"Like fighting a fire with a water pistol": A qualitative study of the work experiences of critical care nurses during the COVID-19 pandemic.

AIM: To understand the experience of critical care nurses during the COVID-19 pandemic, through the application of the Job-Demand-Resource model of occupational stress. DESIGN: Qualitative interview study. METHODS: Twenty-eight critical care nurses (CCN) working in ICU in the UK NHS during the COVID-19 pandemic took part in semi-structured interviews between May 2021 and May 2022. Interviews were guided by the constructs of the Job-Demand Resource model. Data were analysed using framework analysis. RESULTS: The most difficult job demands were the pace and amount, complexity, physical and emotional effort of their work. Prolonged high demands led to CCN experiencing emotional and physical exhaustion, burnout, post-traumatic stress symptoms and impaired sleep. Support from colleagues and supervisors was a core job resource. Sustained demands and impaired physical and psychological well-being had negative organizational consequences with CCN expressing increased intention to leave their role. CONCLUSIONS: The combination of high demands and reduced resources had negative impacts on the psychological well-being of nurses which is translating into increased consideration of leaving their profession. IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE: The full impacts of the pandemic on the mental health of CCN are unlikely to resolve without appropriate interventions. IMPACT: Managers of healthcare systems should use these findings to inform: (i) the structure and organization of critical care workplaces so that they support staff to be well, and (ii) supportive interventions for staff who are carrying significant psychological distress as a result of working during and after the pandemic. These changes are required to improve staff recruitment and retention. REPORTING METHOD: We used the COREQ guidelines for reporting qualitative studies. PATIENT AND PUBLIC CONTRIBUTION: Six CCN provided input to survey content and interview schedule. Two authors and members of the study team (T.S. and S.C.) worked in critical care during the pandemic.

Exploring differential item functioning in the SF-36 by demographic, clinical, psychological and social factors in an osteoarthritis population.

BACKGROUND: The SF-36 is a very commonly used generic measure of health outcome in osteoarthritis (OA). An important, but frequently overlooked, aspect of validating health outcome measures is to establish if items work in the same way across subgroup of a population. That is, if respondents have the same 'true' level of outcome, does the item give the same score in different subgroups or is it biased towards one subgroup or another. Differential item functioning (DIF) can identify items that may be biased for one group or another and has been applied to measuring patient reported outcomes. Items may show DIF for different conditions and between cultures, however the SF-36 has not been specifically examined in an osteoarthritis population nor in a UK population. Hence, the aim of the study was to apply the DIF method to the SF-36 for a UK OA population. METHODS: The sample comprised a community sample of 763 people with OA who participated in the Somerset and Avon Survey of Health. The SF-36 was explored for DIF with respect to demographic, social, clinical and psychological factors. Well developed ordinal regression models were used to identify DIF items. RESULTS: DIF items were found by age (6 items), employment status (6 items), social class (2 items), mood (2 items), hip v knee (2 items), social deprivation (1 item) and body mass index (1 item). Although the impact of the DIF items rarely had a significant effect on the conclusions of group comparisons, in most cases there was a significant change in effect size. CONCLUSIONS: Overall, the SF-36 performed well with only a small number of DIF items identified, a reassuring finding in view of the frequent use of the SF-36 in OA. Nevertheless, where DIF items were identified it would be advisable to analyse data taking account of DIF items, especially when age effects are the focus of interest.

Exploring differential item functioning in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

