[Assessment of surveys of adolescents about smoking and the use of alcohol and cannabis in Spain].

INTRODUCTION Monitoring health-related behaviors in adolescence requires instruments capable of providing valid data The objective of this paper is to review and assess existing information sources on smoking and alcohol and cannabis use by age and sex among adolescents in Spain. METHODS A search was carried out for studies with repeated observations over time, and their methods and characteristics reviewed. For each study, the number of surveys, their frequency and their sample size are assessed, as well as the instrument used, the available indicators, and the availability, accessibility and comparability of the information. RESULTS Five sources of information providing data over extended periods of time with accessible data are identified: the National survey on drug use in secondary-school children (Encuesta estatal sobre uso de drogas en estudiantes de secundaria; ESTUDES); the Health behavior in school-aged children study (ECERSHBSC); the Monitoring system for risk factors associated with non-transmissible diseases in young people (Sistema de Vigilancia de Factores de Riesgo Asociados a Enfermedades No Transmisibles dirigido a poblacion juvenil; SIVFRENT-J); the Study of risk factors in secondary school children (Estudio de factores de riesgo en estudiantes de secundaria; FRESC); and the Monitoring study of health behaviors in adolescents (Estudio de monitorizacion de las conductas de salud de los adolescents; EMCSAT). Two of the surveys cover the whole of Spain, one is regional, and two are city-specific. All use solid methods and representative sampling techniques. In some, changes have occurred that make comparison of the evolution of some indicators difficult. Report accessibility is variable; comparability is limited for some surveys. Some provide almost no stratified data. CONCLUSIONS There are valuable sources of data, but all have shortcomings. Changing the measurement instrument in a survey for comparison with others raises dilemmas as to the internal comparability of series.