The Association of Health Locus of Control with Clinical and Psychosocial Aspects of Living with Multiple Sclerosis

Health Locus of control (LOC) refers to one's beliefs regarding control over one's health. This study aimed to determine the relationship between LOC on clinical and psychosocial aspects associated with multiple sclerosis (MS). 5059 participants with MS completed a questionnaire pack including the Multidimensional Health Locus of Control Scale. Associations between LOC and sociodemographic (age, gender, educational level) and clinical variables (duration, disability, depression, anxiety, self-efficacy, QoL) were explored. LOC was found to be significantly associated with all of the clinical variables and age, but not gender or educational level. When controlling for level of disability, Chance (CLOC) was associated with higher self-efficacy, lower anxiety and higher QoL than Powerful Others (PLOC), while Internal (ILOC) had no association. The proportion with ILOC preference was lower in increased disability. In MS, believing that health is controlled mainly by chance confers the most benefit with regard to quality of life. There is prima-facie evidence that LOC preference changes with MS progression, in a pattern that is protective against psychological distress.

Prevalence of depression in amyotrophic lateral sclerosis/motor neuron disease: multi-attribute ascertainment and trajectories over 30 months

Objective: Evidence is equivocal about the prevalence of depression in amyotrophic lateral sclerosis (ALS). This study uses a multi-attribute ascertainment of the prevalence of depression and examines this prevalence over time. Methods: Patients with ALS were recruited into the Trajectories of Outcome in Neurological Conditions (TONiC-ALS) study. Caseness was identified by the Modified-Hospital Anxiety and Depression Scale (M-HADS). In addition, participants provided data on co-morbidities and medication use. A combination of the three was used to derive the estimate for the prevalence of depression, treated or untreated. Longitudinal data were analyzed by trajectory analysis of interval level M-HADS-Depression data. Results: Among 1120 participants, the mean age was 65.0 years (SD 10.7), 60.4% male, and the median duration since diagnosis was 9 months (IQR 4-24). Caseness of probable depression at baseline, defined by M-HADS-Depression, was 6.45% (95%CI: 5.1-8.0). Taken together with antidepressant medication and co-morbidity data, the prevalence of depression was 23.1% (95%CI: 20.7-25.6). Of those with depression, 17.8% were untreated. Trajectory analysis identified three groups, one of which contained the most cases; the level of depression for each group remained almost constant over time. Conclusion: Depression affects almost a quarter of those with ALS, largely confined to a single trajectory group. Prevalence estimates based on screening for current depressive symptoms substantially under-estimate the population experiencing depression. Future prevalence studies should differentiate data based on current symptoms from those including treated patients. Both have their place in assessing depression and the response by the health care system, including medication, depending upon the hypothesis under test.

POS1113 CONSTRUCT VALIDITY, RELIABILITY, RESPONSIVENESS AND INTERVAL SCALE TRANSFORMATION OF THE WESTERN ONTARIO AND MCMASTER UNIVERSITIES OSTEOARTHRITIS INDEX (WOMAC) IN PATIENTS UNDERGOING KNEE ARTHROPLASTY

Background

Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is commonly used in research studies of knee osteoarthritis (OA). It is commonly reported as ordinal raw scores. Previous validation studies using Rasch models requires item deletion. Conversion table to Interval scale for meaningful measurement is not available.

Objectives

We aim to evaluate the fit of WOMAC to the Rasch model in a large sample of patients with knee OA who have undergone knee arthroplasty (KA) to derive the transformation table for interval scale measurement.

Methods

We used data collected from knee OA patients undergoing KA before surgery and at 6-months after KA. We collected demographics, WOMAC, Short-form-36 (SF-36) and Oxford Knee Score (OKS) with the latter two as comparison. WOMAC was calibrated for fit to Rasch model for monotonicity, homogeneity, local item independence and absence of differential item functioning (DIF) in a randomly selected sample of 300 patients from each time point. Parameter estimates were then imported into the full data set to provide the necessary estimates of all the scales. We report responsiveness through Standard Error of Measurement (SEM); Smallest Detectable Difference (SDD), %SDD and effect sizes (ES) between pre-operative and 6-months. Transformation tables of the ordinal to interval values for WOMAC was performed.