BACKGROUND: The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a widely used patient reported outcome in osteoarthritis. An important, but frequently overlooked, aspect of validating health outcome measures is to establish if items exhibit differential item functioning (DIF). That is, if respondents have the same underlying level of an attribute, does the item give the same score in different subgroups or is it biased towards one subgroup or another. The aim of the study was to explore DIF in the Likert format WOMAC for the first time in a UK osteoarthritis population with respect to demographic, social, clinical and psychological factors. METHODS: The sample comprised a community sample of 763 people with osteoarthritis who participated in the Somerset and Avon Survey of Health. The WOMAC was explored for DIF by gender, age, social deprivation, social class, employment status, distress, body mass index and clinical factors. Ordinal regression models were used to identify DIF items. RESULTS: After adjusting for age, two items were identified for the physical functioning subscale as having DIF with age identified as the DIF factor for 2 items, gender for 1 item and body mass index for 1 item. For the WOMAC pain subscale, for people with hip osteoarthritis one item was identified with age-related DIF. The impact of the DIF items rarely had a significant effect on the conclusions of group comparisons. CONCLUSIONS: Overall, the WOMAC performed well with only a small number of DIF items identified. However, as DIF items were identified in for the WOMAC physical functioning subscale it would be advisable to analyse data taking into account the possible impact of the DIF items when weight, gender or especially age effects, are the focus of interest in UK-based osteoarthritis studies. Similarly for the WOMAC pain subscale in people with hip osteoarthritis it would be worthwhile to analyse data taking into account the possible impact of the DIF item when age comparisons are of primary interest.

Exploring the relationships between International Classification of Functioning, Disability and Health (ICF) constructs of Impairment, Activity Limitation and Participation Restriction in people with osteoarthritis prior to joint replacement.

BACKGROUND: The International Classification of Functioning, Disability and Health (ICF) proposes three main constructs, impairment (I), activity limitation (A) and participation restriction (P). The ICF model allows for all paths between the constructs to be explored, with significant paths likely to vary for different conditions. The relationships between I, A and P have been explored in some conditions but not previously in people with osteoarthritis prior to joint replacement. The aim of this paper is to examine these relationships using separate measures of each construct and structural equation modelling. METHODS: A geographical cohort of 413 patients with osteoarthritis about to undergo hip and knee joint replacement completed the Aberdeen measures of Impairment, Activity Limitation and Participation Restriction (Ab-IAP). Confirmatory factor analysis was used to test the three factor (I, A, P) measurement model. Structural equation modelling was used to explore the I, A and P pathways in the ICF model. RESULTS: There was support from confirmatory factor analysis for the three factor I, A, P measurement model. The structural equation model had good fit [S-B Chi-square = 439.45, df = 149, CFI robust = 0.91, RMSEA robust = 0.07] and indicated significant pathways between I and A (standardised coefficient = 0.76 p < 0.0001) and between A and P (standardised coefficient = 0.75 p < 0.0001). However, the path between I and P was not significant (standardised coefficient = 0.01). CONCLUSION: The significant pathways suggest that treatments and interventions aimed at reducing impairment, such as joint replacement, may only affect P indirectly, through A, however, longitudinal data would be needed to establish this.

Listening to patients: using verbal data in the validation of the Aberdeen Measures of Impairment, Activity Limitation and Participation Restriction (Ab-IAP).

BACKGROUND: The purpose of the study was to evaluate the validity of the self-administered Aberdeen Measures of Impairment, Activity Limitation and Participation Restriction (Ab-IAP): by investigating how participants interpret and respond to questions using the cognitive interviewing technique. METHODS: Twenty patients with osteoarthritis of the knee or hip participated in a cognitive interview whilst completing the Ab-IAP. Interviews were conducted using the concurrent 'think aloud' design. All interviews were audio recorded and transcribed verbatim and analysed (i) using a standardised classification scheme to identify four types of response problems and (ii) thematically using the constant comparative technique. RESULTS: Participants used various response strategies when answering questions about impairment, activity limitations and participation restriction. Problems were judged to be present in 3.1% of participants' responses for the item Ab-IAP. Thematic analysis provided insight into the type and nature of problems people experienced when completing the Ab-IAP measures. The problems identified were mainly comprehension and response problems. CONCLUSIONS: Participants had minimal difficulties completing the Ab-IAP; however those difficulties identified have prompted suggestions for improving the measures. The cognitive interviews produced results that were compatible with statistical analysis of the measures.. Cognitive interviewing was beneficial for testing the validity and acceptability of new Ab-IAP measures. The results demonstrates that the Ab-IAP, in addition to being theoretically-based and having good psychometric properties, elicits appropriate responses.

Measuring the ICF components of impairment, activity limitation and participation restriction: an item analysis using classical test theory and item response theory.

