Defining Quality of Life Levels to Enhance Clinical Interpretation in Multiple Sclerosis: Application of a Novel Clustering MethodJournal articlePierre Michel, Karine Baumstarck, Laurent Boyer, Oscar Fernandez, Peter Flachenecker, Jean Pelletier, Anderson Loundou, Badih Ghattas, Pascal Auquier and on behalf of Group, Medical Care, Volume 55, Issue 1, pp. e1, 2017

To enhance the use of quality of life (QoL) measures in clinical practice, it is pertinent to help clinicians interpret QoL scores.

The aim of this study was to define clusters of QoL levels from a specific questionnaire (MusiQoL) for multiple sclerosis (MS) patients using a new method of interpretable clustering based on unsupervised binary trees and to test the validity regarding clinical and functional outcomes.

In this international, multicenter, cross-sectional study, patients with MS were classified using a hierarchical top-down method of Clustering using Unsupervised Binary Trees. The clustering tree was built using the 9 dimension scores of the MusiQoL in 2 stages, growing and tree reduction (pruning and joining). A 3-group structure was considered, as follows: “high,” “moderate,” and “low” QoL levels. Clinical and QoL data were compared between the 3 clusters.

A total of 1361 patients were analyzed: 87 were classified with “low,” 1173 with “moderate,” and 101 with “high” QoL levels. The clustering showed satisfactory properties, including repeatability (using bootstrap) and discriminancy (using factor analysis). The 3 clusters consistently differentiated patients based on sociodemographic and clinical characteristics, and the QoL scores were assessed using a generic questionnaire, ensuring the clinical validity of the clustering.

The study suggests that Clustering using Unsupervised Binary Trees is an original, innovative, and relevant classification method to define clusters of QoL levels in MS patients.

Validation of the generic medical interview satisfaction scale: the G-MISS questionnaireJournal articleAxel Maurice-Szamburski, Pierre Michel, Anderson Loundou, Pascal Auquier, Health and Quality of Life Outcomes, Volume 15, Issue 1, pp. 36, 2017

Patients have about seven medical consultations a year. Despite the importance of medical interviews in the healthcare process, there is no generic instrument to assess patients’ experiences in general practices, medical specialties, and surgical specialties. The main objective was to validate a questionnaire assessing patients’ experiences with medical consultations in various practices.

Clustering nominal data using unsupervised binary decision trees: Comparisons with the state of the art methodsJournal articleBadih Ghattas, Pierre Michel and Laurent Boyer, Pattern Recognition, Volume 67, pp. 177-185, 2017

In this work, we propose an extension of CUBT (clustering using unsupervised binary trees) to nominal data. For this purpose, we primarily use heterogeneity criteria and dissimilarity measures based on mutual information, entropy and Hamming distance. We show that for this type of data, CUBT outperforms most of the existing methods. We also provide and justify some guidelines and heuristics to tune the parameters in CUBT. Extensive comparisons are done with other well known approaches using simulations, and two examples of real datasets applications are given.

The development of the SGI-16: a shortened sensory gating deficit and distractibility questionnaire for adults with ADHDJournal articleJean-Arthur Micoulaud-Franchi, Régis Lopez, Pierre Michel, Laura Brandejsky, Stéphanie Bioulac, Pierre Philip, Christophe Lançon and Laurent Boyer, Attention Deficit and Hyperactivity Disorders, Volume 9, Issue 3, pp. 179-187, 2017

The Sensory Gating Inventory (SGI) is a questionnaire composed of 36 items designed to investigate abnormal perception related to the inability to control sensitivity to sensory stimuli frequently reported in adult with ADHD. This questionnaire can be considered too lengthy to be taken by people with ADHD, and a shortened version is needed. One hundred and sixty-three adults with ADHD responded to the SGI-36. An item reduction process took into account both the results of statistical analyses and the expertise of a steering committee. Construct validity, reliability, and external validity were tested for a short version (16 items). The structure of the SGI-16 was confirmed by principal components factor analysis. Cronbach's alpha coefficients ranged from 0.78 to 0.89. The SGI-16 dimension scores were highly correlated with their respective SGI-36 dimension scores. The SGI-16 seems to be both appropriate and useful for use in clinical practice to investigate perceptual abnormalities in adults with ADHD.

