Liver enzyme inducing anticonvulsant drug use is associated with prevalent vertebral fracture.

Abstract

It is unclear whether prevalent vertebral fractures are associated with use of anticonvulsant drugs, especially those that induce liver enzymes (LEI) that metabolize drugs and vitamin D. Our purpose was to estimate the prevalence of vertebral fracture on densitometric lateral spine images according to duration of prior anticonvulsant medication use. Our study population was 11,822 individuals (mean [sd] age 76.1 [6.8] years, 94% female) who had bone densitometry with VFA between 2010 and 2018. Cumulative prior exposure to LEI anticonvulsants (carbamazepine, phenobarbital, phenytoin, valproic acid, n = 538), non-LEI anticonvulsants (clonazepam, gabapentin, levetiracetam, others, n = 2786), and other non-clonazepam benzodiazepines (n = 5082) was determined using linked pharmacy records. Prevalent vertebral fractures were identified on VFA images using the modified ABQ method. Logistic regression models were used to estimate the association of anticonvulsant drug exposure with prevalent vertebral fractures. Prevalence of one or more vertebral fractures was 16.1% for the entire analytic cohort, and 27.0%, 19.0%, and 18.5% for those with ≥ 2years of prior LEI anticonvulsant use, non-LEI anticonvulsant use, and other benzodiazepine use, respectively. Adjusted for multiple covariates, use of prior LEI anticonvulsant medication for ≥ 2years was associated with prevalent fracture on VFA (OR 1.48 [95% CI 1.04, 2.10]). LEI anticonvulsant use for ≥ 2years is associated with higher vertebral fracture prevalence. Lateral spine VFA imaging at the time of bone densitometry may be appropriate for older individuals who have used LEI anticonvulsant medications for ≥ 2years.