Health and quality of life of patients with haemophilia: A national study of 124 Danish men.

PURPOSE: In the past decades, haemophilia treatment has greatly improved the health of persons with haemophilia (PWH). This study compares PWH to the general population on social conditions and health. METHODS: In December 2021, all Danes with moderate or severe haemophilia A or B, or von Willebrands disease type 3 were invited to participate in an online self-report survey concerning sociodemographic factors, self-rated health, teeth status, chronic health conditions, symptoms and loneliness. This study compares responses from the 124 adult male PWH with responses from a male general population sample (N = 4849). Analyses used logistic regression, controlling for age and highest completed education. RESULTS: Fewer PWH were in the oldest age group (65-84 years). Controlling for age, no significant differences were found regarding cohabitation status or education. Fewer PWH were employed (OR = .48, [.33-.71])-particularly in the 45-64 age group. PWH were less likely to report good health (OR = .49, [.31-.77]). The odds of joint disease was much higher (OR = 13.00, [8.37-20.28]). Also, hypertension (OR = 2.25, [1.13-5.65]) and previous stroke (OR = 2.51, [1.44-3.50]) were more frequent. PWH were more likely to report pain in the arms/hands/legs/hips (OR = 2.94, [1.92-4.52]), but less likely to report pain in the head/neck/shoulder (OR = .66, [.45-.96]). CONCLUSION: The disease burden of haemophilia has improved so PWH resembles the general population in areas such as marriage and education. However, even for young PWH, the disease still imposes a significant burden from hemophilia arthropathy and pain in extremities and joints. Middle-aged PWH also have poorer levels of employment than same-aged peers.

The improved health utility of once-weekly subcutaneous semaglutide 2.4 mg compared with placebo in the STEP 1-4 obesity trials.

AIM: To assess health utility values in the Semaglutide Treatment Effect in People with obesity (STEP) 1-4 trials. MATERIALS AND METHODS: The STEP 1-4 phase 3a, 68-week, double-blind randomized controlled trials assessed the efficacy and safety of semaglutide 2.4 mg versus placebo in individuals with a body mass index (BMI) of 30 kg/m2 or higher or a BMI of 27 kg/m2 or higher and at least one comorbidity (STEP 1, 3 and 4), or a BMI of 27 kg/m2 or higher and type 2 diabetes (STEP 2). Patients received lifestyle intervention plus intensive behavioural therapy in STEP 3. Health-related quality of life was assessed using the Short Form 36-item Health Survey version 2 (SF-36v2) at baseline and week 68. Scores were converted into Short Form Six-Dimension version 2 (SF-6Dv2) utility scores or mapped onto the European Quality of Life Five-Dimension Three-Level (EQ-5D-3L) utility index using UK health utility weights. RESULTS: At week 68, semaglutide 2.4 mg was associated with minor health utility score improvements from baseline (all trials), while scores for placebo typically decreased. SF-6Dv2 treatment differences by week 68 for semaglutide 2.4 mg versus placebo were significant in STEP 1 and 4 (P ≤ .001), but not STEP 2 or 3. EQ-5D-3L treatment differences by week 68 for semaglutide 2.4 mg versus placebo were significant in STEP 1, 2 and 4 (P < .001 for all), but not STEP 3. CONCLUSIONS: Semaglutide 2.4 mg was associated with improvement in health utility scores compared with placebo, reaching statistical significance in STEP 1, 2 and 4.

Establishing thresholds for meaningful within-individual change using longitudinal item response theory.

