External Construct Validity Research Articles

Reliability and Validity of the Turkish Version of the Abiloco-Kids

ABILOCO-Kids is a scale that assesses the walking ability of children with Cerebral Palsy (CP) from the viewpoint of parental perception. The aim of this study was to translate the ABILOCO-Kids scale into Turkish and to establish its reliability and validity in children with CP. Turkish children were recruited in this study. ABILOCO-Kids is a scale developed by Caty and et al. This scale assess the walking ability of children with CP focusing on the activity domain of the International Classification of Functioning, Disability and Health (ICF). The ABILOCO-Kids scale was translated from English into Turkish using the forward-backward-forward method. The motor functions of the 63 children participating in the study were evaluated by the Gross Motor Function Classification System (GMFCS) and the Gross Motor Function Measurement-88 (GMFM-88). The ABILOCO-Kids scale was repeated in 30 children after one week to establish test-retest reliability. While internal and external construct validity were investigated using Rasch analysis and Spearman correlation coefficient, respectively; reliability was evaluated in terms of internal consistency by Cronbach’s alpha and Person Separation Index (PSI). All items of the ABILOCO-Kids were found to fit the Rasch Model (chi-square 14.35 (df = 20), p = 0.813). The internal construct validity was good, overall mean item fit residual was −0.109 (SD: 0.719) and mean person fit residual was −0.215 (SD: 0.817). The reliability was good with Cronbach’s Alpha of 0.98 and PSI of 0.99. When the test-retest was examined via Differential Item Functioning (DIF) by time, none of the items showed DIF. Spearman correlation coefficients of the ABILOCO-Kids scale in relation to the GMFM and GMFCS were r = 0.824, p < 0.001; r = −0.788, p < 0.001 respectively. The Turkish version of the ABILOCO-Kids scale is a valid, reliable and unidimensional scale for children with CP. This scale will allow the differences in the locomotion of children with CP to be evaluated from the perspective of the family.

Measuring HIV- and TB-related stigma among health care workers in South Africa: a validation and reliability study.

Recent evidence indicates that human immunodeficiency virus (HIV) and tuberculosis (TB) related stigma act as a key barrier to the utilisation of associated occupational health services by South African health care workers (HCWs). It also highlights a dearth of appropriate tools to measure HIV and TB stigma among HCWs. To test four scales measuring different aspects of stigma: respondent's external stigma (RES) and others' external stigma (OES) towards TB as well as HIV across different professional categories of HCWs. The current study employs data from a study on HIV and TB stigma among HCWs, a cluster randomised controlled trial for the collection of data among 882 HCWs in the Free State Province of South Africa. Confirmatory factor analyses and structural equation modelling were used to assess the validity and reliability of the scales. All four scales displayed adequate internal construct validity. Subsequent analysis demonstrated that all four scales were metric-invariant, and that the OES scales were even scalar-invariant across patient and support staff groups. The scales displayed good reliability and external construct validity. Our results support the use of the scales developed to measure TB and HIV stigma among HCWs. Further research is, however, needed to fine tune the instruments and test them across different resource-limited countries.

Cross-Cultural Adaptation and Validation of the SWAL-QoL Questionnaire in Greek.

