Adherence to levothyroxine treatment among patients with hypothyroidism in Oman: a national cross-sectional study

Hormone replacement therapy with levothyroxine is considered the treatment of choice for hypothyroidism; however, non-adherence is a major contributor to poor treatment outcomes. This study aimed to evaluate levels of drug adherence (DA) to levothyroxine therapy among Omani adults with hypothyroidism and to explore related sociodemographic and clinical factors.

A national, multi-center, cross-sectional survey was carried out from August to December 2021 at 18 primary healthcare centers across all governorates of Oman. A total of 415 Omani adults were recruited. Data were collected using a pre-tested, Arabic-language questionnaire completed by trained researchers during face-to-face interviews with the participants. Level of DA was determined using the 8-item Morisky Medication Adherence Scale (MMAS-8).

A total of 400 Omani adults participated in the study (response rate: 96.4%). The mean age was 41.9 ± 12.4 years old (range: 18-78 years) and 90.3% were female. According to their MMAS-8 scores, 157 (39.2%), 139 (34.8%), and 104 (26.0%) participants demonstrated low, medium, and high DA, respectively. No significant correlations were observed between level of DA and any sociodemographic or clinical characteristics, including age, gender, education, duration of treatment, and family history of thyroid disease (p > 0.050).

Only a quarter of Omani patients with hypothyroidism reported high levels of adherence to levothyroxine treatment, likely as a result of lack of awareness of the disease and the importance of maintaining an euthyroid state. Further studies using more objective measures of DA are recommended to determine correlates of non-compliance to levothyroxine therapy among Omani patients.