Table 1.

The Tromsø Study^a

	Age group (years)	Men				Women
		Attendees		Non-attendees		Attendees		Non-attendees
		n (%)	Age, mean (years)	n	Age, mean (years)	n (%)	Age, mean (years)	n	Age, mean (years)
Tromsø 1 (1974)	20–49	6595 (74.4)	33.7	2271	30.2	–
Tromsø 2 (1979–80)	20–54b	8477 (73.8)	35.7	3004	31.3	8144 (81.8)	32.9	1815	28.7
Tromsø 3 (1986–87)	12–67c	10 963 (71.7)	37.6	4318	32.5	10 863 (79.0)	35.4	2882	29.9
Tromsø 4 (1994–95)	25–97	12 865 (69.6)	46.6	5615	40.9	14 293 (74.9)	47.2	4785	44.1
Tromsø 5 (2001–02)	30–89	3511 (75.7)	59.9	1125	46.0	4619 (80.8)	59.4	1098	50.8
Tromsø 6 (2007–08)	30–87	6054 (62.9)	57.5	3571	54.5	6930 (68.4)	57.5	3207	58.1

^aExamination year, age groups included and attendance rate. Number of subjects (n), mean age in the six different surveys according to gender and attendance.

^b20–49 years in women.

^cAll men aged 20–61 years and women aged 20–56 years were invited (see text).