The purpose of this study was to translate and adapt the 44-item SWAL-QoL into Greek and examine its internal consistency, test-retest reliability, external construct validity, and discriminant validity in order to provide a validated dysphagia-specific QoL instrument in the Greek language. The instrument was translated into Greek using the back translation to ensure linguistic validity and was culturally adapted resulting in the SWAL-QoL-GR. Two groups of participants were included: a patient group of 86 adults (48 males; age range: 18-87 years) diagnosed with oropharyngeal dysphagia, and an age-matched healthy control group (39 adults; 19 males; age range: 18-84 years). The Greek 30-item version of the WHOQOL-BREF was used for assessment of construct validity. Overall, the questionnaire achieved good to excellent psychometric values. Internal consistency of all 10 subscales and the physical symptoms scale of the SWAL-QoL-GR assessed by Cronbach's α was good to excellent (0.811<α<0.940). Test-retest validity was found to be good to excellentas well. In addition, moderate to strong correlations were found between seven of the ten subscales of the SWAL-QoL-GR with limited items of the WHOQΟL-BREF (0.401<ρ<0.65), supporting good construct validity of the SWAL-QoL-GR. The SWAL-QoL-GR also correctly differentiated between patients with dysphagia and age-matched healthy controls (p<0.001) on all 11 scales, further indicating excellent discriminant validity. Finally, no significant differences were found between the two sexes. This cultural adaptation and validation allows the use of this tool in Greece, further enhancing our clinical and scientific efforts to increase the evidence-based practice resources for dysphagia rehabilitation in Greece.

Computational Social Science Methodology, Anyone?

Abstract. This article reviews computational social science methods and their relation to conventional methodology and statistics. Computational social science has three important features. Firstly, it often involves big data; data sets so large that conventional database and analysis techniques cannot handle them with ease. Secondly, dealing with these big data sets has given rise to analysis techniques that are specially developed for big data. Given the size of the data, resampling and cross-validation approaches become feasible that allow both data-driven exploration and checks on overfitting the data. A third important feature is simulation, especially agent-based simulation. Here size also matters. Agent-based simulation is well known in social science, but modern computer equipment and software allows simulations of unprecedented scale. Many of these techniques, especially the resampling and cross-validation approaches, are potentially very useful for social scientists. Given the relatively small size of social science “big data” is useful to explore how well these techniques perform with smaller data sets. Social science methodology can contribute to this field by exploring if well-known methodological distinctions between external validity, internal validity, and construct validity can help clear up discussions on data quality (veracity) in computational social science.

Validation of the Arabic Version of the Infant Feeding Intentions Scale Among Lebanese Women.

The Infant Feeding Intentions (IFI) scale was shown to reliably measure maternal intentions to initiate breastfeeding and continue exclusive breastfeeding until 1, 3, or 6 months in English and Spanish but not in Arab contexts. Research aim: This study aimed to validate an Arabic version of the IFI scale (IFI-A) and examine its ability to predict exclusive breastfeeding at 1, 3, or 6 months in pregnant Lebanese women. The internal consistency reliability and construct validity of the IFI-A scale were tested on 50 pregnant women (Group 1), whereas its predictive ability was tested on 196 pregnant women (Group 2), who were surveyed monthly about their infants' nutrition method until 6 months. The IFI-A scale's Cronbach's alpha internal consistency reliability is .82. Its corrected item-total correlations ranged from .26 for Item 2 ("at least give breastfeeding a try") to .86 for Item 4 ("will be exclusively breastfeeding at 3 months"). Exploratory factor analysis revealed that it is unidimensional. IFI-A scores correlated significantly with exclusive breastfeeding duration in Group 1 ( r = .624; p = .001) and with participants' breastfeeding attitude ( r = .390; p < .001) and previous breastfeeding duration ( r = .237; p = .011) in Group 2, thus confirming its external construct validity. In adjusted analysis, the IFI-A scale predicted exclusive breastfeeding at 3 months, albeit weakly (odds ratio = 1.16; 95% confidence interval [0.99, 1.36]), but not at 1 or 6 months. The IFI-A scale is a reliable and valid tool to assess maternal feeding intentions and predict exclusive breastfeeding at 3 months in the Arab context. Further studies are needed in other Arab contexts to confirm our findings.

Psychometric Evaluation of the Parkinson's Disease Activities of Daily Living Scale.

