Rasch Analysis of the International Quality of Life Basic Data Set Version 2.0.

OBJECTIVE: To examine the internal construct validity of the International Spinal Cord Injury Quality of Life Basic Data Set Version 2.0 (QoL-BDS V2.0) and compare this with the internal construct validity of the original version of the QoL-BDS. DESIGN: International cross-sectional psychometric study. SETTING: Spinal rehabilitation units, clinics, and community. PARTICIPANTS: The study involved 5 sites and 4 countries, 2 of whose primary language is not English. Each site included a consecutive sample of inpatients with spinal cord injury or disease (SCI/D) and a convenience sample of individuals with SCI/D living in the community (N=565). MAIN OUTCOME MEASURES: The QoL-BDS V2.0 consists of the 3 original items on satisfaction with life as a whole, physical health, psychological health of the QoL-BDS, and an additional item on satisfaction with social life. All 4 items are answered on a 0-10 numeric rating scale. Rasch analysis was performed on versions 1.0 and 2.0 of the QoL-BDS to examine the ordering of the items' response options, item scaling, reliability, item fit, local item independence, differential item functioning, and unidimensionality. RESULTS: The sample included 565 participants with 57% outpatients and 43% inpatients. Mean age was 51.4 years; 71% were male; 65% had a traumatic injury, 40% had tetraplegia, and 67% were wheelchair users. Item thresholds were collapsed for ordering, and subsequent analyses showed good internal construct validity for the QoL-BDS V2.0 with a person separation reliability of 0.76 and Cronbach α of 0.81. Infit and outfit statistics ranged 0.62-0.91. No local dependencies and multidimensionality were found. Differential item functioning was observed only for country and inpatients vs outpatients but not for other participants' characteristics. Differences in internal construct validity between the 3-item and 4-item versions were minimal. CONCLUSIONS: The results of this Rasch analysis support the internal construct validity of the QoL-BDS V2.0.

Demographic and environmental factors associated with disability in India, Laos, and Tajikistan: a population-based cross-sectional study.

BACKGROUND: The number of people experiencing functional limitations due to health conditions (capacity) is expected to increase in low and middle-income countries as populations age and rates of non-communicable disease rise. This trend could raise the prevalence and levels of disability worldwide. Understanding the demographic and environmental factors associated with disability can inform the design of policy interventions to make societies more accessible and inclusive for all. METHODS: Approximately 2,500-3,000 participants in each of India, Laos, and Tajikistan responded to the Gallup World Poll and the World Health Organization's Brief Model Disability Survey through face-to-face interviews. For each country, random forest regression was performed to explore the associations of demographic and environmental factors with disability while controlling for capacity. Using the variable importance measures generated by the random forest models, linear regression models were built in a stepwise manner for each country to predict disability level based on these contextual factors. RESULTS: Capacity was strongly associated with disability in all three countries. Most of the variance in disability was explained by minimally adjusted linear models that included only capacity, sex, and age. Inclusion of additional demographic factors and environmental factors explained slightly more of the variance in disability score. Across all three countries, the level of basic infrastructure, public services, and financial stability were moderately associated with disability. Age, sex, employment status, the use of assistive technologies, and other factors had associations with disability that were highly variable across countries. CONCLUSION: While capacity was the main determinant of disability, individual demographic and environmental factors were associated with disability in a country-specific manner while controlling for the effects of capacity.

Change in environmental barriers experienced over a 5-year period by people living with spinal cord injury in Switzerland: a prospective cohort study.

