Table 4. Number of deaths from all-cause and lung cancer and relative risk by changes in smoking status and reasons for quitting smoking.

Follow-up period/Changes in smoking status		Number of participants	Person-years	All-cause				Lung cancer
				Number of deaths	Crude mortality	Relative riskf	(95% CI)	Number of deaths	Crude mortality	Relative riskf	(95% CI)
Period 2a
NS→NS		50,149	246,874	1,055	427	Reference	—	58	23	Reference	—
FS→FS		9,437	45,765	450	983	1.34	(1.17–1.54)	41	90	1.77	(1.08–2.90)
CS→FS	Allc	3,537	16,880	257	1,522	2.40	(2.05–2.80)	39	231	5.45	(3.34–8.90)
	Illnessd	951	4,383	119	2,715	3.54	(2.87–4.36)	15	342	6.55	(3.44–12.47)
	Otherse	1,367	6,616	63	952	1.53	(1.17–2.00)	16	242	5.97	(3.18–11.22)
CS→CS		18,681	90,825	899	990	1.78	(1.57–2.00)	109	120	3.36	(2.19–5.15)
Period 3b
NS→NS		44,363	217,093	1,312	604	Reference	—	64	29	Reference	—
FS→FS		10,742	51,494	724	1,406	1.42	(1.26–1.60)	51	99	2.11	(1.33–3.35)
CS→FS	Allc	3,378	16,014	312	1,948	2.14	(1.86–2.47)	44	275	6.59	(4.38–9.91)
	Illnessd	1,387	6,428	191	2,971	2.95	(2.48–3.50)	24	373	7.90	(4.55–13.73)
	Otherse	1,326	6,416	75	1,169	1.43	(1.12–1.83)	12	187	5.04	(2.55–9.94)
CS→CS		13,458	64,696	881	1,362	1.96	(1.75–2.20)	131	202	6.49	(4.08–10.31)

CI, confidence interval; CS, current smoker; FS, former smoker; NS, never smoker.

^aPeriod 2 used smoking status from Q00 and Q05, starting at Q05 survey and followed up for five years.

^bPeriod 3 used smoking status from Q05 and Q10, starting at Q10 survey and followed up for five years.

^cAll refers to the participants wo quit smoking during two adjacent surveys.

^dIllness refers to the participants who quit smoking due to illness during two adjacent surveys.

^eOthers refers to the participants who quit smoking due to other reasons during two adjacent surveys.

^fAdjusted for sex, age, and public health center area.