Results

Data was analysed for 1136 patients (mean age 65.9 years, 69% female) who underwent KA. WOMAC pain, function and total scores had adequate fit to unidimensional Rasch model with good reliability (Person Separation Index: 0.76, 0.80 and 0.79). No item deletion was required. The SEM, SDD and %SDD of WOMAC total were 4.4, 6.9, 10.1, and ES was 1.97 between pre-operative and 6-months. No significant DIF was seen for age, sex, body mass index, education level or uni-compartmental versus total KA. WOMAC pain, function and total scales were transformed to interval scales.

Conclusion

The WOMAC total, pain and function scales had adequate fit to the Rasch model, providing unidimensional measure with good reliability and responsiveness. Transformation of WOMAC to interval scale measurement is feasible and applicable to wide ranges of studies.

Table 1.

Fit of Scales of WOMAC to the Rasch Model

WOMAC/ subscaleResidualsConditional Chi-SquareReliabilityUnidimens-ionalityECVResponsiveness (Interval Scale)ItemPersonValue(df)PPSIΑ% Significant t-testsSEMSDDES(6m-baseline)Pain2.4990.77918.7(10)0.0440.760.873.031.02.91.042.11Stiffness1.2150.46257.0(9)<0.0010.600.822.53----Functioning2.4960.70247.0(42)0.2740.800.941.160.9310.22.491.91Total4.1930.69943.3(58)0.9250.800.802.030.909.94.41.97

Acknowledgements

This study is supported by Singapore National Medical Research Council (NMRC/HSRG/0061/2016 and NMRC/CSAINV/022/2017).

Disclosure of Interests

Ying Ying Leung Speakers bureau: Received speaker fee from AbbVie, DKSH, Janssen, Novartis and Pfizer., Julian Thumboo: None declared, Seng Jin Yeo: None declared, Vikki Wylde: None declared, Alan Tennant: None declared

61 Outcomes of An Advanced Nurse Practitioner-Led Pops Service in A District General Hospital

Introduction

There is an increased need for geriatrician input to older adults outside of the medical wards. There is a lack of geriatricians to contribute to these services. An example includes the Proactive care of older people undergoing surgery (POPS) service where geriatricians perform comprehensive geriatric assessment (CGA) to identify comorbidities and geriatric syndromes which may lead to poor post-operative outcomes. Advanced nurse practitioners (ANP) are highly skilled staff members and are increasingly used to provide the POPS service. We wanted to review the outcomes of our Nurse Led POPS service.

Methods

Patients aged over 70 admitted as an emergency to upper gastrointestinal and colorectal surgery were assessed by the POPS ANP using CGA. Assessments were completed on a proforma. Data was collected prospectively on a data collection form documenting new issues detected and interventions made. The results were analysed using an Excel spreadsheet.

Results

147 patients were reviewed by the ANP between November 2018 and March 2019. All patients were screened for frailty, cognitive impairment and delirium. 37.41% were clinically frail, 17.72% had cognitive impairment and 11.56% had delirium. New issues were identified in 90.47% of these patients; polypharmacy (80.27%), new catheter (53.74%), weight loss (46.94%), incontinence (36.05%), falls (29.25%) and pain (25.17%). Medical issues were also identified including electrolyte abnormalities (47% patients), acute kidney injury (22% patients), cardiac issues (8% patients) and respiratory problems (7% patients). Additional interventions included stopping medication (27.89%), starting new medication (20.41%), requesting further investigations (97.28%), referring to allied health professionals (95.24%) and advanced care planning (15.65%).

Conclusions

A POPS ANP can effectively conduct CGA identifying new medical issues and geriatric syndromes missed by the surgical teams in an acute setting.