PURPOSE: Thresholds for meaningful within-individual change (MWIC) are useful for interpreting patient-reported outcome measures (PROM). Transition ratings (TR) have been recommended as anchors to establish MWIC. Traditional statistical methods for analyzing MWIC such as mean change analysis, receiver operating characteristic (ROC) analysis, and predictive modeling ignore problems of floor/ceiling effects and measurement error in the PROM scores and the TR item. We present a novel approach to MWIC estimation for multi-item scales using longitudinal item response theory (LIRT). METHODS: A Graded Response LIRT model for baseline and follow-up PROM data was expanded to include a TR item measuring latent change. The LIRT threshold parameter for the TR established the MWIC threshold on the latent metric, from which the observed PROM score MWIC threshold was estimated. We compared the LIRT approach and traditional methods using an example data set with baseline and three follow-up assessments differing by magnitude of score improvement, variance of score improvement, and baseline-follow-up score correlation. RESULTS: The LIRT model provided good fit to the data. LIRT estimates of observed PROM MWIC varied between 3 and 4 points score improvement. In contrast, results from traditional methods varied from 2 to 10 points-strongly associated with proportion of self-rated improvement. Best agreement between methods was seen when approximately 50% rated their health as improved. CONCLUSION: Results from traditional analyses of anchor-based MWIC are impacted by study conditions. LIRT constitutes a promising and more robust analytic approach to identifying thresholds for MWIC.

Estimating a Preference-Based Index for Mental Health From the Recovering Quality of Life Measure: Valuation of Recovering Quality of Life Utility Index.

BACKGROUND: There are increasing concerns about the appropriateness of generic preference-based measures to capture health benefits in the area of mental health. OBJECTIVES: The aim of this study is to estimate preference weights for a new measure, Recovering Quality of Life (ReQoL-10), to better capture the benefits of mental healthcare. METHODS: Psychometric analyses of a larger sample of mental health service users (n = 4266) using confirmatory factor analyses and item response theory were used to derive a health state classification system and inform the selection of health states for utility assessment. A valuation survey with members of the UK public representative in terms of age, sex, and region was conducted using face-to-face interviewer administered time-trade-off with props. A series of regression models were fitted to the data and the best performing model selected for the scoring algorithm. RESULTS: The ReQoL-Utility Index (UI) classification system comprises 6 mental health items and 1 physical health item. Sixty-four health states were valued by 305 participants. The preferred model was a random effects model, with significant and consistent coefficients and best model fit. Estimated utilities modeled for all health states ranged from -0.195 (state worse than dead) to 1 (best possible state). CONCLUSIONS: The development of the ReQoL-UI is based on a novel application of item response theory methods for generating the classification system and selecting health states for valuation. Conventional time-trade-off was used to elicit utility values that are modeled to enable the generation of QALYs for use in cost-utility analysis of mental health interventions.

Associations between physical and psychosocial work environment factors and sickness absence incidence depend on the lengths of the sickness absence episodes: a prospective study of 27 678 Danish employees.

OBJECTIVES: This study examined if the association between work environment factors and sickness absence (SA) depended on the inclusion or exclusion of short-term SA episodes. METHODS: We linked the 'Work Environment and Health in Denmark' survey with the 'Danish Register of Work Absences' (n=27 678). Using covariate adjusted Cox regression, we examined the associations between work environment factors and SA by changing the cut-off points for the length of the SA episodes, for example, episodes ≥1 day, ≥6 days and ≥21 days. We examined three physical work environment factors: 'Back bend or twisted', 'Lifting or carrying', 'Wet hands' and three psychosocial work environment factors: 'Poor influence', 'Role conflicts' and 'Bullying'. RESULTS: 'Back bend or twisted' and 'Lifting or carrying' had small significant HRs for SA episodes ≥1 day and large and highly significant HRs for SA episodes ≥6 days and ≥21 days. 'Wet hands' had small significant HRs for SA episodes ≥1 day for both sexes and large and highly significant HR for ≥6 days for women. HRs of all three psychosocial factors were highly significant for SA episodes ≥1 day and ≥6 days for both sexes, and 'Poor influence' and 'Role conflicts' were significant for SA episodes ≥21 days for women. CONCLUSIONS: The physical work factors had higher associations with SA when SA episodes of 1-5 days were excluded and focus was on SA episodes ≥6 days. The psychosocial work factors were strongly associated with SA both with and without SA episodes of 1-5 days included in the analyses.

