Interpreting scores on multiple sclerosis-specific patient reported outcome measures (the PRIMUS and U-FIS)

BACKGROUND: The PRIMUS is a Multiple Sclerosis (MS)-specific suite of outcome measures including assessments of QoL (PRIMUS QoL, scored 0-22) and activity limitations (PRIMUS Activities, scored 0-30). The U-FIS is a measure of fatigue impact (scored 0-66). These measures have been fully validated previously using an MS sample with mixed diagnoses. The aim of the present study was to validate the measures further in a specifically Relapse Remitting MS (RRMS) sample and to provide preliminary evidence of the responder definitions (RD; also known as minimal important difference) for these instruments. METHODS: Data were derived from a multi-country efficacy trial of MS patients with assessments at baseline and 12 months. Baseline data were used to assess the internal reliability and validity of the measures. Both anchor-based and distribution-based approaches were employed for estimating RD. Anchor-based estimates were based on published RD values for the EQ-5D and were assessed for those improving and deteriorating separately. Distribution-based estimates were based on standard error of measurement (SEM), change score equivalent to 0.30, and change score equivalent to 0.50, effect sizes (ES). RESULTS: The sample included 911 RRMS patients (67.3% female, age mean (SD) 36.2 (8.4) years, duration of MS mean (SD) 4.8 (5.2) years). Results showed that the PRIMUS and U-FIS had good internal consistency. Appropriate correlations were observed with comparator instruments and both measures were able to distinguish between participants based on Expanded Disability Status Scale scores and time since diagnosis. The anchor-based and distribution-based RD estimates were: PRIMUS Activities range = 1.2-2.3, PRIMUS QoL range = 1.0-2.2, and U-FIS range = 2.4-7.0. CONCLUSIONS: The results show that the PRIMUS and U-FIS are valid instruments for use with RRMS patients. The analyses provide preliminary information on how to interpret scores on the scales. These data will be useful for assessing treatment efficacy and for powering clinical studies. TRIAL REFERENCE NUMBER: ClinicalTrials.gov Identifier NCT00340834

Measuring the psychosocial consequences of screening

The last three decades have seen a dramatic rise in the implementation of screening programmes for cancer in industrialised countries. However, in contrast to screening for infectious diseases, most cancer screening programmes only have the potential to reduce mortality; they cannot lower the incidence of cancer in a population. In fact, most cancer screening programmes have been shown to increase the incidence of the disease as a consequence of over-diagnosis. A further dilemma of cancer screening programmes is that they do not distinguish between healthy people and those with disease. Rather, they identify a continuum of disease severity. Consequently, many healthy people who have abnormal screening tests are wrongly diagnosed. Indeed, studies have demonstrated that for each screening-prevented death from cancer, at least 200 false-positive results are given. Therefore, screening has the potential to be harmful as well as beneficial. The psychosocial consequences of false-positive screening results cannot be determined by diagnostic tests or by other technical means. Instead, patient reported outcome measures must be employed. To measure the outcomes of screening accurately and comprehensively patient reported outcome measures have to capture; the nature and extent of the psychosocial consequences and how these change over time. The outcome measures used must have high content validity and their psychometric properties should be determined prior to their use in the specific population. In particular it is important to establish unidimensionality, additivity and item ordering through the application of Item Response Theory

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

<p>Abstract</p> <p>Background</p> <p>Pulmonary 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.</p> <p>Methods</p> <p>Items 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.</p> <p>Results</p> <p>The 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.</p> <p>Conclusion</p> <p>The 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.</p

Development and psychometric assessment of the COPD and Asthma Sleep Impact Scale (CASIS)

<p>Abstract</p> <p>Background</p> <p>Patients with respiratory disease experience disturbed sleep, but there is no widely accepted measure of sleep impairment due to respiratory disease. We developed and evaluated the psychometric performance of a patient-reported measure to assess the impact on sleep due to respiratory disease, the COPD and Asthma Sleep Impact Scale (CASIS).</p> <p>Methods</p> <p>Identification of the items forming the CASIS was guided by patient interviews and focus groups. An observational study involving patients from the US and UK was then conducted to assess the psychometric characteristics of the measure.</p> <p>Results</p> <p>Qualitative data from 162 patients were used to develop the CASIS (n = 78 COPD; n = 84 asthma). The observational study included 311 patients with COPD and 324 patients with asthma. The final seven items used in the CASIS were identified based on factor and item response theory analyses. Internal consistency was 0.90 (COPD) and 0.92 (asthma), and test-retest reliability was 0.84 (both groups). In the COPD sample, CASIS scores were significantly correlated with the Saint George's Respiratory Questionnaire scores (all p < 0.0001) and differed significantly by patient-reported disease severity, exacerbation status, and overall health status (all p ≤ 0.005). In the asthma sample, CASIS scores were significantly correlated with the Asthma Quality of Life Questionnaire scores (all p < 0.0001) and differed significantly by clinician and patient-reported disease severity, exacerbation status, and overall health status (all p ≤ 0.0005).</p> <p>Conclusion</p> <p>The CASIS shows good internal consistency, test-retest reliability, and construct validity and may be useful in helping to understand the impact that COPD and asthma have on sleep outcomes.</p

Retraction: Psychometric characteristics of the ankylosing spondylitis quality of life questionnaire, short form 36 health survey, and functional assessment of chronic illness therapy-fatigue subscale

Retraction of Revicki DA, Rentz AM, Luo MP, Wong RL, Doward LC, McKenna SP: Psychometric characteristics of the ankylosing spondylitis quality of life questionnaire, short form 36 health survey, and functional assessment of chronic illness therapy-fatigue subscale. Health and Quality of Life Outcomes 2009, 7: 6