The Valued Life Activities Scale (VLAs): linguistic validation, cultural adaptation and psychometric testing in people with rheumatic and musculoskeletal diseases in the UK

Background

The Valued Life Activities Scale (VLAs) measures difficulty in daily activities and social participation. With various versions involving a different number of items, we have linguistically and culturally adopted the full VLAs (33-items) and psychometrically tested it in adults with rheumatic and musculoskeletal diseases in the United Kingdom.

Methods

Participants with Rheumatoid Arthritis, Ankylosing Spondylitis, Chronic Pain/ Fibromyalgia, Chronic Hand/ Upper Limb Conditions, Osteoarthritis, Systemic Lupus, Systemic Sclerosis and Primary Sjogren’s Syndrome were recruited from out-patient clinics in National Health Service Hospitals, General Practice and patient organisations in the UK. Phase1 involved linguistic and cultural adaptation: forward translation to British English; synthesis; expert panel review and cognitive debriefing interviews. In Phase2 participants completed postal questionnaires to assess internal construct validity using (i) Confirmatory Factor Analysis (CFA) (ii) Mokken scaling and (iii) Rasch model.

Results

Responders (n = 1544) had mean age of 59 years (SD13.3) and 77.2% women. A CFA failed to support a total score from the 33-items (Chi Square 3552:df 464: p < 0.0001). Mokken scaling indicated a strong non-parametric association between items. Fit to the Rasch model indicated that the VLAs was characterised by multidimensionality and item misfit, which may have been influenced by clusters of residual item correlations. An item banking approach resolved a 25-item calibrated set whose application could accommodate the ‘does not apply to me’ response option.

Conclusions

The UK version of the VLAs failed to satisfy classical and modern psychometric standards for complete item sets. However, as the scale is not usually applied in complete format, an item bank approach calibrated 25 items with fit to the Rasch model. Suitable Computer Adaptive Testing (CAT) software could implement the item set, giving patients the choice of whether an item applies to them, or not.

The WHOQOL-BREF: a modern psychometric evaluation of its internal construct validity in people with multiple sclerosis

PURPOSE

Symptoms of Multiple Sclerosis (MS) differentially impact upon quality of life (QoL) and a comprehensive measure is required for use in observational and interventional studies. This study examines the abbreviated World Health Organisation Quality of Life tool (WHOQOL-BREF) which was designed to be used as a broad measure of QoL across different cultures and diseases.

METHODS

Data were collected from 3186 subjects as part of the TONiC study in MS and was examined with a systematic, iterative approach using Rasch analysis to investigate the internal construct validity of the WHOQOL-BREF.

RESULTS

Mean age was 49.8 years (SD 11.8), disease duration was 11.2 years (SD 9.6) and 73.2% were female. Subjects represented all stages of MS with EDSS scores of 0-4, 4.5-6.5, 7-7.5 and ≥ 8 seen in 49.8%, 38.5%, 6.8% and 4.9% of patients, respectively. Using a super-item approach, it was possible to demonstrate fit to the assumptions of the Rasch model for 3 of the 4 domains of the WHOQOL-BREF (physical, psychological and environment) as well as a broad 24-item total score. In addition, item subsets derived from the stem of each question were shown to function as novel scales measuring impact and life satisfaction. We have provided transformation tables from ordinal raw scores to interval scales where data are complete.

CONCLUSIONS

The validation of multiple conceptual frameworks validates the WHOQOL-BREF as a powerful and flexible end-point for use in clinical trials and in testing conceptual models of factors influencing QoL in MS.

Revisiting the disabilities of the arm, shoulder and hand (DASH) and QuickDASH in rheumatoid arthritis

Background

Limitations in upper limb functioning are common in Musculoskeletal disorders and the Disabilities of the Arm, Shoulder and Hand scale (DASH) has gained widespread use in this context. However, various concerns have been raised about its construct validity and so this study seeks to examine this and other psychometric aspects of both the DASH and QuickDASH from a modern test theory perspective.