An item response theory analysis of an item pool for the recovering quality of life (ReQoL) measure.

PURPOSE: ReQoL-10 and ReQoL-20 have been developed for use as outcome measures with individuals aged 16 and over, experiencing mental health difficulties. This paper reports modelling results from the item response theory (IRT) analyses that were used for item reduction. METHODS: From several stages of preparatory work including focus groups and a previous psychometric survey, a pool of items was developed. After confirming that the ReQoL item pool was sufficiently unidimensional for scoring, IRT model parameters were estimated using Samejima's Graded Response Model (GRM). All 39 mental health items were evaluated with respect to item fit and differential item function regarding age, gender, ethnicity, and diagnosis. Scales were evaluated regarding overall measurement precision and known-groups validity (by care setting type and self-rating of overall mental health). RESULTS: The study recruited 4266 participants with a wide range of mental health diagnoses from multiple settings. The IRT parameters demonstrated excellent coverage of the latent construct with the centres of item information functions ranging from - 0.98 to 0.21 and with discrimination slope parameters from 1.4 to 3.6. We identified only two poorly fitting items and no evidence of differential item functioning of concern. Scales showed excellent measurement precision and known-groups validity. CONCLUSION: The results from the IRT analyses confirm the robust structure properties and internal construct validity of the ReQoL instruments. The strong psychometric evidence generated guided item selection for the final versions of the ReQoL measures.

Disability pension among persons with chronic disease: Differential impact of a Danish policy reform.

BACKGROUND: In 2013, Denmark implemented a reform that tightened the criteria for disability pension, expanded a subsidized job scheme ('flexi-job') and introduced a new vocational rehabilitation scheme. The overall aim of the reform was to keep more persons attached to the labour market. This study investigates the impact of the reform among persons with chronic disease and whether this impact differed across groups defined by labour market affiliation and chronic disease type. METHODS: The study was conducted as a register-based, nationwide cohort study. The study population included 480 809 persons between 40 and 64 years of age, who suffered from at least one of six chronic diseases. Hazard ratios (HR) and 95% confidence intervals (CI) of being awarded disability pension or flexi-job in the 5 years after vs. the 5 years prior to the reform were estimated. RESULTS: Overall, the probability of being awarded disability pension was halved after the reform (HR = 0.49, CI: 0.47-0.50). The impact was largest for persons receiving sickness absence benefits (HR = 0.31, CI: 0.24-0.39) and for persons with functional disorders (HR = 0.38, CI: 0.32-0.44). Also, the impact was larger for persons working in manual jobs than for persons working in non-manual jobs. The probability of being awarded a flexi-job was decreased by one-fourth (HR = 0.76, CI: 0.74-0.79) with the largest impact for high-skilled persons working in non-manual jobs. CONCLUSION: Access to disability pension and flexi-job decreased after the reform. This impact varied according to labour market affiliation and chronic disease type.

Determinants of voluntary early retirement for older workers with and without chronic diseases: A Danish prospective study.

Aims: This study explored differences in determinants (i.e. health-related, work-related and social factors) of voluntary early retirement between older workers with and without chronic diseases in Denmark. Methods: Workers aged 56-64 years who were members of a voluntary early retirement scheme were selected from the Danish National Working Environment Survey (2008-2009) and were followed in a public register for four years. Cox regression analyses were performed separately for older workers with and without chronic disease to identify the associations between determinants and voluntary early retirement. To explore the differences between groups, an interaction term between the determinant and having a chronic disease was included in the analyses for the total population. Results: Among 1861 eligible older workers, determinants associated with a higher risk of voluntary early retirement included poorer self-rated health, more depressive symptoms, a higher physical workload, lower job satisfaction and lower influence at work. For older workers with a chronic disease (n=1185), the presence of work-family conflict was also associated with a higher risk of voluntary early retirement, whereas for those with no chronic disease (n=676), a poorer relationship with colleagues was an additional determinant. Higher emotional demands, a higher work pace and higher quantitative demands were not significantly associated with voluntary early retirement for either group. None of the interaction terms was found to be statistically significant (p>0.05). Conclusions: Determinants associated with voluntary early retirement did not significantly differ between older workers with or without a chronic disease in Denmark. We conclude that several health-related, work-related and social factors are important for prolonged labour force participation of older workers (with and without a chronic disease).

