Monday, September 22, 2008

Abstracts from Medline

Today I found several abstracts related to medication non-adherence, specifically these four that deal with measurement. All are from the HighWire Press out of Stanford.


ONE: Testing the psychometric properties of the Medication Adherence Scale in patients with heart failure

Many factors may contribute to medication nonadherence in heart failure (HF), but no standard measure exists to evaluate factors associated with nonadherence. To fill this gap, we developed the Medication Adherence Scale (MAS) and tested its reliability and validity in patients with HF.

Questionnaire data were collected from 100 patients with HF at baseline using the MAS, and objective adherence data were collected for 3 consecutive months using the Medication Event Monitoring System.

Principal component analysis yielded three factors that explained 63% of the variance in medication adherence: knowledge, attitudes, and barriers to medication adherence. Cronbach's alphas for these subscales ranged from .75 to .94, which supported their internal consistency. The Spearman rho correlation coefficients between the Medication Event Monitoring System and Knowledge, Attitudes, and Barriers scores were .25 to .31 (P < .05), demonstrating support for construct validity.

These results support the reliability and validity of the MAS as a measure of knowledge, attitudes, and barriers of medication adherence.

TWO: Revision and validation of the medication adherence self-efficacy scale (MASES) in hypertensive African Americans

Study purpose was to revise and examine the validity of the Medication Adherence Self-Efficacy Scale (MASES) in an independent sample of 168 hypertensive African Americans: mean age 54 years (SD = 12.36); 86% female; 76% high school education or greater. Participants provided demographic information; completed the MASES, self-report and electronic measures of medication adherence at baseline and three months.

Confirmatory (CFA), exploratory (EFA) factor analyses, and classical test theory (CTT) analyses suggested that MASES is unidimensional and internally reliable. Item response theory (IRT) analyses led to a revised 13-item version of the scale: MASES-R. EFA, CTT, and IRT results provide a foundation of support for MASES-R reliability and validity for African Americans with hypertension. Research examining MASES-R psychometric properties in other ethnic groups will improve generalizability of findings and utility of the scale across groups. The MASES-R is brief, quick to administer, and can capture useful data on adherence self-efficacy.

THREE: Methods of assessing adherence to inhaled corticosteroid therapy in children and adolescents: adherence rates and their implications for clinical practice

Nonadherence to inhaled corticosteroid therapy is common and has a negative effect on clinical control, as well as increasing morbidity rates, mortality rates and health care costs. This review was conducted using direct searches, together with the following sources: Medline; HighWire; and the Latin American and Caribbean Health Sciences Literature database. Searches included articles published between 1992 and 2008. The following methods of assessing adherence, listed in ascending order by degree of objectivity, were identified: patient or family reports; clinical judgment; weighing/dispensing of medication, electronic medication monitoring; and (rarely) biochemical analysis.

Adherence rates ranged from 30 to 70%. It is recognized that the degree of adherence determined by patient/family reports or by clinical judgment is exaggerated in comparison with that obtained using electronic medication monitors. Physicians should bear in mind that true adherence rates are lower than those reported by patients, and this should be considered in cases of poor clinical control. Weighing the spray quantifies the medication and infers adherence. However, there can be deliberate emptying of inhalers and medication sharing. Pharmacies provide the dates on which the medication was dispensed and refilled. This strategy is valid and should be used in Brazil.

The use of electronic medication monitors, which provide the date and time of each triggering of the medication device, although costly, is the most accurate method of assessing adherence. The results obtained with such monitors demonstrate that adherence was lower than expected. Physicians should improve their knowledge on patient adherence and use accurate methods of assessing such adherence.

FOUR: Evidence-based Assessment of Adherence to Medical Treatments in Pediatric Psychology

Adherence to medical regimens for children and adolescents with chronic conditions is generally below 50% and is considered the single, greatest cause of treatment failure. As the prevalence of chronic illnesses in pediatric populations increases and awareness of the negative consequences of poor adherence become clearer, the need for reliable and valid measures of adherence has grown.

This review evaluated empirical evidence for 18 measures utilizing three assessment methods: (a) self-report or structured interviews, (b) daily diary methods, and (c) electronic monitors.

Ten measures met the "well-established" evidence-based (EBA) criteria.

Several recommendations for improving adherence assessment were made. In particular, consideration should be given to the use of innovative technologies that provide a window into the "real time" behaviors of patients and families. Providing written treatment plans, identifying barriers to good adherence, and examining racial and ethnic differences in attitudes, beliefs and behaviors affecting adherence were strongly recommended.

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