The association between anti-thyroid antibodies and quality of life in patients with Hashimoto's thyroiditis: a systematic review and meta-analysis

OBJECTIVE The aim of this review was to evaluate the association between anti-thyroid antibodies and quality of life in people with euthyroid Hashimoto thyroiditis. INTRODUCTION Patients with Hashimoto thyroiditis report symptom distress more often than those with non-autoimmune thyroid disorders. Therefore, anti-thyroid antibodies may be related to decreased quality of life in persons with Hashimoto thyroiditis. The etiology of lingering symptoms, even in euthyroidism, remains unknown. The relationship between anti-thyroid antibodies and quality of life for people with Hashimoto thyroiditis has not been evaluated in a systematic review. INCLUSION CRITERIA The participants were males and females at least 12 years of age, in any country, with Hashimoto thyroiditis. Participants not in a euthyroid state were excluded from this review. In this review, the exposure was the presence of anti-thyroid antibodies and the primary outcome was quality of life as measured by a validated scale. METHODS A three-step search strategy was implemented with an initial search of PubMed and CINAHL. A comprehensive database search using all identified keywords and index terms was undertaken in March 2019 for relevant published literature, gray literature, and clinical trial registries. The final updates to the search strategies were conducted in December 2019. The search was limited to studies published in English after 1956. Two independent reviewers completed screening for inclusion and utilized the recommended JBI approach to critical appraisal, study selection, data extraction, and data synthesis. The findings are presented in a meta-analysis and in a narrative synthesis, which includes tables and figures. RESULTS All 13 studies had high methodological quality. Four studies found a significant correlation (P < 0.05) between the presence of anti-thyroid antibodies and quality of life. A fifth study found a significant correlation (P < 0.001) between higher antibody levels and quality of life. A meta-analysis was conducted using two cross-sectional studies, which revealed that the summative small effect size was statistically significant and suggested a lower quality of life in antibody-positive patients. Due to the heterogeneity of the studies, a narrative synthesis was conducted for the three secondary outcomes: symptom distress, executive function, and mental health. Three studies found a statistically significant (P < 0.05) correlation between symptom distress and antibodies, two studies found a statistically significant (P < 0.05) association between executive function and antibodies, and all but one study found a statistically significant (P < 0.05) relationship between mental health and antibodies. CONCLUSIONS The findings in this review did not reveal a definitive relationship between antibodies and quality of life. However, our meta-analysis suggested a link between anti-thyroid antibodies and decreased quality of life in euthyroid children and adults. Though not conclusive, poor mental health and symptom distress may be associated with anti-thyroid antibodies. Therefore, it may be beneficial to periodically evaluate the quality of life and mental health in euthyroid patients with positive antibodies. It is unlikely that antibodies and executive functions are related. The studies and our review's limitations require replication of findings to confirm a connection between antibodies, quality of life, and the secondary outcomes. Future research should continue to evaluate the relationship between anti-thyroid antibodies and the quality of life in individuals with euthyroid Hashimoto thyroiditis. SYSTEMATIC REVIEW REGISTRATION NUMBER PROSPERO CRD42018084663.