Effort-reward imbalance at work and weight changes in a nationwide cohort of workers in Denmark.

OBJECTIVE: To investigate the relation between effort-reward imbalance (ERI) at work and subsequent weight changes. METHODS: We included participants from a population-based cohort of workers in Denmark (mean age = 47 years, 54% women) with two (n = 9005) or three repeated measurements (n = 5710). We investigated the association between (a) ERI (ie, the mismatch between high efforts spent and low rewards received at work) at baseline and weight changes after a 2-year follow-up (defined as ≥5% increase or decrease in body mass index (BMI) vs stable), and (b) onset and remission of ERI and subsequent changes in BMI. Using multinomial logistic regression we calculated risk ratios (RR) and 95% confidence intervals (CI), adjusted for sex, age, education, cohabitation, migration background, and follow-up time. RESULTS: After 2 years, 15% had an increase and 13% a decrease in BMI. Exposure to ERI at baseline yielded RRs of 1.09 (95% CI: 0.95-1.25) and 1.04 (95% CI: 0.90-1.20) for the increase and decrease in BMI, respectively. There were no differences between sex and baseline BMI in stratified analyses. The onset of ERI yielded RRs of 1.04 (95% CI: 0.82-1.31) and 1.15 (95% CI: 0.84-1.57) for subsequent increase and decrease in BMI. The RRs for the remission of ERI and subsequent increase and decrease in BMI were 0.92 (95% CI: 0.71-1.20) and 0.78 (95% CI: 0.53-1.13), respectively. Of the ERI components, high rewards were associated with a lower risk of BMI increase. CONCLUSION: ERI was not a risk factor for weight changes. Future studies may investigate whether this result is generalizable to other occupational cohorts and settings.

Health-related quality of life predicted subsequent health care resource utilization in patients with active cancer.

PURPOSE: The objective of this study was to estimate the association between SF-12v2® Health Survey (SF-12v2) scores and subsequent health care resource utilization (HCRU) among patients with cancer. METHODS: We analyzed 18+ year participants in the Medical Expenditure Panel Survey, diagnosed with active cancer or malignancy (n = 647). HCRU was measured by total medical expenditures (MEs) and number of medical events (EVs) in the 6 months following the SF-12v2 assessment. The effect of SF-12v2 scores (physical (PCS) and mental (MCS) component summary scores and the SF-6D health-utility score) on HCRU was estimated using generalized linear models. Estimates were obtained for the entire sample and for the four cancer groups present in the sample: breast, prostate, skin, and lung. RESULTS: For PCS and MCS, a one-point better score was associated with 2% lower MEs (P < 0.001) and 2.5% lower MEs (P = 0.015), respectively. A 0.05-point better SF-6D score was associated with 7% lower MEs (P = 0.003). PCS and SF-6D were more strongly associated with MEs for prostate cancer patients (P = 0.009 and P = 0.003) and PCS was more strongly associated with MEs for skin cancer patients (P = 0.019), compared to other cancer groups. A 1-point better PCS predicted 1% lower EVs, while a 0.05 better SF-6D score predicted 4% lower EVs. CONCLUSIONS: The significant associations between SF-12v2 scores from oncology patients and subsequent HCRU can guide interpretations of SF-12v2 scores in evaluation of therapies and in health policy decisions.

Exploring the item sets of the Recovering Quality of Life (ReQoL) measures using factor analysis.

