Frailty, depression, and quality of life in acute care for elderly: a serial mediation and moderated mediation study in Taiwan - Chau-Nee Chen; Tzu-Jung Fang; Cheng-Fang Hsieh; Chun-Chang Chen; Yu-Fu Chen; Hong-Yaw Chen; Pin-Yu Lai; Yu-Han Lu; Hon-Yi Shi (International Journal for Quality in Health Care, 2026)