Letter to the Editor From Zhang et al: Preoperative Serum Calcium Level Predicts Postoperative Mortality in Older Adult Patients With Hip Fracture: A Prospective Cohort Study of 2333 Patients

We are writing to articulate certain concerns and offer supplementary context regarding the research conducted by Dong-Yang Li et al.1 Their study concludes that the preoperative serum calcium level is nonlinearly associated with mortality in older adults with hip fractures, revealing a U-shaped relationship, and suggests its potential utility as a prognostic predictor. Although this study undoubtedly enriches our understanding of this pivotal subject matter, I contend that it may benefit from further deliberation and elucidation.