PURPOSE: This paper presents two studies exploring the latent structure of item sets used in the development of the Recovering Quality of Life mental health outcome measures: ReQoL-10 and ReQoL-20. METHOD: In study 1, 2262 participants completed an initial set of 61 items. In study 2, 4266 participants completed a reduced set of 40 items. Study 2 evaluated two formats of the questionnaires: one version where the items were intermingled and one where the positively worded and negatively worded items were presented as two separate blocks. Exploratory and confirmatory factor analyses were conducted on both datasets where models were specified using ordinal treatment of the item responses. Dimensionality based on the conceptual framework and methods effects reflecting the mixture of positively worded and negatively worded items were explored. Factor invariance was tested across the intermingled and block formats. RESULTS: In both studies, a bi-factor model (study 1: RMSEA = 0.061; CFI = 0.954; study 2: RMSEA = 0.066; CFI = 0.971) with one general factor and two local factors (positively worded questions and negatively worded questions) was preferred. The loadings on the general factor were higher than on the two local factors suggesting that the ReQoL scale scores can be understood in terms of a general factor. Insignificant differences were found between the intermingled and block formats. CONCLUSIONS: The analyses confirmed that the ReQoL item sets are sufficiently unidimensional to proceed to item response theory analysis. The model was robust across different ordering of positive and negative items.

Effect of tardive dyskinesia on quality of life in patients with bipolar disorder, major depressive disorder, and schizophrenia.

PURPOSE: Tardive dyskinesia (TD) is a common but serious hyperkinetic movement disorder and side effect of antipsychotic medications used to treat bipolar disorder (BD), major depressive disorder (MDD), and schizophrenia (SZ). The purpose of this study was to evaluate health-related quality of life (HRQoL) in a population with diagnoses for BD, MDD, or SZ by comparing patients with TD (n = 197) with those without TD (n = 219). HRQoL in each group was also compared with HRQoL of the general population. METHODS: This study employed a cross-sectional web-based survey. HRQoL was assessed by four instruments: the SF-12 Health Survey, Version 2 (SF-12v2), the Quality of Life Enjoyment and Satisfaction Questionnaire, Short Form (Q-LES-Q-SF), the Social Withdrawal subscale of the Internalized Stigma of Mental Illness Scale (SW-ISMI); and two questions on movement disorders. RESULTS: Patients with TD had significantly worse HRQoL and social withdrawal than those without. The differences were more pronounced for physical HRQoL domains than for mental health domains. Patients with more-severe TD, assessed through either self-rating or clinician rating, experienced significantly worse HRQoL than did those with less-severe TD. The impact of TD was substantially greater in patients with SZ than in those with BD or MDD. Compared with the general population, patients with BD, MDD, or SZ experienced significantly worse HRQoL regardless of TD status, although this deficit in HRQoL was greater among those with TD. CONCLUSIONS: The presence of TD is associated with worse HRQoL and social withdrawal. The most severe impact of TD is on physical aspects of patients' HRQoL.

Recovering Quality of Life (ReQoL): a new generic self-reported outcome measure for use with people experiencing mental health difficulties.

BACKGROUND: Outcome measures for mental health services need to adopt a service-user recovery focus. Aims To develop and validate a 10- and 20-item self-report recovery-focused quality of life outcome measure named Recovering Quality of Life (ReQoL). METHOD: Qualitative methods for item development and initial testing, and quantitative methods for item reduction and scale construction were used. Data from >6500 service users were factor analysed and item response theory models employed to inform item selection. The measures were tested for reliability, validity and responsiveness. RESULTS: ReQoL-10 and ReQoL-20 contain positively and negatively worded items covering seven themes: activity, hope, belonging and relationships, self-perception, well-being, autonomy, and physical health. Both versions achieved acceptable internal consistency, test-retest reliability (>0.85), known-group differences, convergence with related measures, and were responsive over time (standardised response mean (SRM) > 0.4). They performed marginally better than the Short Warwick-Edinburgh Mental Well-being Scale and markedly better than the EQ-5D. CONCLUSIONS: Both versions are appropriate for measuring service-user recovery-focused quality of life outcomes. Declaration of interest M.B. and J.Co. were members of the research group that developed the Clinical Outcomes in Routine Evaluation (CORE) outcome measures.

