Menurut pemahaman saya, dalam konteks ini
non-adherence = non-compliance
Jadi,
non-adherence to oral medications = ketidakpatuhan (pasien) minum obat

Ref.:
Treatment *non-adherence* remains one of the greatest challenges in psychiatry. It has been estimated that 20–50% of any patient population is at least partially *non-compliant*, and that in patients with schizophrenia and related psychotic disorders rates can run as high as 70–80% (Breen & Thornhill, 1998). *Adherence* has been defined as *the extent to which a person’s behaviour coincides with the medical advice* given (Sackett & Haynes, 1976). The definition of *non-adherence* includes *failure to enter a treatment programme, premature termination of therapy and incomplete implementation of instructions* (including prescriptions).