Reply to: Revisiting Safety Assessments of Baclofen and Tizanidine in Older Adults

We thank the authors of this letter for their interest in our study [1]. The letter highlights several characteristics of our observational study design; specifically, our focus on serious injury outcomes associated with the prescription of baclofen and tizanidine in a population of ambulatory older adult patients. The goal of our study was to assess the risk for well-documented, serious injuries associated with the study drugs that would be coded in and retrieved from comprehensive electronic medical records of ambulatory older adults. We agree with the letter authors who reiterate our discussion of the limitations of the methods of an observational study design to determine drug exposure (computerized prescription dispensing data) and clinical outcomes (from ICD coding). More specific drug exposure data would be the ideal but was determined to be impractical in an observational study of this size (study population over 87,000 patients, with > 118,000 episodes of prescription drug dispenses). Further, studying other less serious and less readily identifiable adverse effects (e.g., delirium, urinary retention, or “near fall” events) was not the focus of our study. Finally, our investigators feel that the risks demonstrated for baclofen and tizanidine in this ambulatory patient population may be generalizable to more vulnerable older patients residing in skilled nursing facilities, palliative care or in hospice, for whom prescribing of SMRs including baclofen and tizanidine should generally be avoided. Monique M. George: study concept and design, analysis and interpretation of data, preparation of manuscript. Robert L. Deamer: concept and design, analysis and interpretation of data, preparation of manuscript. This research was supported by a grant from the Regional Research Committee of Kaiser Permanente Southern California, RRC grant number: KP-RRC-20200701. The authors declare no conflicts of interest. This publication is linked to a related Letter to the Editor by Li et al. To view this article, visit https://doi.org/10.1111/jgs.70215.