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Biomedical subjects

Alan Tennant

Publications and source records attributed to Alan Tennant.

At least 19 recordsLinked to original sources
PubMed2007

The Foot Posture Index: Rasch analysis of a novel, foot-specific outcome measure.

OBJECTIVE: To investigate the internal construct validity of a clinician-assessed measure of foot position, the Foot Posture Index (FPI), versions FPI-8 and FPI-6. DESIGN: Rasch analysis of baseline FPI scores from studies conducted during the development of the instrument. SETTING: A community-based and a hospital-based study, conducted at 2 institutions. PARTICIPANTS: Measures were obtained from 143 participants (98 men, 45 women; age range, 8-65y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Rasch analysis was undertaken using RUMM2020 software in order to evaluate the following properties of the FPI: unidimensionality of each item included in the FPI, the differential item functioning (DIF) of each item, and item and person separation indices. RESULTS: In the developmental draft of the instrument, the 8-item FPI-8 showed some misfit to the Rasch model (chi(16)(2) test=27.63, P=.03), indicating lack of unidimensionality. Two items were identified as problematic in the Rasch modeling: Achilles' tendon insertion (Helbing's sign), which showed illogical response ordering and "congruence of the lateral border of the foot," which showed misfit, indicating that this item may be measuring a different construct (chi(2)(2) test=15.35, P<.01). All FPI-8 items showed an absence of DIF, and the person separation index (PSI) was good (PSI=.88). The revised FPI-6, which does not include the 2 problematic items, showed unidimensionality (chi(12)(2) test=11.49, P=.49), indicating a good overall fit to the model, and improvement over the preliminary version. With the removal of the 2 problematic items, there were no disordered thresholds; all items remained DIF free and all individual items displayed a good fit to the model. The person-separation index for the FPI was similar for both the 8-item (FPI-8=.880) and 6-item (FPI-6=.884) versions. CONCLUSIONS: The original FPI-8 showed significant mismatching to the model. The 2 items in the FPI-8 that were identified as problematic in clinical validation studies were also found to be contributing to the lack of fit to the Rasch model. The finalized 6-item instrument showed good metric properties, including good individual item fit and good overall fit to the model, along with a lack of differential item functioning. This analysis provides further evidence for the validity of the FPI-6 as a clinical instrument for use in screening studies and shows that it has the potential to be analyzed using parametric strategies.

Adolescent↗
PubMed2006

Impact of multiple joint problems on daily living tasks in people in the community over age fifty-five.

OBJECTIVE: To establish the prevalence of multiple joint problems and their impact on everyday tasks. METHODS: A random sample of the UK population was assessed using a postal questionnaire. Data on overall joint pain, swelling and stiffness, and activities of daily living were obtained from 16,222 individuals >55 years of age (86% response rate). Prevalence estimates of joint problems were established and the impact of multiple joint pathologies on common physical tasks was determined. RESULTS: Single joint involvement was unusual (median joint involvement 4). Although the knee was the most frequently involved joint (220.30 per 1,000), isolated knee pathology accounted for only 1 in 11 patients with knee pain. Although single joint disorders increased the risk of experiencing functional difficulty, this risk was substantially increased with multiple joint problems: individuals with knee and feet problems were 14 times more likely to experience difficulty standing and walking than those without knee problems (odds ratio [OR] 14.50); knee and hip problems increased the risk >12 times (OR 12.43) whereas knee, back, feet, and hip involvement increased the risk 60 times (OR 62.41). CONCLUSION: Multiple-site joint problems are much more common than single joint problems. Although individual joint problems have a considerable impact on a person's functional ability, this risk is substantially increased when other joints are involved. With the increasing burden associated with the aging population, it is essential that the management of joint pain be considered in light of the impact of multiple, rather than single, joint problems.

Activities of Daily Living↗
PubMed2006

Evaluation of the Edinburgh Post Natal Depression Scale using Rasch analysis.

