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Kessels R, Moerbeek M, Bloemers J, van der Heijden PGM. A multilevel structural equation model for assessing a drug effect on a patient-reported outcome measure in on-demand medication data. Biom J 2021; 63:1652-1672. [PMID: 34270801 PMCID: PMC9292391 DOI: 10.1002/bimj.202100046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/07/2021] [Accepted: 06/19/2021] [Indexed: 11/08/2022]
Abstract
We analyze data from a clinical trial investigating the effect of an on-demand drug for women with low sexual desire. These data consist of a varying number of measurements/events across patients of when the drug was taken, including data on a patient-reported outcome consisting of five items measuring an unobserved construct (latent variable). Traditionally, these data are aggregated prior to analysis by composing one sum score per event and averaging this sum score over all observed events. In this paper, we explain the drawbacks of this aggregating approach. One drawback is that these averages have different standard errors because the variance of the underlying events differs between patients and because the number of events per patient differs. Another drawback is the implicit assumption that all items have equal weight in relation to the latent variable being measured. We propose a multilevel structural equation model, treating the events (level 1) as nested observations within patients (level 2), as alternative analysis method to overcome these drawbacks. The model we apply includes a factor model measuring a latent variable at the level of the event and at the level of the patient. Then, in the same model, the latent variables are regressed on covariates to assess the drug effect. We discuss the inferences obtained about the efficacy of the on-demand drug using our proposed model. We further illustrate how to test for measurement invariance across grouping covariates and levels using the same model.
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Affiliation(s)
- Rob Kessels
- Emotional Brain BV, Almere, The Netherlands.,Department of Biometrics, Netherlands Cancer Institute, Amsterdam, The Netherlands
| | - Mirjam Moerbeek
- Department of Methodology and Statistics, Utrecht University, Utrecht, The Netherlands
| | - Jos Bloemers
- Emotional Brain BV, Almere, The Netherlands.,Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus Institute of Neuroscience, Utrecht University, Utrecht, The Netherlands
| | - Peter G M van der Heijden
- Department of Methodology and Statistics, Utrecht University, Utrecht, The Netherlands.,Department of Social Statistics and Demography, University of Southampton, Southampton, United Kingdom
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Catan L, Boariu M, Amaricai E, Popa D, Puenea G, Drăgoi M, Stratul Ș, Drăgoi RG. Predicting functional disability in patients with spondyloarthritis using a CRP-based algorithm: A 3-year prospective study. Exp Ther Med 2020; 21:89. [PMID: 33363600 DOI: 10.3892/etm.2020.9521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 09/10/2020] [Indexed: 01/22/2023] Open
Abstract
This prospective study explored the link between values of C-reactive protein (CRP) in patients with SpA (ankylosing spondylitis, psoriatic arthritis, reactive arthritis, or arthritis-related inflammatory bowel disease) and functional disability in order to derive an algorithm that may predict functional disability based on disease activity. Patients diagnosed with Spa were classified into five groups based on the type of therapy and they were followed up for 3 years. Group 1: Symptomatic medication alone; Group 2: Disease-modifying antirheumatic drugs (DMARDs); Group 3: DMARDs and 30 rehabilitation sessions twice a year; Group 4: Group 3 therapy and biologic anti-tumor necrosis factor-alpha (anti-TNF-α) drugs; and Group 5: Group 4 therapy and, in addition, a daily home-adapted kinesiotherapy program. CRP, modified Health Assessment Questionnaire (mHAQ-S), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and T-score of the patients were recorded. Correlation and multivariate regression analyses were conducted using demographic data, CRP, and mHAQ-S scores to derive the CRP-mHAQ-S correlation algorithm. Statistical analysis included the chi-square, Mann-Whitney, and multiple regression tests and repeated measures analysis of variance. A total of 144 patients were enrolled, all of whom completed the study. The best predictive model (P<0.001) provided the algorithm mHAQ-S36=17.14+0.12xCRP0-0.24xCRP12-0.15xCRP36 (CRP0, CRP12, and CRP36 correspond to CRP levels at baseline, 12, and 36 months, respectively, and mHAQ-S36 to mHAQ-S score at 36 months). This derived algorithm based on objective CRP assessment may have implications in the prediction of functional disability evolution in patients with SpA.
