Adherence to levothyroxine prescription in patients with hypothyroidism

Hypothyroidism occurs in 1-2% of the general population, is associated with significant morbidity and requires continuous treatment with levothyroxine.

To determine the effectiveness, adherence and safety of levothyroxine therapy in patients with hypothyroidism.

The Morisky-Green adherence test was applied, and effectiveness was determined by measuring thyroid-stimulating hormone (TSH) in 330 patients with with hypothyroidism; the mean age was 64+-15 years and 76% was women.

Median TSH was 2.09 mIU/L (interquartile range: 1.16-3.61 mIU/L). Two hundred thirty-five (71%) patients had TSH levels in the euthyroid range, 64 (19%) in the hypothyroid range and 31 (9%) in the hyperthyroid range. Complete, moderate and lack of adherence with levothyroxine was reported in 283 (86%), 29 (9%) and 18 (5%) of patients, respectively. The presence of anemia (odds ratio (OR): 0.37, 95% confidence intervals (CI): 0.15-0.98) or the need of doses over 100 µg/day (OR: 0.47, 95%CI: 0.28-0.80) increased the probability of having an abnormal TSH level.

In a large proportion of these patients, TSH levels were controlled, and most patients were adherent to levothyroxine therapy.