We aimed to assess the association between postoperative new-onset proteinuria, all-cause mortality, and decline in kidney function in Chinese people who underwent surgery. The exposure variable was the dipstick proteinuria values from the initial postoperative urinalysis within 30 days after surgery, categorized as negative, trace, 1+, and ≥2+. The primary outcome was 30-day mortality. The secondary outcomes included 1-year mortality and composite kidney outcome assessed using the postoperative estimated glomerular filtration rate.

Inclusion Criteria:

• surgery patients

Exclusion Criteria:

• kidney or urinary surgery
• missing urinalysis results
• dipstick proteinuria indicated a value of "≥ trace" at least once preoperatively
• with dialysis, end-stage renal disease, or with urinary tract infection at baseline
• missing follow-up information

Using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, participants aged ≥16 years who underwent surgery from January 2000 to December 2022 were included.