Work-unit social capital and long-term sickness absence: a prospective cohort study of 32 053 hospital employees.

OBJECTIVE: There is a lack of studies investigating social capital at the workplace level in small and relatively homogeneous work-units. The aim of the study was to investigate whether work-unit social capital predicts a lower risk of individual long-term sickness absence among Danish hospital employees followed prospectively for 1 year. METHODS: This study is based on the Well-being in HospitAL Employees cohort. The study sample consisted of 32 053 individuals nested within 2182 work-units in the Capital Region of Denmark. Work-unit social capital was measured with an eight-item scale covering elements of trust, justice and collaboration between employees and leaders. Social capital at the work-unit level was computed as the aggregated mean of individual-level social capital within each work-unit. Data on long-term sickness absence were retrieved from the employers' payroll system and were operationalised as ≥29 consecutive days of sickness absence. We used a 12-point difference in social capital as the metric in our analyses and conducted two-level hierarchical logistic regression analysis. Adjustments were made for sex, age, seniority, occupational group and part-time work at the individual level, and work-unit size, the proportion of female employees and the proportion of part-time work at the work-unit level. RESULTS: The OR for long-term sickness absence associated with a 12-point higher work-unit social capital was 0.73 (95% CI 0.68 to 0.78). Further, we found an association between higher work-unit social capital and lower long-term sickness absence across quartiles of social capital: compared with the lowest quartile, the OR for long-term sickness absence in the highest quartile was 0.51 (95% CI 0.44 to 0.60). CONCLUSION: Our study provides support for work-unit social capital being a protective factor for individual long-term sickness absence among hospital employees in the Capital Region of Denmark.

Conversion of standard retrospective patient-reported outcomes to momentary versions: cognitive interviewing reveals varying degrees of momentary compatibility.

PURPOSE: The purpose of this study was to adapt different domains of an existing retrospective questionnaire to momentary versions, to use and assess cognitive interviewing for evaluating the new versions, and to compare momentary compatibility (i.e. an item's potential to be validly converted to a momentary version) across different scales. METHODS: Initial momentary versions of retrospective patient-reported outcomes were produced by converting present perfect tense wording to present tense wording. Cognitive interviews were conducted iteratively with 21 patients to determine which reference period they actually employed, and to identify problems with new, revised versions. A think-aloud interview protocol was supplemented with non-specific concurrent and specific retrospective probing. The momentary compatibility of each item was evaluated by calculating the proportion of interviews wherein momentary reference periods were identified; problems were categorized according to cognitive aspects of survey methodology taxonomy. The efficiency of various cognitive interviewing techniques was determined by evaluating whether applied reference periods were identified by think-aloud alone or by supplementary probes. RESULTS: The momentary compatibility varied from 5 to 100% across items. Cognitive interviews revealed potential problems of various severities in the majority of items. Think-aloud alone was sufficient at determining the applied reference period in one-third of the cases, and the efficiency of additional concurrent and retrospective probing was 50 and 94%, respectively. CONCLUSIONS: Cognitive interviewing techniques proved useful for developing and evaluating momentary items. Researchers should be aware of the applied reference period and of emerging problems when evaluating adapted momentary items, since not all concepts are suitable. We recommend the proposed method in future adaptations of existing instruments.

Does workplace social capital protect against long-term sickness absence? Linking workplace aggregated social capital to sickness absence registry data.