BACKGROUND: The International Classification of Functioning, Disability and Health (ICF) proposes three main health outcomes, Impairment (I), Activity Limitation (A) and Participation Restriction (P), but good measures of these constructs are needed The aim of this study was to use both Classical Test Theory (CTT) and Item Response Theory (IRT) methods to carry out an item analysis to improve measurement of these three components in patients having joint replacement surgery mainly for osteoarthritis (OA). METHODS: A geographical cohort of patients about to undergo lower limb joint replacement was invited to participate. Five hundred and twenty four patients completed ICF items that had been previously identified as measuring only a single ICF construct in patients with osteoarthritis. There were 13 I, 26 A and 20 P items. The SF-36 was used to explore the construct validity of the resultant I, A and P measures. The CTT and IRT analyses were run separately to identify items for inclusion or exclusion in the measurement of each construct. The results from both analyses were compared and contrasted. RESULTS: Overall, the item analysis resulted in the removal of 4 I items, 9 A items and 11 P items. CTT and IRT identified the same 14 items for removal, with CTT additionally excluding 3 items, and IRT a further 7 items. In a preliminary exploration of reliability and validity, the new measures appeared acceptable. CONCLUSION: New measures were developed that reflect the ICF components of Impairment, Activity Limitation and Participation Restriction for patients with advanced arthritis. The resulting Aberdeen IAP measures (Ab-IAP) comprising I (Ab-I, 9 items), A (Ab-A, 17 items), and P (Ab-P, 9 items) met the criteria of conventional psychometric (CTT) analyses and the additional criteria (information and discrimination) of IRT. The use of both methods was more informative than the use of only one of these methods. Thus combining CTT and IRT appears to be a valuable tool in the development of measures.

Activity and affect: repeated within-participant assessment in people after joint replacement surgery.

OBJECTIVE: Between-participant research has shown that high negative affectivity predicts greater activity limitations and vice versa. This study examined both between- and within-participant associations of negative and positive affectivity with activity levels using ecological momentary assessment. METHOD: Participants were 25 people who had undergone joint replacement surgery 12 months previously. Participants made multiple reports of their activity and positive and negative affectivity over a single day using a computerized diary. Activity was also objectively recorded using an activity monitor. The following day, participants made a self-report of their activity over the measurement day and general positive and negative affectivity levels were recorded. RESULTS: Higher self-reported walking time over the whole measurement day was associated with higher general positive affectivity but not negative affectivity. However, using ecological momentary assessment, higher diary reports of negative affectivity predicted increased activity levels while positive affectivity neither predicted nor was predicted by activity. CONCLUSION: These findings demonstrate the importance of within-participant methodology in detecting subtle and immediate effects of individuals' mood on behavior that may differ from findings investigating between-participant effects over longer time periods.

Spousal caregiver confidence and recovery from ambulatory activity limitations in stroke survivors.

OBJECTIVE: This study examined whether spousal confidence in care-recipient recovery can predict recovery from activity limitations following stroke and how spousal confidence relates to stroke survivor self-efficacy for recovery. DESIGN: A prospective design was used. Measures were gathered from stroke survivor/spouse dyads at two time points, both postdischarge from the hospital following stroke (N=109). MAIN OUTCOME MEASURES: The dependent variable was recovery from ambulatory activity limitations over 6 weeks, as measured by the Functional Limitations Profile. A single spousal confidence item was tailored to an ambulatory behavior that the stroke survivors could not perform at Time 1. RESULTS: Spousal confidence was correlated with ambulation recovery (r=-0.23, p<.05) and stroke survivor self-efficacy for recovery (r=.25, p<.05). Higher spousal confidence was associated with a better recovery and greater stroke survivor self-efficacy for recovery, but not with initial health status or practical support received. CONCLUSION: The relationship between caregiver confidence, care-recipient self-efficacy for recovery, and recovery outcomes needs further elucidation.

MOBILE and the provision of total joint replacement.

