Clearing the Air on Effects of Smoking in Asthma

Bilun Gemicioglu, MD, PhD

A study comparing asthma symptoms and risk factors among adult smokers and non-smokers was presented in the same week that a published study provided evidence of those symptoms varying with the age of initial exposure to smoking.

Bilun Gemicioglu, MD, PhD, from the IU Cerrahpasa Faculty of Medicine's Department of Pulmonary Diseases, in Istanbul, Turkey, presented a comparison of smoker and non-smoker adult asthmatics at the joint meeting of the American Academy of Allergy, Asthma and Immunology and the World Allergy Organization (AAAAI/WAO) in Orlando, Florida March 2 to 5, 2018.

Gemicioglu acknowledged that smoking is a well-known trigger for asthma patients, but explained that the study sought to compare the presentation of asthma symptoms between adult smokers and non-smokers, as well their risk factors and comorbidities.

The investigators identified 500 patients living in the urban area of Istanbul who had been diagnosed with asthma for at least one year, comprising 353 smokers, 88 ex-smokers, and 59 who had never smoked. Each was surveyed on symptoms, habits, and circumstances over a year follow-up with a web-based data entry program.

There were no statistically significant group differences in reported symptoms such as a cough, wheeze, chest tightness, and dyspnea. There were also no differences in such risk factors as pet sensitivity, home heating methods or presence of mold.

Comorbidities occurring in both groups included allergic conjunctivitis and rhinitis. Smokers and ex-smokers did have a higher incidence of atopic dermatitis (13.9% and 12.7%) compared to non-smokers (3.4%), and smokers had, expectedly, a higher incidence of hypertension.

"Smoker and ex-smoker asthma patients of the urban area had similar asthma symptoms and risk factors," Gemicioglu told attendees, "but they had higher hypertension and allergic dermatitis comorbidities than non-smoker asthma patients."

In a study published online one day after the meeting in Environmental Research, Bircan Erbas, PhD, Department of Public Health, La Trobe University, Melbourne, Australia, and colleagues also acknowledge well-known links between smoking and asthma.

"There is a plethora of evidence to suggest that smokers compared to non-smokers have a higher risk of asthma," Erbas and colleagues observe. "Therefore, we know that smoking is harmful for respiratory health when comparing with a reference group of non-smokers."

What has not been well studied, they point out, is whether those risks differ depending on when in life the exposure to smoking occurs.

"The relative importance of early life smoking exposure, the age of starting smoking as well as total pack-years of smoking among ever-smokers is not known," Erbas and colleagues indicated.

Their study identified over 10,000 adults (5,348 men) from 29 centers in 14 countries who reported to be current or former smokers on the European Community Respiratory Health Survey (ECRHS I) initiated in 1991-1994. The study cohort was stratified by the window of exposure: from maternal smoking in utero and smoking in the household during postnatal and childhood period to smoking in adolescence and in adulthood.

Among the findings was that respiratory symptoms and asthma were more frequent in adults if their mother smoked during pregnancy; and, in men, also if mother smoked during their childhood. Wheeze and ≥3 respiratory symptoms declined with later smoking debut among women.

"Among ever smokers, smoking exposure in each stage of the lifespan show persistent harmful effects for adult respiratory health, while women appeared to be more vulnerable to an early age of smoking debut and amount of smoking in adulthood," Erbas and colleagues reported.

The study comparing asthma symptoms and risk factors in smokers and non-smokers was described in Presentation 741 at the AAAAI/WAO meeting in Orlando Florida, March 2-5.