SAN FRANCISCO — A diagnosis of subclinical hyperthyroidism significantly increases the risk of death from any cause in the subsequent 10 years, especially among elderly patients, according to Dr. Patrick Haentjens.
The increased risk of death starts low and increases up until about age 80, with an overall increased risk of 41%, Dr. Haentjens said at the annual meeting of the Endocrine Society. After age 80, competing causes of death eliminate the association with thyroid dysfunction.
When translated to an absolute risk of death, excess mortality for a white U.S. woman diagnosed at age 70 was only 1.5% at 2 years, but increased to almost 9% by 10 years, said Dr. Haentjens of the Center for Outcomes Research, University of Ziekenhuis, Brussels. Men seemed to fare worse; for a white U.S. man diagnosed at age 70, the excess mortality risk was 2% at 2 years, 6% at 5 years, and almost 11% at 10 years after the diagnosis.
However, Dr. Haentjens' meta-analysis found no significantly increased mortality risk associated with subclinical hypothyroidism. The study was published online in the European Journal of Endocrinology (doi:10.1530/EJE-08-0110
The meta-analysis included nine papers, which reported data on seven cohorts with subclinical hyperthyroidism (290 patients) and nine cohorts with subclinical hypothyroidism (1,580 patients). The individual studies compared long-term outcomes among these patients and 13,000 euthyroid controls. Follow-up ranged from 2 to 20 years.
Among the seven cohorts with subclinical hyperthyroidism, the hazard ratio for all-cause mortality ranged from 0.84 to 2.22. Only one paper (Lancet 2001;358:861-5) found a significant increase. However, in the pooled analysis, the overall risk was significantly increased, with a hazard ratio of 1.41, compared with euthyroid controls. Among the nine cohorts that explored all-cause mortality in patients with subclinical hypothyroidism, the hazard ratio ranged from 0.49 to 2. Three studies found significant differences, but one of them reported a significantly decreased risk of all-cause mortality, while the other two reported a significantly increased risk. Overall, the pooled analysis did not show an increased all-cause mortality risk.