Modern joint replacements have been available for 45 years, but we still do not have clear indications for these interventions, and we do not know how to optimize the outcome for patients who agree to have them done. The MOBILE programme has been investigating these issues in relation to primary total hip and knee joint replacements, using mixed methods research. There have been five main strands: (1) Epidemiological investigations to find out who is receiving total hip and knee replacements in the National Health Service (NHS). This has shown that there are extensive variations in different regions of the UK, with inequalities and probable inequities in the provision of these operations; (2) Epidemiological work to ascertain the population-based needs for the operations, showing under-provision of knee joint replacements, and a relative reluctance of both patients and GPs to consider knee surgery; (3) Quantitative and qualitative research into the views of patients, health care professionals and the public on the indications for, and prioritization of, total hip and knee joint replacements. This has shown lack of agreement within or between professional groups, as well as a mismatch between the views of patients and the public, and those of professionals; (4) Theoretical and experimental work on patient-related outcome measures, and the development of new instruments to assess both pain and function in people with osteoarthritis, based on the International Classification of Function, as well as a new integrated model of function; (5) Cohort studies of patients undergoing hip or knee joint replacements to find out what the determinants of good and bad outcomes are. These studies have emphasized the huge variation in disease severity at the time of surgery. The challenge now is to use and implement our findings for maximum patient benefit.

Theoretical framework and methodological development of common subjective health outcome measures in osteoarthritis: a critical review.

Subjective measures involving clinician ratings or patient self-assessments have become recognised as an important tool for the assessment of health outcome. The value of a health outcome measure is usually assessed by a psychometric evaluation of its reliability, validity and responsiveness. However, psychometric testing involves an accumulation of evidence and has recognised limitations. It has been suggested that an evaluation of how well a measure has been developed would be a useful additional criteria in assessing the value of a measure. This paper explored the theoretical background and methodological development of subjective health status measures commonly used in osteoarthritis research. Fourteen subjective health outcome measures commonly used in osteoarthritis research were examined. Each measure was explored on the basis of their i) theoretical framework (was there a definition of what was being assessed and was it part of a theoretical model?) and ii) methodological development (what was the scaling strategy, how were the items generated and reduced, what was the response format and what was the scoring method?). Only the AIMS, SF-36 and WHOQOL defined what they were assessing (i.e. the construct of interest) and no measure assessed was part of a theoretical model. None of the clinician report measures appeared to have implemented a scaling procedure or described the rationale for the items selected or scoring system. Of the patient self-report measures, the AIMS, MPQ, OXFORD, SF-36, WHOQOL and WOMAC appeared to follow a standard psychometric scaling method. The DRP and EuroQol used alternative scaling methods. The review highlighted the general lack of theoretical framework for both clinician report and patient self-report measures. This review also drew attention to the wide variation in the methodological development of commonly used measures in OA. While, in general the patient self-report measures had good methodological development, the clinician report measures appeared less well developed. It would be of value if new measures defined the construct of interest and, that the construct, be part of theoretical model. By ensuring measures are both theoretically and empirically valid then improvements in subjective health outcome measures should be possible.

Recovery from disability after stroke as a target for a behavioural intervention: results of a randomized controlled trial.

PURPOSE: Disability following stroke is highly prevalent and is predicted by psychological variables such as control cognitions and emotions, in addition to clinical variables. This study evaluated the effectiveness of a workbook-based intervention, designed to change cognitions about control, in improving outcomes for patients and their carers. METHOD: At discharge, stroke patients were randomly allocated (with their carers) to a 5-week intervention (n = 103) or control (normal care: n = 100). The main outcome (at 6 months) was recovery from disability using a performance measure, with distress and satisfaction as additional outcomes. RESULTS: The intervention group showed significantly better disability recovery, allowing for initial levels of disability, than those in the control group, F(1,201) = 5.61, p = 0.019. Groups did not differ in distress or satisfaction with care for patients or carers. The only psychological process variable improved by the intervention was Confidence in Recovery but this did not mediate the effects on recovery. CONCLUSIONS: A large proportion of intervention participants did not complete the workbook tasks. This was perhaps associated with the fairly low level of personal contact with workbook providers. The modest success of this intervention suggests that it may be possible to develop effective behavioural interventions to enhance recovery from disability in stroke patients.

What do Demand-Control and Effort-Reward work stress questionnaires really measure? A discriminant content validity study of relevance and representativeness of measures.