BACKGROUND: The Edinburgh Postnatal Depression Scale (EPDS) is a 10 item self-rating post-natal depression scale which has seen widespread use in epidemiological and clinical studies. Concern has been raised over the validity of the EPDS as a single summed scale, with suggestions that it measures two separate aspects, one of depressive feelings, the other of anxiety. METHODS: As part of a larger cross-sectional study conducted in Melbourne, Australia, a community sample (324 women, ranging in age from 18 to 44 years: mean = 32 yrs, SD = 4.6), was obtained by inviting primiparous women to participate voluntarily in this study. Data from the EPDS were fitted to the Rasch measurement model and tested for appropriate category ordering, for item bias through Differential Item Functioning (DIF) analysis, and for unidimensionality through tests of the assumption of local independence. RESULTS: Rasch analysis of the data from the ten item scale initially demonstrated a lack of fit to the model with a significant Item-Trait Interaction total chi-square (chi Square = 82.8, df = 40; p < .001). Removal of two items (items 7 and 8) resulted in a non-significant Item-Trait Interaction total chi-square with a residual mean value for items of -0.467 with a standard deviation of 0.850, showing fit to the model. No DIF existed in the final 8-item scale (EPDS-8) and all items showed fit to model expectations. Principal Components Analysis of the residuals supported the local independence assumption, and unidimensionality of the revised EPDS-8 scale. Revised cut points were identified for EPDS-8 to maintain the case identification of the original scale. CONCLUSION: The results of this study suggest that EPDS, in its original 10 item form, is not a viable scale for the unidimensional measurement of depression. Rasch analysis suggests that a revised eight item version (EPDS-8) would provide a more psychometrically robust scale. The revised cut points of 7/8 and 9/10 for the EPDS-8 show high levels of agreement with the original case identification for the EPDS-10.

Adolescent↗
PubMed2006

Assessing normative cut points through differential item functioning analysis: an example from the adaptation of the Middlesex Elderly Assessment of Mental State (MEAMS) for use as a cognitive screening test in Turkey.

BACKGROUND: The Middlesex Elderly Assessment of Mental State (MEAMS) was developed as a screening test to detect cognitive impairment in the elderly. It includes 12 subtests, each having a 'pass score'. A series of tasks were undertaken to adapt the measure for use in the adult population in Turkey and to determine the validity of existing cut points for passing subtests, given the wide range of educational level in the Turkish population. This study focuses on identifying and validating the scoring system of the MEAMS for Turkish adult population. METHODS: After the translation procedure, 350 normal subjects and 158 acquired brain injury patients were assessed by the Turkish version of MEAMS. Initially, appropriate pass scores for the normal population were determined through ANOVA post-hoc tests according to age, gender and education. Rasch analysis was then used to test the internal construct validity of the scale and the validity of the cut points for pass scores on the pooled data by using Differential Item Functioning (DIF) analysis within the framework of the Rasch model. RESULTS: Data with the initially modified pass scores were analyzed. DIF was found for certain subtests by age and education, but not for gender. Following this, pass scores were further adjusted and data re-fitted to the model. All subtests were found to fit the Rasch model (mean item fit 0.184, SD 0.319; person fit -0.224, SD 0.557) and DIF was then found to be absent. Thus the final pass scores for all subtests were determined. CONCLUSION: The MEAMS offers a valid assessment of cognitive state for the adult Turkish population, and the revised cut points accommodate for age and education. Further studies are required to ascertain the validity in different diagnostic groups.

Adolescent↗
PubMed2006

Identifying patients at risk of nursing home admission: The Leeds Elderly Assessment Dependency Screening tool (LEADS).

BACKGROUND: Discharge from hospital to a nursing home represents a major event in the life of an older person and should only follow a comprehensive functional and medical assessment. A previous study identified 3 dependency scales able to discriminate across outcomes for older people admitted to an acute setting. We wished to determine if a single dependency scale derived from the 3 scales could be created. In addition could this new scale with other predictors be used as a comprehensive tool to identify patients at risk of nursing home admission. METHODS: Items from the 3 scales were combined and analysed using Rasch Analysis. Sensitivity and specificity analysis and ROC curves were applied to identify the most appropriate cut score. Binary logistic regression using this cut-off, and other predictive variables, were used to create a predictive algorithm score. Sensitivity, specificity and likelihood ratio scores of the algorithm scores were used to identify the best predictive score for risk of nursing home placement. RESULTS: A 17-item (LEADS) scale was derived, which together with four other indicators, had a sensitivity of 88% for patients at risk of nursing home placement, and a specificity of 85% for not needing a nursing home placement, within 2 weeks of admission. CONCLUSION: A combined short 17-item scale of dependency plus other predictive variables can assess the risk of nursing home placement for older people in an acute care setting within 2 weeks of admission. This gives an opportunity for either early discharge planning, or therapeutic intervention to offset the risk of placement.

Aftercare↗
PubMed2006

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 individual's 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.