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Affiliation(s)
- Liliana Catan
- Department of Balneology, Medical Rehabilitation and Rheumatology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Marius Boariu
- Department of Endodontics, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Elena Amaricai
- Department of Balneology, Medical Rehabilitation and Rheumatology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Daniel Popa
- Department of Balneology, Medical Rehabilitation and Rheumatology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania.,Rehabilitation and Rheumatology Department, City University and Emergency Hospital, 300020 Timisoara, Romania
| | - George Puenea
- Department of Balneology, Medical Rehabilitation and Rheumatology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Mihai Drăgoi
- Department of Balneology, Medical Rehabilitation and Rheumatology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania.,Rehabilitation and Rheumatology Department, City University and Emergency Hospital, 300020 Timisoara, Romania
| | - Ștefan Stratul
- Department of Periodontology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Răzvan Gabriel Drăgoi
- Department of Balneology, Medical Rehabilitation and Rheumatology, 'Victor Babes' University of Medicine and Pharmacy, 300041 Timisoara, Romania.,Rehabilitation and Rheumatology Department, City University and Emergency Hospital, 300020 Timisoara, Romania
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Chua KC, Böhnke JR, Prince M, Banerjee S. Health-related quality-of-life assessment in dementia: Evidence of cross-cultural validity in Latin America. Psychol Assess 2019; 31:1264-1277. [PMID: 31282701 PMCID: PMC6818683 DOI: 10.1037/pas0000743] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 04/24/2019] [Accepted: 05/16/2019] [Indexed: 11/17/2022]
Abstract
All health-related quality-of-life (HRQL) measures for dementia have been developed in high-income countries and none were validated for cross-cultural use. Yet, the global majority of people living with dementia reside in low- and middle-income countries. We therefore investigated the measurement invariance of a set of self- and informant-report HRQL measures developed in the United Kingdom when used in Latin America. Self-reported HRQL was obtained using (DEMQOL) at a memory assessment service in the United Kingdom (n = 868) and a population cohort study in Latin America (n = 417). Informant reports were collected using DEMQOL-Proxy at both sites (n = 909 and n = 495). Multiple-group confirmatory bifactor models for ordered categorical item responses were estimated to evaluate measurement invariance. Results support configural, metric, and scalar invariance for the concept of general HRQL in DEMQOL and DEMQOL-Proxy. The dominant impact of general HRQL on item responses was evident across U.K. English and Ibero American Spanish versions of DEMQOL (ωh = 0.87-0.90) and DEMQOL-Proxy (ωh = 0.88-0.89). Ratings of "positive emotion" did not show a major impact on general HRQL appraisal, particularly for Latin American respondents. Item information curves show that self- and informant-reports were highly informative about the presence rather than the absence of HRQL impairment. We found no major difference in conceptual meaning, sensitivity, and relevance of DEMQOL and DEMQOL-Proxy for older adults in the United Kingdom and Latin America. Further replication is needed for consensus over which HRQL measures are appropriate for making cross-national comparisons in global dementia research. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
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Affiliation(s)
- Kia-Chong Chua
- Centre for Implementation Science, Institute of Psychiatry, Psychology, and Neuroscience
| | - Jan R Böhnke
- School of Nursing and Health Sciences, University of Dundee
| | - Martin Prince
- King's Global Health Institute, Institute of Psychiatry, Psychology, and Neuroscience, King's College London
| | - Sube Banerjee
- Centre for Dementia Studies, Brighton and Sussex Medical School, University of Sussex
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Barbieri A, Tami M, Bry X, Azria D, Gourgou S, Bascoul-Mollevi C, Lavergne C. EM algorithm estimation of a structural equation model for the longitudinal study of the quality of life. Stat Med 2018; 37:1031-1046. [PMID: 29250835 DOI: 10.1002/sim.7557] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 08/17/2017] [Accepted: 10/17/2017] [Indexed: 11/12/2022]
Abstract
Health-related quality of life (HRQoL) data are measured via patient questionnaires, completed by the patients themselves at different time points. We focused on oncology data gathered through the use of European Organization for Research and Treatment of Cancer questionnaires, which decompose HRQoL into several functional dimensions, several symptomatic dimensions, and the global health status (GHS). We aimed to perform a global analysis of HRQoL and reduce the number of analyses required by using a two-step approach. First, a structural equation model (SEM) was used for each time point; in these models, the GHS is explained by two latent variables. Each latent variable is a factor that summarizes, respectively, the functional dimensions and the symptomatic dimensions to the global measurement. This is achieved through the maximization of the likelihood of each SEM using the EM algorithm, which has the advantage of giving an estimation of the subject-specific factors and the influence of additional explanatory variables. Then, to consider the longitudinal aspect, the GHS variable and the two factors were concatenated for each patient visit at which the questionnaire was completed. The GHS and the two factors estimated in the first step can then be explained by additional explanatory variables using a linear mixed model.
