Implementing culturally relevant interventions that improve patient self-motivation is a strategy that could increase medication adherence, the researchers suggest. Treatment non-adherence in the end-stage renal disease (ESRD) population tends to be high, ranging from 22%–74%.
To assess patient motivation to comply with phosphate binder therapy, investigators led by Kerri Cavanaugh, MD, of Vanderbilt University Medical Center in Nashville, asked 100 ESRD patients (most on dialysis) to take an adapted version of the autonomous regulation (AR) scale. The AR scale allows responses ranging from 1 (not at all true) to 7 (very true). A separate tool, the Morisky Medication Adherence Scale, gauged actual medication usage based on patient reports. The average serum phosphorus level was 5.7 mg/dL.
More than half of patients reported the highest AR score of 7, according to results published online ahead of print by the Journal of Renal Nutrition. Higher AR scores were associated with better medication adherence, and better medication adherence was linked to lower serum phosphorus.
The researchers noticed that results differed by race. Higher AR scores in non-Caucasian patients correlated with lower serum phosphorus. This was not true of Caucasian patients. The most motivated patients were non-Caucasian, older women with average age 53.
Ethnic minority patients were significantly more likely to report the highest AR scores for 3 questions identifying reasons for taking phosphate binders: the medication is important for being as healthy as possible, it is the best thing for my health, and it is important for many aspects of my life.
“Non-white dialysis subjects have an increased prevalence and severity of bone mineral disorder, and perhaps over time, this experience with more severe disease may result in higher AR toward phosphate binders as an adaptive mechanism compared to their white peers,” the investigators explained.
The type of phosphate binder had no bearing on the results. The most commonly taken phosphate binders were sevelamer carbonate (40%) and calcium acetate (33%), although all types were reported.