Medical costs of patient non-adherence to therapy costs the US $106 billion each year, according to an Express Scripts study, and missed opportunities for use of cheaper meds and delivery systems costs another $57 billion.

Factors in non-adherence include patient perceptions of drug efficacy, drug side effects, refill procrastination, co-payments and forgetfulness. Non-adherence is particularly pronounced among patients with diabetes, the number one driver of higher drug spending due to increased utilization and cost per prescription, according to Express Scripts Drug Trend Report, which noted that non-adherent diabetes patients had both statistically and clinically worse outcomes and that 8% of all diabetes patients had at least one related inpatient admission per year at an average cost of $20,500.

Patient preference for more expensive branded drugs is to blame for $51 billion in waste each year, said the pharmacy benefit management firm. Such “behavioral waste” is especially costly in the cholesterol category, where it represents a 35.5% savings opportunity of $24.78 per member per year, said the study.

The PBM said increased use of generics and lower-cost brands have saved its clients $1.4 billion, with half of that coming through behavior-centric programs in partnership with clients.