Repeatability of a questionnaire to assess respiratory symptoms in smokers

Parental reporting of childrens' coughing is biased

Assessment of cough in the clinical setting as well as in community-based studies of respiratory epidemiology has relied on self-reports. To examine the accuracy and potential for systematic bias in reported cough during a field study, questionnaires administered to parents about their childrens' coughing were compared to overnight cough recordings performed in 145 homes in the community of Wallaceburg, Canada. Percentage agreement between reported and recorded coughing was low, with kappa statistics ranging from 0.02-0.10. Compared to non-smoking parents, smokers under-reported their childrens' coughing (p = 0.01). The association found between parental smoking and recorded coughing was biased towards the null when reported coughing was substituted for recorded coughing: the odds ratio between parental smoking and recorded coughing was 3.1 (95% CI: 1.1-8.8) whereas for reported coughing it was 0.6 (95% CI: 0.2-1.7), the difference in the odds ratios being significant at p = 0.03. When carrying out field surveys, consideration should be given to measuring cough in a subsample of the population in order to estimate the degree of bias inherent in the questionnaire-based results.

Prevalence of chronic cough and phlegm among male cigar and pipe smokers: results of the Scottish Heart Health Study

BACKGROUND

Previous studies investigating the effect of cigar or pipe smoking on the occurrence of chronic cough and chronic phlegm have reported prevalences among cigar and pipe smokers lying between those of non-smokers and current cigarette smokers. This study uses data on previous cigarette consumption, current cigar or pipe consumption, and biochemical markers of smoking to provide a detailed analysis of chronic cough and chronic phlegm among cigar and pipe smokers.

METHODS

A total of 10,359 men and women aged 40-59 years were sampled for the Scottish Heart Health Study between 1984 and 1986. Prevalence of chronic cough and chronic phlegm among male cigar and pipe smokers (non-cigarette smokers) was compared with those who had never smoked, between ex-smokers of cigarettes and those who had never smoked cigarettes, between cigar-only and pipe-only smokers, and by cigar or pipe consumption levels.

RESULTS

In all, 463 ex-smokers of cigarettes and 154 who had never smoked cigarettes were cigar or pipe smokers; 1080 had never smoked any form of tobacco. Ex-cigarette smokers smoked and inhaled more than those who had never smoked cigarettes. Among the ex-cigarette smokers, cigar or pipe smokers had 1.63-1.71 times the prevalence of both chronic cough and chronic phlegm than those who had never smoked (1.31-1.36 among cigar only smokers; 2.23-2.84 among pipe only smokers). A strong positive dose-response effect was found between the prevalence of symptoms and cigar or pipe consumption.

CONCLUSIONS

Cigar and pipe smokers have a higher prevalence of chronic cough and phlegm than those who have never smoked, and the difference is more marked in pipe-only smokers than in cigar-only smokers. Both categories show a positive dose-response effect. Among cigar and pipe smokers, ex-cigarette smokers have a higher prevalence of symptoms than those who have never smoked cigarettes, which may be because they inhale more or may be attributable to previous cigarette smoking.

Respiratory effects of lowering tar and nicotine levels of cigarettes smoked by young male middle tar smokers. I. Design of a randomised controlled trial

STUDY OBJECTIVE

The aim was to investigate the effect on respiratory health of male middle tar smokers changing the tar and nicotine levels of the cigarettes they smoke for a six month period.

DESIGN

This was a randomised controlled trial. Middle tar smokers were randomly allocated to smoke one of three different types of cigarette (low tar, middle nicotine; middle tar, middle nicotine; and low tar, low nicotine) in place of their usual cigarette for a six month period. Main outcome measures were assessment of respiratory health by documenting respiratory symptoms and peak expiratory flow rates, and of nicotine inhalation by measuring the urinary excretion of nicotine metabolites.

SETTING

21 local authority districts of England.

SUBJECTS

Participants were male middle tar smokers aged 18-44 years.

MAIN RESULTS

Postal questionnaires were sent to 265,016 individuals selected from the electoral registers of 21 local authority districts of England; 64% of questionnaires were returned revealing 7736 men aged 18-44 years who smoked only middle tar cigarettes. Of these, 7029 (90%) were sent a health warning and 707 (10%) were not; the latter acted as a control group to assess the effect of the health warning. Of the 7029 men who had received a health warning and were visited at the recruitment stage, 2666 agreed and were eligible to participate in the trial although only 1541 (58% of those who agreed and were eligible) actually started smoking the study cigarettes; 643 men (24% of those willing to participate at the beginning of the trial and 42% of those who actually started smoking the study cigarettes) completed the trial smoking the study cigarettes. Of these, 213 were in the low tar middle nicotine group, 220 were in the middle tar middle nicotine group, and 210 were in the low tar low nicotine group.

CONCLUSIONS

This study shows the feasibility of identifying and recruiting sufficient numbers of male middle tar smokers, with adequate numbers completing the trial, to detect any changes in respiratory health over a six month period.

The impact of quitting smoking on symptoms of chronic bronchitis: results of the Scottish Heart Health Study

Scotland has high rates of death from diseases of the respiratory system and high rates of smoking, especially among women. Data on self reported smoking and prevalence of chronic cough and chronic phlegm among 10,359 men and women aged 40-59 years were obtained from the Scottish Heart Health Study. Overall, current cigarette smokers had rates of chronic cough and chronic phlegm four to five times those of never smokers after standardisation for age (32.3% v 6.5% for men and 24% v 5.5% for women for chronic cough; 31% v 8.3% for men and 21% v 5.5% for women for chronic phlegm). Ex-smokers' symptom rates were a little above those of never smokers and were significant for chronic cough among women and chronic phlegm among men. Men had higher symptom rates than women and this was true for smokers, ex-smokers, and never smokers. The higher rates among men could not be explained by higher cotinine concentrations. Tests to detect "deceivers" among ex-smokers and never smokers using biochemical validation suggested that 87 (1.5%) respondents were in fact smoking; they were excluded from analyses. There were substantially lower rates of chronic cough and chronic phlegm within a year of stopping smoking, and two to four years after stopping 89-99% of the difference between current smokers and never smokers was accounted for (99% and 93% for men and women with chronic cough, 96% and 89% for men and women with chronic phlegm). Even 10 years after stopping, rates of symptoms among ex-smokers remained a little above those of never smokers (except for women with chronic phlegm), though these differences were not statistically significant. Former heavy smokers continued to have rates of chronic cough and chronic phlegm that were higher than those of former light and moderate smokers (though not significantly so). These are cross sectional data, but they emphasise the importance for chronic bronchitis symptoms of giving up cigarette smoking, though the amount previously smoked continues to exert a small influence.