Psychometric Evaluation of the Medication Adherence Report Scale in Caregivers of Low-Income, Urban, African American Children with Poorly Controlled Asthma

Background: Asthma morbidity and mortality are disproportionately higher among low-income, urban, African American children. Medication adherence, specifically daily use of long-term controller medication, is associated with better asthma control and decreased asthma morbidity, but lower rates of medication adherence have been reported for this vulnerable population (Desai & Oppenheimer, 2011; NAEPP-EPR3, 2007). Accurately assessing asthma medication usage among low-income, urban, African American children is essential to reduce asthma health disparities. The purpose of this study was to examine the factor structure of the established five-item Medication Adherence Report Scale (MARS) in a sample of caregivers of low-income, urban, African American children with persistent, uncontrolled asthma.

Method: This secondary data analysis used baseline data from a randomized clinical trial evaluating the efficacy of an environmental control educational intervention (N =207) for children with persistent asthma and frequent asthma-related Emergency Department visits. Confirmatory factor analysis (CFA) using Mplus version 8 examined the factor structure of the MARS. Construct validity was assessed using a regression model which included caregiver-reported daily controller medication adherence; Asthma Medication Ratio (AMR), a ratio of controller medication refills over total asthma medication refills calculated from pharmacy records; asthma control (NAEPP-EPR3, 2007); and caregiver perception of asthma control as predictors of the MARS.

Results: Caregivers were female (97%) and the majority were living in poverty (45.7% annual income <$20,000). The mean MARS score for the youths (mean age=6.3 years) was 21.8, reflecting high caregiver-reported adherence. Although most caregivers also reported their child had well controlled asthma in the past four weeks (57.7%), based on national guidelines, all youths had uncontrolled asthma (100%). Confirmatory factor analysis indicated that a five-item one-factor model marginally fit the data based on the fit indices: χ² (5) = 31.71, p < 0.001; RMSEA ≤ .161; CFI = 0.986; TLI = 0.971; and WRMR = 0.979. The MARS (α=0.75) was not significantly associated with AMR, asthma control, or caregiver perception of asthma control.

Conclusions: Findings suggests the MARS does not correlate with objective measures of asthma medication adherence or asthma control in families of low-income, urban, African American youths with uncontrolled asthma and should be used with caution. Yet, it is critical for health care providers to assess and monitor medication adherence at every visit, especially given the discordance between caregiver perception of adherence and child asthma control level. Social workers are well-positioned to explore barriers to medication adherence and elicit caregiver health beliefs about medication adherence. Social workers can also advocate for health care providers to build a shared understanding of medication adherence with the family to optimize health outcomes among low-income, urban, African American children with asthma.

References:

Desai, M., & Oppenheimer, J. J. (2011). Medication adherence in the asthmatic child and adolescent. Current Allergy And Asthma Reports, 11(6), 454–464.

National Asthma Education and Prevention Program (2007). Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. National Heart, L