Figures
- Fig. 1—
Forced expiratory volume in one second (FEV1) decline expressed as a percentage of the decline in 100% of continuing smokers in those studies for which this measure was available. All but one of these studies show a relative reduction in FEV1 decline.
- Fig. 2—
Relative risk (RR)/hazard ratio (HR)/mortality rate (MR) ratio of mortality due to chronic obstructive pulmonary disease after smoking cessation (▪) compared with continuing smoking (▴; RR 1.0).
- Fig. 3—
Risk of all-cause mortality after smoking cessation expressed as a percentage of the risk in 100% of continuing smokers. The majority of these studies show a reduction in risk. #: females alone.
Tables
- Table 1—
Effects of smoking cessation on chronic obstructive pulmonary disease(COPD) morbidity
First author [ref.] Study Subjects n Age yrs Follow-up# yrs ΔFEV1 mL·yr−1 Summary effect Comments Clinically based Fletcher 15 London, UK 792 working M 30–59 8 -80 (heavy smokers), -62 (light smokers), -37 (ex-smokers) with mild obstruction + Spirometry was performed every 6 months Hughes 13 London, UK 56 M with emphysema 45–63 3–13 -58 (smokers), -15 (ex-smokers; p<0.001) + Greater VC decline in smokers than ex-smokers Anthonisen 12 NIH (USA) 985 COPD Pts (FEV1 < 60% pred) 53–68 3 -44 (smokers, ex-smokers) 0 Spirometry was performed every 3 months. Postma 14 Groningen, NL 81 moderate–severe COPD Pts 39–57 2–21 -85 (smokers), -49 (ex-smokers; p<0.05) + Kessler 20 Strasbourg, FR 64 moderate–severe COPD Pts 57–72 2.5 ND 0 No difference in COPD exacerbation hospitalisation risk for ex- and current smokers (univariate analysis) Garcia-Aymerich 21 Barcelona, ES 86 Cs (hospitalised, COPD exacerbation); 86 C (stable COPD) 60–78 Cross-sectional ND - Current smoking associated with less hospitalisation than ex-smoking (OR 0.30) Kanner 18 LHS (USA) 5887 mild–moderate COPD Pts 35–60 5 Greater decline in smokers, but not ex-smokers, with more than one LRTI annually (p = 0.0001) + Ex-smokers had fewer self-reported LRTI episodes than current smokers (p = 0.0003) Anthonisen 8 LHS (USA) 5887 mild–moderate COPD Pts 35–60 11 -66 (M smokers), -30 (M ex-smokers), -54 (F smokers), -22 (F ex-smokers) + Anthonisen 17 LHS (USA) 5887 mild–moderate COPD Pts 35–60 5 ND 0 No difference between treatment groups or smokers versus ex-smokers in hospitalisation rate for respiratory causes Makris 19 Heraklion, GR 102 moderate–severe COPD Pts 60–70 3 74 (decline faster in current than ex-smokers; p = 0.004) + Both current and ex-smokers with frequent COPD exacerbations had faster FEV1-decline Population-based Tashkin 27 Los Angeles, CA, USA 2401 (Gen Pop sample) 25–64 5 Same unquantified decline in current/ex-smoking M with COPD 0/+ Ex-smoking F with COPD had smaller declines than current smokers (p<0.002) Sherrill 28 Tucson, AZ, USA 3805 M/F (random cluster) ≥18 17 M quitters in lowest FEV1/FVC quartile had similar decline to current smokers 0/+ F quitters in the lowest FEV1/FVC quartile had slower decline than current smokers Burchfiel 22 Honolulu Heart Program (USA) 4451 Japanese–American M 45–68 6 -18.8 (quitters with COPD, n = 64), -31.4 (smokers with COPD, n = 199; p = 0.024) + Adjusted for baseline FEV1 and amount smoked Pelkonen 23 Helsinki, FI 1711 M from two rural areas 40–59 15 -62.9 (smokers), -48.4 (ex-smokers; p<0.001) in lowest FEV0.75 tertile + Godtfredsen 29 Copenhagen, DK 19709 (Gen Pop sample, three pooled studies) 20–93 14 ND + Risk of hospitalisation for COPD lower in long-term ex-smokers (HR 0.30) and quitters (HR 0.53) than current smokers. LØkke 31 Copenhagen DK 8045 M/F from CCHS 30–60 25 ND + OR for developing COPD showed increasing trend with shorter duration of smoking cessation compared to never-smokers Mannino 25 Lexington, KY, USA 15536 M/F from ARIC study 44–66 3 ND + OR for rapid FEV1 decline not higher in ex- than never-smokers (1.0); OR in current smokers 1.3 (95% CI 1.2–1.5) Lindberg 24 Luleå, SE 1109 M/F with RS 36–67 10 -43/-35 (M/F smokers), -35/-27 (M/F ex-smokers; p<0.05) + Equal decline in never- and long-term ex-smokers; similar in quitters, re-starters and smokers Δ: change; FEV1: forced expiratory volume in one second; NIH: National Institutes of Health; NL: the Netherlands; FR: France; ES: Spain; LHS: Lung Health Study; GR: Greece; FI: Finland; DK: Denmark; SE: Sweden; M: male; Pt: patient; % pred: % predicted; Cs: cases; C: controls; Gen Pop: general population; CCHS: Copenhagen City Heart Study; ARIC: Atherosclerosis Risk in Communities; RS: respiratory symptoms; ND: not determined; LRTI: lower respiratory tract illness; FVC: forced vital capacity; FEV0.75: forced expiratory volume in 0.75 seconds; VC: vital capacity; OR: odds ratio; F: female; HR: hazard ratio; CI: confidence interval; +: ex-smokers/quitters showed benefits over current smokers; -: current smokers showed benefits over ex-smokers/quitters; 0: no difference between the two groups. #: after smoking cessation.
