Table 3.

Differences in the Perceived Ages of the Face and Surroundings Within Twin Pairs

	Older Looking Twin Dies First (SD)	Older Looking Twin Dies Second (SD)	Difference Between Groups (95% CI)
Seven years of follow-up, number of subjects	48	35	83
Difference in perceived ages*	4.7 (2.6)	2.9 (2.4)	1.7 (0.6 to 2.8)
Difference in face perceived ages†	2.8 (2.9)	1.4 (2.4)	1.4 (0.3 to 2.6)
Difference in surrounding perceived ages‡	1.8 (2.6)	1.6 (2.3)	0.3 (−0.8 to 1.4)
Seven to 12 years of follow-up, number of subjects	32	25	57
Difference in perceived ages*	3.0 (2.2)	3.1 (1.9)	−0.01 (−1.0 to 1.2)
Difference in face perceived ages†	1.5 (2.4)	1.6 (2.2)	−0.1 (−1.3 to 1.2)
Difference in surrounding perceived ages‡	1.5 (2.2)	1.6 (2.3)	−0.1 (−1.3 to 1.1)

Notes: Analyses based on twin pairs where at least one had died before 31st January 2008 (7 years of follow-up) and repeated for twin pairs still alive 7 years after the photograph were taken and where at least one had died before 31st December 2013 (7–12 years of follow-up). CI = confidence interval; SD = standard deviation.

*Mean of the difference in the perceived ages of the original photographs O^faceO^surr − Y^faceY^surr.

^†Mean of the difference in the perceived ages of the twins’ faces when controlling for the surroundings, that is, mean of O^faceO^surr − Y^faceO^surr & O^faceY^surr − Y^faceY^surr.

^‡Mean of the difference in the perceived ages of the twins’ surroundings when controlling for the face, that is, mean of O^faceO^surr − O^faceY^surr & Y^faceO^surr − Y^faceY^surr. Note, the sum of ^† and ^‡ equals * bar rounding errors.