Dm Meads

Development and validation of a preference based measure derived from the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) for use in cost utility analyses

BackgroundPulmonary Hypertension is a severe and incurable disease with poor prognosis. A suite of new disease-specific measures – the Cambridge Pulmonary Hypertension Outcome Review (CAMPHOR) – was recently developed for use in this condition. The purpose of this study was to develop and validate a preference based measure from the CAMPHOR that could be used in cost-utility analyses.MethodsItems were selected that covered major issues covered by the CAMPHOR QoL scale (activities, travelling, dependence and communication). These were used to create 36 health states that were valued by 249 people representative of the UK adult population, using the time trade-off (TTO) technique. Data from the TTO interviews were analysed using both aggregate and individual level modelling. Finally, the original CAMPHOR validation data were used to validate the new preference based model.ResultsThe predicted health state values ranged from 0.962 to 0.136. The mean level model selected for analyzing the data had good explanatory power (0.936), did not systematically over- or underestimate the observed mean health state values and showed no evidence of auto correlation in the prediction errors. The value of less than 1 reflects a background level of ill health in state 1111, as judged by the respondents. Scores derived from the new measure had excellent test-retest reliability (0.85) and construct validity. The CAMPHOR utility score appears better able to distinguish between WHO functional classes (II and III) than the EQ-5D and SF-6D.ConclusionThe tariff derived in this study can be used to classify an individual into a health state based on their responses to the CAMPHOR. The results of this study widen the evidence base for conducting economic evaluations of interventions designed to improve QoL for patients with PH.

Methodological aspects of differential item functioning in the Rasch model

Summary Items do not always function equally in different groups (e.g. across genders, languages and cultures). Consequently, where patient-reported outcomes are used and different groups are compared, data should be checked for differential item functioning (DIF). An item that functions with the same constant magnitude of difference across a construct measured possesses uniform DIF. In contrast, non-uniform DIF is characterised by an uneven difference in item function across the latent variable measured. The aims of this paper are to report on the methodological aspects of DIF using Rasch analysis and to demonstrate how the mean scores in a scale can be adjusted due to uniform DIF. Different examples of DIF are reported including examples of differences between the mean scores before and after adjusting for an identified uniform DIF. In conclusion, the difference between subpopulations and, therefore, other outcomes such as economic impact could be under or overestimated if one or more items in a dimension possess DIF.

Quality of life in infants and children with atopic dermatitis: Addressing issues of differential item functioning across countries in multinational clinical trials

BackgroundA previous study had identified 45 items assessing the impact of atopic dermatitis (AD) on the whole family. From these it was intended to develop two separate scales, one assessing impact on carers and the other determining the effect on the child.MethodsThe 45 items were included in three clinical trials designed to test the efficacy of a new topical treatment (pimecrolimus, Elidel cream 1%) in the treatment of AD in infants and children and in validation studies in the UK, US, Germany, France and the Netherlands. Rasch analyses were undertaken to determine whether an internationally valid, unidimensional scale could be developed that would inform on the direct impact of AD on the child.ResultsRasch analyses applied to the data from the trials indicated that the draft measure consisted of two scales, one assessing the QoL of the carer and the other (consisting of 12 items) measuring the impact of AD on the child. Three of the 12 potential items failed to fit the measurement model in Europe and five in the US. In addition, four items exhibiting differential item functioning (DIF) by country were identified. After removing the misfitting items and controlling for DIF it was possible to derive a scale; The Childhood Impact of Atopic Dermatitis (CIAD) with good item fit for each trial analysis. Analysis of the validation data from each of the different countries confirmed that the CIAD had adequate internal consistency, reproducibility and construct validity.The CIAD demonstrated the benefits of treatment with Elidel over placebo in the European trial. A similar (non-significant) trend was found for the US trials.ConclusionThe study represents a novel method of dealing with the problem of DIF associated with different cultures. Such problems are likely to arise in any multinational study involving patient-reported outcome measures, as items in the scales are likely to be valued differently in different cultures. However, where all items in a scale fit both a single theoretical construct and the Rasch measurement model, it is feasible to conceive of outcome measures with a different set of items in each language.