STUDY DESIGN: Cohort study with two measurement occasions. OBJECTIVES: To investigate change in environmental barriers experienced by people living with spinal cord injury (SCI) over a 5-year period. SETTING: Community, Switzerland. METHODS: Data were from the Swiss spinal cord injury (SwiSCI) survey. Main outcome measure was the Nottwil Environmental Factors Inventory-Short Form. Random-effects Poisson regression featuring between-within estimation was used to examine predictors of the number of environmental barriers and of its change over time. RESULTS: One thousand five hundred and forty-nine persons participated in Survey 2012 and 1530 participated in Survey 2017; 761 participated in both surveys. In both surveys most participants reported at least three barriers. Leading issues were unfavorable climate, inaccessibility of buildings and public spaces, and lack of or insufficiently adapted means of transportation. Reporting of barriers related to climate, finances, and state services declined over time. Between subjects, having more health problems, lesser physical independence, poorer mental health, and a lower household income were related to a higher number of barriers experienced. Within subjects, improvements in income, physical independence, and mental health over time were related to a reduction in barriers. CONCLUSIONS: Inaccessibility of buildings and places and problems with transportation remained major barriers over a 5-year period and should be priorities of Swiss disability policy. People with reduced mental and physical health, and those with lower income are vulnerable groups deserving specific attention. Policies targeting income and life-long rehabilitation targeting health promotion and maintenance may be suitable means to reduce the experience of environmental barriers.

Factors associated with labor market participation of persons with traumatic SCI in Switzerland: analyzing the predictive power of social background, health, functional independence, and the environment.

STUDY DESIGN: Cross-sectional study using data from the 2012 community survey of the Swiss Spinal Cord Injury Cohort Study. OBJECTIVES: To identify associations between selected factors related to the social background, health, functional independence, and the environment of persons with spinal cord injury (SCI) and their labor market participation. SETTING: Community-based, Switzerland. METHODS: Labor market participation (i.e., involvement in paid work or not) was determined for a sample of 966 persons with traumatic SCI who were of employable age at the time of the survey. Applying an exploratory approach, potential predictors of labor market participation were selected based on the literature and using a bidirectional stepwise variable selection approach. Descriptive statistics were calculated and weighted bootstrapped multiple logistic regressions were applied to describe the associations between the selected predictor variables and labor market participation, controlling for sociodemographic and SCI-related characteristics. RESULTS: A total of 568 (58.8%) of the participants were involved in paid work at the time of the survey. From the 17 selected predictor variables, general functional independence and Swiss citizenship showed a significant positive association, and chronic pain a negative association with involvement in paid work. CONCLUSIONS: Beyond previously established sociodemographic and injury-related risk factors such as female gender, low education, and high lesion severity, functional independence, chronic pain, and nationality proved crucial for labor market participation. These factors should receive particular attention in medical and vocational strategies striving for a sustainable work integration of persons with SCI.

Validation of the World Health Organization Disability Assessment Schedule 2.0 in adults with spinal cord injury in Taiwan: a psychometric study.

STUDY DESIGN: Psychometric study including exploratory factor analysis and Rasch analysis. OBJECTIVE: The aim of the present study was to examine the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) in terms of its dimensionality and metric properties in a sample of people with spinal cord injury (SCI). SETTING: Two hundred and thirty-nine hospitals in Taiwan METHODS: Secondary analysis of cross-sectional data from the National Disability Determination System in Taiwan, including data of individuals with more than 1-year chronic spinal cord injury and over 18 years of age. We would ask the all 6 domains of WHODAS 2.0, except those participants who were not working in present, based on the WHODAS 2.0 manual. RESULTS: Data from 521 persons were included. The internal consistency of WHODAS 2.0 was high for all six domains (Cronbach's α between 0.87-0.99). The exploratory factor analysis supported the original six domain structure of WHODAS 2.0 to a large extent. Rasch analysis provided domain scores usable for measurement at the individual level and an overall WHODAS 2.0 score that takes into account the multidimensionality of the instrument. CONCLUSIONS: WHODAS 2.0 provides a reliable and valid instrument to measure relevant aspects of "activity and participation" in the context of functioning in people with SCI in Taiwan and may guide their rehabilitation.

The Impact of Missing Values and Single Imputation upon Rasch Analysis Outcomes: A Simulation Study.

Imputation becomes common practice through availability of easy-to-use algorithms and software. This study aims to determine if different imputation strategies are robust to the extent and type of missingness, local item dependencies (LID), differential item functioning (DIF), and misfit when doing a Rasch analysis. Four samples were simulated and represented a sample with good metric properties, a sample with LID, a sample with DIF, and a sample with LID and DIF. Missing values were generated with increasing proportion and were either missing at random or completely at random. Four imputation techniques were applied before Rasch analysis and deviation of the results and the quality of fit compared. Imputation strategies showed good performance with less than 15% of missingness. The analysis with missing values performed best in recovering statistical estimates. The best strategy, when doing a Rasch analysis, is the analysis with missing values. If for some reason imputation is necessary, we recommend using the expectation-maximization algorithm.