OBJECTIVES: The Demand-Control (DC) and Effort-Reward Imbalance (ERI) models predict health in a work context. Self-report measures of the four key constructs (demand, control, effort, and reward) have been developed and it is important that these measures have good content validity uncontaminated by content from other constructs. We assessed relevance (whether items reflect the constructs) and representativeness (whether all aspects of the construct are assessed, and all items contribute to that assessment) across the instruments and items. METHODS: Two studies examined fourteen demand/control items from the Job Content Questionnaire and seventeen effort/reward items from the Effort-Reward Imbalance measure using discriminant content validation and a third study developed new methods to assess instrument representativeness. Both methods use judges' ratings and construct definitions to get transparent quantitative estimates of construct validity. Study 1 used dictionary definitions while studies 2 and 3 used published phrases to define constructs. RESULTS: Overall, 3/5 demand items, 4/9 control items, 1/6 effort items, and 7/11 reward items were uniquely classified to the appropriate theoretical construct and were therefore 'pure' items with discriminant content validity (DCV). All pure items measured a defining phrase. However, both the DC and ERI assessment instruments failed to assess all defining aspects. CONCLUSIONS: Finding good discriminant content validity for demand and reward measures means these measures are usable and our quantitative results can guide item selection. By contrast, effort and control measures had limitations (in relevance and representativeness) presenting a challenge to the implementation of the theories. Statement of contribution What is already known on this subject? While the reliability and construct validity of Demand-Control and Effort-Reward-Imbalance (DC and ERI) work stress measures are routinely reported, there has not been adequate investigation of their content validity. This paper investigates their content validity in terms of both relevance and representativeness and provides a model for the investigation of content validity of measures in health psychology more generally. What does this study add? A new application of an existing method, discriminant content validity, and a new method of assessing instrument representativeness. 'Pure' DC and ERI items are identified, as are constructs that are not fully represented by their assessment instruments. The findings are important for studies attempting to distinguish between the main DC and ERI work stress constructs. The quantitative results can be used to guide item selection for future studies.

Anxiety and depression 3 years following stroke: demographic, clinical, and psychological predictors.

OBJECTIVES: Our earlier work had established that moderate depression significantly decreased over the first 6 months after stroke, whereas anxiety levels remained moderate but stable. This study examines the factors predictive of anxiety and depression to 3 years. METHODS: Patients were assessed on six occasions: on hospital admission, 10-20 days following admission, 1 and 6 months following discharge, and 1 and 3 years poststroke, with 38 of the original sample of 101 taking part at Year 3. Demographic and clinical variables, disability, handicap, and psychological measures were used to predict 3-year anxiety and depression, controlling for earlier levels of anxiety or depression. RESULTS: Multiple regression analyses of anxiety at 3 years, controlling for gender and previous anxiety, demonstrated that neither of the significant partial correlates of 6-month depression or satisfaction with treatment persisted. Gender effects persisted when controlling for previous anxiety. Multiple regression analyses of depression at 3 years, controlling for early depression, found that exercise, treatment satisfaction, anxiety, and handicap added significantly to the prediction of lower depression. CONCLUSIONS: Anxiety remains stable over 3 years poststroke and is best explained by prior, early, anxiety, and female gender. Depression reduces over time and was explained by modifiable cognitions and behaviours, which replicates previous findings.

Extending the demand-control model to informal caregiving.

OBJECTIVE: Karasek's demand-control model of job strain was used in an attempt to extend previous work examining the psychological impact of informal caregiving in stroke. METHOD: Data were gathered from 138 informal caregivers/patient dyads at two time points. The dependent variables were the caregiver's anxiety and depression [Hospital Anxiety and Depression Scale (HADS)]. The predictor variables were caregiver demand (stroke survivor's assessment of their physical and psychosocial functional limitations) and control (caregiver's perceived control over stroke survivor's recovery). RESULTS: In a cross-sectional analysis of Times 1 and 2 data, main effects for demand and/or control were detected for anxiety and depression. Contrary to prediction, in longitudinal analysis of change, it was found that decreasing control, along with increasing demand, was associated with reduced distress. CONCLUSION: The model was moderately successful in predicting emotional distress. The relative importance of caregiver demand and control in predicting outcomes changed over time in these data. Attempts to replicate these findings are recommended.