Methods

Participants in the study were eligible if they had a confirmed diagnosis of Rheumatoid Arthritis (RA). They were mailed a questionnaire booklet which included the DASH. Construct validity was examined by fit to the Rasch measurement model. The degree of precision of both the DASH and QuickDASH were considered through their Standard Error of Measurement (SEM).

Results

Three hundred and thirty-seven subjects with confirmed RA took part, with a mean age of 62.0 years (SD12.1); 73.6% (n = 252) were female. The median standardized score on the DASH was 33 (IQR 17.5–55.0). Significant misfit of the DASH and QuickDASH was observed but, after accommodating local dependency among items in a two-testlet solution, satisfactory fit was obtained, supporting the unidimensionality of the total sets and the sufficiency of the raw (ordinal or standardized) scores.

Conclusion

Having accommodated local response dependency in the DASH and QuickDASH item sets, their total scores are shown to be valid, given they satisfy the Rasch model assumptions. The Rasch transformation should be used whenever all items are used to calculate a change score, or to apply parametric statistics within an RA population.

Significance and innovations

Most previous modern psychometric analyses of both the DASH and QuickDASH have failed to fully address the effect of a breach of the local independence assumption upon construct validity.

Accommodating this problem by creating ‘super items’ or testlets, removes this effect and shows that both versions of the scale are valid and unidimensional, as applied with a bi-factor equivalent solution to an RA population.

The Standard Error of Measurement of a scale can be biased by failing to take into account the local dependency in the data which inflates reliability and thus making the SEM appear better (i.e. smaller) than the true value without bias.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2414-6) contains supplementary material, which is available to authorized users.

Development and validation of Spasticity Index-Amyotrophic Lateral Sclerosis

OBJECTIVES

Spasticity is a common and disabling feature of amyotrophic lateral sclerosis (ALS). There are currently no validated ALS-specific measures of spasticity. The aim of this study was to develop and use a self-report outcome measure for spasticity in ALS.

METHODS

Following semi-structured interviews with 11 ALS patients, a draft scale was administered across ALS clinics in the UK. Internal validity of the scale was examined using the Rasch model. The numerical rating scale (NRS) for spasticity and Leeds Spasticity scale (LSS) were co-administered. The final scale was used in a path model of spasticity and quality of life.

RESULTS

A total of 465 patients (mean age 64.7 years (SD 10), 59% male) with ALS participated. Spasticity was reported by 80% of subjects. A pool of 71 items representing main themes of physical symptoms, negative impact and modifying factors was subject to an iterative process of item reduction by Rasch analysis resulting in a 20-item scale-the Spasticity Index for ALS (SI-ALS)-which was unidimensional and free from differential item functioning. Moderate correlations were found with LSS and NRS-spasticity. Incorporating the latent estimate of spasticity into a path model, greater spasticity reduced quality of life and motor function; higher motor function was associated with better quality of life.

CONCLUSIONS

The SI-ALS is a disease-specific self-report scale, which provides a robust interval-level measure of spasticity in ALS. Spasticity has a substantial impact on quality of life in ALS.

A study of the internal construct and predictive validity of the SMART assessment for emergence from vegetative state

OBJECTIVE

The Sensory Modality Assessment and Rehabilitation Technique (SMART) was developed to assess the levels of awareness, functional, sensory and communicative abilities of adults in vegetative (VS) or minimally-conscious states following severe brain injury. The current study seeks to ascertain if a total score can be derived from the individual assessments contained within SMART and to test the internal construct and predictive validity of that total score.

SUBJECTS

Persons in VS were recruited over a 3-year period and current status was determined after a 17-year follow-up.

DESIGN

Data were evaluated by fit to the Rasch model. Predictive validity for emergence from VS was ascertained through an Area-Under-the-Curve [AUC] analysis.

