Table 3.

Smoking Characteristics of Spouses Enrolled in the Atherosclerosis Risk in Communities Study, 1986–1998^a

Baseline Characteristic	Correlation Between Spouses	Individual Data		Paired Data
		Mean (SD) for Husbands	Mean (SD) for Wives	Mean Difference (SD)b	P Valuec
Age started smoking, yearsd,e	0.10	17.5 (3.9)	19.8 (5.5)	−2.3 (6.4)	<0.001
Age stopped smoking, yearsf	0.42	42.1 (10.5)	39.5 (11.1)	2.6 (11.6)	<0.001
No. of years smokedd	0.29	29.5 (11.7)	26.2 (11.4)	3.4 (13.9)	<0.001
No. of cigarettes per dayd	0.23	23.3 (12.0)	16.5 (9.9)	6.8 (13.8)	<0.001
No. of pack-yearsd	0.28	35.4 (23.9)	23.4 (17.7)	12.0 (25.1)	<0.001

Abbreviation: SD, standard deviation.

^a Sample sizes vary because these analyses were limited to spouse pairs in which both individuals reported these characteristics.

^b Mean difference between husbands and wives.

^c P values based on paired t test.

^d Among pairs in which both spouses were either former or current smokers.

^e To account for improbable values, we set the lowest age at which a subject could have started smoking to 7 years.

^f Among pairs in which both members were former smokers.