Characterizing the Temporal Aspects of Tobacco Use and Its Related Diseases

Abstract

Tobacco use is a causative agent of various diseases including cancer, cardiovascular diseases (CVD), chronic obstructive pulmonary disease (COPD) and other non-communicable diseases (NCDs). However, the way in which complex time-varying tobacco use patterns shape disease risk is less well understood. In the United States (US), smoking prevalence has declined, but the use of alternative tobacco products (chewing tobacco, snus, snuff, e-cigarettes) has remained constant or is increasing. These changes further complicate the relationship between tobacco exposure and health outcomes at the population and individual levels. Globally, there is a drastic shift in global tobacco use from high-income countries to low- and middle- income countries, where the burden of tobacco-related NCDs is predicted to rise 70% by 2030. This dissertation seeks to address the temporal aspects of tobacco use and its related health conditions to further assess the health and financial costs of the tobacco use epidemic globally. This dissertation addresses the temporal relationship of tobacco use and its related diseases in three parts. First, the Tobacco Use Supplement of the Current Population Survey was used with joinpoint regression analysis to better understand trends and factors related to smokeless tobacco use (SLT) and cigarette smoking in the US. We found that while smoking continues to decrease, SLT has remained constant since the early 2000s. In addition, we found that while smoking cessation rates doubled from 2002 to 2010, SLT cessation rates remained constant. Second, individual smoking history information from the Nurses’ Health Study and Health Professionals’ Follow-up Study were used to develop and validate a COPD risk prediction model. By including detailed smoking information, we improved the model calibration and predictability. The resulting model was then used to investigate how time-varying cigarette smoking exposures, characterized by duration, intensity, time since quitting, determine COPD risk. Third, population-based cancer surveillance lung cancer data from four cancer registries were used to characterize and project sex-specific lung cancer incidence trends by histology in Thailand using joinpoint regression, age-period cohort, and Nordpred models. We found that lung cancer trends vary greatly by sex, region and histology, and projected rates of adenocarcinoma will continue to increase compared to those of squamous-cell carcinoma. This dissertation shows the benefits of, and need for, incorporating for the temporal aspects of tobacco exposure and disease outcomes, and provides examples of methodological approaches that can be used for the analysis of epidemiological time trends. Use of these and other methods is critical to properly assess the current and future burden of tobacco use, and the impact of interventions to reduce its burden.