smoking cessation: 20-30yrs to normalize mortality rates

smoking cessation: 20-30yrs to normalize mortality rates
MG
Modest, Geoffrey (HMFP - Medicine)
​Modest, Geoffrey (HMFP - Medicine)​
Wed 1/24/2024 8:46 AM

A study based on the National Health Interview Survey (NHIS) from 1997-2018 assessed the association of smoking cessation and mortality from cardiovascular, cancer, and respiratory diseases (see smoking cessation 30 yrs til dec mortality JAMAIntMed2023 in dropbox or . doi:10.1001/jamainternmed.2023.6419. 

  

Details: 

-- 438,015 adults were included in NHIS, a cross-sectional household interview study, which included regular annual assessments of smoking rates (a questionnaire-based health survey with lots of questions about demographics, living situation, and health issues; very few questions about diet, a bit more about exercise, one question about stress but in the context of whether one participated in mindfulness-based stress reduction); this information was linked with the National Death Index 

--mean age 47, 56% female, 76501 Hispanic/63083 non-Hispanic Black/270183 non-Hispanic White/ 28248 other. 

-- causes of death, over 5.0 million person-years of followup: 

    -- cardiovascular: 11860 

    -- cancer: 10935 

    -- respiratory: 2060 

-- the researchers compared self-reported current and never smokers with former smokers who quit smoking by 10-year intervals: quitting for 1-9 yrs, 10-19yrs, 20-29yrs, at least 30yrs for cardiovascular, cancer and respiratory deaths at ages 25 to 89 years. 

-- they excluded  those with <5yrs of smoking or had quit smoking <1yr before recruitment; they also did not include those with pre-existing self-reported cardiovascular disease, cancer or respiratory disease 

-- cause-specific morality rates were adjusted for age, sex, education, race/ethnicity, and alcohol consumption 

  

Results: 

-- Comparing current vs never smokers: 

    -- cardiovascular deaths: >2-fold the rate, RR 2.30 (2.17-2.44) 

    -- cancer deaths: >3-fold the rate, RR 3.38 (3.19-3.58) 

    --respiratory deaths: >13-fold the rate, RR 13.21 (11.46-15.45) 

  

-- the following graphs depict the excess mortality avoided at various latencies after quitting smoking (eg, stopping for 1-9 years led to avoiding an estimated 64% of excess cardiovascular deaths, 53% of cancer deaths, and 57% of respiratory deaths) 

Commentary:

-- in 2021, the MMWR reported that 46 million US adults (18.7%) were currently using “any tobacco product”, with cigarettes being 11.5% of the adult population and e-cigarettes 4.5% ( https://www.cdc.gov/mmwr/volumes/72/wr/mm7218a1.htm?s_cid=mm7218a1_w ). Though this still represents 1 in 9 adults smoking, this number reflects a huge decrease since the pivotal Surgeon General’s 1965 anti-smoking report (graph from Statistica 2024):

 





 -- this study adds to the prior studies done, though with more granular data, noting: 

    -- there are huge benefits associated with smoking cessation, and the bulk of them (50% of so) accrue in the first decade after quitting 

    -- the cardiovascular mortality benefit of former smokers peaks out around 20 years after quitting, then being quite similar to that of never-smokers 

    -- but, there are lingering smoking-attributable deaths up to 30 years later (more so for respiratory, then cancer, and least for cardiovascular mortality) 

-- another study assessed smokers exposed to arsenic and radon, noting that smoking has a synergistic effect in lung cancer incidence; this study similarly found that smoking cessation for 10 years led to halving the risk of lung cancer:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8921458/ 

  

Limitations: 

-- this was a self-reported questionnaire-based study, and there may well be discrepancies between these reports and the reality 

-- though this was a large and cross-sectional household study, the primary goal was not smoking or smoking cessation; therefore this study did not include relevant information that might have affected the results: 

    – no information on other inter-related health issues, such as diet, exercise, stress levels, depression, occupational or recreational exposures, air pollution, passive smoking exposure, etc, etc, which might affect these fatal outcomes 

    – no information on the other risk factors for cardiovascular disease, such as diabetes, obesity, other inflammatory conditions etc: see https://gmodestmedblogs.blogspot.com/2023/10/update-ascvd-risk-factor-critique.html 

        – and these omissions could affect the validity of their results 

-- death certificates do not necessarily reflect the actual cause of death. In many cases the cause is quite speculative: a patient with cancer dies at home. Is the cause of death the cancer? An MI? a PE? An intentional overdose? The rate of errors, of course, is hard to measure. One study found that “despite the importance of accurate death certification, errors are common. Studies at various academic institutions have found errors in cause and/or manner of death certification to occur in approximately 33% to 41% of cases, with disproportionate overrepresentation of cardiovascular causes of death” (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4504663/#:~:text=Despite%20the%20importance%20of%20accurate,of%20cardiovascular%20causes%20of%20death. ) 

    -- there is a similar pitfall in assessing GFR, also a pivotal factor in determining renal dosing of medications, where there is a notably poor correlation between the estimated eGFR by either creatinine or cystatin C, yet we may not prescribe an important medication if the eGFR is reported as <30, as if it were a line drawn in the sand: see https://gmodestmedblogs.blogspot.com/2022/07/egfr-not-such-great-estimate-of-renal.html which found that eGFR had wide range of differences from measured GFR, and a pretty high probability that eGFR (by cystatin or creatinine) would be at least 1 and sometimes 2 stages different from the measured GFR. 

    -- ie, both of these examples reflect our need to be circumspect when we use death certificates or eGFR readings as if they were accurate in both public health epidemiology and direct patient care…. 

-- it is likely that some patients who quit smoking died because they had lung cancer, or severe heart disease, etc, and may well have been included in the “quitter group”. So, the mortality associated with quitting cigarettes may actually be less than reported, if we were to exclude those who quit because they had a short life expectancy. 

-- given that people often quit smoking several times, going back and forth with smoking/quitting, it is unclear how this is incorporated into their statistical assessment. It is clear that there is a benefit to quitting, as per this and other studies, but the benefits may be much greater in those who quit in one attempt vs those going through 5 attempts perhaps with even a few years of additional smoking among the 30 years of follow-up 

-- there is no differentiation by amount of cigarettes smoked: those who had smoked 2 packs a day for 40 years may well be a different group with different future risks and outcomes than those smoking 2 cigarettes/day for 6 years. 

-- this was a mortality study, and we know that many of the adverse effects of smoking lead to profound disabilities (COPD, prolonged cancer treatments, heart failure, etc) that may well affect huge numbers of people: mortality is not the only bad outcome 

  

So, it turns out that smoking is not so good for you……  but the smoking-related mortality may well decrease significantly with smoking cessation, within 10 years of quitting. 

-- though we should also incorporate into our discussions with patients that the sooner they quit the better, and by a lot: smoking can still have profound mortality effects even 30 years later (as well as increasing morbidity the longer one smokes) 

-- perhaps the graph above may be a useful tool for some patients to see the very large benefit of smoking cessation 

-- and, i think, the real goal is complete abstention: a systematic review/meta-analysis suggested that smoking even one cigarette/d is harmful, having about ½ the attributable risk of smoking as 20 cigarettes/day in terms of cardiovascular outcomes:  https://gmodestmedblogs.blogspot.com/2018/01/smoking-just-one-cigarette-one-too-many.html 

  

geoff 

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