Systematic Review and Meta-analysis from Viswanathan et al. (2015) assessing the effect of MTM intervientions among outpatients with chronic illnesses.  Evidence was graded as insufficient for most outcomes because of inconsistency and imprecision that stem in part from underlying heterogeneity in populations and interventions. Medication therapy management interventions may reduce the frequency of some medication-related problems, including nonadherence, and lower some health care use and costs, but the evidence is insufficient with respect to improvement in health outcomes.