Objective To evaluate a set of psychometric properties (i.e., data completeness, targeting, and external construct validity) of the Parkinson's disease Activities of Daily Living Scale (PADLS) in people with Parkinson's disease (PD). Specific attention was paid to the association between PADLS and PD severity, according to the Hoehn & Yahr (H&Y) staging. Methods The sample included 251 persons with PD (mean age 70 [SD 9] years). Data collection comprised a self-administered postal survey, structured interviews, and clinical assessments at home visits. Results Data completeness was 99.6% and the mean PADLS score was 2.1. Floor and ceiling effects were 22% and 2%, respectively. PADLS scores were more strongly associated (rs > 0.5) with perceived functional independence, ADL dependency, walking difficulties, and self-rated PD severity than with variables such as PD duration and cognitive function (rs < 0.5). PADLS scores differed across H&Y stages (Kruskal-Wallis test, p < 0.001). Those in H&Y stages IV-V had more ADL disability than those in stage III (Mann–Whitney U test, p < 0.001), whereas there were no significant differences between the other stages. Conclusion PADLS revealed excellent data completeness, acceptable targeting, and external construct validity. It seems to be well suited as a rough estimate of ADL disability in people with PD.

Psychometric analysis of the Salutogenic Health Indicator Scale (SHIS) in adolescents.

The aim of this study was to test the psychometric properties of the Salutogenic Health Indicator Scale (SHIS) in an adolescent population. The investigation was performed among Swedish students aged 13-15 years ( n = 817; 58% girls). The SHIS was assessed for respondent acceptability, and its psychometric properties were evaluated according to classical test theory (regarding unidimensionality, targeting, reliability, and external construct validity). The adolescents found it easy to complete the questionnaire, which was completed in an average of 4 minutes. Exploratory factor analysis, which is based on polychoric correlations, identified one factor, supporting the instrument's unidimensionality. Floor/ceiling effects were ⩽ 3.3%. Reliability estimates yielded a Cronbach's alpha value of 0.93; the test-retest reliability ( n = 50; 2-week interval) coefficients were 0.89 for the total SHIS score and 0.52-0.79 for item scores. Spearman correlations with other variables were based on a priori expectations (self-rated general health, 0.595; depressive symptoms, -0.773; anxiety, -0.577; and sleep problems, 0.519). Our observations support both the acceptability and the psychometric properties of the SHIS as a brief, unidimensional assessment tool for salutogenic health in adolescents. Further studies using modern test theory are needed to better understand the measurement properties of the SHIS, including the functioning of its response categories and its comparability between adolescents and adults.

Assessment of Burden Among Family Caregivers of People With Parkinson's Disease Using the Zarit Burden Interview

ContextPrevious studies have supported the psychometric properties of the 22-Item Zarit Burden Interview (ZBI-22) scale among family caregivers of people with various disorders, including Parkinson's disease (PD). However, its short forms have not been psychometrically tested among PD family caregivers, and available psychometric analyses have not accounted for the ordinal nature of item-level data. ObjectivesTo assess the psychometric properties of the ZBI-22 and its short forms among family caregivers of people with PD, while taking account for the ordinal nature of data. MethodsCross-sectional postal survey ZBI-22 data from 66 family caregiver members (59% women; mean age 69.6 years) of a local Swedish PD society branch were analyzed according to classical test theory methods based on polychoric/polyserial correlations. ResultsMissing item responses were ≤ 5%. Corrected item-total correlations were ≥ 0.42 and floor/ceiling effects were <20%, besides for the briefest (4- and 1-item) short forms (20% and 40% floor effects, respectively). Reliability was good for all scales (ordinal alpha 0.89–0.95). External construct validity was in general accordance with a priori expectations. Short forms demonstrated good criterion-related validity (rs 0.87–0.99) and discriminative ability (area under the curve, 0.91–0.98) relative to the full ZBI-22. ConclusionThis study provides support for the reliability and validity of the ZBI-22 and its various short forms for use among PD family caregivers. In studies where caregiver burden is a central outcome, either ZBI-22 or ZBI-12 is suggested for use; other short forms can be used when caregiver burden is of less central focus or for clinical screening.

