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Long-term thyroxine therapy increases fracture risk in older adults
Older adults assigned thyroxine therapy have an increased risk for incident fracture over 6 years, according to recent study findings.
In a retrospective cohort study, Annika Viniol, MD, professor of family medicine at the University of Marburg, Germany, and colleagues analyzed insurance claims data from 798,770 adults aged at least 60 years in the Health Risk Institute research database from 2008 to 2013 (51.8% women; mean age, 72 years). Adults prescribed repeated thyroxine therapy were considered the exposure group (n = 93,252; 11.7%); the remainder (n = 705,518; 88.3%) were considered controls. Primary outcome was any incident fracture during the follow-up period; secondary outcome was any incident fracture of the pelvis or femur.
In Cox regression analysis, researchers found that patients assigned thyroxine have a 6.4% higher risk for incident fracture vs. controls (P < .0001) and a 3% higher risk for fracture of the pelvis or femur (P = .0336).
Researchers also found the fracture risk decreased with increasing age after adjustment. In a model stratified by age only, patients aged 60 to 69 years had a 30% increased risk for any fracture, whereas adults aged 70 to 79 years had a 28.9% increased risk and those aged 80 to 89 years had a 12.9% increased risk (P < .0001 for all).
“Our finding that thyroxine has a stronger influence on fracture risk in younger elderly ... than in older elderly was unexpected,” the researchers wrote. “We assume that the detected effect modification within age groups may be linked to the strength of causality. In higher age groups, the frequency of other causes of osteoporosis (independent from thyroxine) and falls increases, so that, in turn, the attributable risk of thyroxine decreases.” – by Regina Schaffer
Disclosure: Two of the researchers are employees of Elsevier GmbH.