RESULTS

Sixty people in VS were assessed on several occasions. Average age on admission was 38.8 years; 30 had anoxic brain damage; 21 traumatic injury. The Rasch analysis indicated the raw score was a sufficient statistic for awareness. Over half [55%] failed to emerge from VS. For those with anoxic brain injury, a SMART cut point of 85 gave an AUC of 0.966 (95% CI = 0.910-1.00) for emergence, as did a cut point of 68 for those with traumatic brain injury.

DISCUSSION

The current analysis suggests that SMART may have important predictive attributes for emergence (or lack thereof). No change in status of those discharged in VS has been reported to this present day.

The Neurological Sleep Index: A suite of new sleep scales for multiple sclerosis

Objective

The objective of this study was to develop patient-reported outcome measures for sleep dysfunction and sleepiness in multiple sclerosis (MS), since there are currently no MS-specific measurement tools for these clinically important entities.

Methods

Items were generated from semi-structured interviews followed by cognitive debrief. A 42-item pool was administered to patients with MS at three neuroscience centres in the UK. Comparator scales were co-administered. Constructs were validated by Rasch analysis, guided by initial exploratory factor analysis.

Results

There were two supraordinate qualitative themes of diurnal sleepiness and non-restorative nocturnal sleep. Rasch analysis on 722 records produced three scales, which corresponded to diurnal sleepiness, non-restorative nocturnal sleep and fragmented nocturnal sleep. All had excellent fit parameters, were unidimensional and were free from differential item functioning. A summed raw score cut-point of 31/48 in the Diurnal Sleepiness Scale equated to the standard cut-point of 10 on the Epworth Sleepiness Scale (ESS).

Conclusion

Three high-quality measurement scales were developed, and together they compose the Neurological Sleep Index for MS (NSI-MS). The Diurnal Sleepiness Scale might provide an alternative to the ESS. The Non-Restorative Nocturnal Sleep Scale and the Fragmented Nocturnal Sleep Scale appear to be the only such measures for use in MS.

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.

Is the Epworth sleepiness scale suitable for use in stroke?

BACKGROUND

The Epworth Sleepiness Scale (ESS-8) is frequently used in stroke but has never been validated for this condition. There is concern regarding the suitability of the driving item (item 8). A summed raw score of 10 or more (from a maximum of 24) signifies pathological sleepiness.

OBJECTIVE

To determine the construct validity of the ESS-8 by Rasch analysis and in particular to determine whether omission of item 8 confounds the scale.

METHOD

A pack containing the ESS-8 and questions regarding sleep and demographics was sent to 999 patients who had experienced a stroke within the past 4 years. Data were assessed for fit to the Rasch model.

RESULTS

Analysis of 269 records revealed a unidimensional scale that was free from differential item functioning by age and sex with good overall fit to the Rasch model. Item 4 had disordered thresholds. Analysis of the ESS without item 8 (ESS-7) also revealed a valid scale. Equating person locations between the ESS-8 and ESS-7 showed no differences below a summed raw score of 18.

CONCLUSION

The ESS-8 has good construct validity for use in stroke and is reliable at the cutpoint of 10. Summed raw scores below 18 will be unaffected if nondrivers either score as zero or simply omit item 8. The scale is therefore robust for detecting cases of pathological sleepiness in stroke but may not be suitable for measuring high levels of sleepiness in a sample containing both drivers and nondrivers. Instead, the ESS-7 could be used for this purpose.

Predicting the need for institutional care shortly after admission to rehabilitation: Rasch analysis and predictive validity of the BRASS Index

BACKGROUND

Effective discharge planning is increasingly recognised as a critical component of hospital-based Rehabilitation. The BRASS index is a risk screening tool for identification, shortly after hospital admission, of patients who are at risk of post-discharge problems.

AIM

To evaluate the internal construct validity and reliability of the Blaylock Risk Assessment Screening Score (BRASS) within the rehabilitation setting.

DESIGN

Observational prospective study.

SETTING

Rehabilitation ward of an Italian district hospital.

POPULATION

One hundred and four consecutively admitted patients.