Development and validation of the living with chronic obstructive pulmonary disease questionnaire

PurposeAvailable patient-reported outcome (PRO) measures for chronic obstructive pulmonary disease (COPD) focus primarily on impairment (symptoms) and activities (functioning). The purpose of the study was to develop a patient-based PRO measure for COPD that captures the overall everyday impact of living with COPD from the patient’s perspective.MethodsLCOPD items (Living with COPD Questionnaire) were generated from qualitative interviews in the UK and focus groups in the USA. The draft measure was tested for face and content validity in both countries. Item reduction and testing for reproducibility and construct validity was conducted via Rasch and traditional psychometric analyses.ResultsThe draft LCOPD was found to be relevant and acceptable to patients in the UK (Nxa0=xa019) and US (Nxa0=xa016). Application of Rasch analysis to data collected in validation studies (nxa0=xa0162 in the UK and 145 in US) identified a 22-item scale that measured a single construct in both countries. Psychometric analyses indicated that this version was internally consistent and reproducible. Scores on the measure were related as expected to clinician ratings of disease severity and patient ratings of COPD severity and general health.ConclusionsThe LCOPD is a new measure examining the everyday impact of living with COPD. It demonstrates good scaling properties and may prove valuable in understanding treatment benefits.

PMH46 ASSESSING THE CROSS-CULTURAL COMPARABILITY OF THE CENTRE FOR EPIDEMIOLOGIC STUDIES DEPRESSION SCALE (CES-D)

Conclusions Findings confirm previous research indicating the original CES-D (with the exception of the French version) does not fit the Rasch model. The short-form also misfit in the UK and Ger-many suggesting that this version is not standard across countries. Rasch is a valuable tool for establishing the cross-cultural comparability of PROs. There was significant country-related DIF associated with both the original and short-form scale suggesting it is not safe to pool or compare CES-D data from these countries. DIF may be overcome by splitting items. An optimal CES-D may contain different items in different countries. Finally, the inclusion of both positively and negatively worded items in a PRO should be avoided as it may introduce bias. Objectives The Centre for Epidemiologic Studies Depression Scale (CES-D)[1] has been translated into over 40 languages and is frequently used in clinical trials. It comprises 20 (16 negative, 4 positive) statements relating to depression and has frequency based four-point response options. The total score is the sum of item scores (reversed for positive items) and ranges 0-60. The study aim was to examine whether CES-D data (original and the Rasch-derived, 10-item short-form [2]) fit the Rasch model (one-parameter logistic item response theory) in several countries and whether data collected from these countries could validly be pooled. Methodology Previously collected CES-D data were available from depressed individuals in the UK (n= 177), US (n=100), Germany (n=78), and France (n=124). Data were subjected to Rasch analysis [3] using RUMM [4]. Analyses included: Test of fit to the Rasch model via Chi 2 statistics (overall scale and item fit). Significant Chi 2 (p<0.001) indicates significant deviation from model expectations and lack of unidimension-ality (indicating items should not be summed). Evaluation of response category threshold order and residuals. Assessment of differential item functioning (DIF) [5] between countries. DIF indicates a difference in the response pattern between groups (countries) and it is not valid to combine data from these groups. Tests of DIF were made using ANOVA models. P values <0.001 were taken to indicate significant Chi 2 and ANOVA for DIF because of the number of tests conducted. P values < 0.01 and > 0.001 were taken to indicate borderline significance. Original CES-D Rasch analysis of the individual country data showed that the CES-D did not fit the model in the UK or Germany and exhibited borderline misfit in the US. Details are included in Table 1. …

PES16 SCALING PROPERTIES OF THE DERMATOLOGY LIFE QUALITY INDEX (DLQI)