Preliminary stages of cross-cultural adaptation of the Brazilian Portuguese version of McMaster Family Assessment Device

ABSTRACT Objective To carry out the preliminary stages of the cross-cultural adaptation of the Family Assessment Device (FAD) to Brazilian Portuguese language and examine its reliability. Methods The translation and cross-cultural adaptation of the FAD were developed according to the methods internationally recommended. The resulting product was applied to 80 individuals who completed the questionnaire on two different occasions, seven days apart. Internal consistency was obtained through Cronbach’s alpha, and reliability was estimated by using the Bland and Altman method. Results The internal consistency obtained was very good (Cronbach’s alpha = 0.910). The mean differences of FAD dimensions found in the Bland and Altman test were the following: -0.21 (Problem Solving); -0.32 (Communication); -0.17 (Roles); 0.2 (Affective Responsiveness); -0.27 (Affective Involvement); -0.08 (Behavior Control); -0.02 (General Functioning). Conclusion The processes of translation and cross-cultural adaptation were successful. Assessment of the structural validity and external construct validity is recommended for the improvement of the Brazilian version.

The Development and Piloting of Parallel Scales Measuring External and Internal HIV and Tuberculosis Stigma Among Healthcare Workers in the Free State Province, South Africa.

The dual burden of tuberculosis and human immunodeficiency virus (HIV) is severely impacting the South African healthcare workforce. However, the use of on-site occupational health services is hampered by stigma among the healthcare workforce. The success of stigma-reduction interventions is difficult to evaluate because of a dearth of appropriate scientific tools to measure stigma in this specific professional setting. The current pilot study aimed to develop and test a range of scales measuring different aspects of stigma-internal and external stigma toward tuberculosis as well as HIV-in a South African healthcare setting. The study employed data of a sample of 200 staff members of a large hospital in Bloemfontein, South Africa. Confirmatory factor analysis produced 7 scales, displaying internal construct validity: (1) colleagues' external HIV stigma, (2) colleagues' actions against external HIV stigma, (3) respondent's external HIV stigma, (4) respondent's internal HIV stigma, (5) colleagues' external tuberculosis stigma, (6) respondent's external tuberculosis stigma, and (7) respondent's internal tuberculosis stigma. Subsequent analyses (reliability analysis, structural equation modeling) demonstrated that the scales displayed good psychometric properties in terms of reliability and external construct validity. The study outcomes support the use of the developed scales as a valid and reliable means to measure levels of tuberculosis- and HIV-related stigma among the healthcare workforce in a resource-limited context. Future studies should build on these findings to fine-tune the instruments and apply them to larger study populations across a range of different resource-limited healthcare settings with high HIV and tuberculosis prevalence.

A New Measure of Home Exercise Benefits and Barriers

Background: To increase physical activity among college students, new approaches are needed including the exploration of home-based exercise. However, research related to potential facilitators and barriers to exercising at home is limited. Purpose: The goal of this study was to develop a reliable and valid measure that can assess predictors of home exercise. Methods: A systematic approach was used to develop items for the new measure and to examine its psychometric properties. Principal component analysis (PCA) was used to investigate the internal structure of the measure. External validity and initial construct validity were examined using correlations of the new subscale measures with existing valid measures of exercise. Results: Two hundred thirty-two adults (65% women and 72% white) completed a cross-sectional survey. The final PCA solution resulted in a 28-item measure with 7 distinct subscales with individual item loadings ranging from 0.64 to 0.91. These subscales comprised 3 higher order scales of Barriers to Home Exercise, Benefits of Home Exercise, and Barriers to Public Exercise. All demonstrated good internal consistency and external validity. Discussion: The measure developed in this study delineates important predictors of home exercise. Translation to Health Education Practice: This measure can be used to develop tailored interventions to promote home-based exercise.

