SEATTLE — Older adults in the general population have an elevated risk of fractures related to osteoporosis if they take certain antiepileptic drugs, according to a population-based analysis.
“Prior studies have shown that antiepileptic drugs [AEDs] are associated with an increased risk of bone loss and fractures,” presenting author Jane McChesney said at the annual meeting of the American Academy of Neurology. “However, population-based data assessing the association between AEDs and osteoporotic-related fractures are scarce.”
“This study found that AEDs, except for fatty acid derivatives, are associated with an increased risk of osteoporotic-related fractures in men and women over age 50,” Ms. McChesney said. “This is concerning as many of these AEDs are not only used to manage epilepsy, but are also widely used in older adults for the treatment of neuropathic pain, headaches, and psychiatric conditions, to name a few.”
Ms. McChesney, a nursing student at the University of Calgary, Alta., and colleagues analyzed population-based data from the province of Manitoba for the years 1996–2004.
Individuals were included if they were at least 50 years of age and had continuous health care coverage during the study period. They were excluded if they had taken osteoprotective medications in the year before a fracture or were residents of long-term care facilities.
Fractures were ascertained from diagnostic codes and were limited to vertebral, wrist, and hip fractures that were not related to severe trauma, according to Ms. McChesney.
Using the fracture date as the index date, each older adult with a fracture was matched with three fracture-free older adults by age, sex, ethnicity, and number of comorbidities.
Use of AEDs, defined as dispensation of a prescription to the individual in the past 4 months, was assessed from a drug database containing virtually all pharmacy dispensations for the province.
Analyses were based on 15,792 older adults who had experienced a fracture and 47,289 older adults who had not, Ms. McChesney reported. Overall, 70% were female, 62% were aged 70 years or older, and 67% had three or more comorbidities.
Fractures most commonly occurred in the wrist (52%), followed by the hip (26%) and vertebrae (22%).
After adjustment for social and demographic characteristics, home care, and comorbidities known to affect fracture risk, older adults had elevated odds of fracture if they used carbamazepine (odds ratio, 1.9), clonazepam (1.3), gabapentin (1.6), phenobarbital (2.2), and phenytoin (2.1). In contrast, their odds were not elevated if they used valproic acid.
It remains unknown if osteoprotective agents are beneficial in this context, she acknowledged, and that would be an important focus of additional research.
Ms. McChesney reported that she had no disclosures to make in relation to the study.