Academic journal article International Journal of Clinical and Health Psychology

Psychometric Properties of the Eight-Item Morisky Medication Adherence Scale (MMAS-8) in a Psychiatric Outpatient Setting

Academic journal article International Journal of Clinical and Health Psychology

Psychometric Properties of the Eight-Item Morisky Medication Adherence Scale (MMAS-8) in a Psychiatric Outpatient Setting

Article excerpt

Non-adherence to well-prescribed psychiatric medications compromises the effectiveness of available treatments and has been associated with poor treatment outcomes such as increased risk of relapse and recurrence as well as higher health-care costs (Geddes, Carney, & Davies, 2003; Velligan et al., 2009, 2010). At present, the extent to which patients follow psychiatric advice is a major concern and an important challenge to the practice of psychiatry. In fact, rates of non-adherence to medication in psychiatric patients range between 28 and 52% in patients with major depressive disorder, 20 and 50% in patients with bipolar disorder, and 20 and 72% in patients with schizophrenia (Julius, Novitsky, & Dubin, 2009).

Currently, there is no 'gold standard' measure of medication adherence, given that all the measures available have their limitations (Osterberg & Blaschke, 2005). Nonadherence can be measured directly or indirectly. Direct methods of assessing medication non-adherence detect the presence of the drug in a patient's body using assays for the drug, drug metabolites, or other markers in urine, blood, or other bodily fluids. However, such methods are rarely used because of their high cost and inability to provide feedback at the point of care (Voils, Hoyle, Thorpe, Maciejewski, & Yancy, 2011). Moreover, their results can be influenced by factors other than adherence such as drug or food interactions, physiological variability, dosing schedules, and the half-life of drugs (Roberts & Turner, 1988; Smith, Psaty, Heckbert, Tracy, & Cornell, 1999). Indirect methods measure medication non-adherence by analyzing behavior. They include electronic drug monitoring, pill counts, pharmacy refills, medical record review, directly observed therapy, clinician assessment, and self-reports. The poor availability and high cost of electronic monitoring of dosing schedules limit the feasibility of this method (Choo et al., 1999). As regards pill counts, prescriptions may be filled some time before needed and patients may not accurately recall the date medications were started; drugs may not be stored in their original containers and/or tablets from other bottles may be added to the new container (Shelly, Vik, & Maxwell, 2005). Although self-reports carry a potential risk of misstatements or response biases, they provide a reasonably accurate estimate of adherence (Osterberg & Blaschke, 2005). Self-reports have the following advantages: they are brief, inexpensive, and applicable in various settings. In addition, they can provide immediate feedback at the point of care and reveal underlying issues that contribute to nonadherence (Voils et al., 2011).

The eight-item Morisky Medication Adherence Scale (MMAS-8) (Morisky, Ang, Krousel-Wood, & Ward, 2008) is a structured self-report measure of medication-taking behavior. It was developed from a previously validated four-item scale (Morisky, Green, & Levine, 1986) and supplemented with additional items addressing the circumstances surrounding adherence behavior. This measure was designed to facilitate the recognition of barriers to and behaviors associated with adherence to chronic medications such as psychiatric drugs. The scale provides information on behaviors related to medication use that may be unintentional (e.g., forgetfulness) or intentional (e.g., not taking medications because of side effects). Besides its authors, other researchers (e.g., Gupta & Goren, 2013) have provided evidence of good psychometric properties of the scale. The MMAS-8 is currently available in 33 languages and is widely used in various types of studies (i.e., Al-Qazaz et al., 2010; Kim et al., 2014; Yan et al., 2014).

The purpose of this study was to explore the psychometric properties of the Spanish version of the eight-item Morisky Medication Adherence Scale (MMAS-8) in a psychiatric outpatient setting. We are aware of the debate about the appropriateness of certain diagnostic labels (Pemberton & Wainwright, 2014; Robles et al. …

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