Antidepressants, antianxiety drugs frequently detected in plasma of older adults admitted for hip fracture, study finds

Of the patient population studied, nearly two-thirds had psychotropic or analgesic drugs or both detected in their blood.

Use of antidepressants and antianxiety drugs may be common in older patients admitted to the hospital with hip fracture, according to a new study.

Researchers in Norway performed a study of patients' plasma levels of antidepressants and antianxiety drugs at hospital admission for hip fracture. They hypothesized that plasma drug levels would provide a better measure of medication use than pharmacy registry data or drug records, which indicate dispensation rather than consumption. Plasma samples for patients 65 years of age or older were analyzed for psychotropic drugs, weak opioid analgesics, and alcohol. Odds ratios were compared for frequency of drugs detected in hip fracture patients and prescription frequency of the same drugs in a reference population matched for age, time, and region. Study results were published online March 7 by the British Journal of Clinical Pharmacology.

Two hundred fifty patients admitted to the hospital for hip fracture were included in the study and provided plasma samples. Median age was 84 years, and most patients (76%) were women. Of the 250 patients, 158 (63%) had psychotropic or analgesic drugs or both detected in their plasma, while alcohol was detected in 19 patients (7.6%). The most commonly detected drug group was z-hypnotics and benzodiazepines, which were present in 111 patients (44%). Diazepam (odds ratio, 1.6; 95% CI, 1.1 to 2.4), nitrazepam (odds ratio, 2.3; 95% CI, 1.3 to 4.1), selective serotonin reuptake inhibitors (odds ratio, 1.9; 95% CI, 1.3 to 2.9), and mirtazapine (odds ratio, 2.3; 95% CI, 1.2 to 4.3) were significantly more likely to be present in plasma samples from the study population than in prescription data from the reference population. In the study population, concordance of recorded and measured drugs for z-hypnotics and benzodiazepines was poor.

The authors noted that they did not know how much time had passed between last intake of drugs and blood sampling or between the time the patient fell and the time of hospital admission. They pointed out that the case group was much smaller than the reference population. However, they concluded that use of antidepressants and benzodiazepines is more common among older adults admitted to the hospital with hip fracture than is prescription of these drugs among older adults in the community. In addition, they found that these drugs were often detected in the plasma of hip fracture patients even if they were not listed in the medical record. “Our findings, which were based on objective determination of drug use in hip fracture patients, therefore support what previously has been shown in prescription studies: that treatment with benzodiazepines and antidepressants is associated with increased risk of hip fractures,” the study authors wrote.