What Affects the Quality of Score Transformations? Potential Issues in True-Score Equating Using the Partial Credit Model.

This simulation study investigated to what extent departures from construct similarity as well as differences in the difficulty and targeting of scales impact the score transformation when scales are equated by means of concurrent calibration using the partial credit model with a common person design. Practical implications of the simulation results are discussed with a focus on scale equating in health-related research settings. The study simulated data for two scales, varying the number of items and the sample sizes. The factor correlation between scales was used to operationalize construct similarity. Targeting of the scales was operationalized through increasing departure from equal difficulty and by varying the dispersion of the item and person parameters in each scale. The results show that low similarity between scales goes along with lower transformation precision. In cases with equal levels of similarity, precision improves in settings where the range of the item parameters is encompassing the person parameters range. With decreasing similarity, score transformation precision benefits more from good targeting. Difficulty shifts up to two logits somewhat increased the estimation bias but without affecting the transformation precision. The observed robustness against difficulty shifts supports the advantage of applying a true-score equating methods over identity equating, which was used as a naive baseline method for comparison. Finally, larger sample size did not improve the transformation precision in this study, longer scales improved only marginally the quality of the equating. The insights from the simulation study are used in a real-data example.

WHO Functioning and Disability Disaggregation (FDD11) tool: a reliable approach for disaggregating data by disability.

BACKGROUND: There is a global scarcity of good quality disability data, which has contributed to a lack of political will to address the challenges that persons with disabilities face. The current paper proposes a way forward to overcome this gap by demonstrating the psychometric properties of the World Health Organization Functioning and Disability Disaggregation Tool (FDD11) - a brief disability disaggregation instrument that countries can use. RESULTS: The study demonstrated that FDD11 is a valid and reliable tool. Unidimensionality of the scale produced by each calibration was supported by the factor analysis performed. The analysis indicated good fit of the items, and targeting of the items was deemed to be sufficient. The person separation index was 0.82, indicating good reliability of the final scale. CONCLUSION: FDD11 provides a good opportunity to researchers and governments to capture good quality disability data and to disaggregate existing data by disability. The tool can facilitate low- and middle-income countries in their efforts to develop evidenced-based policies to address any barriers faced by persons with disabilities, to monitor the implementation of the Convention on the Rights of Persons with Disabilities and the Sustainable Development Goals, and to take stock of the challenges that still remain.

A Rasch-Based Comparison of the Functional Independence Measure and Spinal Cord Independence Measure for Outcome and Quality in the Rehabilitation of Persons with Spinal Cord Injury.

OBJECTIVE: The Functional Independence Measure (FIM™) and spinal cord injury (SCI)-specific Spinal Cord Independence Measure (SCIM) are commonly used tools for outcome measurement and quality reporting in rehabilitation. The objective of this study was to investigate the psychometric properties of FIM™ and SCIM and to equate the 2 scales. METHODS: First, content equivalence of FIM™ and SCIM was established through qualitative linking with the International Classification for Functioning, Disability and Health (ICF). Secondly, a Rasch analysis of overlapping contents determined the metric properties of the scales and provided the empirical basis for scale equating. Furthermore, a transformation table for FIM™ and SCIM was created and evaluated. SUBJECTS: Patients with SCI in Swiss inpatient rehabilitation in 2017-18. RESULTS: The ICF linking and a separate Rasch analysis of FIM™ restricted the analysis to the motor scales of FIM™ and SCIM. The Rasch analysis of these scales showed good metric properties. The co-calibration of FIM™ and SCIM motor scores was supported with good fit to the Rasch model. The operational range of SCIM is larger than for FIM™ motor scale. DISCUSSION: This study supports the advantage of using SCIM compared with FIM™ for assessing the functional independence of patients with SCI in rehabilitation.

Generating comprehensive functioning and disability data worldwide: development process, data analyses strategy and reliability of the WHO and World Bank Model Disability Survey.