A tool for sexual minority mental health research: The Patient Health Questionnaire (PHQ-9) as a depressive symptom severity measure for sexual minority women in Viet Nam

ABSTRACTIn a context with limited attention to mental health and prevalent sexual prejudice, valid measurements are a key first step to understanding the psychological suffering of sexual minority populations. We adapted the Patient Health Questionnaire as a depressive symptom severity measure for Vietnamese sexual minority women, ensuring its cultural relevance and suitability for Internet-based research. Psychometric evaluation found that the scale is mostly unidimensional and has good convergent validity, good external construct validity, and excellent reliability. The sample's high endorsement of scale items emphasizes the need to study minority stress and mental health in this population.

Validation of the food access survey tool to assess household food insecurity in rural Bangladesh.

BackgroundPerception-based Likert scale are commonly used to assess household food insecurity. The aim of this study was to evaluate the psychometric properties and external construct validity of the 9-item Food Access Survey Tool (FAST) in a population-based randomized controlled trial.MethodsParticipating women (n = 11,992) were asked to recall the frequencies of nine food insecurity experiences over the past 6 months on a 5-point Likert scale. The Rasch partial credit model was used to study the item category severity and differential item functioning (DIF) by literacy status, respondents’ age, land ownership and household sizes. Principal component analysis (PCA), non-parametric methods, and cumulative ordinal logistic regression models were applied to examine the Rasch model assumptions, namely unidimensionality, monotonicity and measurement invariance (non-DIF).ResultsAll items demonstrated good model fit with acceptable values of fit statistics (infit). PCA as well as other indices (Cronbach’s alpha = 0.85, scalability coefficient = 0.48) indicated that all items fit in a single statistical dimension. The ordered responses of nine items displayed monotonic increasing item category severity as expected theoretically. All nine items were flagged with statistically significant DIF between key demographic—and socioeconomic subgroups (p < 0.001); however, none of the detected DIF was considered practically significant given small effect sizes (variance explained by group membership and interaction term < 1 %). The total summed score over the polytomous FAST was inversely associated with household wealth, dietary diversity score and maternal body mass index, demonstrating external construct validity.ConclusionThe polytomous FAST is internally and externally valid tool to measure household food insecurity in rural Bangladesh. Validation of this type of studies are recommended for similar Likert food insecurity scales.

Validity and Reliability of a Brief Symptom Checklist to Measure Psychological Health in School-Aged Children

The psychological health of children is a global health concern. The international Health Behavior in School-Aged Children (HBSC) study has surveyed the psychological health of youths in over 40 countries. The HBSC questionnaire includes a brief symptom checklist of psychological complaints, but it has not yet been validated. This study evaluated the construct validity of the psychological health self-report tool used in the HBSC study. We used data from 26,078 participants in the 2010 Canadian HBSC survey. The core HBSC questionnaire measured common psychosomatic complaints using the HBSC symptom checklist (HBSC-SCL). The Canadian survey included an additional series of questions that measure four dimensions of mental health (emotional problems, emotional well-being, behavioral problems, prosocial behavior). We used these items to evaluate the construct validity of psychological symptoms in the HBSC-SCL. We assessed internal construct validity using Cronbach’s alpha and external construct validity using factor analysis and structural equation modelling. Factor analysis showed that the HBSC-SCL measures two factors, psychological and somatic complaints. Psychological complaints included feeling low/depressed, irritable/bad tempered, nervous, and difficulties sleeping. Internal validity of the psychological subscale was good (α = 0.78). This 4-item subscale demonstrated convergent validity with indicators for emotional problems (correlation (r) = −0.79, p < 0.001) and emotional well-being (r = 0.48, p < 0.001), and discriminant validity with indicators for behavioral problems (r = −0.17, p < 0.001) and prosocial behavior (r = 0.02, p < 0.001). Results support the HBSC-SCL psychological subscale as a valid measure of psychological health in school-aged children. Future research is recommended to replicate findings in other youth populations.