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Affiliation(s)
- Antoine Barbieri
- Biometrics Unit, Institut du Cancer Montpellier (ICM), Montpellier, France.,Université de Montpellier, Montpellier, France.,Institut Montpelliérain Alexander Grothendieck (IMAG), Montpellier, France.,Institute of Statistics, Biostatistics and Actuarial sciences, Université catholique de Louvain, Belgium
| | - Myriam Tami
- Université de Montpellier, Montpellier, France.,Institut Montpelliérain Alexander Grothendieck (IMAG), Montpellier, France
| | - Xavier Bry
- Université de Montpellier, Montpellier, France.,Institut Montpelliérain Alexander Grothendieck (IMAG), Montpellier, France
| | - David Azria
- Université de Montpellier, Montpellier, France.,Department of Radiation Oncology, Institut du Cancer Montpellier (ICM), Montpellier, France.,Institut de Recherche en Cancérologie de Montpellier (IRCM), Inserm U1194, Montpellier, France
| | - Sophie Gourgou
- Biometrics Unit, Institut du Cancer Montpellier (ICM), Montpellier, France.,French National Platform Quality of Life and Cancer, Montpellier, France
| | - Caroline Bascoul-Mollevi
- Biometrics Unit, Institut du Cancer Montpellier (ICM), Montpellier, France.,Institut de Recherche en Cancérologie de Montpellier (IRCM), Inserm U1194, Montpellier, France.,French National Platform Quality of Life and Cancer, Montpellier, France
| | - Christian Lavergne
- Institut Montpelliérain Alexander Grothendieck (IMAG), Montpellier, France.,Université Paul-Valéry Montpellier 3, Montpellier, France
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Chua KC, Brown A, Little R, Matthews D, Morton L, Loftus V, Watchurst C, Tait R, Romeo R, Banerjee S. Quality-of-life assessment in dementia: the use of DEMQOL and DEMQOL-Proxy total scores. Qual Life Res 2016; 25:3107-3118. [PMID: 27318488 PMCID: PMC5102947 DOI: 10.1007/s11136-016-1343-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2016] [Indexed: 11/30/2022]
Abstract
PURPOSE There is a need to determine whether health-related quality-of-life (HRQL) assessments in dementia capture what is important, to form a coherent basis for guiding research and clinical and policy decisions. This study investigated structural validity of HRQL assessments made using the DEMQOL system, with particular interest in studying domains that might be central to HRQL, and the external validity of these HRQL measurements. METHODS HRQL of people with dementia was evaluated by 868 self-reports (DEMQOL) and 909 proxy reports (DEMQOL-Proxy) at a community memory service. Exploratory and confirmatory factor analyses (EFA and CFA) were conducted using bifactor models to investigate domains that might be central to general HRQL. Reliability of the general and specific factors measured by the bifactor models was examined using omega (ω) and omega hierarchical (ω h) coefficients. Multiple-indicators multiple-causes models were used to explore the external validity of these HRQL measurements in terms of their associations with other clinical assessments. RESULTS Bifactor models showed adequate goodness of fit, supporting HRQL in dementia as a general construct that underlies a diverse range of health indicators. At the same time, additional factors were necessary to explain residual covariation of items within specific health domains identified from the literature. Based on these models, DEMQOL and DEMQOL-Proxy overall total scores showed excellent reliability (ω h > 0.8). After accounting for common variance due to a general factor, subscale scores were less reliable (ω h < 0.7) for informing on individual differences in specific HRQL domains. Depression was more strongly associated with general HRQL based on DEMQOL than on DEMQOL-Proxy (-0.55 vs -0.22). Cognitive impairment had no reliable association with general HRQL based on DEMQOL or DEMQOL-Proxy. CONCLUSIONS The tenability of a bifactor model of HRQL in dementia suggests that it is possible to retain theoretical focus on the assessment of a general phenomenon, while exploring variation in specific HRQL domains for insights on what may lie at the 'heart' of HRQL for people with dementia. These data suggest that DEMQOL and DEMQOL-Proxy total scores are likely to be accurate measures of individual differences in HRQL, but that subscale scores should not be used. No specific domain was solely responsible for general HRQL at dementia diagnosis. Better HRQL was moderately associated with less depressive symptoms, but this was less apparent based on informant reports. HRQL was not associated with severity of cognitive impairment.
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Affiliation(s)
- Kia-Chong Chua
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK.
| | - Anna Brown
- School of Psychology, University of Kent, Canterbury, UK
| | - Ryan Little
- Croydon Memory Service, South London and Maudsley NHS Foundation Trust, London, UK
| | - David Matthews
- Croydon Memory Service, South London and Maudsley NHS Foundation Trust, London, UK
| | - Liam Morton
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Vanessa Loftus
- Kingston Integrated Health and Social Care Community Mental Health Team for Older People, South West London and St George's NHS Trust, London, UK
| | - Caroline Watchurst
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Rhian Tait
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Renee Romeo
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK
| | - Sube Banerjee
- Brighton and Sussex Medical School, University of Sussex, Brighton, UK
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