Table 3. Number of participants in the JASTIS study (Cohort 4).

Characteristics at baseline	Wave 1	Wave 2
	February 24 to March 13, 2017	January 26 to March 20, 2018
	Number of participants	Respondents of follow-up survey (%)
Cohort 4 (additional new baseline from 2017): designation only for sex and age	5,897	4,641 (78.7)
men, 15–19 years old	144	60 (41.7)
men, 20–29 years old	582	398 (68.4)
men, 30–39 years old	657	528 (80.4)
men, 40–49 years old	628	543 (86.5)
men, 50–59 years old	462	411 (89.0)
men, 60–69 years old	467	428 (91.7)
women, 15–19 years old	148	54 (36.5)
women, 20–29 years old	628	445 (70.9)
women, 30–39 years old	628	473 (75.3)
women, 40–49 years old	629	514 (81.7)
women, 50–59 years old	462	383 (82.9)
women, 60–69 years old	462	404 (87.5)

Response rates in parentheses. Numbers of participants after exclusion of cases with data discrepancies.