A Multidimensional Computerized Adaptive Short-Form Quality of Life Questionnaire Developed and Validated for Multiple Sclerosis: The MusiQoL-MCATJournal articlePierre Michel, Karine Baumstarck, Badih Ghattas, Jean Pelletier, Anderson Loundou, Mohamed Boucekine, Pascal Auquier and Laurent Boyer, Medicine, Volume 95, Issue 14, pp. e3068, 2016

The aim was to develop a multidimensional computerized adaptive short-form questionnaire, the MusiQoL-MCAT, from a fixed-length QoL questionnaire for multiple sclerosis.A total of 1992 patients were enrolled in this international cross-sectional study. The development of the MusiQoL-MCAT was based on the assessment of between-items MIRT model fit followed by real-data simulations. The MCAT algorithm was based on Bayesian maximum a posteriori estimation of latent traits and Kullback-Leibler information item selection. We examined several simulations based on a fixed number of items. Accuracy was assessed using correlations (r) between initial IRT scores and MCAT scores. Precision was assessed using the standard error measurement (SEM) and the root mean square error (RMSE).The multidimensional graded response model was used to estimate item parameters and IRT scores. Among the MCAT simulations, the 16-item version of the MusiQoL-MCAT was selected because the accuracy and precision became stable with 16 items with satisfactory levels (r ≥ 0.9, SEM ≤ 0.55, and RMSE ≤ 0.3). External validity of the MusiQoL-MCAT was satisfactory.The MusiQoL-MCAT presents satisfactory properties and can individually tailor QoL assessment to each patient, making it less burdensome to patients and better adapted for use in clinical practice.

[Psychiatric comorbidities and quality of life in adult individuals with high potential: Relationships with self-esteem]Journal articleChristophe Lançon, Marion Martinelli, Pierre Michel, Matthias Debals, Pascal Auquier, Eric Guedj and Laurent Boyer, Presse Medicale (Paris, France: 1983), Volume 44, Issue 5, pp. e177-184, 2015

OBJECTIVE: The objectives of this study were: 1) to describe the psychiatric comorbidities in adult individuals with high potential; 2) to assess self-esteem and quality of life in comparison with general population; 3) to study the relationships between intelligent quotient (IQ), self-esteem, psychiatric comorbidities and quality of life.
METHODS: This cross-sectional study was conducted in the psychiatric department of a public university hospital (Marseille, France). An outpatient hospital service has been specifically opened to test intelligence since 2012. During a period of six months, it was proposed to all the major individuals with high intellectual potential to receive a psychiatric evaluation using the Mini International Neuropsychiatric Interview (MINI) and to complete self-report questionnaires assessing depression (Beck scale), anxiety (STAI), self-esteem (Rosenberg scale) and quality of life (SF-36). Relationships between IQ, self-esteem, psychiatric comorbidities and quality of life were analyzed using a Bayesian path analysis.
RESULTS: Twenty-eight subjects were included, 8 had an IQ between 115 and 130, and 20 had an IQ>130. Fifty-seven percent of individuals had generalized anxiety, 21.4% a current major depressive episode, and 75% a past major depressive episode. Subjects had a low self-esteem and quality of life levels significantly lower than those in the French general population. Subjects with higher self-esteem levels had more depressive (β=0.726, P<0.001) and anxiety (β=0.335, P<0.001) disorders, associated with lower quality of life levels (β=-0.447, P<0.001 and β=-0.276, P=0.012), suggesting that self-esteem was defensive and inadequate.
CONCLUSION: Our study found a high frequency of psychiatric disorders associated with low levels of self-esteem and quality of life. A psychological treatment focusing on self-esteem may have a beneficial effect on anxiety, depression and quality of life.

Development of a cross-cultural item bank for measuring quality of life related to mental health in multiple sclerosis patientsJournal articlePierre Michel, Pascal Auquier, Karine Baumstarck, Jean Pelletier, Anderson Loundou, Badih Ghattas and Laurent Boyer, Quality of Life Research: An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation, Volume 24, Issue 9, pp. 2261-2271, 2015

OBJECTIVE: Quality of life (QoL) measurements are considered important outcome measures both for research on multiple sclerosis (MS) and in clinical practice. Computerized adaptive testing (CAT) can improve the precision of measurements made using QoL instruments while reducing the burden of testing on patients. Moreover, a cross-cultural approach is also necessary to guarantee the wide applicability of CAT. The aim of this preliminary study was to develop a calibrated item bank that is available in multiple languages and measures QoL related to mental health by combining one generic (SF-36) and one disease-specific questionnaire (MusiQoL).
METHODS: Patients with MS were enrolled in this international, multicenter, cross-sectional study. The psychometric properties of the item bank were based on classical test and item response theories and approaches, including the evaluation of unidimensionality, item response theory model fitting, and analyses of differential item functioning (DIF). Convergent and discriminant validities of the item bank were examined according to socio-demographic, clinical, and QoL features.
RESULTS: A total of 1992 patients with MS and from 15 countries were enrolled in this study to calibrate the 22-item bank developed in this study. The strict monotonicity of the Cronbach's alpha curve, the high eigenvalue ratio estimator (5.50), and the adequate CFA model fit (RMSEA = 0.07 and CFI = 0.95) indicated that a strong assumption of unidimensionality was warranted. The infit mean square statistic ranged from 0.76 to 1.27, indicating a satisfactory item fit. DIF analyses revealed no item biases across geographical areas, confirming the cross-cultural equivalence of the item bank. External validity testing revealed that the item bank scores correlated significantly with QoL scores but also showed discriminant validity for socio-demographic and clinical characteristics.
CONCLUSION: This work demonstrated satisfactory psychometric characteristics for a QoL item bank for MS in multiple languages. This work may offer a common measure for the assessment of QoL in different cultural contexts and for international studies conducted on MS.