Motivation is not enough: prediction of risk behavior following diagnosis of coronary heart disease from the theory of planned behavior.

Perceived behavioral control (PBC) and intention, the proximal predictors from the theory of planned behavior (TPB), were used to predict cardiovascular risk behaviors in 597 patients 1 year after diagnosis with coronary heart disease. The outcome measures were self-report measures of exercise plus objective measures of fitness (distance walked in 6 min) and cotinine-confirmed smoking cessation. In multivariate analyses incorporating both PBC and intention, PBC predicted exercise, distance walked, and smoking cessation, but intention was not a reliable independent predictor of any health behavior measured. Thus, the effective theoretical component of the TPB was PBC. Similar predictions could derive from social-cognitive theory. In coronary patients, behavioral change needs to address issues of action implementation rather than motivational factors alone.

Does the impact of osteoarthritis vary by age, gender and social deprivation? A community study using the International Classification of Functioning, Disability and Health.

UNLABELLED: Abstract Purpose: The aim of the study was to explore if the impact of osteoarthritis varies with respect to age, gender and social deprivation. Impact was defined as impairment, activity limitations and participation restriction (International Classification of Functioning, Disability and Health (ICF)). Investigating the functioning of the ICF model for subgroups is important both practically and theoretically. METHOD: The sample comprised a community sample of 763 people diagnosed with osteoarthritis. Uncontaminated measures of the ICF constructs were developed using discriminant content validity from a pool of 134 items, including the WOMAC and SF-36. Multigroup Structural Equation Modelling was used to explore if the same pathways exist for subgroups of gender, age and social deprivation. RESULTS: Different significant paths were found for gender and social deprivation: impairment did not predict participation restriction for women and those most deprived, whereas these paths were significant for men and those less deprived. No difference in the paths was found for age. CONCLUSIONS: The impact of osteoarthritis appears to vary with respect to gender and social deprivation but not age. This suggests both that osteoarthritis per se does not adequately explain the health outcomes observed and that different clinical approaches may be appropriate for people of different gender and levels of deprivation. Implications of Rehabilitation The ICF model appears to vary with respect to gender and social deprivation for people with osteoarthritis. The ICF model did not appear to vary with respect to age for people with osteoarthritis. Different treatments and interventions for osteoarthritis may need to be targeted for specific gender and social deprivation groups.

Discriminant content validity: a quantitative methodology for assessing content of theory-based measures, with illustrative applications.

OBJECTIVES: In studies involving theoretical constructs, it is important that measures have good content validity and that there is not contamination of measures by content from other constructs. While reliability and construct validity are routinely reported, to date, there has not been a satisfactory, transparent, and systematic method of assessing and reporting content validity. In this paper, we describe a methodology of discriminant content validity (DCV) and illustrate its application in three studies. METHODS: Discriminant content validity involves six steps: construct definition, item selection, judge identification, judgement format, single-sample test of content validity, and assessment of discriminant items. In three studies, these steps were applied to a measure of illness perceptions (IPQ-R) and control cognitions. RESULTS: The IPQ-R performed well with most items being purely related to their target construct, although timeline and consequences had small problems. By contrast, the study of control cognitions identified problems in measuring constructs independently. In the final study, direct estimation response formats for theory of planned behaviour constructs were found to have as good DCV as Likert format. CONCLUSIONS: The DCV method allowed quantitative assessment of each item and can therefore inform the content validity of the measures assessed. The methods can be applied to assess content validity before or after collecting data to select the appropriate items to measure theoretical constructs. Further, the data reported for each item in Appendix S1 can be used in item or measure selection. Statement of contribution What is already known on this subject? There are agreed methods of assessing and reporting construct validity of measures of theoretical constructs, but not their content validity. Content validity is rarely reported in a systematic and transparent manner. What does this study add? The paper proposes discriminant content validity (DCV), a systematic and transparent method of assessing and reporting whether items assess the intended theoretical construct and only that construct. In three studies, DCV was applied to measures of illness perceptions, control cognitions, and theory of planned behaviour response formats. Appendix S1 gives content validity indices for each item of each questionnaire investigated. Discriminant content validity is ideally applied while the measure is being developed, before using to measure the construct(s), but can also be applied after using a measure.

