[Pernicious anemia and autoimmune thyroid diseases in elderly people]

Autoimmune thyroid diseases (ATD), and pernicious anemia (PA) in particular, are common in elderly people. The relationship between both of these is currently being discussed. The objective of this study is to determine the correlation between ATD and PA in elderly people, and if there are other associated factors affecting this relationship.

The factors studied to analyse this association were social-health variables, autoimmune comorbidity (type 1 diabetes and other autoimmune diseases), the taking of drugs that alter vitamin B12 levels (Metformin and protein bomb inhibitors), and the chronological order in which both diseases appear in this population. A logistic regression analysis was performed to determine which of the described variables could have an on both diseases.

The prevalence was 8.2% for ATD and 3.3% for PA, with a progressive increase in the annual incidence in the past 10 years from 7.1 to 12.7 cases per 1,000 persons>65 years for ATI, and from 1.6 to 7.4 cases for PA. PA was found in 18.6% of the patients with ATD, and the 45% of PA presented with ATD, mainly in women (RR=6.0). The average time in diagnosing the second disease was about 8 years. When there was a third autoimmune disease the likelihood of ATD and PA increased fourfold. Patients with ATD and consuming drugs which were affecting the absorption of vitamin B12 had double the probability of developing a PA compared with those who were not taking medications.

The results of this study confirm the association between ATI and AP among people 65 or older, also a progressive increase in the incidence of these diseases.