- Table 2—
Effects of smoking cessation on all-cause and chronic obstructive pulmonary disease (COPD) mortality
First author [ref.] Study Subjects n Follow-up# yrs Mortality outcome Summary effect Comments¶ Clinically based Kanner 33 USA 140 Utah COPD Pts 7–13 All-cause + In a case–control design (sex- and age-matched Pop), 12-yr survival probabilities were 86, 79 and 64% in never-, ex- and current smokers, respectively Postma 34 Groningen, NL 129 severe COPD Pts 18 All-cause + Pts were stratified according to bronchodilator reversibility; relative survival was higher in both current- and ex-smokers with greater reversibility; within each stratum, mortality was lower in ex- than current smokers Anthonisen 12 USA 985 COPD Pts aged 53–68 yrs 3 All-cause 0 Overall mortality was 23% (no difference between current and ex-smokers) Hersh 36 USA 139 M severe COPD Pts aged <53 yrs 8 All-cause + Recent smoking status predicted mortality independently of the effects of lifetime smoking intensity; Pts who were ex-smokers at enrolment had better survival than smokers Anthonisen 17 LHS (USA) 5887 M/F smokers with early COPD (FEV1 55–90%) aged 35–60 yrs 5 CV ? There were 149 deaths during the study, caused largely by lung cancer and CVD; smoking cessation was associated with significant reductions in fatal CVD and coronary artery disease (too few COPD deaths for analysis) Anthonisen 35 USA 5887 M/F smokers with early COPD (FEV1 55–90%) aged 35–60 yrs 14.5 All-cause/ respiratory + After 14.5 yrs of follow-up, 731 patients had died; all-cause/respiratory MR was significantly lower in the special intervention group than in the usual care group Population-based Doll 56 UK 6194 F doctors 22 COPD + COPD MRs lower in ex- than current smokers (5.0 versus 10.5–32.0% (depending on amount smoked)) Rogot 32 USA ∼200000 M US veterans 16 COPD - to + COPD MRs higher in ex- than current smokers until 10 yrs after smoking cessation; thereafter lower MRs in ex- than current smokers (5.2 versus 12.1%) Carstensen 39 SE 25129 M 16 COPD + COPD MRs lower in ex- than current smokers (1.8 versus 1.9–5.3% (depending on amount smoked)) Marcus 41 Honolulu Heart Program (USA) 11136 Japanese–American M aged 45– 65 yrs at enrolment 20 COPD - to + Age-specific COPD MRs calculated at 5-yr intervals (1965–1984); after 10 yrs, MRs were higher in ex- than never- and current smokers; after ≥15 yrs, MRs were similar in never- and ex-smokers and lower than current smokers Tockman 42 USA 36110 M/F aged 35–84 yrs from private census Pop, examined in two 6-yr periods884 M with FEV1 measures(subset of above) All-cause/ COPD + M MRs due to both all causes and COPD were greater in ex- than never-smokers, but lower than MRs for current smokers (p<0.05); this applied to both time periods; same trend for F, but too few COPD deaths in ex-smokers for analysis. Normal FEV1: OR 1 (never-smokers), 1.75 (ex-smokers), 4.80 (current smokers); FEV1 <65% pred: OR 3.71 (never-smokers), 6.50 (ex-smokers), 17.80 (current smokers) Kuller 40 USA 12866 M from MRFIT 10 All-cause + Lower all-cause MR in ex- than current smokers Lange 45 DK 14214 M/F from CCHS 13 COPD + Compared to never-smokers, RR of COPD mortality in F ex-smokers was 11 (95% CI 2.5–53), current smokers 15 (95% CI 3.1–65); RR in M ex-smokers was 3.0 (95% CI 0.9–10), current smokers 6.4 (95% CI 2.0–20) Tverdal 43 NO 68000 M/F aged 35–49 yrs 13 (mean) All-cause + MRs for ex-smokers were