Radiographic Changes Associated with Cigarette Smoking

Abstract

lNTRODUCTION Several studies have shown that cigarette smoking produces macroscopic changes in lung tissuez.3. There is a strong correlation between cigarette smoking and the presence of chronic bronchitis, whilst autopsy studies demonstrate a quantitative relationship between severity of emphysematous destruction and smoking history4.The aim of this investigation was to determine if changes due to smoking are readily detectable on chest radiographs, and if so, how they relate to a history of smoking. A further aim was to determine the most consistent features seen in the chest radiographs of individuals with a smoking history. The results of the study could furthermore be of practical use. Teplickl suggests that documentation of early changes, often overlooked in routine examination of chest radiographs, could prove useful in evaluating suspicious lung changes that may otherwise be regarded as insignificant in routine viewing procedure.A cross sectional study was therefore undertaken using plain film PA and lateral chest radiographs, and statistical analysis of the results performed. METHODS Radiographic SelectionA consecutive series of chest x-rays of patients over 18 years of age presenting to Outpatient and Casualty X-ray Departments was used. A self administered questionnaire provided information on smoking history, occupational exposure to inhaled irritants, and chest disease such as chronic bronchitis, asthma, emphysema and pneumonia. Based on questionnaire information radiographs were not included in this study if there had been a history of occupational exposure to inhaled pollutants such as coal dust, asbestos or silicon dioxide. Radiographs with significant pulmonary abnormalities that substantially obscured the lung fields were also examined. Cases of pulmonary TB, bronchiectasis and fibrosing alveolitis fell into this category. Smokers who had indicated the use of cigars and pipes were omitted from the study as their use is not readily quantifiable.Included in the study were 32 smokers, with a mean age of 52 years (S.D. +/-17.49), 31 exsmokers with a mean age of 65 years (S.D. + /-9.41) and 39 non-smokers with a mean age of 58 years (S.D. +/-18.19). For each smoker, including ex-smokers, cigarette consumption in pack years was calculated as the product of the number of packs of cigarettes (20 cigarettes/pack) smoked per day multiplied by the number of years the subject smoked (Table 1). Consumption varied from 5 to 120 pack years with a mean of 39 pack years (S.D. + /-29.42).An individual with a pack year consumption below 5 was considered to be a non smoker for the purposes of this study. Radiograph ViewingSix staff radiologists and three respiratory physicians served as readers. Their task was to determine whether a chest radiograph was that of a smoker or a non-smoker on the basis of the radiographic appearance alone. No clinical information other than the patient's age was provided. The readers were also requested to record the basis for their decisions on an answer sheet provided, and to facilit...