Adherence to medication is associated with non-planning impulsivity in euthymic bipolar disorder patientsJournal articleRaoul Belzeaux, Laurent Boyer, Pascale Mazzola-Pomietto, Pierre Michel, Nadia Correard, Valerie Aubin, Frank Bellivier, Thierry Bougerol, Emilie Olie, Philippe Courtet, et al., Journal of Affective Disorders, Volume 184, pp. 60-66, 2015

Adherence to medication is a major issue in bipolar disorder. Non-planning impulsivity, defined as a lack of future orientation, has been demonstrated to be the main impulsivity domain altered during euthymia in bipolar disorder patients. It was associated with comorbidities.

To investigate relationship between adherence to medication and non-planning impulsivity, we included 260 euthymic bipolar patients. Adherence to medication was evaluated by Medication Adherence Rating Scale and non-planning impulsivity by Barrat Impulsiveness Scale. Univariate analyses and linear regression were used. We conducted also a path analysis to examine whether non-planning impulsivity had direct or indirect effect on adherence, mediated by comorbidities.

Adherence to medication was correlated with non-planning impulsivity, even after controlling for potential confounding factors in linear regression analysis (Beta standardized coefficient = 0.156; p = 0.015). Path analysis demonstrated only a direct effect of non-planning impulsivity on adherence to medication, and none indirect effect via substance use disorders and anxiety disorders.
LIMITATIONS: Our study is limited by its cross-sectional design and adherence to medication was assessed only by self-questionnaire.

Higher non-planning impulsivity is associated with low medication adherence, without an indirect effect via comorbidities.

How to interpret multidimensional quality of life questionnaires for patients with schizophrenia?Journal articlePierre Michel, Pascal Auquier, Karine Baumstarck, Anderson Loundou, Badih Ghattas, Christophe Lançon and Laurent Boyer, Quality of Life Research: An International Journal of Quality of Life Aspects of Treatment, Care and Rehabilitation, Volume 24, Issue 10, pp. 2483-2492, 2015

PurposeThe classification of patients into distinct categories of quality of life (QoL) levels may be useful for clinicians to interpret QoL scores from multidimensional questionnaires. The aim of this study had been to define clusters of QoL levels from a specific multidimensional questionnaire (SQoL18) for patients with schizophrenia by using a new method of interpretable clustering and to test its validity regarding socio-demographic, clinical, and QoL information.MethodsIn this multicentre cross-sectional study, patients with schizophrenia have been classified using a hierarchical top-down method called clustering using unsupervised binary trees (CUBT). A three-group structure has been employed to define QoL levels as “high”, “moderate”, or “low”. Socio-demographic, clinical, and QoL data have been compared between the three clusters to ensure their clinical relevance.ResultsA total of 514 patients have been analysed: 78 are classified as “low”, 265 as “moderate”, and 171 as “high”. The clustering shows satisfactory statistical properties, including reproducibility (using bootstrap analysis) and discriminancy (using factor analysis). The three clusters consistently differentiate patients. As expected, individuals in the “high” QoL level cluster report the lowest scores on the Positive and Negative Syndrome Scale (p = 0.01) and the Calgary Depression Scale (p < 0.01), and the highest scores on the Global Assessment of Functioning (p < 0.03), the SF36 (p < 0.01), the EuroQol (p < 0.01), and the Quality of Life Inventory (p < 0.01).ConclusionGiven the ease with which this method can be applied, classification using CUBT may be useful for facilitating the interpretation of QoL scores in clinical practice.

Statistical challenges of quality of life and cancer: new avenues for future researchJournal articleLaurent Boyer, Karine Baumstarck, Pierre Michel, Mohamed Boucekine, Amelie Anota, Franck Bonnetain, Joel Coste, Bruno Falissard, Alice Guilleux, Jean-Benoit Hardouin, et al., Expert Review of Pharmacoeconomics & Outcomes Research, Volume 14, Issue 1, pp. 19-22, 2014

Statistical modeling conference on the quality of life measurements of the French National Platform of Quality of Life and Cancer Faculty of Science in Luminy, Marseille, France, 12-13 September 2013 The French National Platform of Quality of Life and Cancer and the statistical team of the Mathematical Institute of Luminy undertook a successful first conference addressing the statistical challenges of measuring the quality of life in the field of oncology. More than 15 presentations were made over a 2-day period by the Faculty of Sciences in Luminy. The conference managed to assemble participants from different disciplines, such as mathematics and statistics, public health, epidemiology and psychology, to debate the key statistical and methodological issues of quality of life measurement and analysis. Three main topics were covered in this conference: the treatment of missing data, the development of item banking and computerised adaptive testing and the detection/understanding of response shift.