Levothyroxine treatment adherence rate and evaluation of related factors in geriatric patients

Aim: This study aimed to determine the rate of compliance with levothyroxine (LT4) therapy in geriatric patients and to investigate the factors associated with treatment non-adherence.

Materials and Methods: This cross-sectional study included 87 patients aged 65 years or older with primary hypothyroidism who attended the Endocrinology and Geriatrics outpatient clinics between August and November 2023. Medication adherence was assessed using a structured questionnaire. Cognitive function was evaluated with the Standardized Mini-Mental State Examination (MMSE) and depressive symptoms with the Yesavage Geriatric Depression Scale (GDS). Statistical analyses included Student's t-test, Mann-Whitney U test, chi-square test, and binary logistic regression; significance was set at p < 0.05.

Results: The mean age of participants was 74.05 ± 6.17 years, and 88.5% were female. The LT4 adherence rate was 56.3% (n = 49). No statistically significant difference was found between adherent and non-adherent groups in terms of age, sex, cognitive status (MMSE: 26.92 ± 2.55 vs. 26.57 ± 3.12; p = 0.57), or depressive symptomatology (GDS: 4.55 ± 3.31 vs. 4.92 ± 3.13; p = 0.59). Median thyroid-stimulating hormone (TSH) levels were significantly higher in PPI users compared to non-users (3.4 vs. 2.7 mIU/L; p = 0.042). Logistic regression analysis did not identify statistically significant independent predictors of non-adherence; however, low educational level (OR: 2.14; p = 0.092) and polypharmacy (OR: 1.87; p = 0.165) showed trends toward increased risk.

Conclusion: LT4 non-adherence affects nearly half of geriatric patients and appears to stem primarily from insufficient knowledge about correct administration conditions rather than cognitive or affective impairment. The significant association between PPI use and elevated TSH levels underscores the importance of reviewing concurrent medications before dose escalation in this population. Clinicians are advised to assess medication administration errors and interacting agents before attributing elevated TSH levels to insufficient dosage.