Adolescent↗
PubMed2005

Development of a foot impact scale for rheumatoid arthritis.

OBJECTIVE: To develop a new foot impact scale to assess foot status in rheumatoid arthritis (RA) using established qualitative methodology and the latest item response techniques (Rasch analysis). METHODS: Foot problems in RA were explored by conducting qualitative interviews that were then used to generate items for a new foot impact scale. Further validation was undertaken following postal surveys and Rasch analysis. RESULTS: Analysis of the first postal survey (n = 192 responses) produced a 63-item binary response, 4-subscale instrument. The 4 subscales covered the domains impairment, activities, participation, and footwear. Following test-retest postal surveys and additional analysis, the instrument was reduced to a 2 subscale, 51-item questionnaire covering the domains of impairments/shoes and activities/participation. Initial results of these subscales indicate good psychometric properties, external validity, and test-retest reliability. CONCLUSION: A foot impact scale to assess the impact of RA and to measure the effect of interventions has been developed. The 2 scales comprising the instrument demonstrate good psychometric properties.

Adult↗
PubMed2005

Using item response theory to explore the psychometric properties of extended matching questions examination in undergraduate medical education.

BACKGROUND: As assessment has been shown to direct learning, it is critical that the examinations developed to test clinical competence in medical undergraduates are valid and reliable. The use of extended matching questions (EMQ) has been advocated to overcome some of the criticisms of using multiple-choice questions to test factual and applied knowledge. METHODS: We analysed the results from the Extended Matching Questions Examination taken by 4th year undergraduate medical students in the academic year 2001 to 2002. Rasch analysis was used to examine whether the set of questions used in the examination mapped on to a unidimensional scale, the degree of difficulty of questions within and between the various medical and surgical specialties and the pattern of responses within individual questions to assess the impact of the distractor options. RESULTS: Analysis of a subset of items and of the full examination demonstrated internal construct validity and the absence of bias on the majority of questions. Three main patterns of response selection were identified. CONCLUSION: Modern psychometric methods based upon the work of Rasch provide a useful approach to the calibration and analysis of EMQ undergraduate medical assessments. The approach allows for a formal test of the unidimensionality of the questions and thus the validity of the summed score. Given the metric calibration which follows fit to the model, it also allows for the establishment of items banks to facilitate continuity and equity in exam standards.

Adult↗
PubMed2005

Admission to hospital following head injury in England: incidence and socio-economic associations.

BACKGROUND: Head injury in England is common. Evidence suggests that socio-economic factors may cause variation in incidence, and this variation may affect planning for services to meet the needs of those who have sustained a head injury. METHODS: Socio-economic data were obtained from the UK Office for National Statistics and merged with Hospital Episodes Statistics obtained from the Department of Health. All patients admitted for head injury with ICD-10 codes S00.0-S09.9 during 2001-2 and 2002-3 were included and collated at the level of the extant Health Authorities (HA) for 2002, and Primary Care Trust (PCT) for 2003. Incidence was determined, and cluster analysis and multiple regression analysis were used to look at patterns and associations. RESULTS: 112,718 patients were admitted during 2001-2 giving a hospitalised incidence rate for England of 229 per 100,000. This rate varied across the English HA's ranging from 91-419 per 100,000. The rate remained unchanged for 2002-3 with a similar magnitude of variation across PCT's. Three clusters of HA's were identified from the 2001-2 data; those typical of London, those of the Shire counties, and those of Other Urban authorities. Socio-economic factors were found to account for a high proportion of the variance in incidence for 2001-2. The same pattern emerged for 2002-3 at the PCT level. The use of public transport for travel to work is associated with a decreased incidence and lifestyle indicators, such as the numbers of young unemployed, increase the incidence. CONCLUSION: Head injury incidence in England varies by a factor of 4.6 across HA's and PCT's. Planning head injury related services at the local level thus needs to be based on local incidence figures rather than regional or national estimates. Socio-economic factors are shown to be associated with admission, including travel to work patterns and lifestyle indicators, which suggests that incidence is amenable to policy initiatives at the macro level as well as preventive programmes targeted at key groups.

Adolescent↗
PubMed2005

Cross-cultural validity of functional independence measure items in stroke: a study using Rasch analysis.

