Health Effects of Cigar, Cigarillo, Pipe, and Hookah Smoking

Grant application to FDA.

Tobacco smoking represents the main single preventable cause of common chronic diseases, including cardiovascular and respiratory diseases and cancer. During the past few decades, the prevalence of cigarette smoking, as the most common type of tobacco use, has been decreasing in the United States and several other high-income countries. However, recent reports have shown an increase in the use of some other tobacco products, including cigarillos and hookah (water-pipe), in the US and many other areas of the world. Among the suggested reason for this increase in use are: relatively lower cost of these products, as they are usually exempted (at least partially) from cigarette specific taxes; the belief that those products are less harmful than cigarettes; hookah smoking may represent an opportunity for social gathering; and hookah bars are generally exempted from restriction on public smoking. Nowadays, the majority of new cigarillo and hookah users are young people. Because of the long latency of health effects of tobacco products, the full range of effects of current patterns of cigarillo and hookah smoking in the US and many other countries may not become apparent for years.

The smoke from cigars, cigarillos, pipe, and hookah contains many toxic compounds found in cigarette smoke, and even using some of these products may expose the smokers to toxic compounds at higher levels per puff. For example, each puff from hookah has reported to deliver 12-times as much smoke as a single cigarette puff. However, little is known about health effects of cigarillos and hookah, and the evidence for cigar and pipe is limited. The prevalence of cigar and pipe smoking has been modest worldwide and the reported increase in the use of cigarillos and hookah in the US and other countries is fairly recent and mainly includes young people. Therefore, the majority of previous studies that investigated the association between cigarette smoking and disease (which have mainly been conducted in the US and other high-income countries) did not investigate that association for other tobacco smoking products, or when they did, the number of participants using those products was not enough to be reported separately or to make a strong conclusion on the association of those products and health outcomes. Historically, hookah smoking has been prevalent in North Africa and West and Central Asia, and only a small number of studies have been published on health outcomes of hookah smoking from those regions. A small number of pooled studies have also reported associations between cigar and pipe smoking and certain adverse health outcomes, with relatively consistent increase of risk of those outcomes. The small number of participants in the majority of the studies that investigated the health effects of tobacco smoking other than cigarette smoking precluded the ability to investigate risk among sub-populations, e.g. by gender and ethnicity.

As the evidence for adverse health effects of smoking tobacco products other than cigarette is limited, we aim to measure the association between smoking of cigars, cigarillos, pipe, and hookah and incidence and mortality from cancer, cardiovascular disease, respiratory disease, as well as overall mortality within the Cohort Consortium, which can provide a sample size large enough to achieve acceptable statistical power to identify any risk associated with the use of those products, and perhaps in different sub-populations (e.g. by sex, ethnicity, and geographical region). We also aim to study the interaction between smoking of cigarettes and of non-cigarette smoking products. This project is expected to generate comprehensive information on the association between smoking tobacco products other than cigarette and cancer risk, which will complement the results obtained from the pooled analysis of consortia of case-control studies, and be relevant to primary prevention programs targeted to the general population. Increasing prevalence of some of these habits among young people in many populations is another important factor emphasizing the need for such research.

The overarching aim of the project is to provide precise estimates of the association between smoking of non-cigarette tobacco products and disease in prospective epidemiologic studies.

To measure the association between smoking of cigars, cigarillos, pipe, and hookah and incidence and mortality from cancer, cardiovascular disease, respiratory disease, as well as overall mortality.

To study the interaction between smoking of cigarettes and of non-cigarette smoking products.

To study differences in risk by type of non-cigarette smoking products, geographic region.

To compare the results obtained from the pooling of prospective studies with those obtained from similar pooling projects of retrospective (case-control) studies.

Full cohort analysis. Smokers will be categorized according to concomitant smoking of other products (pure, predominant, mixed) and according to indicators of amount of smoking. Disease- and cohort-specific confounders will be identified in preliminary analyses. Cohort specific regression coefficients will be combined using random-effects models. Analyses will be stratified by geographic region and time period to explore possible sources of heterogeneity.

The number of pure smokers of non-cigarette products is small in individual cohorts. Results of pooled analyses of case-control studies need to be confirmed by results of prospective studies.

25 overall deaths in pure smokers of cigars or pipe.

Incidence of cancer (overall and tobacco-related cancers); mortality (overall, cancer, CVD [MI, stroke], respiratory diseases, diabetes).

Smoking of at least one among cigars, cigarillos, pipe, or hookah, including variables on duration, amount and time since quitting, if available.

If samples will be available, serum/plasma cotinine will be measured in a subset of study subjects (preferably controls) stratified by smoking of different tobacco products, to validate self-reported smoking status and estimate the amount of misclassification.

Age, sex, ethnicity, socio-economic status (education), cigarette smoking (including quantitative variables), alcohol drinking, personal history of chronic diseases, BMI. The inclusion of key dietary variables for outcomes in which diet might be a confounder will be discussed with researchers involved in the Diet and Cancer Pooling Project.

Yes

No special processing. Serum or plasma if available for cotinine measurements.