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Median age at baseline was 75 years (Table 1Table 1) and was similar among never, former, and current smokers. Six percent of the cohort were current smokers, and almost 56% were former smokers (Table 1Table 1). Of the former smokers, 90% reported quitting prior to age 60 years. Patterns of smoking differed by sex: Men were less likely to be never smokers (31.2% vs 48.0% of women), and male smokers reported smoking more than female smokers (mean pack years of smoking, 18.2 [SD=23.3] for men and 11.6 [SD=18.9] for women). Male smokers were also more likely to start smoking before age 15 years (19.0% vs 9.5% of female smokers).

Table 1 Characteristics of NIH-AARP Participants, Aged Over 70y, Who Completed the 2004–2005 Questionnaire Stratified by Smoking Status Characteristic Never smokers Former smokers Current smokers Quit <60y Quit ≥60y n (%) 60,973 (38.1) 81,137 (50.7) 8,412 (5.3) 9,591 (6.0) Demographic variables Mean age (y) 74.7 (2.6) 74.6 (2.6) 74.9 (2.6) 74.6 (2.6) Sex (% female) 51.6 31.5 43.1 50.9 Education level (% college or higher) 75.0 77.6 73.5 70.7 Race (% non-Hispanic white) 92.1 93.9 93.7 92.1 Marital status (% married) 66.6 74.1 62.6 53.5 Overall health (% fair/poor) 13.2 16.6 25.3 24.6 Age at initiation (% started 15–19y) 0.0 19.0 21.0 22.0 Lifetime pack-years — 21.0 (20.0) 44.6 (27.6) 42.3 (25.6) Pack-years prior to 70y — 21.0 (20.0) 44.6 (27.6) 38.8 (23.8) Alcohol use (grams/day) 0.5 (1.7) 1.1 (2.7) 1.3 (3.1) 1.4 (3.5) BMI (kg/m2) 26.5 (4.9) 26.9 (4.6) 26.9 (4.9) 25.2 (4.7) Total activity time (minutes/day) 25.2 (32.9) 27.2 (34.3) 21.3 (29.6) 17.1 (27.9) Mortality, n (%) All cause 7,378 (12.1) 14,957 (18.4) 2,343 (27.9) 3,175 (33.1) Lung cancer 180 (0.3) 1,464 (1.8) 375 (4.5) 630 (6.6) Other smoking cancer 357 (0.6) 821 (1.0) 88 (1.1) 148 (1.5) Respiratory infection 257 (0.4) 1,299 (1.6) 394 (4.7) 540 (5.6) Heart disease 2,072 (3.4) 4,015 (5.0) 565 (6.7) 722 (7.5) Stroke 455 (0.8) 698 (0.9) 84 (1.0) 132 (1.4) Previous condition, n (%) Hypertension 33,502 (58.2) 47,300 (61.5) 4,930 (62.0) 5,070 (55.9) COPD 2,567 (4.8) 7,390 (5.2) 1,866 (24.7) 2,233 (25.7) Cancer 17,537 (32.3) 26,263 (36.1) 2,698 (35.4) 2,942 (33.4) Stroke 2,227 (4.1) 3,635 (4.9) 534 (7.1) 558 (6.4) Heart attack 10,408 (18.8) 20,087 (27.0) 2,203 (28.8) 1,970 (22.6) View Table in HTML

Current smokers and former smokers who quit between age 60 and 70 years were more likely to report fair/poor health and COPD than never smokers and former smokers who quit before age 60 years (Table 1Table 1). However, the distribution of other previous conditions varied across categories of lifetime smoking use. For example, 22.6% of current smokers reported a previous heart attack, compared with 28.8% of former smokers who quit between age 60 and 70 years, 27.0% of former smokers who quit prior to age 60 years, and 18.8% of never smokers, with similar patterns observed for a prior diagnosis of cancer, stroke, or hypertension.

Mean follow-up time was 6.4 years (range, 0.03–7.23 years). There was high mortality during follow-up, with 25,146 participants dying (15.7% of the cohort). Differences in mortality were observed by baseline smoking status (Table 2Table 2): 12.1% of never smokers died, whereas 16.2%, 19.7%, 23.9%, and 27.9% of former smokers who quit between ages 30–39, 40–49, 50–59, and 60–69 years died, respectively. The highest mortality was observed in current smokers, of whom 33.1% died. In multivariable-adjusted models, current smokers were more than three times more likely to die than never smokers (HR=3.18, 95% CI=3.04, 3.31).

