The pooled analysis confirmed that advanced age, male sex, ASA classification ≥3, dependent functional status, history of smoking, COPD, DM, CHD, arrhythmia, CVA, dementia, CRF, hip arthroplasty, delayed surgery, and preoperative Cr and Alb are significantly associated with POP in elderly patients after hip fracture surgery. The gene discussed is ALB; the disease is dementia.