Risk of Hypothyroidism in Females Who Received Chinese Herbal Medicine for Treatment of Rheumatoid Arthritis: A Matched Nested Case-Control Study

Abstract

Introduction

Thyroid dysfunction is a frequently observed clinical manifestation in females with rheumatoid arthritis (RA). Emerging evidence demonstrates that Chinese herbal medicine (CHM) can safely manage chronic diseases and treatment-related symptoms, but the association between CHM use and hypothyroidism risk in RA females has yet to be fully described. We put forward this population-level nested case-control study to explore the risk of hypothyroidism among them with and without integrating CHM into routine care.

Methods

Firstly, 8 685 females aged 20–80 years, diagnosed with RA between 2002 and 2010, were extracted from a nationwide health claims database. Among them, 192 cases developed hypothyroidism after RA by the end of 2013, and all of the enrollees were randomly matched to 960 controls without hypothyroidism at a 1:5 ratio.

Results

After fitting the conditional logistic regression, we found those ever receiving routine care plus CHM indeed exhibited a lower hypothyroidism risk, with an adjusted odds ratio of 0.60 (95% confidence intervals: 0.44–0.81). Of particular importance was that initiating CHM within the first 3 years after RA onset and having a prolonged usage for more than 365 days were markedly correlated with a lower hypothyroidism chance.

Conclusions

This study implicated that timely integrating CHM into conventional care may substantially reduce hypothyroidism risk among RA females. A further well-designed randomised controlled trial to specify the possible mechanism is needed.