OBJECTIVE: To analyse cross-cultural validity of the Functional Independence Measure (FIM) in patients with stroke using the Rasch model. SETTINGS: Thirty-one rehabilitation facilities within 6 different countries in Europe. PARTICIPANTS: A total of 2546 in-patients at admission, median age 63 years. METHODS: Data from the FIM were evaluated with the Rasch model, using the Rasch analysis package RUMM2020. A detailed analysis of scoring functions of the 7 categories of the FIM items was undertaken prior to testing fit to the model. Categories were re-scored where necessary. Analysis of Differential Item Functioning was undertaken in pooled data for each of the FIM motor and social-cognitive scales, respectively. RESULTS: Disordered thresholds were found on most items when using 7 categories. Fit to the Rasch model varied between countries. Differential Item Functioning was found by country for most items. Adequate fit to the Rasch model was achieved when items were treated as unique for each country and after a few country-specific items were removed. CONCLUSION: Clinical collected data from FIM for patients with stroke cannot be pooled in its raw form, or compared across countries. Comparisons can be made after adjusting for country-specific Differential Item Functioning, though the adjustments for Differential Item Functioning and rating scales may not generalize to other samples.

Activities of Daily Living↗
PubMed2005

Psychometric properties of the Mini-Mental State Examination in patients with acquired brain injury in Turkey.

OBJECTIVE: To evaluate the psychometric properties of Mini-Mental State Examination (MMSE) in patients with acquired brain injury in Turkey. METHODS: A total of 207 patients with acquired brain injury were assessed. Reliability was tested by internal consistency and the person separation index; internal construct validity by Rasch analysis; external construct validity by correlation with cognitive disability; and cross-cultural validity by differential item functioning analysis compared with Italian MMSE data. RESULTS: Reliability was adequate with a Cronbach's alpha of 0.75 and person separation index of 0.76. After collapsing some categories, and adjustment for differential item functioning, internal construct validity was supported by fit of the data to Rasch model. Differential item functioning for culture was found in 2 items and after adjustment, data could be pooled between Turkey and Italy. External construct validity was supported by expected associations. CONCLUSION: The Turkish version of the Mini-Mental State Examination can be used as a cognitive screening tool in acquired brain injury. Cross-cultural validity between Italy and Turkey is supported, given appropriate adjustment for differential item functioning. However, shortfalls in reliability at the individual level, as well as the presence of differential item functioning suggest that a better instrument should be developed to screen for cognitive deficits following acquired brain injury.

Adult↗
PubMed2005

Preliminary study to evaluate the validity of the mini-mental state examination in a normal population in Turkey.

Although the Mini-Mental State Examination (MMSE) is widely used in clinical practice, normative scores for a healthy population have not been documented in Turkey. The aim in this study was to validate the MMSE in a healthy population and to provide normal scores. Internal construct validity of the Turkish version of MMSE among a preliminary sample of 406 normal people was assessed by Rasch unidimensional measurement model. Scores of the normal sample varied according to age and education but not according to sex. The data derived from this sample showed poor fit to the Rasch model (mean item fit, -2.082, SD 3.022). Only four of 11 items met model expectations. There was also differential item functioning by education and age for most items. Thus the internal construct validity of the Turkish MMSE in a normative sample could not be demonstrated by Rasch analysis. The scale failed modern psychometric criteria for scalability. We would therefore suggest other large normative MMSE data sets to be tested in terms of internal construct validity. If these findings are replicated, the validity of MMSE norms and their consequent use in clinical practice should be reconsidered.

Adolescent↗
PubMed2005

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.

Adolescent↗
PubMed2004

Audit of head injury management in Accident and Emergency at two hospitals: implications for NICE CT guidelines.

BACKGROUND: The National Institute for Clinical Excellence (NICE) has produced guidelines on the early management of head injury. This study audits the process of the management of patients with head injury presenting at Accident and Emergency (A&E) departments and examines the impact upon resources of introducing NICE guidelines for eligibility of a CT scan. METHODS: A retrospective audit of consecutive patients of any age, presenting at A&E with a complaint of head injury during one month in two northern District General Hospitals forming part of a single NHS Trust. RESULTS: 419 patients presented with a median age of 15.5 years, and 61% were male. 58% had a Glasgow Coma Score (GCS) recorded and 33 (8%) were admitted. Only four of the ten indicators for a CT scan were routinely assessed, but data were complete for only one (age), and largely absent for another (vomiting). Using just three (incomplete) indicators showed a likely 4 fold increase in the need for a CT scan. CONCLUSIONS: The majority of patients who present with a head injury to Accident and Emergency departments are discharged home. Current assessment processes and associated data collection routines do not provide the information necessary to implement NICE guidelines for CT brain scans. The development of such clinical audit systems in a busy A&E department is likely to require considerable investment in technology and/or staff. The resource implications for radiology are likely to be substantial.

