Muscle relaxants compared for fall risk in older patients

Among new users ages 65 years and older, baclofen was associated with a higher risk of fall compared to tizanidine but no significant increase in risk versus cyclobenzaprine, a study found.

The risk of fall associated with baclofen was greater than that associated with tizanidine but not cyclobenzaprine in older adults, while risk for fracture was comparable with all three drugs, a study found.

To characterize the risk of fall and fracture associated with muscle relaxants in older adults, researchers conducted an active-comparator study using data from a single tertiary health system from January 2005 to December 2018 on adults ages 65 years and older who were newly treated with baclofen, tizanidine, or cyclobenzaprine. The study cohort included 2,205 new baclofen users, 1,103 new tizanidine users, and 9,708 new cyclobenzaprine users. The primary outcome was an ED, hospital, or outpatient visit resulting from a fall, while the secondary outcome was a clinical encounter with fracture. Results were published Nov. 7 by the Journal of the American Geriatrics Society.

The median (interquartile interval [IQI]) duration of prescription was 111 (IQI, 49 to 253) days for baclofen, 114 (IQI, 50 to 290) days for tizanidine, and 114 (IQI, 46 to 275) days for cyclobenzaprine. Baclofen was associated with a higher risk of fall compared to tizanidine (propensity score-based inverse probability of treatment weighting incidence rate, 108.4 vs. 61.9 per 1,000 person-years; subdistribution hazard ratio [SHR], 1.68 [95% CI, 1.20 to 2.36]). The risk of fall associated with baclofen was not significantly different from that associated with cyclobenzaprine (SHR, 1.17; 95% CI, 0.93 to 1.47) with a median follow-up of 106 days. Fracture risk was similar among patients treated with baclofen compared with tizanidine (SHR, 0.85; 95% CI, 0.63 to 1.14) or cyclobenzaprine (SHR, 0.85; 95% CI, 0.67 to 1.07).

The study's findings may inform risk-benefit considerations in the increasingly common clinical encounters where oral muscle relaxants are prescribed, the authors noted.

“The present study suggests the risk of fall should also be considered among potential harms associated with baclofen in older adults regardless of impairment in kidney function,” they wrote. “Given the growing evidence highlighting the fall risk with baclofen use, future prescribing guidelines could consider the inclusion of fall as potential baclofen-associated harm in older adults.”