AIMS: Most previous prospective studies have examined workplace social capital as a resource of the individual. However, literature suggests that social capital is a collective good. In the present study we examined whether a high level of workplace aggregated social capital (WASC) predicts a decreased risk of individual-level long-term sickness absence (LTSA) in Danish private sector employees. METHODS: A sample of 2043 employees (aged 18-64 years, 38.5% women) from 260 Danish private-sector companies filled in a questionnaire on workplace social capital and covariates. WASC was calculated by assigning the company-averaged social capital score to all employees of each company. We derived LTSA, defined as sickness absence of more than three weeks, from a national register. We examined if WASC predicted employee LTSA using multilevel survival analyses, while excluding participants with LTSA in the three months preceding baseline. RESULTS: We found no statistically significant association in any of the analyses. The hazard ratio for LTSA in the fully adjusted model was 0.93 (95% CI 0.77-1.13) per one standard deviation increase in WASC. When using WASC as a categorical exposure we found a statistically non-significant tendency towards a decreased risk of LTSA in employees with medium WASC (fully adjusted model: HR 0.78 (95% CI 0.48-1.27)). Post hoc analyses with workplace social capital as a resource of the individual showed similar results. CONCLUSIONS: WASC did not predict LTSA in this sample of Danish private-sector employees.

The Work Role Functioning Questionnaire v2.0 Showed Consistent Factor Structure Across Six Working Samples.

Objective The Work Role Functioning Questionnaire v2.0 (WRFQ) is an outcome measure linking a persons' health to the ability to meet work demands in the twenty-first century. We aimed to examine the construct validity of the WRFQ in a heterogeneous set of working samples in the Netherlands with mixed clinical conditions and job types to evaluate the comparability of the scale structure. Methods Confirmatory factor and multi-group analyses were conducted in six cross-sectional working samples (total N = 2433) to evaluate and compare a five-factor model structure of the WRFQ (work scheduling demands, output demands, physical demands, mental and social demands, and flexibility demands). Model fit indices were calculated based on RMSEA ≤ 0.08 and CFI ≥ 0.95. After fitting the five-factor model, the multidimensional structure of the instrument was evaluated across samples using a second order factor model. Results The factor structure was robust across samples and a multi-group model had adequate fit (RMSEA = 0.63, CFI = 0.972). In sample specific analyses, minor modifications were necessary in three samples (final RMSEA 0.055-0.080, final CFI between 0.955 and 0.989). Applying the previous first order specifications, a second order factor model had adequate fit in all samples. Conclusion A five-factor model of the WRFQ showed consistent structural validity across samples. A second order factor model showed adequate fit, but the second order factor loadings varied across samples. Therefore subscale scores are recommended to compare across different clinical and working samples.

Work ability in rheumatoid arthritis patients: a register study on the prospective risk of exclusion and probability of returning to work.

Objectives: The aim was to study work ability in patients with RA compared with the general population by investigating the rates and risks of long-term sickness absence, unemployment and disability pension, and the chance of returning to work and the changes in these risks over time (1994-2011). Methods: This was a cohort study with up to 17 years of follow-up (mean 6.95 years/person) including 6677 RA patients of working age (identified in the nationwide DANBIO registry) and 56 955 matched controls from the general population. A multi-state model was used to analyse all shifts between the work-related states (long-term sickness absence, unemployment and disability pension, as well as the chance of returning to work) and calculate hazard rates (HRs). Analyses were stratified by disease duration and controlled for socio-demographic factors, physical job exposure and somatic and psychiatric co-morbidities. Results: RA patients had increased risk of long-term sickness absence (e.g. early RA: HR = 4.00, 95% CI: 3.64, 4.30) and disability pension (e.g. established RA: HR = 2.75, 95% CI: 2.54, 2.98) relative to controls. From 1994-99 to 2006-11, a decrease in the effect of established RA was observed [long-term sickness absence: from HR = 2.25 (95% CI: 1.99, 2.54) to 1.63 (95% CI: 1.51, 1.75); and disability pension: from HR = 3.49 (95% CI: 2.83, 4.32) to 2.40 (95% CI: 2.15, 2.69)]. RA patients had a lower chance of returning to work from long-term sickness absence or unemployment (HR = 0.60, HR=0.80), and this did not change over time. Conclusion: RA patients remain at high risk for long-term sickness absence and disability pension, despite a positive development between 1996-99 and 2006-11. Returning to work after sick leave or unemployment remains a challenge for RA patients.

