Medication Adherence Rating Scale (MARS)

Pharmacy refills show whether patients fill prescriptions (an objective, external measure) but not whether they actually take the medication. MARS asks patients directly about their actual medication-taking behavior. MARS captures intentional non-adherence (skipping doses due to side effects or belief change), which refills cannot detect. Both measures are valuable; together they provide a more complete picture.

MARS is self-report, so it is vulnerable to social desirability bias. However, research shows that patients with good insight often provide honest MARS responses, especially in a non-judgmental clinical environment. Use MARS as a screening tool: high scores suggest good adherence, but low scores warrant exploration (open questions about barriers, direct observation if possible, serum drug levels if available). In psychiatric populations, poor insight may inflate MARS scores, so clinical correlation is essential.

The original 10-item MARS is generic and applies to any medication. Some researchers have adapted it for specific conditions (e.g., MARS-5 for antipsychotics), but the 10-item version is the validated standard and is appropriate across conditions. Disease-specific adaptations are typically minor (e.g., replacing 'medication' with 'your blood pressure pills').

MARS is often used as an outcome measure to evaluate adherence interventions. Studies using MARS show that interventions addressing both belief barriers (e.g., psychoeducation) and practical barriers (e.g., simplified dosing, reminders) produce the largest increases in MARS scores and corresponding clinical improvement.