Gill Gilworth

Construct validity and reliability of the Rivermead Post-Concussion Symptoms Questionnaire

Objectives: To provide further evidence of reliability and internal and external construct validity of the Rivermead Post-Concussion Symptoms Questionnaire (RPQ), which measures severity of postconcussion symptoms following head injury. Design and setting: A cross-sectional study of consecutive patients presenting with a head injury in two urban teaching hospitals and a community trust. Patients: Three hundred and sixty-nine patients returned a questionnaire from 1689 consecutive adult patients (18 years and above) referred to radiology for a skull X-ray following a head injury, and those who were currently under the care of a community-based multidisciplinary head injury team. Method: Internal construct validity tested by fit to the Rasch Measurement model; external construct validity tested by correlations with Rivermead Head Injury Follow-up Questionnaire (RHFUQ); test-retest reliability tested by correlations at two-week intervals. Outcome measures: Rivermead Post-Concussion Symptoms Questionnaire and Rivermead Head Injury Follow-up Questionnaire. Main results: RPQ scores ranged from 0 to 64 (17.3% floor, 0.3% ceiling). Overall fit to the Rasch model was poor (item fit mean-0.416, SD=1.989, chi-squared=172.486, p < 0.01) suggesting a lack of unidimensionality. The items headaches, dizziness and forgetful displayed misfitting residuals and the first two items also displayed significant item trait fit statistics (p < 0.0006). After removing the items headaches, dizziness and subsequently nausea the RPQ demonstrated good fit at overall and individual item levels, both for the remaining 13 items (RPQ-13) and the three items (RPQ-3) which now formed a subsidiary scale. All items functioned consistently across age and gender. The RPQ-13 and RPQ-3 scales showed test-retest reliability coefficients of 0.89 and 0.72 (both p-values < 0.01) and positive correlations with RHFUQ scores (0.83 for RPQ-13, 0.62 for RPQ-3, both p-values< 0.01). Conclusions: As currently used, the RPQ does not meet modern psychometric standards. Its 16 items do not tap into the same underlying construct and should not be summated in a single score. When the RPQ is split into two separate scales, the RPQ-13 and the RPQ-3, each set of items forms a unidimensional construct for people with head injury at three months post injury. These scales show good test-retest reliability and adequate external construct validity.

Working with a brain injury: personal experiences of returning to work following a mild or moderate brain injury.

OBJECTIVE Most brain injuries occur in people of working age. Individuals with mild or moderate injuries may have unrecognized problems affecting return to work. Previous studies have focused on factors that predict return to work after brain injury. There is limited information about the experiences of individuals returning to work. DESIGN Individual interviews explored the work-related expectations and experiences of workers who had sustained mild to moderate brain injury. A sampling frame ensured a spread of participants by age, injury severity and work type. METHODS Thirty-three interviews were conducted 4-6 months post-injury. Most participants had returned to work. Interviews were transcribed verbatim for thematic analysis. RESULTS Key emerging issues for participants were the invisibility of their injury, continuing symptoms affecting their ability to do their job and lack of advice and guidance on returning to work. Return to work support systems were considered to be poorly coordinated and managed. CONCLUSION It is important that healthcare professionals anticipate the vocational rehabilitation needs of patients who have sustained mild to moderate brain injury. These patients may require additional coordinated interventions and specific person-centred information to ensure a successful and, most importantly, a sustained return to work.

Adaptation and cross-cultural validation of the rheumatoid arthritis work instability scale (RA–WIS)

Background: Despite recent advances, work disability in rheumatoid arthritis (RA) remains common. Work disability is frequently preceded by a period of work instability characterised by a mismatch between an individual’s functional abilities and job demands. This could raise the risk of work disability if not resolved. A work instability scale for RA (RA–WIS) has previously been developed to screen for this risk. The objective of this study was the adaptation of this scale into French, Dutch and German. Method: Different language versions of the RA–WIS were produced through a process of forward and back translations. The new scales were tested for face validity. English data from the original developmental study was pooled with data generated through postal surveys in each country. The internal construct and cross-cultural validity of the new scales were assessed using Rasch analysis, including differential item functioning (DIF) by culture. Results: The pooled data showed good fit to the Rasch model and demonstrated strict unidimensionality. DIF was found to be present for six items, but these appeared both to cancel out at the test level and have only a marginal effect on the test score itself. Conclusions: The RA–WIS was shown to be robust to adaptation into different languages. Data fitted Rasch model expectations and strict tests of unidimensionality. This project and the continuing work on further cross-cultural adaptations have the potential to help ensure clinicians across Europe are able to support RA patients to achieve their potential in work through early identification of those most at risk.

Reducing work disability in Ankylosing Spondylitis – development of a work instability scale for AS

BackgroundThe Work Instability Scale for Rheumatoid Arthritis (RA-WIS) is established and is used by physicians to identify patients at risk of job loss for rapid intervention. The study objective was to explore the concept of Work Instability (a mismatch between an individuals abilities and job demands) in Ankylosing Spondylitis (AS) and develop a Work Instability Scale specific to this population.MethodsNew items generated from qualitative interviews were combined with items from the RA-WIS to form a draft AS-WIS. Rasch analysis was used to examine the scaling properties of the AS-WIS using data generated through a postal survey. The scale was validated against a gold standard of expert assessment, a test-retest survey examined reliability.ResultsFifty-seven participants who were in work returned the postal survey. Of the original 55 items 38 were shown to fit the Rasch model (χ2 37.5; df 38; p 0.494) and free of bias for gender and disease duration. Following analysis for discrimination against the gold standard assessments 20 items remained with good fit to the model (χ2 24.8; df 20; p 0.21). Test-retest reliability was 0.94.ConclusionThe AS-WIS is a self-administered scale which meets the stringent requirements of modern measurement. Used as a screening tool it can identify those experiencing a mismatch at work who are at risk of job retention problems and work disability. Work instability is emerging as an important indication for the use of biologics, thus the AS-WIS has the potential to become an important outcome measure.