BACKGROUND: Data on functioning and disability collected at population level is essential to complement mortality and morbidity, to estimate rehabilitation needs of countries and regions and to monitor the Convention on the Rights of Persons with Disabilities (CRPD) and the Sustainable Development Goals (SDGs). The objective of this paper is to briefly report the development process of the WHO Model Disability Survey, its data analysis strategy as well as its reliability and ability to measure low to high levels of functioning and disability across countries. METHODS: The development process is described in detail, and a secondary analysis using Rasch methods is conducted to report reliability and targeting using data from eight national and two regional implementations of the survey. RESULTS: The currently available versions of the Model Disability Survey are presented. The survey has good to very good internal reliability and good targeting in all included countries. CONCLUSION: The participatory and evidence-based development, consideration of the expertise of stakeholders, the availability of previously developed ICF-based surveys, and WHO tools targeting functioning and disability are reflected in its good to very good psychometric properties. The survey has been implemented to date in Afghanistan, Cameroon, Chile, Costa Rica, India, Laos, Pakistan, Philippines, Sri Lanka, and Tajikistan, and is used to inform policy-making, to monitor the CRPD and SDGs and to plan the delivery of rehabilitation services.

Validation of PARADISE 24 and Development of PARADISE-EDEN 36 in Patients with Dementia.

Dementia was one of the conditions focused on in an EU (European Union) project called "PARADISE" (Psychosocial fActors Relevant to brAin DISorders in Europe) that later produced a measure called PARADISE 24, developed within the biopsychosocial model proposed in the International Classification of Functioning Disability and Health (ICF). The aims of this study are to validate PARADISE 24 on a wider sample of patients with mild to moderate dementia to expand PARADISE 24 by defining a more specific scale for dementia, by adding 18 questions specifically selected for dementia, which eventually should be reduced to 12. We enrolled 123 persons with dementia, recruited between July 2017 and July 2019 in home care and long-term care facilities, in Italy, and 80 participants were recruited in Warsaw between January and July 2012 as part of a previous cross-sectional study. The interviews with the patient and/or family were conducted by health professionals alone or as a team by using the Paradise data collection protocol. The psychometric analysis with the Rasch analysis has shown that PARADISE 24 and the selection of 18 additional condition-specific items can be expected to have good measurement properties to assess the functional state in persons with dementia.

Identifying key environmental barriers experienced by persons with mild, moderate, or severe disability in Bankim Health District, Cameroon: a policy-targeted secondary analysis of data obtained with the World Bank and WHO model disability survey.

BACKGROUND: Comprehensive data is key for evidence-informed policy aiming to improve the lives of persons experiencing different levels of disability. The objective of this paper was to identify the environmental barriers - including physical, social, attitudinal, and political barriers - that might become priorities for cross-cutting policies and policies tailored to the needs of persons experiencing severe disability in Cameroon. METHODS: A secondary analysis of data obtained with the WHO Model Disability Survey was completed in the Bankim Health District (N = 559) using random forest regression to determine and compare the impact of the environmental factors on the experience of disability. RESULTS: The physical environment had by far the highest influence on disability, with transportation, toilet of the dwelling, and the dwelling itself being the most important factors. Factors inside one's own home (toilet of the dwelling, and the dwelling itself) were the most important for persons with moderate and severe disability, followed by attitudes of others and issues with accessing health care. CONCLUSION: Our study provides country policy makers with evidence for setting priorities and for the development of evidence-informed policies for the Bankim Health District in Cameroon.

Change in mobility independence over 5 years for persons with chronic spinal cord injury.

