Table 2.

Mean differences in cross-sectional cognitive composite score between participants having major, minor, knee and hip replacement, or other surgeries and the group not exposed to surgery, by APOEε4 status

	Differences in cognitive score (95% CI)*
Surgical procedure groups	n	APOEε4 non-carriers	N	APOEε4 carriers
No surgery	673	Reference	305	Reference
Any surgery	1340	−0.04(−0.45 to 0.38)	618	0.04(−0.60 to 0.69)	p=0.76
Major†	370	−0.04(−0.45 to 0.38)	179	0.04(−0.60 to 0.69)	p=1.00
Minor	412	0.01(−0.41 to 0.40)	193	−0.32(−0.88 to 0.24)	p=0.54
Knee/hip replacement	32	−0.33(−1.47 to 0.81)	14	0.56(−0.82 to 1.93)	p=0.67
Other	526	0.12(−0.36 to 0.39)	232	−0.07 (−0.64 to 0.50)	p=0.86

^*Multiple linear regression analyses, adjusted for sex and age at intake examination.

^†Including cardiac, thoracic, laparotomy, central and peripheral vascular and fracture surgeries. P-values are for interaction between APOE and surgery. APOE = apolipoprotein