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Dabakuyo T.S.,Biostatistics and Epidemiology Unit | Dabakuyo T.S.,University of Sfax | Dabakuyo T.S.,Quality of Life and Cancer Clinical Research Platform | Guillemin F.,French Institute of Health and Medical Research | And 18 more authors.
Quality of Life Research | Year: 2013

Purpose: To characterize response shift effects in patients with breast cancer (BC). Methods: The QLQ-C30, BR23, and EurQOL-EQ-5D were assessed at baseline and at the end of the first hospitalization. We used the then-test approach to characterize changes in internal standards by calculating the mean difference between the then-test (retrospective measure) and pre-test baseline QoL assessments. The Ideal Scale Approach was also used to assess changes in standards by comparing health and QoL expectancies between baseline and the end of the first hospitalization. Successive Comparison Approach was used to assess changes in values through the longitudinal assessment of the relative importance of EuroQOL dimensions. Results: The results of this study showed that recalibration RS effects occurred early after the first hospitalization for 6/15 dimensions of QLQ-C30 (emotional, cognitive, fatigue, insomnia, appetite loss, diarrhea) and 2/8 of BR-23 (future perspective, systemic therapy side effects). Moreover, health and QoL expectancies changed between the baseline and the end of the first hospitalization, and changes in values were seen for the self-care and usual activities dimensions of the EuroQOL-EQ-5D. Conclusions: The occurrence of RS early after the first hospitalization suggests that it needs to be taken into account to interpret QoL changes in BC. © 2012 Springer Science+Business Media B.V. Source

Hamidou Z.,Biostatistics and Epidemiology Unit EA 4184 | Hamidou Z.,Quality of Life and Cancer Clinical Research Platform | Dabakuyo T.S.,Biostatistics and Epidemiology Unit EA 4184 | Dabakuyo T.S.,Quality of Life and Cancer Clinical Research Platform | And 2 more authors.
Expert Review of Pharmacoeconomics and Outcomes Research | Year: 2011

The assessment of longitudinal change in subjective patient-reported outcomes such as health-related quality of life (HRQoL) is a key component of many clinical and research evaluations. A major goal of measuring patient-reported HRQoL is to determine to what extent changes in HRQoL reports over time represent true changes in HRQoL due to treatment or cancer and to what extent they reflect measurement error. Indeed, the subjective assessment of HRQoL change is subject to response-shift effects, whereby health changes lead to shifts in internal standards (i.e., 'recalibration'), values (i.e., 'reprioritization') and conceptualization (i.e., 'reconceptualization') of key HRQoL domains. Response shift is a naturally occurring process that could distort the interpretation of change in HRQoL scores over time in interventional studies. Assessing response shift may therefore be needed to obtain a valid and sensitive assessment of change over time. Several methods to detect and measure the size and the direction of response shift are available. In this article, we summarize the methods used to assess and adjust for the response-shift effect in clinical trials. Nevertheless, our understanding of the parameters and processes associated with response shift is very limited. Further research is still needed to better understand how to measure the different components of response shift and how to take them into account in cancer research. © 2011 Expert Reviews Ltd. Source

Hamidou Z.,Quality of Life and Cancer Clinical Research Platform | Hamidou Z.,College de France | Dabakuyo-Yonli T.S.,Quality of Life and Cancer Clinical Research Platform | Dabakuyo-Yonli T.S.,Biostatistic and Quality of Life Unit | And 17 more authors.
PLoS ONE | Year: 2014

Background: This prospective multicenter study aimed to study the impact of the recalibration component of response-shift (RS) on time to deterioration (TTD) in health related quality of life (QoL) scores in breast cancer (BC) patients and the influence of baseline QoL expectations on TTD. Methods: The EORTC-QLQ-C30 and BR-23 questionnaires were used to assess the QoL in a prospective multicenter study at inclusion (T0), at the end of the first hospitalization (T1) and, three (T2) and 6 months after the first hospitalization (T3). Recalibration was investigated by the then-test method. QoL expectancy was assessed at diagnosis. Deterioration was defined as a 5-point decrease in QoL scores, considered a minimal clinically important difference (MCID). TTD was estimated using the Kaplan-Meier method. Cox regression analyses were used to identify factors influencing TTD. Results: From February 2006 to February 2008, 381 women were included. Recalibration of breast cancer patients' internal standards in the assessment of their QoL had an impact on TTD. Median TTD were significantly shorter when recalibration was not taken into account than when recalibration was taken into account for global health, role-functioning, socialfunctioning, body-image and side effects of systemic therapy. Cox multivariate analyses showed that for body image, when recalibration was taken into account, radiotherapy was associated with a shorter TTD (HR: 0.60[0.38-0.94], whereas, no significant impact of surgery type on TTD was observed. For global health, cognitive and social functioning dimensions, patients expecting a deterioration in their QoL at baseline had a significantly shorter TTD. Conclusions: Our results showed that RS and baseline QoL expectations were associated with time to deterioration in breast cancer patients. © 2014 Hamidou et al. Source

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