OBJECTIVES: To evaluate change in mobility independence (MI) in community dwelling persons with spinal cord injury (SCI). PARTICIPANTS: Community Survey. DESIGN: Cohort study. Rasch analysis was applied to the mobility subscale of the Spinal Cord Independence Measure - Self-Report data from years 2012 to 2017, resulting in a Rasch Mobility Independence Score (RMIS). We employed multilevel modeling to examine RMIS and its change over 5 years, adjusting for demographics and SCI severity; random forest regression was applied to determine the impact of modifiable factors (e.g. environmental factors, home-support) on its change. RESULTS: The analysis included 728 participants. The majority (≈85%) of participants demonstrated little or no change in RMIS from 2012 to 2017; however, a smaller proportion (15%) showed considerably large change of more than 10 on the 100-point scale. A mixed-effects model with random slopes and intercepts described the dataset very well (conditional R2 of 0.95) in terms of demographics and SCI severity. Age was the main predictor of change in RMIS. Considering SCI severity, change in RMIS was related to age for the subgroup with paraplegia, and to time since injury for the subgroup with tetraplegia. No impact of modifiable factors was found. CONCLUSION: RMIS in persons with SCI changes over a period of 5 years, especially in elder patients with paraplegia and persons with incomplete tetraplegia with more than 15 years of time since injury. During routine follow-up change in mobility independence should be assessed in order to timely intervene and prevent mobility loss and participation limitations.

Measuring functioning and disability using household surveys: metric properties of the brief version of the WHO and World Bank model disability survey.

BACKGROUND: The Model Disability Survey (MDS) is the current standard recommended by WHO to collect functioning and disability data. Answering calls from countries requesting a version to be implemented as a module that could be integrated into existing surveys and be used for monitoring disability trends and for data disaggregation, WHO developed the brief MDS. The objectives of this paper are to evaluate the metric properties of the disability metrics generated with the Brief MDS and the precision of the Brief MDS in comparison with the full MDS. RESULTS: The partial credit model, a unidimensional model for polytomous data from the Rasch family, was applied to evaluate psychometric properties using data from national MDS implementations in Chile (N = 12,265) and in Sri Lanka (N = 3000). The Brief MDS generates valid metrics for measuring disability, from the perspectives of capacity and performance, thereby achieving good levels of measurement precision in comparison with its full counterpart. CONCLUSION: Given the scarcity of valid functioning and disability modules for household surveys, the Brief MDS represents a milestone in disability measurement. The Brief MDS is currently used by countries to monitor disability trends over time, which is especially important to evaluate the impact of health policies and public health interventions, to disaggregate indicators of the Sustainable Development Goals, and to monitor the implementation of the UN Convention on the Rights of Persons with Disabilities (CRPD).

Creating a common metric based on existing activities of daily living tools to enable standardized reporting of functioning outcomes achieved during rehabilitation.

OBJECTIVE: Many different assessment tools are used to assess functioning in rehabilitation; this limits the comparability and aggregation of respective data. The aim of this study was to outline the development of an International Classification of Functioning, Disability and Health (ICF)-based interval-scaled common metric for 2 assessment tools assessing activities of daily living: the Functional Independence Measure (FIMTM) and the Extended Barthel Index (EBI), used in Swiss national rehabilitation quality reports. METHODS: The conceptual equivalence of the 2 tools was assessed through their linking to the ICF. The Rasch measurement model was then applied to create a common metric including FIMTM and EBI. SUBJECTS: Secondary analysis of a sample of 265 neurological patients from 5 Swiss clinics. RESULTS: ICF linking found conceptual coherency of the tools. An interval-scaled common metric, including FIMTM and EBI, could be established, given fit to the Rasch model in the related analyses. CONCLUSION: The ICF-based and interval-scaled common metric enables comparison of patients and clinics functioning outcomes when different activities of daily living tools are used. The common metric can be included in a Standardized Assessment and Reporting System for functioning information in order to enable data aggregation and comparability.

Measuring posttraumatic growth and depreciation after spinal cord injury: A Rasch analysis.

