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Study suggests hip fractures not caused by benzodiazepine use after all

January 16, 2007

Policies developed to limit sedative prescriptions based on older studies may need examining

BOSTON—Benzodiazepine use was not shown to be associated with hip fractures after all, according to a new study from the Department of Ambulatory Care and Prevention (of Harvard Medical School and Harvard Pilgrim Health Care). Previous epidemiological studies suggesting an association have been used to support legislation and policy decisions that limit access to these drugs among the elderly. These policies may need to be reexamined based on these new findings, which are being published in the Jan. 16 Annals of Internal Medicine.

Benzodiazepines are sedative drugs prescribed for anxiety, sleep, and seizure disorders. Concerns about abuse, misuse, and adverse effects of these drugs—including hip fractures among the elderly—have prompted state and national policies intended to regulate access to them. Since January 2006, benzodiazepines have been excluded from coverage through the Medicare Part D drug benefit.

Hip fractures are the most serious individual and public health risks attributed to benzodiazepines because they often lead to disability and death among the elderly. An expected benefit of limiting access to these drugs is a decrease in the incidence of falls and resulting hip fractures. However, no data exist to demonstrate this policy effect.

Anita Wagner, PharmD, MPH, DrPH, lead author of the study and assistant professor of ambulatory care and prevention in the Department of Ambulatory Care and Prevention (DACP) of Harvard Medical School and Harvard Pilgrim Health Care, and colleagues studied whether a state policy that drastically decreased use of benzodiazepines resulted in fewer hip fractures among the elderly. They looked for changes in hip fracture rates in a stable population of more than 90,000 Medicaid recipients age 65 and older before and after a policy was implemented in New York in 1989 requiring benzodiazepine prescribing on triplicate forms. Since then, all physicians in the state are required to obtain, pay for, and use serially-numbered triplicate forms to prescribe benzodiazepines. Pharmacists forward one copy of the prescription to state health authorities for surveillance, allowing for monitoring of each physician's prescribing, each pharmacy's dispensing, and each patient's receipt of benzodiazepines.

The policy resulted in an immediate 60 percent reduction in benzodiazepine use among women and 58 percent among men. The neighboring demographically-similar state New Jersey did not regulate benzodiazepine prescribing and benzodiazepine use did not change. Incidence of hip fracture before and after the policy change was similar.

"The policy drastically decreased use of benzodiazepines in New York and we did not see any decline in hip fracture rates compared to New Jersey; in fact, we seem to see an increase in New York over New Jersey," says Wagner.

There are several possible explanations for the study results. Most plausible, however, are biases in the previous studies that found a relationship between these drugs and hip fractures.

"It is very challenging to answer the question whether or not benzodiazepines cause hip fractures. People who get benzodiazepines, such as chronically ill elderly patients with dementia, have conditions, like dementia, that can cause hip fractures—and their hip fractures may not be due to their benzodiazepines," says Wagner.

"The challenge of disentangling the effects of benzodiazepines from other causes of hip fractures in the elderly is especially concerning when study results are used to guide policies that restrict access to medicines for huge populations," says senior author Stephen Soumerai, ScD, professor of ambulatory care and prevention at DACP.

Policy makers may expect that reducing access to benzodiazepines under Medicare Part D and other policies will decrease hip fracture risk. "Our study suggests that these expectations are not justified," says Soumerai.

Additionally, if benzodiazepine medications are abruptly terminated, as may be the case when people lose coverage of a drug, negative effects can occur, such as withdrawal reactions, seizures, emergency department visits, and hospital admissions. These may offset any potential savings achieved by limiting coverage of benzodiazepines.

The investigators are currently funded by a grant from the National Institute on Aging to monitor the impact of the Medicare Drug Benefit. They believe future studies based on these new data will shed additional light on how policies that exclude coverage for benzodiazepines affect the rate of hip fracture among the elderly.

Harvard Medical School