Table 2 Age at Smoking Cessation and Mortality in Participants of the NIH-AARP Study Aged Over 70y Cause of death Smoking status Current (n=9,591) Quit 60–69y (n=8,412) Quit 50–59y (n=19,046) Quit 40–49y (n=21,424) Quit 30–39y (n=21,553) Never (n=60,973) Death from all causes Number of deaths (%) 3,175 (33.1) 2,343 (27.9) 4,553 (23.9) 4,214 (19.7) 3,483 (16.2) 7,378 (12.1) Rate per 100,000 (95% CI) 5,900.22 (5,690.38, 6,110.06) 4,588.35 (4,402.06, 4,774.65) 3,821.28 (3,710.15, 3,932.41) 3,017.59 (2,925.23, 3,109.96) 2,349.6 (2,268, 2,431.2) 1,884.4 (1,840.46, 1,928.34) Multivariable-adjusted hazard ratio (95% CI) 1.00 (ref) 0.77 (0.73, 0.81) 0.64 (0.61, 0.67) 0.51 (0.49, 0.54) 0.41 (0.39, 0.43) 0.32 (0.30, 0.33) Death from lung cancer Number of deaths (%) 630 (6.6) 375 (4.5) 630 (3.3) 441 (2.1) 260 (1.2) 180 (0.3) Rate per 100,000 (95% CI) 1,155.63 (1,063.28, 1,247.98) 741.47 (666.21, 816.72) 528.9 (487.55, 570.25) 318.33 (288.21, 348.44) 177.09 (154.56, 199.62) 44.8 (38.1, 51.49) Multivariable-adjusted hazard ratio (95% CI) 1.00 (ref) 0.64 (0.56, 0.73) 0.46 (0.41, 0.51) 0.28 (0.25, 0.32) 0.16 (0.14, 0.19) 0.04 (0.03, 0.05) Death from other smoking-related cancers Number of deaths (%) 205 (2.1) 149 (1.8) 346 (1.8) 361 (1.7) 332 (1.5) 619 (1.0) Rate per 100,000 (95% CI) 282.13 (235.74, 328.52) 175.63 (138.82, 212.44) 198.92 (173.62, 224.21) 159.19 (138.19, 180.19) 123.69 (105.95, 141.44) 94.04 (84.1, 103.98) Multivariable-adjusted hazard ratio (95% CI) 1.00 (ref) 0.72 (0.60, 0.87) 0.73 (0.62, 0.84) 0.66 (0.57, 0.77) 0.57 (0.49, 0.66) 0.46 (0.40, 0.53) Death from respiratory infection Number of deaths (%) 540 (5.6) 394 (4.7) 602 (3.2) 369 (1.7) 206 (1.0) 257 (0.4) Rate per 100,000 (95% CI) 984.85 (899.87, 1,069.83) 769.42 (693.25, 845.6) 510.72 (469.87, 551.58) 269.6 (241.68, 297.52) 138.54 (118.74, 158.33) 64.2 (56.16, 72.23) Multivariable-adjusted hazard ratio (95% CI) 1.00 (ref) 0.78 (0.68, 0.89) 0.52 (0.46, 0.58) 0.28 (0.25, 0.32) 0.16 (0.13, 0.18) 0.07 (0.06, 0.08) Death from heart disease Number of deaths (%) 722 (7.5) 565 (6.7) 1,210 (6.4) 1,159 (5.4) 939 (4.4) 2,072 (3.4) Rate per 100,000 (95% CI) 1,358.68 (1,257.43, 1,459.94) 1,104.7 (1,013.36, 1,196.04) 1,010.01 (953.03, 1,066.98) 817.19 (769.55, 864.83) 623.14 (581.55, 664.74) 540.09 (516.36, 563.83) Multivariable-adjusted hazard ratio (95% CI) 1.00 (ref) 0.79 (0.71, 0.89) 0.73 (0.66, 0.80) 0.60 (0.55, 0.66) 0.46 (0.42, 0.51) 0.39 (0.35, 0.42) Death from stroke Number of deaths (%) 132 (1.4) 84 (1.0) 178 (0.9) 189 (0.9) 180 (0.8) 455 (0.8) Rate per 100,000 (95% CI) 246.14 (203.22, 289.07) 163.74 (128.64, 198.83) 149.86 (127.82, 171.91) 138.72 (118.63, 158.81) 124.3 (105.26, 143.34) 111.47 (100.97, 121.96) Multivariable-adjusted hazard ratio (95% CI) 1.00 (ref) 0.66 (0.50, 0.86) 0.61 (0.49, 0.77) 0.57 (0.45, 0.71) 0.52 (0.42, 0.65) 0.45 (0.37, 0.55) View Table in HTML

