Investigating the Bidirectional Association of Rheumatoid Arthritis and Thyroid Function: A Methodologic Assessment of Mendelian Randomization.

OBJECTIVE: Rheumatoid arthritis (RA) and thyroid dysfunction are frequently observed in the same patient. However, whether they co-occur or exhibit a causal relationship remains uncertain. We aimed to systematically investigate the causal relationship between RA and thyroid function using a large sample and advanced methods. METHODS: Bidirectional two-sample Mendelian randomization (MR) analysis was performed based on RA and six thyroid function trait data sets from the European population. The robustness of the results was demonstrated using multiple MR methods and a series of sensitivity analyses. Multivariable MR using Bayesian model averaging (MR-BMA) was performed to adjust for possible competing risk factors. A sensitivity data set, which included data from patients with seropositive RA and controls, was used to repeat the analyses. Furthermore, enrichment analysis was employed to discover the underlying mechanism between RA and thyroid functions. RESULTS: A significantly positive causal effect was identified for RA on autoimmune thyroid disease (AITD) as well as for AITD on RA (P < 0.001). Further sensitivity analyses showed consistent causal estimates from a variety of MR methods. After removing the outliers, MR-BMA results showed that RA and AITD were independent risk factors in their bidirectional causality, even in the presence of other competing risk factors (adjusted P < 0.05). Enrichment analysis showed immune cell activation and immune response play crucial roles in them. CONCLUSION: Our results illustrate the significant bidirectional causal effect of RA and AITD, which holds even in multiple competing risk factors. Clinical screening for thyroid dysfunction in patients with RA deserves further attention, and vice versa.

[Studies on direct and indirect economic burden of disease and related factor in countryside of Qingdao city in 2001].

OBJECTIVE: To study the condition of economic burden of disease in the countryside and to explore the related factors. METHODS: Human capital method and two-step method were used in the calculation of economic burden of disease. RESULTS: The total economic burden of disease among 3359 persons was 3072 225 Yuan. Noncommunicable conditions were accounted for 62.95%, while communicable disease, maternal and perinatal conditions accounted for 24.25%, and injury accounted for 9.83% respectively. The direct economic burden of disease was 1,559,619 Yuan and the indirect economic burden of disease was 1,472,606 Yuan. The economic burden of disease for each person was 914 Yuan. The equal burden of disease among patients with disability and without disability were 3070 Yuan and 680 Yuan respectively (P < 0.001). There was significant difference among different age groups. The influencing factors were found to include having noncommunicable disease, age, disability and the condition of marriage. CONCLUSION: Corresponding policy to cope with conditions of different age groups needs to be developed to reduce the economic burden of disease in the countryside.