The quality of the health care provider-patient relationship is one of the most important health system factors impacting adherence.  A good relationship with encouragement and reinforcement is a crucial element in adherence.  Health-care system barriers include difficulties in scheduling appointments, lack of providers, use of restrictive and changing formularies, and increased drug/co-payment costs.  Many older patients have multiple illnesses and are treated by several providers.   Continuity and coordination of care are particularly important for older patients.