Relative to current smokers, the risk of all-cause mortality was lowest among never smokers (HR=0.32, 95% CI=0.30, 0.33) and former smokers who quit at age 30–39 years (HR=0.41, 95% CI=0.39, 0.43). The benefits of quitting at an older age were lower, although still substantial, with observed HRs of 0.51 (95% CI=0.49, 0.54), 0.64 (95% CI=0.61, 0.67), and 0.77 (95% CI=0.73, 0.81) for quitting between ages 40–49, 50–59, and 60–69, respectively. Similar findings were observed for each examined smoking-related cause of death. Adjustment for age at initiation and maximum smoking intensity had little effect on these risk estimates (data not shown).

Mortality rates were lower for women than men at each level of smoking use; however, the HRs for smoking were similar in both sexes (Figure 1Figure 1, Appendix Table 1Appendix Table 1, available online). HRs were similar among participants who died in the first 5 versus 6–7 years of follow-up, and participants who were aged ≤75 or >75 years at study baseline. For participants who quit smoking in their 60s, the protective effect of smoking cessation on mortality was slightly stronger when restricted to participants who had not been previously diagnosed with cancer, COPD, stroke, or heart disease. This was most evident for death from heart attack, stroke, and respiratory infection.

Associations with time since smoking cessation were examined (Appendix Table 2Appendix Table 2, available online). Participants who reported quitting smoking 1–4 years before baseline were more likely to report being in fair/poor health (28.8%) than current smokers (23.7%), former smokers who quit 5–10 years before baseline (23.8%), or former smokers who quit >10 years before baseline (16.6%), suggesting that disease symptoms were one of the main contributors to quitting in this age group. Relative to current smokers, former smokers who quit >10 years before baseline had substantially reduced risk of all-cause mortality (HR=0.66, 95% CI=0.64, 0.69). Similar findings were observed for each examined smoking-related cause of death. By contrast, former smokers who quit 5–10 years before baseline had similar mortality risks as current smokers (HR=1.07, 95% CI=1.01, 1.14), whereas former smokers who quit 1–4 years before baseline had higher risks than current smokers (HR=1.35, 95% CI=1.26, 1.46). There were similar patterns for death from lung cancer, other smoking-related cancers, and respiratory disease.

Among current smokers, age at smoking initiation and cigarettes smoked per day after age 70 years were examined (Figure 1Figure 1, Table 3Table 3). There was a strong inverse association of mortality with age at initiation. Relative to participants who started smoking after age 30 years, HRs for all-cause mortality for participants who started smoking between ages 25–29, 20–24, 15–19, and <15 years were 1.36 (95% CI=1.09, 1.71), 1.44 (95% CI=1.21, 1.72), 1.59 (95% CI=1.34, 1.89), and 1.74 (95% CI=1.45, 2.08), respectively. HRs were similar across each examined cause of mortality, although the number of deaths in some categories was low, resulting in wide CIs.

