Letter: Incremental Value and Outcome Modelling in Frailty Assessment for Older Patients with Inflammatory Bowel Disease. Author's Reply

We would like to thank Dr. Liu and colleagues for their interest in our work [1] and their comments on our manuscript [2]. We would like to address their comments and clarify several important aspects of our work. Dr. Liu et al. noted that it remained unanswered whether a geriatric assessment provides incremental clinical utility and adds prognostic information over simpler frailty screening tools. They argued that prior studies on frailty in older patients with Inflammatory Bowel Disease (IBD) have considered broader clinical context, including comorbidity burden and treatment-related factors. We did not adjust for comorbidity separately because comorbidity is already incorporated in our geriatric assessment. In the cited articles, Kochar et al. (2020, 2022) adjusted or stratified their analyses for the type of IBD medication; however, they did not adjust for clinical or biochemical disease activity [3, 4]. Qian et al. did not adjust for disease activity nor for the type of IBD medication in their analyses [5]. In the baseline paper of our cohort by Asscher et al., the type of IBD medication was not associated with the number of geriatric deficits, whereas clinical and biochemical disease activity were identified as important determinants for the number of deficits in geriatric assessment [6]. Our adjustment for biochemical disease activity provides a more direct assessment of the inflammatory burden in relation to frailty, rather than using treatment patterns as an indirect proxy for disease severity. In the baseline paper, other factors that could represent disease severity such as disease phenotype were tested but were not found to be associated with deficits in geriatric assessment [6]. We found that patients with severe deficits (4–5 impaired domains) in geriatric assessment were at greatest risk for hospitalisations. When further evaluated, we found that the somatic domain and its components appeared to contribute the most to this increased risk. However, our findings suggest that it is the accumulation of deficits that best captures frailty, as the adjusted hazard ratio (aHR) found for the somatic domain does fully explain the aHR of nearly 3.5 observed for severe deficits. In addition, individual deficits may interact and have cumulative effects [7]. We agree with Dr. Liu et al. that recurrent hospitalisations are important in relation to frailty. They may not only reflect the underlying frailty status but can also contribute to its progression, as hospitalisation itself can negatively impact the level of frailty. However, due to the relatively short follow-up period in our study, the number of patients with multiple hospitalisations was too low to perform formal analyses. In summary, coming back to the incremental value of a geriatric assessment over screening tools, we think that selecting the right frailty screening tool depends on its purpose. If the goal is risk stratification, a simple screening tool may suffice. If the goal is helping older patients to get through a disease flare by optimising their health status, the geriatric assessment has clear additional value by the identification of underlying actionable vulnerabilities. ‘The authors’ declarations of personal and financial interests are unchanged from those in the original article [2]’. A. B. Fons: writing – original draft, conceptualization, investigation. P. W. J. Maljaars: supervision, writing – review and editing, conceptualization, investigation. The authors have nothing to report. This article is linked to Fons et al. papers. To view these articles, visit https://doi.org/10.1111/apt.70594 and https://doi.org/10.1111/apt.70632. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.