Retrospective analysis cognitive function changes in elderly depressive patients after gastrointestinal tumor surgery and exploration of cholinergic mechanism

Table 2 Multivariate logistic regression analysis variable assignment

Independent variable	Coding instruction	Variable type	Reference group/unit
Age	Actual value (years)	Continuous	Per 1-year increase
Pre-operative HAMD score	Actual value (points)	Continuous	Per 1-point increase
Operative time	Actual value (minute)	Continuous	Per 10-minute increase
Intra-operative blood loss	Actual value (mL)	Continuous	Per 50-mL increase
Intra-operative anticholinergic use	0 = no, 1 = yes	Binary	Reference: No use (0)
24-hour post-operative VAS score	Actual value (points)	Continuous	Per 1-point increase
Post-operative infection	0 = no, 1 = yes	Binary	Reference: No infection (0)
Pre-operative IL-6	Actual value (pg/mL)	Continuous	Per 1 pg/mL increase
Post-operative IL-6	Actual value (pg/mL)	Continuous	Per 1 pg/mL increase
IL-6 change rate	(Post-operative - pre-operative)/pre-operative × 100%	Continuous	Per 10% increase
Pre-operative TNF-α	Actual value (pg/mL)	Continuous	Per 1 pg/mL increase
Post-operative TNF-α	Actual value (pg/mL)	Continuous	Per 1 pg/mL increase
TNF-α change rate	(Post-operative - pre-operative)/pre-operative × 100%	Continuous	Per 10% increase
Pre-operative CHE activity	Actual value (U/L)	Continuous	Per 100 U/L increase
Post-operative CHE activity	Actual value (U/L)	Continuous	Per 100 U/L increase
CHE change rate	(Post-operative - pre-operative)/pre-operative × 100%	Continuous	Per 1% increase

HAMD: Hamilton Depression Rating Scale; VAS: Visual Analog Scale; IL-6: Interleukin-6; TNF-α: Tumor necrosis factor-alpha; CHE: Cholinesterase.