Table 3 Age at Smoking Initiation and Mortality Among Current Smokers Aged Over 70y, in the NIH-AARP Study Cause of death Age at initiation (y) <15 (n=2,105) 15–19 (n=3,847) 20–24 (n=2,485) 25–29 (n=526) 30+ (n=628) Death from all causes Number of deaths (%) 791 (37.6) 1,328 (34.5) 757 (30.5) 154 (29.3) 145 (23.1) Rate per 100,000 (95% CI) 6,563.23 (6,053.34, 7,073.11) 5,862.03 (5,546.16, 6,177.89) 5,306.42 (4,916.89, 5,695.95) 5,030.64 (4,220.65, 5,840.64) 3,705.65 (3,061.08, 4,350.22) Multivariable-adjusted hazard ratio (95% CI) 1.74 (1.45, 2.08) 1.59 (1.34, 1.89) 1.44 (1.21, 1.72) 1.36 (1.09, 1.71) 1.00 (ref) Death from lung cancer Number of deaths (%) 154 (7.3) 281 (7.3) 146 (5.9) 28 (5.3) 21 (3.3) Rate per 100,000 (95% CI) 1,237.49 (1,022, 1,452.98) 1,244.19 (1,098.49, 1,389.89) 1,033.95 (861.4, 1,206.51) 931.48 (580.59, 1,282.37) 480.81 (265.17, 696.45) Multivariable-adjusted hazard ratio (95% CI) 2.35 (1.48, 3.73) 2.36 (1.51, 3.68) 1.92 (1.22, 3.04) 1.69 (0.96, 2.98) 1.00 (ref) Death from other smoking-related cancers Number of deaths (%) 52 (2.5) 87 (2.3) 45 (1.8) 11 (2.1) 10 (1.6) Rate per 100,000 (95% CI) 383.78 (267.20, 500.37) 382.91 (302.31, 463.51) 326.19 (228.30, 424.09) 375.27 (149.66, 600.88) 280.22 (94.26, 466.19) Multivariable-adjusted hazard ratio (95% CI) 1.17 (0.66, 2.08) 1.25 (0.73, 2.15) 1.04 (0.59, 1.83) 1.00 (0.47, 2.14) 1.00 (ref) Death from respiratory infection Number of deaths (%) 164 (7.8) 230 (6.0) 107 (4.3) 22 (4.2) 17 (2.7) Rate per 100,000 (95% CI) 1,450.07 (1,203.78, 1,696.37) 1,023.19 (890.75, 1,155.64) 706.26 (568.18, 844.35) 679.49 (390.51, 968.47) 435.94 (214.9, 656.98) Multivariable-adjusted hazard ratio (95% CI) 3.50 (2.11, 5.79) 2.52 (1.54, 4.12) 1.81 (1.09, 3.02) 1.70 (0.91, 3.21) 1.00 (ref) Death from heart disease Number of deaths (%) 184 (8.7) 274 (7.1) 179 (7.2) 38 (7.2) 47 (7.5) Rate per 100,000 (95% CI) 1,534.99 (1,286.15, 1,783.83) 1,206.9 (1,063.69, 1,350.11) 1,267.59 (1,076.41, 1,458.78) 1,257.97 (850.48, 1,665.46) 1,304.16 (906.02, 1,702.3) Multivariable-adjusted hazard ratio (95% CI) 1.21 (0.88, 1.68) 0.99 (0.72, 1.35) 1.04 (0.75, 1.43) 1.03 (0.67, 1.58) 1.00 (ref) Death from stroke Number of deaths (%) 21 (1.0) 63 (1.6) 31 (1.3) 11 (2.1) 6 (1.0) Rate per 100,000 (95% CI) 170.93 (89.42, 252.43) 274.11 (206.26, 341.96) 207.3 (132.06, 282.54) 357.37 (142.11, 572.63) 151.61 (23.32, 279.89) Multivariable-adjusted hazard ratio (95% CI) 1.26 (0.50, 3.17) 1.95 (0.84, 4.51) 1.54 (0.64, 3.69) 2.44 (0.90, 6.59) 1.00 (ref) View Table in HTML

Finally, current and former smokers with greater cumulative exposure to cigarettes had higher mortality risks than those with a lower exposure (Appendix Table 3Appendix Table 3, available online). Furthermore, those who smoked more cigarettes per day after age 70 years had higher mortality risk than those who smoked fewer cigarettes per day at this age (Appendix Table 4Appendix Table 4, available online). Notably, those who smoked 31–40 cigarettes per day had the highest risk of mortality, with lower risk observed in those who smoked ≥40 cigarettes per day.