Are the mental representations of people with osteoarthritis consistent with the International Classification of Functioning Disability and Health?

PURPOSE: This study examined whether the mental representations of people with osteoarthritis (OA) were consistent with the International Classification of Functioning Disability and Health (ICF) model. METHODS: A geographical cohort of 202 people with OA about to have joint replacement surgery completed postal questionnaires. Mental representations were measured by asking participants what they were hoping for from their joint replacement. Two expert judges classified these illness representations to the main ICF constructs of Impairment (I), Activity Limitation (A) and Participation Restriction (P). RESULTS: There was strong agreement between the expert judges. There were a similar number of illness representations for each of the ICF constructs. The primary biomedical route of the ICF model was suggested by the ordering of the participants' illness representations i.e. I to A to P. CONCLUSIONS: The mental representations of people with OA were consistent with the ICF theoretical framework with all three ICF constructs of importance. It appeared that people with OA implicitly apply a biomedical causal model of disability, suggesting that treatments and interventions aimed at reducing impairment may only affect P indirectly, through A. Additionally, the methods provide a novel way of exploring the potential causal relationships between constructs of the ICF model.

Predicting the ICECAP-O capability index from the WOMAC osteoarthritis index: is mapping onto capability from condition-specific health status questionnaires feasible?

BACKGROUND: There is a growing interest in the application of the capability approach in health economic analysis. The aim of the research reported here is to assess the feasibility of mapping from a condition-specific questionnaire (Western Ontario and McMaster Universities [WOMAC] Osteoarthritis Index) to a capability well-being questionnaire (ICEpop CAPability measure for Older people [ICECAP-O]). METHODS: . One hundred five osteoarthritis patients requiring joint replacement completed the 5 attributes on the ICECAP-O (attachment, security, role, enjoyment, and control) and the 3 WOMAC categories (pain, stiffness, and physical function). The prediction data set consisted of baseline scores, whereas follow-up data were used to validate the predictions. The mapping algorithms used ordinary least squares and multinomial logistic regression models to predict the relationship between WOMAC scores, categories, or items and ICECAP-O scores or the 5 ICECAP-O attributes. RESULTS: . ICECAP-O scores predicted from WOMAC category scores produced the lowest mapping error statistics (mean absolute error = 0.0832; mean squared error = 0.0142) as well as highest goodness of fit (R(2) = 0.3976). Prediction of ICECAP-O attributes from WOMAC category scores was possible for the majority of capability dimensions. The "control" attribute and physical function WOMAC category exhibited the strongest relationship (R(2) = 0.2143). The "attachment" attribute proved difficult to predict from any WOMAC category, which is in line with intuition given this attribute captures psychological well-being rather than pain, stiffness, or physical function. CONCLUSION: . This is the first study to investigate the predictive ability of a condition-specific measure of health onto capability. The results presented here suggest it is feasible to map from condition-specific measures to an overall capability index, although WOMAC cannot predict individual capability in its entirety. Although the results here are encouraging for those interested in using ICECAP-O, given the small validation sample size applied, further research will be required to verify these findings.

Content validity of the Dutch version of the Neck Bournemouth Questionnaire.

OBJECTIVE: Mechanical neck pain is a common human phenomenon. In most cases, no patho-anatomical lesion can be identified with the limitations of current radiological imaging. Therefore it is preferable to assess patients with neck pain with a focus on functioning and health, within a biopsychosocial model. The Neck Bournemouth Questionnaire aims to assess biopsychosocial aspects of neck pain. However, the content validity of the Neck Bournemouth Questionnaire Dutch language version (NBQ-NL) in relation to the International Classification of Functioning, Disability and Health (ICF) is unknown. The purpose of the study was to examine the content validity of the NBQ-NL in relation to the health components of the ICF. METHOD: Content validity was assessed in relation to the ICF, by means of Discriminant Content Validity (DCV). RESULTS: The results indicate that the NBQ-NL measures four components of the five ICF (impairment, activity, participation and personal factors). CONCLUSION: The NBQ is a multidimensional questionnaire, representing four of the five components of the ICF.