METHODS

Using classical psychometric methods and Rasch analysis (RA), the internal construct validity and reliability of the BRASS were examined. Also, external and predictive validity of the Rasch-modified BRASS (RMB) score were determined.

RESULTS

Reliability of the original BRASS was low (Cronbach's alpha=0.595) and factor analyses showed that it was clearly multidimensional. A RA, based on a reduced 7-BRASS item set (RMB), satisfied model's expectations. Reliability was 0.777. The RMB scores strongly correlated with the original BRASS (rho=0.952; P<0.000) and with FIM™ admission scores (rho=-0.853; P<0.000). A RMB score of 12 was associated with an increased risk of nursing home admission (RR=2.1, 95%CI=1.7-2.5), whereas a score of 17 was associated to a higher risk of length of stay >28 days (RR=7.6, 95%CI=1.8-31.9).

CONCLUSION

This study demonstrated that the original BRASS was multidimensional and unreliable. However, the RMB holds adequate internal construct validity and is sufficiently reliable as a predictor of discharge problems for group, but not individual use.

CLINICAL REHABILITATION IMPACT

The application of tools and methods (such as the BRASS Index) developed under the biomedical paradigm in a Physical and Rehabilitation Medicine setting may have limitations. Further research is needed to develop, within the rehabilitation setting, a valid measuring tool of risk of post-discharge problems at the individual level.

Perceived changes and minimum clinically important difference of the Neurological Fatigue Index for multiple sclerosis (NFI-MS)

The determination of the minimum clinically important difference (MCID) is an important aspect of scale development. The Neurological Fatigue Index for multiple sclerosis (NFI-MS) was administered before and after expected change or stability in fatigue in 208 multiple sclerosis (MS) patients. The overall change scores of the NFI-MS accorded with perceived direction of change; importantly, no change was seen when none was perceived. Using the interval level NFI-MS scores, the largest MCID equated to 2.49 points on the Summary scale, 2.36 points on the Physical scale, 0.84 points on the Cognitive scale, 0.97 on the Diurnal Sleep scale and 1.95 on the Nocturnal Sleep scale. Our conclusion is that the NFI-MS responds as expected to changes in fatigue and has desirably small MCID scores.

The unidimensional self-efficacy scale for MS (USE-MS): developing a patient based and patient reported outcome

Background:

Self-efficacy concerns the individual’s belief that he or she is capable of performing a certain task and producing a desired effect, i.e. it reflects the person’s perceptions of their capability for specific tasks, as distinct from their actual ability. Self-efficacy has been shown to influence motivation, psychological well-being, adherence with treatment regimes and quality of life in multiple sclerosis and other conditions.

Objective:

To develop a unidimensional scale of MS self-efficacy with robust psychometric properties, suitable for patient self report.

Methods:

A questionnaire pack covering three MS self-efficacy scales, the Dispositional Resilience Scale and demographic data was posted to MS patients from two MS databases. Data underwent Rasch analysis.

Results:

Response rate was 309/600 (51.5%). None of the existing MS self-efficacy scales were unidimensional. A new 12-item scale, created by combining items from our two scales, was shown to fit the Rasch model, was unidimensional, and invariant for gender, education and disease duration.

Conclusion:

The Unidimensional Self-Efficacy scale for MS (USE-MS) provides a simple summated scale for an ordinal estimate of a persons’ self efficacy. A transformation to interval scaling is available for use in the calculation of change scores and effect sizes.

Development of a patient reported outcome measure for fatigue in motor neurone disease: the Neurological Fatigue Index (NFI-MND)

BACKGROUND

The objective of this research was to develop a disease-specific measure for fatigue in patients with motor neurone disease (MND) by generating data that would fit the Rasch measurement model. Fatigue was defined as reversible motor weakness and whole-body tiredness that was predominantly brought on by muscular exertion and was partially relieved by rest.

