Table 1.

Summary of the PICOS elements included in the systematic review

	Inclusion criteria	Exclusion criteria
Population/patients	Human subjects	Animals
	18 years or older	Children
	Patients with diagnosed primary hypothyroidism or subclinical hypothyroidism	Pregnant women/patients with secondary or tertiary hypothyroidism/hyperthyroid patients/patients previously treated for thyroid cancer
	Receiving levothyroxine treatment	Other forms of hormone replacement therapy/combination therapy
Intervention	Interventions of any type, intensity and frequency, with length greater than 6 weeks used to investigate effect of clinical, behavioural or pharmcogenomic factors on levothyroxine therapy	N/A
Comparators/control	A control or comparative group is necessary. This can be placebo/no treatment/standard therapy/usual care/alternative treatment	No control/comparative group
Outcome	Primary outcome; quantitative effect of clinical/behavioural/pharmacogenomic factors on TSH levels Secondary outcome (s); quantitative effect of clinical/behavioural/ Pharmacogenomics factors on T4 and T3 levels/any short term effects/mortality/morbidity/quality of life/treatment complications/adverse effects/rate of relapse/physical functioning/social functioning	Reviews only focused on the quantitative effect of clinical/behavioural/ Pharmacogenomics factors on T4 and T3 levels
Study design	RCTs, case-control studies, cohort studies, observational studies, cross sectional studies, longitudinal studies, case studies	N/A