Screening for the risk of job loss in multiple sclerosis (MS): development of an MS-specific Work Instability Scale (MS-WIS).

Background: Multiple Sclerosis (MS) mainly presents amongst those of working age. Depending upon the type of MS, many people embark upon a long period of managing their day-to-day work-related needs in the face of intermittent and sometimes persistent disabling symptoms. The objective of this study was to explore the concept of work instability (WI) following the onset of MS and develop a Work Instability Scale (WIS) specific to this population. Method: WI amongst those with MS in work was explored through qualitative interviews which were then used to generate items for a WIS. Rasch analysis was used to refine the scaling properties of the MS-WIS, which was then validated against expert vocational assessment by occupational health physiotherapists and ergonomists. Results: The resulting measure is a 22-item, self-administered scale which can be scored in three bands indicating low, medium and high risk of WI (job retention) problems. The scale meets modern psychometric requirements for measurement, indicated by adequate fit to the Rasch model with absence of local dependency and differential item functioning (DIF) by age, gender and hours worked. Conclusions: The scale presents an opportunity in routine clinical practice to take positive action to reduce sickness absence and prevent job loss.

Screening for job loss: Development of a work instability scale for traumatic brain injury

Objective: The objective of this study was to explore the concept of work instability (a mis-match between an individuals functional and cognitive abilities and the demands of their job) following traumatic brain injury (TBI) and develop a work instability scale specific to this population. Method: Work instability (WI) following TBI was explored through qualitative interviews which were then used to generate items for a work instability scale (WIS). Rasch analysis was used to examine the scaling properties of the TBI-WIS which was then validated against a gold standard of expert vocational assessment by occupational psychologists. Results and conclusion: The resulting measure is a 36 item, self-administered scale which can be scored in three bands indicating low, medium and high risk of job retention problems. The scale meets modern psychometric requirements for measurement and presents an opportunity in routine clinical practice to take positive action to prevent job loss.

The development and validation of the Office Work Screen

BACKGROUND The prevalence and costs to both employers and individuals of musculoskeletal disorders and associated psychosocial factors are well documented. There is increasing evidence that early identification is the key to the prevention of chronicity and sickness absence. AIMS The study aimed to develop and validate a screening questionnaire, capturing relevant psychosocial issues and musculoskeletal symptoms, to measure work instability (WI) in office workers. METHODS The staged methodology was based upon Rasch analysis and included item banking from existing Work Instability scales and analysis of new data from postal surveys. The criterion validity of the emerging scale was examined using vocational assessments by occupational physiotherapists. RESULTS A 62-item questionnaire was returned by 153 employees from two different settings. The data were fitted to the Rasch model and 26 items were found to fit model expectations (chi-square P= 0.07), satisfy strict requirements for unidimensionality and discriminate across expert defined levels of WI. Reliability was 0.9, indicating suitability for use at the individual level. Absence of item bias was shown for age, gender and if the individual had been off sick from work in the past 3 months, suggesting the scale is robust to variations in workforce composition and sickness absence rates. CONCLUSIONS The Office Work Screen is a short questionnaire incorporating both musculoskeletal symptoms and relevant psychosocial factors in one dimension. This new questionnaire may facilitate workforce screening, individual monitoring and proactive targeting of interventions (for example, vocational rehabilitation) to prevent or minimize sickness absence in office workers.

The Manual Work Instability Scale: development and validation

BACKGROUND Increasing awareness of the burden of absenteeism and reduced performance at work highlights the importance of early identification of individuals experiencing work instability (WI), a mismatch between functional and cognitive abilities and job demands. AIMS To develop and validate a screening questionnaire to measure WI in manual workers. METHODS Questionnaire items were generated via qualitative interviews with manual workers and a draft survey instrument was completed by workers in a variety of fields. Rasch analysis was used interactively to assess the psychometric aspects of the emerging scale, including unidimensionality and absence of item bias (differential item functioning). RESULTS A total of 17 qualitative interviews generated 110 potential items for the questionnaire. The item set resolved to a 25-item scale, which satisfied model expectations (item residual mean = -0.13, SD = 1.04; person residual mean = -0.29, SD = 0.75), had good reliability (alpha = 0.86) and strict unidimensionality (t-test 7.5% confidence interval 3.8-11.2). CONCLUSIONS The Manual Work Instability Scale is a short psychometrically robust questionnaire based on the concept of WI, which incorporates both musculoskeletal symptoms and relevant psychosocial factors. It may prove effective in screening and identifying WI in workers in predominantly physical occupations.

Living with Behçet’s Disease

The unpredictable course of BD has far reaching effects on individuals’ lives influencing relationships, day to day activities as well as more significant life events. The emotional impact of living with this illness should not be underestimated.