METHODS

Qualitative interviews were undertaken to confirm the suitability of a previously identified set of 52 neurological fatigue items as relevant to patients with MND. Patients were recruited from five U.K. MND clinics. Questionnaires were administered during clinic or by post. A sub-sample of patients completed the questionnaire again after 2-4 weeks to assess test-retest validity. Exploratory factor analyses and Rasch analysis were conducted on the item set.

RESULTS

Qualitative interviews with ten MND patients confirmed the suitability of 52 previously identified neurological fatigue items as relevant to patients with MND. 298 patients consented to completing the initial questionnaire including this item set, with an additional 78 patients completing the questionnaire a second time after 4-6 weeks. Exploratory Factor Analysis identified five potential subscales that could be conceptualised as representing: 'Energy', 'Reversible muscular weakness' (shortened to 'Weakness'), 'Concentration', 'Effects of heat' and 'Rest'. Of the original five factors, two factors 'Energy' and 'Weakness' met the expectations of the Rasch model. A higher order fatigue summary scale, consisting of items from the 'Energy' and 'Weakness' subscales, was found to fit the Rasch model and have acceptable unidimensionality. The two scales and the higher order summary scale were shown to fulfil model expectations, including assumptions of unidimensionality, local independency and an absence of differential item functioning.

CONCLUSIONS

The Neurological Fatigue Index for MND (NFI-MND) is a simple, easy-to-administer fatigue scale. It consists of an 8-item fatigue summary scale in addition to separate scales for measuring fatigue experienced as reversible muscular weakness and fatigue expressed as feelings of low energy and whole body tiredness. The underlying two factor structure supports the patient concept of fatigue derived from qualitative interviews in this population. All three scales were shown to be reliable and capable of interval level measurement.

Construct Validity of the Holistic Complementary and Alternative Medicines Questionnaire (HCAMQ)-An Investigation Using Modern Psychometric Approaches

The scientific basis of efficacy studies of complementary medicine requires the availability of validated measures. The Holistic Complementary and Alternative Medicine Questionnaire (HCAMQ) is one such measure. This article aimed to examine its construct validity, using a modern psychometric approach. The HCAMQ was completed by 221 patients (mean age 66.8, SD 8.29, 58% females) with chronic stable pain predominantly from a single joint (hip or knee) of mechanical origin, waiting for a hip (40%) or knee (60%) joint replacement, on enrolment in a study investigating the effects of acupuncture and placebo controls. The HCAMQ contains a Holistic Health (HH) Subscale (five items) and a CAM subscale (six items). Validity of the subscales was tested using Cronbach alpha's, factor analysis, Mokken scaling and Rasch analysis, which did not support the original two-factor structure of the scale. A five-item HH subscale and a four-item CAM subscale (worded in a negative direction) fitted the Rasch model and were unidimensional (χ2 = 8.44, P = 0.39, PSI = 0.69 versus χ2 = 17.33, P = 0.03, PSI = 0.77). Two CAM items (worded in the positive direction) had significant misfit. In conclusion, we have shown that the original two-factor structure of the HCAMQ could not be supported but that two valid shortened subscales can be used, one for HH Beliefs (four-item HH), and the other for CAM Beliefs (four-item CAM). It is recommended that consideration is given to rewording the two discarded positively worded CAM questions to enhance construct validity.

Rasch analysis of the Modified Fatigue Impact Scale (MFIS) in multiple sclerosis

BACKGROUND

The 21-item Modified Fatigue Impact Scale (MFIS) has been recommended as an outcome measure for use in multiple sclerosis and is commonly used to generate an overall score of fatigue.

OBJECTIVE

To test if the MFIS total score is valid by application of the Rasch measurement model.

METHOD

The MFIS was sent by post to patients with clinically definite multiple sclerosis in two centres in the UK. Data were fitted to the Rasch model.

RESULTS

Analysis was based on 415 records (55% response). The 21-item scale did not fit the Rasch model mainly because of multidimensionality. The scale was found to contain a "physical" dimension and a "cognitive" dimension, consistent with the original subscale structure. Valid physical and cognitive subscales were derived after deletion of some items.