An Exploratory Study on Using Principal-Component Analysis and Confirmatory Factor Analysis to Identify Bolt-On Dimensions: The EQ-5D Case Study.

OBJECTIVE: Generic preference-based measures such as the EuroQol five-dimensional questionnaire (EQ-5D) are used in economic evaluation, but may not be appropriate for all conditions. When this happens, a possible solution is adding bolt-ons to expand their descriptive systems. Using review-based methods, studies published to date claimed the relevance of bolt-ons in the presence of poor psychometric results. This approach does not identify the specific dimensions missing from the Generic preference-based measure core descriptive system, and is inappropriate for identifying dimensions that might improve the measure generically. This study explores the use of principal-component analysis (PCA) and confirmatory factor analysis (CFA) for bolt-on identification in the EQ-5D. METHODS: Data were drawn from the international Multi-Instrument Comparison study, which is an online survey on health and well-being measures in five countries. Analysis was based on a pool of 92 items from nine instruments. Initial content analysis provided a theoretical framework for PCA results interpretation and CFA model development. PCA was used to investigate the underlining dimensional structure and whether EQ-5D items were represented in the identified constructs. CFA was used to confirm the structure. CFA was cross-validated in random halves of the sample. RESULTS: PCA suggested a nine-component solution, which was confirmed by CFA. This included psychological symptoms, physical functioning, and pain, which were covered by the EQ-5D, and satisfaction, speech/cognition,relationships, hearing, vision, and energy/sleep which were not. These latter factors may represent relevant candidate bolt-ons. CONCLUSIONS: PCA and CFA appear useful methods for identifying potential bolt-ons dimensions for an instrument such as the EQ-5D.

Worklife expectancy in a cohort of Danish employees aged 55-65 years - comparing a multi-state Cox proportional hazard approach with conventional multi-state life tables.

BACKGROUND: Work life expectancy (WLE) expresses the expected time a person will remain in the labor market until he or she retires. This paper compares a life table approach to estimating WLE to an approach based on multi-state proportional hazards models. The two methods are used to estimate WLE in Danish members and non-members of an early retirement pensioning (ERP) scheme according to levels of health. METHODS: In 2008, data on self-rated health (SRH) was collected from 5212 employees 55-65 years of age. Data on previous and subsequent long-term sickness absence, unemployment, returning to work, and disability pension was collected from national registers. WLE was estimated from multi-state life tables and through multi-state models. RESULTS: Results from the multi-state model approach agreed with the life table approach but provided narrower confidence intervals for small groups. The shortest WLE was seen for employees with poor SRH and ERP membership while the longest WLE was seen for those with good SRH and no ERP membership. Employees aged 55-56 years with poor SRH but no ERP membership had shorter WLE than employees with good SRH and ERP membership. Relative WLE reversed for the two groups after age 57. At age 55, employees with poor SRH could be expected to spend approximately 12 months on long-term sick leave and 9-10 months unemployed before they retired - regardless of ERP membership. ERP members with poor SRH could be expected to spend 4.6 years working, while non-members could be expected to spend 7.1 years working. CONCLUSION: WLE estimated through multi-state models provided an effective way to summarize complex data on labor market affiliation. WLE differed noticeably between members and non-members of the ERP scheme. It has been hypothesized that while ERP membership would prompt some employees to retire earlier than they would have done otherwise, this effect would be partly offset by reduced time spent on long-term sick leave or unemployment. Our data showed no indication of such an effect, but this could be due to residual confounding and self-selection of people with poor health into the ERP scheme.