Clinical Summary
Clinical Summary: Beyond Pharmacology: Do Tablet Shape, Size, and Color Influence Medication Adherence in Psychiatric Outpatients?
Psychiatric patients often stop medication for reasons that extend beyond efficacy and adverse effects, including how a tablet looks and feels. This study asks a practical question for outpatient care: whether common preferences about tablet shape, size, and color actually translate into better adherence, or whether clinicians should focus their efforts elsewhere.
Design
This cross-sectional observational study
N
232 adult outpatients
Population
232 adult outpatients (aged ≥18 years) with diverse psychiatric diagnoses (eg, depression, anxiety, bipolar affective disorder) who were taking oral medications for at least 1 month
Duration
over 6 months (April–October 2024)
Key Findings
- Overall adherence was 74.1% (MARS score: 6–10; 95% CI, 68.1–79.3%).
- Adherence varied by diagnosis, with the lowest rate in psychosis at 30.8% (95% CI, 12.7–57.6%) and the highest in generalized anxiety disorder at 85.0% (95% CI, 64.0–94.8%).
- Patients most often preferred oval/oblong shapes (43.5%), small sizes (41.4%), and white colors (41.8%).
- Patients most often disliked large sizes (53.4%), flat-circular shapes (40.5%), and red colors (33.6%).
- No significant associations emerged between any preference/dislike and adherence (all P > .05; χ2 = 1.90–4.64; Cramér’s V = 0.09–0.14), and clinical variables showed no impact on adherence (P = .081 to P = .760).
Clinical Bottom Line
Changing tablet shape, size, or color alone is unlikely to improve medication adherence in psychiatric outpatients. In routine practice, adherence work should center more on diagnosis-specific barriers, insight, and psychosocial factors than on tablet esthetics.
Practice Implications
- Do not expect formulation esthetic changes alone to improve adherence when all attribute-adherence associations were nonsignificant (all P > .05; χ2 = 1.90–4.64; Cramér’s V = 0.09–0.14).
- If adherence problems persist, pay particular attention to patients with psychosis, whose adherence rate was 30.8% (95% CI, 12.7–57.6%), versus 85.0% (95% CI, 64.0–94.8%) in generalized anxiety disorder.
- When choosing among equivalent oral formulations, consider acceptability preferences—especially avoiding large tablets, which were disliked by 53.4%, along with flat-circular shapes (40.5%) and red colors (33.6%).
- Interpret self-reported adherence cautiously: the study used MARS, and the article notes only moderate concordance with objective measures (ĸ=0.4–0.6), so consider objective checks when adherence remains uncertain.