PES14 RESPONSIVENESS OF SELF-REPORTED VISUAL FUNCTIONING IN AGE-RELATED MACULAR DEGENERATION (AMD) PATIENTS TO GENERAL HEALTH AND CHANGES IN VISUAL ACUITY IN A PHASE I/II RANDOMIZED CONTROLLED TRIAL OF LUCENTIS (RANIBIZUMAB; RHUFAB V2) Globe D,Tonnu IQ, Chang TS, Fine J University of Southern California, Los Angeles, CA, USA; Genentech, Inc, South San Francisco, CA, USA OBJECTIVES: Evaluate association of National Eye Institute Visual Functioning Questionnaire-25 (VFQ-25) score changes with systemic comorbidities and visual acuity (VA) changes in neovascular AMD patients in a phase I/II randomized controlled trial of Lucentis (ranibizumab; rhuFab V2). METHODS: At baseline and three months, 57 patients completed the VFQ-25 (self-reported visual function) and VA was measured. The presence of seven comorbidities was recorded at baseline. VA score (number of lines read) was converted to a weighted log of the minimum angle of resolution (0.25 worse eye logMAR + 0.75 better eye logMAR). To estimate the relative association of changes in VA and comorbidities with changes in VFQ-25 scores, separate regression models of three-month changes in each subscale score on the logMAR scores were developed for each comorbidity. RESULTS: Mean number of comorbidities was 3, including: 25 (44%) hypertension, 24 (42%) arthritis, 14 (25%) hearing loss, 12 (21%) diabetes, 12 (21%) psychiatric disease, 12 (21%) back pain, 11 (19%) cancer. Due to small sample size, only VA estimates in the regression were significant after controlling, individually, for the comorbidities. For all models, a one-line (0.1 logMAR) worsening in VA was significantly associated with decreased subscale scores, particularly those related to central vision (Near Activities, Distance Activities). VA alone explained 11% of the variation in the VFQ-25 change between baseline and 3 months in the Near Activities subscale. Inclusion of an individual comorbidity improved the explanatory power of the models slightly (r): to 12% for hypertension, hearing loss, diabetes, psychiatric disease, cancer, and back pain, 13% for arthritis subjects, and 14% when summing all comorbidites a patient had. CONCLUSIONS: Some selected VFQ-25 subscale scores were decreased with the presence of visual impairment and comorbidities. Systemic diseases should be included in VFQ25 assessments to control for differences between patients and samples.

PCV52 VALIDATION OF THE CAMBRIDGE PULMONARY HYPERTENSION OUTCOME REVIEW (CAMPHOR) QUESTIONNAIRE

PCV49 CHRONIC VENOUS DISEASE AND DEPRESSIVE SYMPTOMATOLOGY Guex JJ, Myon E, Marionneau N,Taieb C Societe Francaise de Phlebologie, Nice, France; Health Economics & Quality of Life Dept, Boulogne-Billancourt, France OBJECTIVES: The objective of our study was to assess depressive symptomatology (DS) among CVD affected women. METHODS: Symptomatic women patients suffering from CVD (CEAP C0 to C4), aged over 18, newly treated by their GP with a phlebotropic drug were enrolled in the study. Every patient completed a self-questionnaire including the CES-D scale at day 0, day three and seven. A score over 17 indicates a possible DS, a score over 23 indicates a probable DS. RESULTS: This analysis includes the first 371 patients assessed at day 0, D3 and D7. The mean age was 45.0 years old (SD = 11, n = 370). The mean CES-D scores at day 0, D3 and D7, were respectively 14.9 (SD = 10.2), 13.7 (SD = 8.9) and 12.8 (SD = 10.1). The results highlight a possible DS in our population (score over 17) for 36.3%, 32.3% and 29.0% respectively at day 0, D3 and D7 (p < 0.01, n = 328). Patients that have expressed a probable DS were 74 at inclusion (22.0% of the population); they show a significant improvement of their status assessed by CES-D. From those 74 patients, only 50 still had a score over 23 at D3 and 46 at D7 showing a decrease of 37.8% of the number of patients expressing a probable DS (p < 0.0001, n = 74, matched test J0-J7). CONCLUSIONS: In the study of Rield assessing depressive symptoms in older women (age 65 to 75), 23.1% of women reported high depressive symptoms (CES-D score over 16). CVD result in psychological effects that seriously affect patients’ lives. Following patient management and the use of a phlebotropic drug the prevalence of DS decreased rapidly showing evidence of the relevance of this management.

