(HealthDay News) — The effects of trials to improve medication adherence are inconsistent, with few studies of the highest quality demonstrating improvement in both adherence and clinical outcome, according to a review published online in The Cochrane Library.

Robby Nieuwlaat, PhD, from McMaster University in Hamilton, Canada, and colleagues conducted a systematic review to examine the effects of interventions intended to enhance patient adherence to prescribed medications for medical conditions. 

Due to considerable heterogeneity in terms of medical conditions, patient population, intervention, measures of adherence and clinical outcomes, the authors conducted a qualitative analysis of 182 randomized controlled trials.

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The researchers found that 17 trials had the lowest risk for bias for study design features and their primary clinical outcome. The trials at lowest risk for bias tended to involve complex interventions with multiple components, including support from family, peers and health professionals such as pharmacists, who often delivered education, counseling and/or daily treatment support. 

Improvements in both medication adherence and clinical outcomes were reported by only five of these trials, and there were no common intervention characteristics. There were no large improvements in adherence or clinical outcomes, even with the most effective interventions.

“The research in this field needs advances, including improved design of feasible long-term interventions, objective adherence measures and sufficient study power to detect improvements in patient-important clinical outcomes,” the researchers wrote.

One author disclosed financial ties to Boehringer Ingelheim.


  1. Nieuwlaat R et al. Cochrane Library. 2014;doi:10.1002/14651858.CD000011.pub4.