Curtailing tobacco use: first we need to know the numbers.

www.thelancet.com Vol 380 August 18, 2012 629 Data, transformed through aggregation and analysis into useful information, are key elements for decision making. This notion is true in general and has become a precept for promotion of health and control of disease. Tobacco use globally is the main preventable contributor to poor health and premature death. In The Lancet, Gary Giovino and colleagues describe the acquisition of high-quality data for tobacco use from 14 countries through the employment of welldesigned and well-implemented surveys, the Global Adult Tobacco Survey (GATS), with 16 countries studied in total. GATS was originally developed by the US Centers for Disease Control and Prevention (CDC) and has been widely applied by host countries working with CDC and WHO. Accurate data are needed on the characteristics of tobacco users (eg, age, sex, income, and occupation), how tobacco is used (smoking cigarettes, bidis, or water pipes vs chewing tobacco or taking snuff ), and where and why people use tobacco. Such data are vital for planning purposes, such as designing interventions and targeting at-risk groups, and for evaluation and programme assessment purposes, such as establishment of the baseline and examination of data after an intervention has been applied (ie, whether or not an intervention works). Eff ective policy development and assessment depend on such data and information. Thus, a reliable measurement technique that can be used by all countries to obtain this information has been desperately needed to address the huge global health threat of tobacco use. GATS off ers such a technique: the standardised questionnaires it employs enable, for the fi rst time, comparative data analysis. Impressively, GATS already covers more than half the world’s population. Giovino and colleagues’ report off ers a spectrum of global tobacco use, and the diff erences between nations are interesting and important. Although many more men than women smoke in all countries surveyed, the prevalence of current smoking for women varies greatly, from 0·5% in Egypt to 24·4% in Poland. How people use tobacco varies substantially, as does the age at which people start tobacco use. These data are not static. With behaviours and lifestyle in fl ux globally and marketing Curtailing tobacco use: fi rst we need to know the numbers Pending such analyses, how should clinicians now apply Wong and colleagues’ data to their patients? We suggest that the two broad indications for treatment that apply to all chronic diseases—loss of quality of life and danger (in this case, a scenario of moderate to severe loss of lung function in association with evidence of continuing disease progression)—should be the basis for intervention. Patients with functionally mild disease should not be treated with long-term azithromycin unless there is major morbidity or evidence of disease progression despite adherence to physiotherapy and the early use of broad spectrum antibiotics for infective exacerbations. We urge researchers designing interventional protocols in any chronic disease to plan to investigate treatment eff ects against baseline measures of disease severity and patterns of disease behaviour. Without these analyses, how can clinicians know with confi dence which patients to treat?