PMC19 IMPROVING THE SCALING PROPERTIES OF THE PSYCHOLOGICAL GENERAL WELL-BEING SCALE (PGWB)

potential values. RESULTS: Frequency distribution of the EQ5Dindex was tri-modal and difficult to describe in summary statistics. In all, 27 possible values (11%) were responsible for 92% of all observations, 14 possible values had no observations, and 24.7% of returns had an EQ5Dindex of 1.0. There are a number of categories that are rarely used e.g., severe mobility problems and severe self care problems. There was a close correlation between weighted scale and simple addition of responses (R = 0.87). There were 6.8% of responses with an EQ-5Dindex £0.0. There was a low correlation between the EQ5Dindex with the general health question of the SF36 and the arbitrary, continuous valuation of health status above. The ranking of mean estimates was intuitively correct. CONCLUSIONS: The number of theoretical values that are represented was sparse. The EQ5Dindex distribution results in no easily describable parametric distribution, and the correlation with other general health measures was low. Given that these subjects are hospital treated, too many may have a health status of 1.0, and too many are also in a health status notionally equal to or worse than death. Decisions based on the EQ5Dindex now have enormous health and commercial implications. The EQ5D classifies the right health factors but the sensitivity and scoring methods need urgent revaluation: good but needs improving.

PSN23 FACTORS INFLUENCING QUALITY OF LIFE IN ATOPIC DERMATITIS

References: McKenna SP, Whalley D, Dewar AL, Erdman RA, Kohlmann T, Niero M, Baro E, Cook SA, Crickx B, Frech F, van Assche D. International development of the Parents Index of Quality of Life in Atopic Dermatitis (PIQoL-AD). Qual Life Res. 2005 Feb;14(1):231-41. Whalley D, McKenna SP, Dewar AL, Erdman RA, Kohlmann T, Niero M, Cook SA, Crickx B, Herdman MJ, Frech F, Van Assche D. A new instrument for assessing quality of life in atopic dermatitis:international development of the Quality of Life Index for Atopic Dermatitis (QoLIAD). Br J Dermatol. 2004 Feb;150(2):274-83. Objectives

PES18 INTERPRETATION OF SCORES ON THE PSORIASIS INDEX OF QOL (PSORIQOL)

PES17 LIVING WITH A DERMATOSIS: A NATIONAL SURVEY OF QUALITY OF LIFE IN BELGIUM Lambert J, De la Brassinne M, Myon E, Martin N, Monnier F, Weckx H,Taieb C Royal Belgium Society of Dermatology, Brussels, Belgium; Health Economics & Quality of Life Dept, Boulogne-Billancourt, France; IRPF, Boulogne-Billancourt, France; AVENE Dermatological Laboratories, Brussels, Belgium OBJECTIVES: To assess the consequences of dermatological diseases on the quality of life of the patients. METHODS: Every Belgian Dermatologist received a sample of 30 questionnaires including the DLQI and the SF-12 that they distributed during the “National Week of Dermatology” to the first 30 patients coming to the consulting room. The SF-12 is a generic measure of health status, composed of two dimensions, a Physical one (PCS-12) and a Mental one (MCS-12). The lower the score, the more the quality of life is affected. The DLQI is a questionnaire designed to measure and compare disability in different skin conditions. The higher the score, the more the quality of life is affected. RESULTS: The male/female ratio was 37%/63% and the mean age was 46.76 years. Concerning the patients ‘state of health, MCS-12 and PCS-12 were respectively 43.8 (SD = 11.3) and 48.1 (SD = 9.4); with a significant difference in the mental dimension between Flemish (46.4, SD = 10.6) and Walloons (40.7, SD = 11.3) (p = 0.0001). The quality of life score, assessed by the DLQI, shows a quality of life’s impairment with a score of 6.1 (SD = 5.9). CONCLUSIONS: Our population reflect a QoL impairment comparable to the ranges obtained when initially validating the DLQI; i.e. for patients suffering psoriasis the DLQI mean score was 8.9, it was 4.3 for patients suffering from acne, and 6.7 for patients with viral warts. Concerning patients’ health status we observe for every patient, whatever his skin disease was, an important impairment in the mental dimension of the SF-12 compared to a standard population and a slight one for the physical dimension (except for patients with acne who are younger, mean age = 28 years old).