Psychometric evaluation of the Medication Satisfaction Questionnaire (MSQ) to assess satisfaction with antipsychotic medication among schizophrenia patients

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Abstract

The Medication Satisfaction Questionnaire (MSQ) is a single-item questionnaire which evaluates satisfaction with antipsychotic medication in schizophrenia patients. This study evaluated the reliability and validity for its use in research and clinical settings. Data pooled across treatment groups (control vs. Paliperidone ER) from a randomized 6-week study were used to conduct four psychometric assessments of the MSQ: (1) test–retest reliability, (2) convergent validity, (3) known-groups validity, and (4) minimally important difference (MID). This analysis included 191 randomized subjects. Test–retest reliability was evaluated for patients with no change in satisfaction from weeks 2 to 4 and weeks 4 to 6 (ICC = 0.80; 0.83, respectively). Convergent validity was demonstrated through large correlations with Treatment Satisfaction Questionnaire for Medication (TSQM) global score (r = 0.72–0.77), and through small correlations with variables measuring clinical symptoms and functioning (e.g., Positive and Negative Syndrome Scale (PANSS) total score [r =  0.30 to − 0.17], CGI-S [r =  0.35 to − 0.27], SF-36 Physical Functioning Score [r = 0.18] and side effects and extrapiramidal measures (including UKU, ESRS-A, SAS). Mean MSQ scores were significantly different between those who completed and discontinued the study, and between different satisfaction groups based on TSQM, demonstrating good known-groups validity. MID estimates for the MSQ ranged from 0.47 (standard error of measurement) to 0.58 (anchor-based method). Results suggest that the MSQ has acceptable reliability and validity, making this single-item questionnaire appropriate and easy to use in clinical research and potentially in clinical practice. A 1-point change on the MSQ may be considered clinically meaningful.

Introduction

Schizophrenia is a severe chronic mental illness. Substantial research has demonstrated that schizophrenia impairs patients' health-related quality of life (Addington & Addington, 2000, Bell & Bryson, 2001, Bryson & Bell, 2003, Bryson et al., 1998, Gaite et al., 2002, Green et al., 2000, Kasckow et al., 2001, McGurk et al., 2003, Palmer et al., 2002, Pinikahana et al., 2002, Sharma & Antonova, 2003). Meta-analyses have demonstrated that antipsychotic medications are efficacious in reducing acute positive symptoms of schizophrenia and maintenance therapy with antipsychotic medications reduces the risk of relapse of acute episodes (Dixon et al., 1995). However, antipsychotics may cause unpleasant side effects, and rates of noncompliance with treatment are relatively high in schizophrenia populations (Lieberman et al., 2005, Thieda et al., 2003).

Recent research suggests that satisfaction with treatment is associated with improved treatment compliance and improved psychotic symptoms (Canuso et al., 2009, Gharabawi et al., 2006). Furthermore, the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study demonstrated an association between positive attitudes toward medication among schizophrenia patients and lower rates of study discontinuation (Mohamed et al., 2009). Thus, it is important to accurately evaluate patient satisfaction with medication treatment using validated instruments that can be utilized in clinical trials and practice.

The Medication Satisfaction Questionnaire (MSQ) is a single-item, patient-rated instrument designed to assess treatment satisfaction among patients with schizophrenia (Kalali, 1999a, Kalali, 1999b). In clinical trials, the MSQ has been shown to distinguish active drug from placebo as well as differentiate two active comparators (Gharabawi et al., 2006, Potkin et al., 2006). However, the reliability and validity of the MSQ have not been previously demonstrated. The objective of this analysis was to evaluate the psychometric properties of the MSQ to demonstrate its value as a simple, reliable, and easy to use tool for evaluating treatment satisfaction in research and clinical settings.

Section snippets

Data source

Data used in this psychometric evaluation were obtained from a 6-week, prospective, randomized, international study1 conducted at 50 study centers from October 2007–July 2008 designed to evaluate medication satisfaction after at least 4 weeks of Paliperidone ER (6, 9 or 12 mg/day) treatment in outpatients with schizophrenia who were considered suboptimally responsive to their current treatment with oral risperidone

Study population

A total of 191 ITT patients were included in the analysis set. Baseline sociodemographic and clinical information about sample can be found in Table 1. Overall, 177 (92.7%) patients completed the clinical study.

Descriptive statistics

Descriptive statistics for MSQ at baseline and weeks 2, 4, and 6 are presented in Table 2a. As expected, given the entry criteria for the study, mean satisfaction levels were skewed toward the lower end of the dissatisfaction scale at baseline with constrained range (mean = 2.7, SD = 0.8,

Discussion

Research suggests that patient satisfaction with antipsychotic medication is positively associated with treatment compliance, thus, it is important to monitor patients' treatment satisfaction (Gharabawi et al., 2006, Mohamed et al., 2009). The purpose of this analysis was to evaluate the psychometric properties of the MSQ to validate the tool for use in clinical research settings, as well as to define a clinically meaningful difference on the MSQ.

The results of the psychometric assessment are

Conclusion

The MSQ, a simple-to-use, single-item questionnaire, is a reliable and valid instrument for evaluating satisfaction with antipsychotic treatments among patients with schizophrenia. Further, a 1.0-point change on the MSQ reflects a clinically meaningful difference in treatment satisfaction. The MSQ has been successfully employed in clinical trials, and should be considered for use in clinical practice as satisfaction with antipsychotic medication is positively associated with treatment

Role of funding source

Funding for this manuscript was provided by Ortho-McNeil Janssen Scientific Affairs, LLC.

Contributors

Margaret K. Vernon contributed to this manuscript by designing the analysis plan, overseeing the analyses, and by taking the lead role in writing and revising this manuscript.

Dennis A. Revicki contributed to this manuscript by providing guidance and oversight to the analysis plan and by reviewing and contributing to the writing of this manuscript.

George Awad, as a research consultant, contributed to this manuscript in the discussion of the design, interpretation of data, and review of the

Conflict of interest

Funding for this manuscript was provided by Ortho-McNeil Janssen Scientific Affairs, LLC. Margaret K. Vernon, Dennis A. Revicki, and Sally Mannix are salaried employees of United BioSource Corporation (UBC). UBC was provided payment by Ortho-McNeil Janssen for manuscript preparation services.

Riad Dirani, Jessica Panish, Carla M. Canuso, and Augusto Grinspan are full-time employees of Ortho-McNeil Janssen Scientific Affairs, LLC, and Johnson & Johnson stockholders.

Dr. Awad and Dr. Kalali provide

Acknowledgments

The authors thank Julie McCormack (UBC) and Ray Hsieh (UBC) for their assistance with planning and conducting analyses. The authors thank Fritz Hamme (UBC) for assistance with drafting and formatting this manuscript.

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    The MSQ is copyrighted by A. Kalali and is available free of charge from www.iscdd.org.

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