Smoking and Total Mortality

The certainty of evidence is upgraded by large magnitude of effect and by a dose-response gradient.

A longitudinal population-based, nationally representative health survey 1 investigating in the US the mortality risks associated with current and former use of cigars, pipes, and cigarettes included 357 420 persons (51 150 deaths). Exclusive current cigarette smokers (HR 1.98; 95% CI 1.93 to 2.02) and exclusive current cigar smokers (HR 1.20; 95% CI 1.03 to1.38) had higher all-cause mortality risks than never tobacco users. Exclusive current cigarette smokers (HR 4.06; 95% CI 3.84 to 4.29), exclusive current cigar smokers (HR 1.61; 95% CI 1.11 to 2.32), and exclusive current pipe smokers (HR 1.58; 95% CI 1.05 to 2.38) had an elevated risk of dying from a tobacco-related cancer (including bladder, esophagus, larynx, lung, oral cavity, and pancreas). Among current nondaily cigarette users, statistically significant associations were observed with deaths from lung cancer (HR 6.24; 95% CI 5.17 to 7.54), oral cancer (HR 4.62; 95% CI 1.84 to 11.58), circulatory death (HR 1.43; 95% CI 1.30 to 1.57), cardiovascular death (HR 1.24; 95% CI 1.11 to 1.39), cerebrovascular death (stroke) (HR 1.39; 95% CI 1.12 to 1.74), and chronic obstructive pulmonary disease (HR 7.66; 95% CI 6.09 to 9.64) as well as for daily smokers.

In a prospective study 2, 1.2 million UK women were asked at entry whether they were current or ex-smokers, and how many cigarettes they currently smoked and resurveyed postally about 3 and 8 years later. All were followed through national mortality records (mean 12 woman-years, SD 2). For 12-year mortality, those smoking at baseline had a mortality rate ratio of 2.76 (95% CI 2.71 to 2.81) compared with never-smokers, even though 44% of the baseline smokers who responded to the 8-year resurvey had by then stopped smoking. Mortality was tripled, largely irrespective of age, in those still smoking at the 3-year resurvey (RR 2.97, 95% CI 2.88 to 3.07).

In another prospective cohort study 3 of 290 215 adults data were gathered with a questionnaire assessing lifetime cigarette smoking history. Hazard ratios (HRs) and 95% CIs were determined for all-cause mortality and cause-specific mortality through the end of 2011. 159 (9.1%) and 1493 (22.5%) of these individuals reported consistently smoking fewer than 1 or 1 to 10 cigarettes per day (CPD) in each age period that they smoked, respectively. Relative to never smokers, consistent smokers of fewer than 1 CPD (HR 1.64, 95% CI 1.07 to 2.51) and 1 to 10 CPD (HR 1.87, 95% CI 1.64 to 2.13) had a higher all-cause mortality risk. Associations were similar in women and men for all-cause mortality and were observed across a range of smoking-related causes of death, with an especially strong association with lung cancer (HR 9.12, 95% CI 2.92 to 28.47, and HR 11.61, 95% CI 8.25 to 16.35 for <1 and 1-10 CPD, respectively). Former smokers had progressively lower risks with younger age at cessation. For example, the HRs for consistent smokers of fewer than 1 and 1 to 10 CPD who quit at 50 years or older were 1.44 (95% CI 1.12 to 1.85) and 1.42 (95% CI 1.27 to -1.59), respectively.

A prospective study 4 of 204 953 individuals aged≥45 years assessed tobacco smoking to mortality in Australia. Overall, 5 593 deaths accrued during follow-up (874 120 person-years; mean: 4.26 years); 7.7% of participants were current smokers and 34.1% past smokers at baseline. Compared to never-smokers, the adjusted RR (95% CI) of mortality was 2.96 (2.69 to 3.25) in current smokers and was similar in men (RR 2.82, 95% CI (2.49 to 3.19) and women (RR 3.08, 95% CI 2.63 to 3.60) and according to birth cohort. Mortality RRs increased with increasing smoking intensity, with around two- and four-fold increases in mortality in current smokers of ≤14 (mean 10/day) and ≥25 cigarettes/day, respectively, compared to never-smokers. Among past smokers, mortality diminished gradually with increasing time since cessation and did not differ significantly from never-smokers in those quitting prior to age 45. Current smokers are estimated to die an average of 10 years earlier than non-smokers.

References

• Christensen CH, Rostron B, Cosgrove C et al. Association of Cigarette, Cigar, and Pipe Use With Mortality Risk in the US Population. JAMA Intern Med 2018;178(4):469-476. [PubMed]
• Pirie K, Peto R, Reeves GK et al. The 21st century hazards of smoking and benefits of stopping: a prospective study of one million women in the UK. Lancet 2013;381(9861):133-41. [PubMed]
• Inoue-Choi M, Liao LM, Reyes-Guzman C et al. Association of Long-term, Low-Intensity Smoking With All-Cause and Cause-Specific Mortality in the National Institutes of Health-AARP Diet and Health Study. JAMA Intern Med 2017;177(1):87-95. [PubMed]
• Banks E, Joshy G, Weber MF et al. Tobacco smoking and all-cause mortality in a large Australian cohort study: findings from a mature epidemic with current low smoking prevalence. BMC Med 2015;13():38. [PubMed]