Assessment of tobacco exposure in former smokers eligible for lung cancer screening

Results from a cross-sectional study have shown that former smokers eligible for lung cancer screening should be asked about their recent tobacco use and exposure, while counseling about the harms of these 2 risk factors is warranted.

Results of a cross-sectional study of 2013-2018 National Health and Nutrition Survey (NHANES) data found that former smokers eligible for lung cancer screening (LCS) should be asked about their smoking and their recent exposure to tobacco, while advising them on the harmful effects of these 2 risk factors is justified.

The findings were published in the Journal of General Internal Medicine.

Updated recommendations from the United States Preventive Services Task Force (USPSTF) state that all adults between the ages of 50 and 80 with a 20-pack-year smoking history and who currently smoke or have quit within the past 15 years should undergo an LCS, the authors wrote.

However, “while the recommendations are clear for current smokers presenting for LCS, the guidelines for counseling former smokers are not well defined,” they added.

To better understand ex-smokers’ behavior and identify high-risk ex-smokers who would benefit from targeted counseling at the time of the LCS, researchers assessed anonymized NHANES data from 472 LCS-eligible ex-smokers.

All participants had smoked at least 100 cigarettes in their lifetime and were not current smokers at the time of the survey. The main study outcomes were recent tobacco use and exposure. “Former smokers with no recent smoking were classified as having recently been exposed to tobacco if their cotinine level was greater than 0.05 ng/mL,” the researchers explained.

Cotinine is a metabolite of nicotine reflecting recent exposure. Any cotinine level above the racial/ethnic thresholds for smoking, or reported smoking within the last 5 days constituted “recent smoking”.

The majority of LCS-eligible former smokers were non-Hispanic white (82.7%), male (67.1%), and had incomes more than 100% above the federal poverty level (83.3%).

The analyzes revealed:

  • 1 in 5 former smokers eligible for the LCS, or a total of 1,416,485 adults drawn from the US population, had recently used tobacco (21.4%; 95% CI, 15.8%-27.0%), about a third of whom each used cigarettes, e-cigarettes, or other tobacco products
  • While 17.5% of former smokers reported having recently used a tobacco product in the past 5 days, 19.7% had cotinine levels indicative of active smoking above racial/ethnic thresholds
  • Among former smokers with no recent smoking, more than half (53.0%; 95% CI 44.6% to 61.4%) had cotinine levels indicative of recent tobacco exposure
  • Groups with a higher percentage of recent smoking than their counterparts include men, those who quit in the last 0-3 years, and those living with a family smoker

High levels of recent tobacco use and exposure among former LCS-eligible smokers underscore the need for improved provider assessment and counseling, the researchers wrote.

“Providers can use this data to inform strategies that improve assessments and target former smokers for counseling about their ongoing risk of tobacco dependence, disease, and mortality, particularly for cardiovascular and respiratory disease,” they said.

Additional clarification of smoking assessment advice may also be helpful in minimizing misclassification of current smokers, while asking about any smoking in the previous month may better characterize this patient population.

Environmental interventions may be particularly helpful for these patients, the authors added. “Patients can be informed that there is no safe level of smoke exposure and advised to make a smoke-free house rule, not only for the continued risk of developing lung cancer, but more immediately for cardiovascular health.”

Biomarker-based exposure via cotinine levels may also be beneficial to better classify former smokers exposed to secondhand smoke; however, high-sensitivity laboratory tests for cotinine may not be widely available.

“Future studies should assess whether including cotinine levels can alter patient behavior and outcomes, and what the cost-effectiveness of this approach might be,” the researchers said.

The self-reported nature of current smoking status limits the analysis.

Reference

Hood-Medland EA, Dove MS, Tong EK. Gaps in assessment and counseling among former smokers eligible for lung cancer screening in US adults. J Gen Med Intern. Published online April 26, 2022. doi:10.1007/s11606-022-07542-0

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