: common mental disorder; GAD: generalized anxiety disorder; SHA: severe health anxiety; MDD: major depressive disorder; PTSD: posttraumatic stress disorder; OCD: obsessive compulsive disorder; . See
cWHODAS 2.0: World Health Organization Disability Assessment Schedule 2.0.
dThe 12-60 scale has items scored 1-5, the 0-48 scale has items scored 0-4, and the 0-100 scale is the 0-48 scale divided by 48 and then multiplied by 100.
eAnother sample (n=135) in this study completed the WHODAS 2.0 on a computer, but not via the Internet.
fUnknown; author could not be reached.
Although the primary aim of these trials was not to study the psychometric properties of the WHODAS 2.0, these studies presented estimates of both internal consistency (Cronbach alpha≥.83) and baseline mean scores that are very much in line with data in this trial, and thus lend further support to the validity and generalizability of our findings.
This is, to date, the most extensive investigation into the psychometric properties of the self-rated 12-item version of the WHODAS 2.0 when administered via the Internet to individuals with anxiety and stress disorders. When administered online to individuals with anxiety and stress disorders, the WHODAS 2.0 exhibits high internal consistency, high convergent validity, adequate test-retest reliability, and is sensitive to change. We conclude that the psychometric properties of the self-rated 12-item version of the WHODAS 2.0 are acceptable when the instrument is administered via the Internet to individuals with anxiety and stress disorders, but suggest that the three subfactors found in this study be reported alongside the sum score to facilitate comparisons between studies.
Search strategy and data collection for brief review.
Flowchart illustrating study selection process for brief review.
area under the curve
cognitive behavior therapy
comparative fit index
Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition)
Generalized Anxiety Disorder seven-item scale
Health Anxiety Inventory
intraclass correlation coefficient
International Classification of Diseases, Tenth Revision
item-total correlations
Montgomery-Åsberg Depression Rating Scale-self-report
Perceived Stress Scale
root mean square error of approximation
Sheehan Disability Scale
standardized root mean square residual
Tucker-Lewis index
Work Ability Index
World Health Organization Disability Assessment Schedule 2.0
This work was supported by Karolinska Institutet and Stockholm County Council, which are public institutions that did not influence the study design, execution, or publication process.
All authors made significant contributions to the planning, recruitment, execution, analysis, and publication of this study.
None declared.