Adolescent↗
PubMed2004

Issues in cross-cultural validity: example from the adaptation, reliability, and validity testing of a Turkish version of the Stanford Health Assessment Questionnaire.

OBJECTIVE: Guidelines have been established for cross-cultural adaptation of outcome measures. However, invariance across cultures must also be demonstrated through analysis of Differential Item Functioning (DIF). This is tested in the context of a Turkish adaptation of the Health Assessment Questionnaire (HAQ). METHODS: Internal construct validity of the adapted HAQ is assessed by Rasch analysis; reliability, by internal consistency and the intraclass correlation coefficient; external construct validity, by association with impairments and American College of Rheumatology functional stages. Cross-cultural validity is tested through DIF by comparison with data from the UK version of the HAQ. RESULTS: The adapted version of the HAQ demonstrated good internal construct validity through fit of the data to the Rasch model (mean item fit 0.205; SD 0.998). Reliability was excellent (alpha = 0.97) and external construct validity was confirmed by expected associations. DIF for culture was found in only 1 item. CONCLUSIONS: Cross-cultural validity was found to be sufficient for use in international studies between the UK and Turkey. Future adaptation of instruments should include analysis of DIF at the field testing stage in the adaptation process.

Activities of Daily Living↗
PubMed2004

Assessing and adjusting for cross-cultural validity of impairment and activity limitation scales through differential item functioning within the framework of the Rasch model: the PRO-ESOR project.

INTRODUCTION: In Europe it is common for outcome measures to be translated for use in other languages. This adaptation may be complicated by culturally specific approaches to certain tasks; for example, bathing. In this context the issue of cross-cultural validity becomes paramount. OBJECTIVE: To facilitate the pooling of data in international studies, a project set out to evaluate the cross-cultural validity of impairment and activity limitation measures used in rehabilitation from the perspective of the Rasch measurement model. METHODS: Cross-cultural validity is assessed through an analysis of Differential Item Functioning (DIF) within the context of additive conjoint measurement expressed through the Rasch model. Data from patients undergoing rehabilitation for stroke was provided from 62 centers across Europe. Two commonly used outcome measures, the Mini-Mental State Examination (MMSE) and the Functional Independence Measure (FIM) motor scale are used to illustrate the approach. RESULTS: Pooled data from 3 countries for the MMSE were shown to fit the Rasch model with only 1 item displaying DIF by country. In contrast, many items from the FIM expressed DIF and misfit to the model. Consequently they were allowed to be unique across countries, so resolving the lack of fit to the model. CONCLUSIONS: Where data are to be pooled for international studies, analysis of DIF by culture is essential. Where DIF is observed, adjustments can be made to allow for cultural differences in outcome measurement.

Activities of Daily Living↗
PubMed2004

An audit of the editorial process and peer review in the journal Clinical rehabilitation.

OBJECTIVE: To investigate the editorial process on papers submitted to a scientific journal. DESIGN: Descriptive and correlational analysis. SETTING: A single specialist rehabilitation journal from mid-1999 to mid-2003. SUBJECTS: The Editor, peer reviewers and authors. INTERVENTIONS: Submitted papers were initially screened, the majority were subject to review, and a decision was made on whether or not to publish. Reviewers scored papers on 11 items using a 0 (bad)-10 (good) scale. MEASURES: Time delays and rating of each paper on a pro-forma. RESULTS: The number of papers submitted each year increased from 136 to 209. Between 19% and 31% were rejected without review and 17-24% were rejected later. The proportion accepted dropped from 64% to 47%. The median delay between arrival and first author contact in papers subject to review was stable between 67 and 76 days. Agreement between reviewers was low with an intraclass correlation coefficient (ICC) varying between 0.12 and 0.27 and disagreement of 3 or more points in 32-51%. The main factor associated with eventual acceptance was the sum of the 'overall recommendation score' given by the two reviewers, but 20% of the variance in final decision was unexplained by the reviewers' scoring. The number of randomized trials published increased from 5 in 1996 to 21 in 2002. CONCLUSIONS: The influence of the Editor on final decisions remains significant, particularly for papers 'on the margin'; decisions on publication in this journal are guided by but not determined by reviewers.

Peer Review, Research↗