The Validity of Auditor Industry Specialization Measures

SUMMARYIn this research note, we examine the validity of the measures of auditor industry specialization in empirical archival audit research. Industry specialist auditors are auditors who have developed a specific expertise and are therefore able to provide high quality and more efficient services to their clients. Over the years, research scholars have developed a multiplicity of measures of industry specialization (ISP). We compare 30 ISP measures and find that the use of different ISP proxies results in inconsistent classifications of auditors as specialists. Using audit fee and earnings quality models, we further show that these inconsistencies have a significant effect on the inferences drawn from the models using ISP measures. We conclude that ISP measures exhibit a low degree of internal and external construct validity. This represents an important measurement challenge for researchers and casts some doubts on the robustness of prior empirical evidence found in auditor industry specialization research.

External Responsiveness of the Yo-Yo IR Test Level 1 in High-level Male Soccer Players.

The aim of this study was to assess the external responsiveness, construct validity and internal responsiveness of the Yo-Yo Intermittent Recovery test level 1 and its sub-maximal version in semi-professional players. Tests and friendly matches were performed during the preseason and regular season. The distance covered above 15 km·h(-1) was considered as an indicator of the physical match performance. Construct validity and external responsiveness were examined by correlations between test and physical match performance (preseason and regular season) and training-induced changes. Internal responsiveness was determined as Cohen's effect size, standardized response mean and signal-to-noise ratio. The physical match performance increased after training (34.8%). The Yo-Yo Intermittent Recovery test level 1 improved after training (40.2%), showed longitudinal (r=0.69) and construct validity (r=0.73 and 0.59, preseason and regular season) and had higher internal responsiveness compared to its sub-maximal version. The heart rate at the 6(th) minute in the sub-maximal version did not show longitudinal (r=-0.38) and construct validity (r=0.01 and -0.06, preseason and regular season) and did not significantly change after training (-0.3%). The rate of perceived exertion decreased in the sub-maximal version (- 29.8%). In conclusion, the Yo-Yo Intermittent Recovery test level 1 is valid and responsive, while the validity of its sub-maximal version is questionable.

Inventário de medos III: Avaliação das qualidades psicométricas em uma amostra portuguesa

Este estudo teve como objetivo avaliar as qualidades psicométricas do Fear Survey Schedule-III, em uma amostra portuguesa. Participaram 1.980 sujeitos selecionados por conveniência a partir de uma população adulta normativa. As idades dos participantes estavam compreendidas entre os 18 e os 80 anos (M = 39,5, DP = 8,5), sendo 59% do sexo feminino. As qualidades psicométricas da escala foram avaliadas em suas facetas de sensibilidade psicométrica, validade de construto e confiabilidade. A validade externa de construto foi avaliada com análise multigrupos em amostra aleatória e independente da amostra de validação inicial. O modelo fatorial original proposto apresentou um ajustamento inaceitável à amostra de validação. Procedeu-se ao refinamento do modelo de medida em uma parte da amostra, selecionada aleatoriamente. Em conclusão, o modelo de medida simplificado apresentou uma boa qualidade de ajustamento fatorial e foi invariante em uma segunda amostra independente da primeira. Propôs-se uma nova estrutura hierárquica, com fator de 2ª ordem designado por "Medos", que revelou boas qualidades psicométricas (sensibilidade, validade de construto e confiabilidade).

Adaptation and Validation of Clinimetric Tools: Validation Process and Transcultural Adaptation of the Fybromyalgia Participation Questionnaire to Spanish Patients

