Development of a Nomogram-Based Prediction Model for Postoperative Delirium in Patients After Total Hip Arthroplasty: A Retrospective Cohort Study.

The study was retrospective and used routine records, so selection and information bias are possible and the model cannot show that any factor causes delirium. It came from one hospital, and the model was only internally validated, so its accuracy in other units or patient groups is unproven. Incomplete records were excluded, and blinding of predictor assessment to outcome was not applicable because of the retrospective design. Whether catheterisation was clinically necessary was not recorded in detail, so the catheter association may reflect patient severity or practice rather than a modifiable nursing factor. The sample was mostly older adults, so findings may not apply to younger patients despite age 18 or older inclusion.

Funded by Dalian Municipal Health Commission and China Scholarship Council; funders had no role in design, collection, analysis, publication or manuscript preparation. Authors declared no conflicts of interest.

Do not treat the nomogram as a validated clinical tool or assume the four factors cause delirium. It was developed from one hospital's retrospective records, had no external validation, and cannot establish causation.