I believe the medical community refers to this as "patient non-compliance". It's an important factor for doctors to consider; it often makes sense to prescribe

I believe the medical community refers to this as "patient non-compliance". It's an important factor for doctors to consider; it often makes sense to prescribe a "worse" medication if the "more effective" medicine has side effects which often cause patients to stop early or to skip or forget doses. New formulations of drugs are often advertised to doctors as being just as effective as previous versions but with "improved patient compliance" due to easier dosing schedules (e.g., daily instead of every 8 hours) or fewer side effects.