PURPOSE: Individuals with spinal cord injury (SCI) may experience both positive (posttraumatic growth, PTG) and negative (posttraumatic depreciation, PTD) psychological changes following the injury. PTG and PTD were assessed using the 10-item short form of the Posttraumatic Growth Inventory (PTGI-SF) and 10 matched negatively worded items for PTD (selected from the PTGI-42) within the Swiss Spinal Cord Injury Cohort Study (SwiSCI). This item selection is henceforth called PTG/D-SF. The objective of this study was to test the metric properties of the PTG/D-SF to determine the best strategy to derive reliable sum scores and to test the validity of several different structural conceptualizations. METHOD: Using cross-sectional data (N = 278), a series of unidimensional and multidimensional Rasch analyses of the PTG/D-SF (N = 20) were performed. Rasch analyses were conducted separately for the items or by domains to investigate dimensionality, monotonicity, item and model fit, and local item dependency of the instrument. RESULTS: The separate PTG and PTD items or their domains can be summated to form a unidimensional scale. Aggregation into domains improved the score distribution and increased the scope of the instruments. The reliability of the sum score for PTG was good (Person Separation: 0.81); the one for PTD was admissible (Person Separation: 0.77). CONCLUSION: PTG and PTD should be understood as distinct constructs rather than two ends of a continuum. Findings support the use of a PTG total score and to some degree the PTD total score. Future work could adapt the PTD items to improve the performance of the scale. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The Functional Independence Measure 18-item version can be reported as a unidimensional interval-scaled metric: Internal construct validity revisited.

OBJECTIVE: Since the 1990s the Functional Independence Measure (FIM™) was believed to measure 2 different constructs, represented by its motor and cognitive subscales. The practice of reporting FIM™ total scores, together with recent developments in the understanding of the influence of locally dependent items on fit to the Rasch model, raises the question of whether the FIM™ 18-item version can be reported as a unidimensional interval-scaled metric. DESIGN: Rasch analysis of the FIM™ using testlet approaches to accommodate local response dependency. PATIENTS: A calibration sample containing 946 cases of data from 11,103 patients undergoing neurological or musculoskeletal rehabilitation in Switzerland in 2016. RESULTS: Baseline analysis and the traditional testlet approach showed no fit with the Rasch model. When items were grouped into 2 testlets, fit to the Rasch model was achieved, indicating unidimensionality across all 18 items. A transformation table to convert FIM™ raw ordinal scores to the corresponding Rasch interval scaled values was created. CONCLUSION: This study provides evidence that FIM™ total scores represent a unidimensional set of items, supporting their use in clinical practice and outcome reporting when applying the respective transformation table. This provides a basis for standardized reporting of functioning.

Applying the ICF linking rules to compare population-based data from different sources: an exemplary analysis of tools used to collect information on disability.

BACKGROUND: Data on disability are regularly collected by different institutions or ministries using specific tools for different purposes, for instance to estimate the prevalence of disability or eligibility of specific populations for social benefits. The interoperability of disability data collected in countries is essential for policy making and to monitor the implementation of the Convention on the Rights of Persons with Disabilities. The first objective of this paper is to map and compare tools that collect data on disability for different purposes, more specifically the Brazilian National Health Survey and the Brazilian Functioning Index to the World Health Organization (WHO) and the World Bank Model Disability Survey (MDS), currently recommended as a standard tool for disability measurement. The second objective is to demonstrate the usefulness and value of the International Classification of Functioning, Disability and Health Linking Rules to map and compare population-based surveys and other content-related tools collecting data on disability, even when these have already been developed based on the International Classification of Functioning, Disability and Health. METHODS: Disability information collected with the three different tools was mapped and compared using the International Classification of Functioning, Disability and Health Linking Rules. RESULTS: Although the disability module in the Brazilian National Health Survey is fundamentally different from the MDS, the mapping disclosed that several modules of the Brazilian National Health Survey already cover many aspects necessary to estimate prevalence and understand disability as currently recommended by the WHO and the World Bank. The Brazilian Functioning Index and the MDS are both based on the International Classification of Functioning, Disability and Health and are very similar in the approach and content of their questions on functioning. Specific information on environmental factors is essential to identify needs and barriers, as well as to devise procedures to reduce injustice and inequalities. This information is still not targeted broadly enough in both the Brazilian National Health Survey and the Brazilian Functioning Index. CONCLUSIONS: Overall, this mapping exercise showed that applying the International Classification of Functioning, Disability and Health linking rules to population-based data coming from different sources provides researchers and stakeholders involved in decision-making with standardized and straightforward information about overlaps and gaps. Implications for Rehabilitation Data on functioning and disability regularly collected with different purposes and by different institutions or ministries within a country can be compared using the International Classification of Functioning, Disability and Health as a reference framework and the International Classification of Functioning, Disability and Health linking rules. The recently published refinements of the International Classification of Functioning, Disability and Health Linking Rules go beyond the sole linking to International Classification of Functioning, Disability and Health categories and provide standardized procedures to document the perspective of linked questions or the categorization of response options. They are therefore useful to compared tools that have been developed based on the International Classification of Functioning, Disability and Health. The current disability module of the Brazilian Health Survey needs a revision to be suitable to collect data on disability that is Convention on the Rights of Persons with Disabilities conform and guarantees interoperability with disability data from other sources in Brazil, especially from disability assessment for social benefits and implementation of policies.