CONCLUSION

The MFIS cannot be used to generate a single overall score of fatigue. The conceptual interaction between the two dimensions remains unclear, which poses problems when interpreting change scores in these individual scales. Studies in which a global MFIS score was used as either an outcome measure or selection tool may need to be re-evaluated.

Modelling 5-year functional outcome in a major traumatic injury survivor cohort

AIM

To estimate associations between possible predictors of functional disability outcome at 5 years in a working adult population cohort of survivors of major traumatic injury and to develop a prognostic model of outcome.

DESIGN

Population based retrospective cohort study.

POPULATION

Persons who had experienced major traumatic injury (Injury Seventy Score >15) in the area of the former Yorkshire Regional Health Authority during the period 30 September 1988 to 1 October 1989 and who survived for 5 years (average 5.3 years).

METHODS

The same interviewer saw each survivor at their home and used the OPCS Adult Disability Schedule to ascertain levels of functional disability. Disability scores for each survivor were then combined in accordance with the OPCS guidance to calculate a level of disability between 0 (no disability) to 10 (maximum disability). The OPCS level was then dichotomised with a cut-point at 4/5. Possible predictor and confounding variables from pre-injury, injury and post-injury periods were modelled in a logistic regression to identify those that predicted outcome level. Two reduced models were developed to allow early prognosis of late outcome.

RESULTS

The full model correctly classified 91% of observed outcomes. Inpatient length of stay OR 1.031 (95% CI 1.014,1.048) per day predicted poorer 5-year outcome; Glasgow Coma Score OR 0.790(0.629,0.992) per 1 point increase; stay in Intensive Care Unit OR 0.931 (0.877,0.987) per day; attainment of degree-level education OR 0.014 (0.000,0.707); single civil status OR 0.110 (0.013,0.908); being taken initially to a hospital with a neurosurgical facility OR 0.064(0.010,0.420); being in paid work during the 2 weeks before index injury OR 0.093(0.009,0.969) predicted better 5-year disability outcome. Two reduced models were constructed that included a simple set of variables, one of these models excluded any rehabilitation variables but still correctly classified 85% of the observed outcomes.

CONCLUSION

As well as level of traumatic brain injury (TBI) and total inpatient stay, Pre-injury educational attainment and employment, civil status, immediate care in a hospital with a neurosurgical facility and stay in an Intensive Care Unit determined 5-year outcome. It is possible to efficiently predict outcome at an early stage. Previous work on predictors of disablement have suffered from large selection and attrition biases.

Modification and validation of the Lysholm Knee Scale to assess articular cartilage damage

OBJECTIVE

The Lysholm Knee Scale is an 8-item questionnaire originally designed as an outcome measure for ligament reconstruction but is commonly used as a measure for knee chondral damage. This study tests the scale's internal construct validity using the Rasch model, a measurement model which sets strict standards for the quality of measurement derived from the scale. The study also investigates the level of agreement between scores from patients and physiotherapists; and reviews the present weighting system.

DESIGN

One hundred and fifty-seven patients with knee chondral damage awaiting surgery completed the Lysholm as part of a multicentre clinical trial based in 16 UK and two Norwegian hospitals. The patients were assessed by a physiotherapist who independently completed the Lysholm on the same day.

RESULTS

Fit to the Rasch model was achieved [mean item fit -0.26, standard deviation (SD) 1.01] after removal of one item (Swelling). With no differential item functioning (DIF) by rater, the intraclass correlation coefficient was 0.9 [95% confidence interval (CI): 0.86-0.93] and a Bland-Altman plot showed no consistent difference in rating.

CONCLUSIONS

The Lysholm Knee Scale satisfies Rasch model expectations after removal of the swelling item. Generally there is a high degree of agreement between the patient and professional ratings. By removing the swelling item and using unweighted scores, a modified version of the Lysholm Knee Scale is recommended as an outcome measure for knee chondral damage.