intermediate to rates for never-smokers and smokers in both M and F Ben-Shlomo 38 UK 19018 M from Whitehall Study 18 COPD + Annual COPD MRs in never-, ex- and current smokers were 0.68, 0.95 and 2.2 per thousand study population Sunyer 44 ES 477 M from Barcelona aged >65 yrs 8 COPD 0 There were similar prevalences of self-reported respiratory illness in ex- and current smokers, and similar annual COPD MRs (6.0 versus 1.7 per thousand study population in never-smokers) Knuiman 48 AU 4277 M/F from the Busselton Health Study 20–26 All-cause - Per 10% decrease in FEV1, HR of all-cause mortality was 1.195 (95% CI 1.124–1.271) in ex-smokers and 1.167 (95% CI 1.108–1.229) in current smokers compared to never-smokers Engstrom 49 SE 291 smoking M born 1914 14 CV 0 CV MRs in current- and ex-smokers similar by FEV1 decline tertile Pelkonen 46 FI 1582 middle-aged M 30 All-cause/ COPD +/- Compared to current smokers, there was lower total mortality in never- smokers, long-term ex-smokers and quitters; RR of COPD mortality in ex-smokers was 2.51 (95% CI 0.65–9.70) compared to current smokers. Godtfredsen 47 DK 19732 M/F from 3 Copenhagen Pop studies 15.5 (mean) All-cause/COPD +/0 RR of COPD mortality after smoking cessation was 0.77 (95% CI 0.44–1.35) compared to current smokers; HR of all-cause mortality was 0.65 (95% CI 0.56–0.74); no comparison was made with never-smokers Mannino 50 USA 5542 M/F aged 25–74 yrs from NHANES 22 All-cause + HR of all-cause mortality in a multivariate adjusted model was 1.1 in ex-smokers (95% CI 0.9–1.4), 1.4 in current smokers (95% CI 1.2–1.7) Doll 37, 55 UK 34439 M UK doctors 40, 50 All-cause/ COPD + COPD MRs in ex-smokers were intermediate between those of never-smokers and current smokers; RR of all-cause mortality lower in ex- than current smokers (1.3 versus 2.2) Chinese Ho 51 HK 2030 M/F aged ≥70 yrs 3 All-cause/COPD 0/- Similar all-cause MRs in ex- and current smokers; higher rate of respiratory mortality in F ex-smokers (RR 2.3 (95% CI 1.3–4.0)) Lam 53 HK 1268 retired male cadres aged ≥60 yrs 12 COPD - RR of COPD mortality 2.13 (95% CI 0.55–8.30) in current smokers; 4.10 (95% CI 1.18–14.28) in ex-smokers Hsu 52 TW 4049 M/F aged ≥60 yrs 7 All-cause/ COPD 0 No differences between ex- and current smokers for all-cause or cause-specific mortality; this study does not meet standard quality criteria Lam 54 HK 56167 M/F aged ≥65 yrs 4 (mean) All-cause/ COPD +/- RR of all-cause mortality in ex-smokers was 1.39 (95% CI 1.23–1.56) in M and 1.43 (95% CI 1.25–1.64) in F; rates were significantly higher in current smokers; COPD MRs were higher in ex- than current smokers NL: the Netherlands; LHS: Lung Health Study; SE: Sweden; DK: Denmark; NO: Norway; ES: Spain; AU: Australia; FI: Finland; HK: Hong Kong; TW: Taiwan; Pt: patient; M: male; F: female; FEV1: forced expiratory volume in one second; Pop: population; MRFIT: Multiple Risk Factor Intervention Trial; CCHS: Copenhagen City Heart Study; NHANES: National Health and Nutrition Examination Survey; CV: cardiovascular; CVD: cardiovascular disease; MR: mortality rate; OR: odds ratio; % pred: % predicted; RR: relative risk; CI: confidence interval; HR: hazard ratio; +: risks lower in ex-smokers than smokers (benefits of quitting); -: risks higher in ex-smokers than smokers; 0: risks similar in ex-smokers and smokers; ?: results not clear. #: after smoking cessation; ¶: RR and HR of never-smokers (reference group) = 1.0.