All metrics are equal, but some metrics are more equal than others: A systematic search and review on the use of the term 'metric'.

OBJECTIVE: To examine the use of the term 'metric' in health and social sciences' literature, focusing on the interval scale implication of the term in Modern Test Theory (MTT). MATERIALS AND METHODS: A systematic search and review on MTT studies including 'metric' or 'interval scale' was performed in the health and social sciences literature. The search was restricted to 2001-2005 and 2011-2015. A Text Mining algorithm was employed to operationalize the eligibility criteria and to explore the uses of 'metric'. The paradigm of each included article (Rasch Measurement Theory (RMT), Item Response Theory (IRT) or both), as well as its type (Theoretical, Methodological, Teaching, Application, Miscellaneous) were determined. An inductive thematic analysis on the first three types was performed. RESULTS: 70.6% of the 1337 included articles were allocated to RMT, and 68.4% were application papers. Among the number of uses of 'metric', it was predominantly a synonym of 'scale'; as adjective, it referred to measurement or quantification. Three incompatible themes 'only RMT/all MTT/no MTT models can provide interval measures' were identified, but 'interval scale' was considerably more mentioned in RMT than in IRT. CONCLUSION: 'Metric' is used in many different ways, and there is no consensus on which MTT metric has interval scale properties. Nevertheless, when using the term 'metric', the authors should specify the level of the metric being used (ordinal, ordered, interval, ratio), and justify why according to them the metric is at that level.

Self-Efficacy and Pressure Ulcer Prevention After Spinal Cord Injury-Results From a Nationwide Community Survey in Switzerland (SwiSCI).

BACKGROUND: Pressure ulcers (PUs) are a common and severe health condition in persons with spinal cord injury (SCI). Skin-care strategies for PU prevention are usually provided during initial rehabilitation. However, individuals with SCI often do not perform these strategies continuously, especially after discharge. The influence of psychological factors such as general self-efficacy (GSE) on the performance of PU prevention behavior has not yet been sufficiently explored. OBJECTIVE: To investigate whether persons with greater levels of GSE are more likely to perform skin-care strategies for PU prevention regularly. DESIGN: Nationwide cross-sectional survey within the Swiss Spinal Cord Injury Cohort Study. SETTING: Community setting, data collection between 2011 and 2013. PARTICIPANTS: A total of 456 subjects with a traumatic or nontraumatic SCI living in Switzerland. METHODS: Associations between GSE and PU prevention behavior were analyzed by multivariate proportional odds regression models, including potential sociodemographic, lesion-related, and lifestyle-related confounders without and with interaction terms between GSE and potential effect modifiers. MAIN OUTCOME MEASUREMENTS: Self-efficacy was assessed by the GSE scale comprising 10 items. PU preventive behavior was operationalized using 5 items of an adapted version of the Spinal Cord Injury Lifestyle scale. Both measurements were components of a self-administered questionnaire. RESULTS: Based on the regression model without interaction terms, GSE levels were not associated with skin-care PU prevention. After we included interaction terms, the final model showed statistically significant associations between GSE and 3 skin-care items with odds ratios ranging from 1.09 to 1.17 (all P < .001). The slightly positive effect of GSE on PU prevention behavior was restricted to persons who sustained their SCI at a younger age. CONCLUSIONS: GSE was generally not associated with skin-care PU prevention behavior among persons with SCI in this study. In further research, it might be of interest to assess SCI-specific concepts of self-efficacy. LEVEL OF EVIDENCE: III.