Trends in Psychiatry and Psychotherapy
Trends in Psychiatry and Psychotherapy
Original Article

Reliability and validity of the Medication Adherence Rating Scale in a cohort of patients with schizophrenia from Nigeria

Confiabilidade e validade da Medication Adherence Rating Scale em uma coorte de pacientes com esquizofrenia na Nigéria

Godspower O. Owie; Sunday O. Olotu; Bawo O. James

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Abstract Introduction Assessing adherence in schizophrenia facilitates interventions that optimize outcomes. Adherence rating questionnaires are feasible and non-intrusive; however, no validated measure exists in sub-Saharan Africa. We aimed to assess the psychometric properties of the 10-item Medication Adherence Rating Scale (MARS). Methods This was a cross-sectional study of a cohort of patients with schizophrenia (n=230). A sociodemographic questionnaire, the Mini International Neuropsychiatric Interview (MINI), Positive and Negative Syndrome Scale (PANSS), Scale for the Unawareness of Mental Disorder (SUMD) and the MARS were all administered by an interviewer. Results The MARS demonstrated good reliability (Cronbach’s alpha: 0.76). The scale was reducible to a 3-factor construct (1 – medication adherence behavior, 2 – attitude to taking medications, and 3 – negative side effects and attitude to psychotropics), with significant though weak external validity in relation to psychopathology (p<0.001) and insight (p<0.001). The first factor showed good internal consistency (α=0.80), comprising six items that could serve as a reliable proxy measure of adherence in place of the MARS Conclusion The MARS demonstrated fair psychometric characteristics in assessing adherence in patients with schizophrenia in this cohort. The scale may be useful in the dimensional assessment of medication adherence for schizophrenia in sub-Saharan African settings.


Medication adherence, schizophrenia, rating scale, reliability, validity


Resumo Introdução Avaliar adesão ao tratamento na esquizofrenia facilita intervenções que otimizam desfechos. Questionários de avaliação da adesão são factíveis e não intrusivos; no entanto, não há uma medida validada na África subsaariana. O objetivo deste estudo foi avaliar as propriedades psicométricas da escala de 10 itens intitulada Medication Adherence Rating Scale (MARS). Métodos Este foi um estudo transversal de uma coorte de pacientes com esquizofrenia (n=230). Um questionário sociodemográfico e os instrumentos Mini International Neuropsychiatric Interview (MINI), Positive and Negative Syndrome Scale (PANSS), Scale for the Unawareness of Mental Disorder (SUMD) e a MARS foram todos administrados por um entrevistador. Resultados A MARS demonstrou boa confiabilidade (alfa de Cronbach: 0,76). Foi possível reduzir a escala a um construto de 3 fatores (1 – comportamento de adesão à medicação, 2 – atitude em relação a tomar medicação, e 3 – efeitos colaterais negativos e atitude em relação aos psicotrópicos), com validade externa significativa, embora fraca, em relação à psicopatologia (p<0,001) e ao insight (p<0,001). O primeiro fator mostrou boa consistência interna (α=0,80), incluindo seis itens que poderiam servir como uma medida substituta confiável de adesão no lugar da MARS Conclusão A MARS demonstrou características psicométricas satisfatórias ao avaliar adesão em pacientes com esquizofrenia nesta coorte. A escala pode ser útil na avaliação dimensional da adesão ao tratamento para esquizofrenia em contextos africanos subsaarianos.


Adesão à medicação, esquizofrenia, escala, confiabilidade, validade


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