Quality tools for the assessment of social and functional participation in patients suffering from fibromyalgia are few and far between. The Fibromyalgia Participation Questionnaire (FPQ) achieves reliable results in its original version in German and this project aims to achieve a translated, culturally adapted and validated version of it in Spanish. The questionnaire has been translated according to the FACIT methodology and tested at the Unidad de Gestion Clinica de Salud Mental (mental health department) in North Almeria. Once the preliminary tests were carried out, the final version of the questionnaire was created. The final version underwent a validation process, during which its psychometric properties were analysed, and its reliability evaluated through internal consistency and test-retest, Cronbach's alpha and Pearson's correlation coefficient. Several different types of validity were also analysed including external validity, construct and convergent validity estimated using correlation coefficients, content validity using empirical evaluation and discriminant validity using a DIF analysis. Floor and ceiling effects were also evaluated. The process in its entirety has been approved by the Comite Etico de Investigacion Clinica (research ethics committee for clinical investigation) in Almeria. The validation of the FPQ into different languages will provide medical professionals with a new tool for the assessment of patients with fibromyalgia, which will allow for improved treatment methods based on results.

Translation and validation of Portuguese of a questionnaire for evaluation of psychosomatic symptoms in adults with atopic dermatitis.

BACKGROUNDatopic dermatitis is directly related to psychological stress, reduced quality of life and psychosomatic symptoms. The Psychosomatic Scale for Atopic Dermatitis is the only questionnaire developed specifically for assessment of psychosomatization in atopic dermatitis. OBJECTIVESthe objective of this study was to cross-culturally adapt and validate a Brazilian-Portuguese version of the Psychosomatic Scale for Atopic Dermatitis. METHODSadaptation consisted of independent translation and backtranslation by three bilingual translators, followed by a pre-test. The Psychosomatic Scale for Atopic Dermatitis and the Dermatology Life Quality Index were self-administered to 47 patients with atopic dermatitis. Disease severity was evaluated using the Eczema Area and Severity Index. Factor analysis was used to identify the dimensions of the Brazilian Portuguese version of the Psychosomatic Scale for Atopic Dermatitis. Internal consistency and convergence validity were also analyzed. Reproducibility was assessed using the Kappa coefficient. RESULTSfactor analysis revealed a two-dimensional structure: stress/laziness/insecurity (I) and maladjustment/social relationships (II), explaining 54.4% of total variance. All dimensions revealed excellent internal consistency. External construct validity was confirmed by positive correlations between the Psychosomatic Scale for Atopic Dermatitis and the Dermatology Life Quality Index. Test-retest reliability was excellent, with k>0.7 for all questions. CONCLUSIONSthe Brazilian Portuguese version of the Psychosomatic Scale for Atopic Dermatitis demonstrated acceptable psychometric properties and can be used for the evaluation of psychosomatic symptoms in patients with atopic dermatitis and as a tool in clinical and epidemiological research.

Adaptation and validation of the Ankylosing Spondylitis Work Instability Scale (AS-WIS) for use in Turkey.

The Ankylosing Spondylitis Work Instability Scale (AS-WIS) is a recently developed 20-item measure to assess work instability in AS. This study aimed to adapt the AS-WIS to Turkish and to test its reliability and validity. After the translation process, 132 AS patients were assessed by the AS-WIS, Bath AS Disease Activity Index, Bath AS Functional Index and the AS Quality of Life Questionnaire. Reliability was tested by internal consistency, person separation index (PSI) and intra-class correlation coefficient (ICC); internal construct validity by Rasch analysis; external construct validity by associations with comparator scales and cross-cultural validity by comparison with the original UK data. Reliability of the Turkish AS-WIS was good with Cronbach's α and PSI of 0.88 and test-retest ICC of 0.91. Data showed good fit to Rasch model [mean item fit: -0.477 (SD 1.047), Chi-square interaction: 60.9 (df = 40, p = 0.018)]. There was no differential item functioning by age, gender, disease duration or work type. The scale was strictly unidimensional. 51 % of the patients were at moderate risk, and 9 % were at high risk of having to give up their work. External construct validity was confirmed by expected correlations with comparator scales, and a clear gradient of disease activity and functional status across increasing levels of risk. Cross-cultural validity showed some differences in item locations, but this cancelled out at the test level. Turkish version of the AS-WIS is reliable, valid and available for use in routine clinical setting to identify patients who are at risk of having to give up their current job.