Questionnaire-based second-hand smoke assessment in adults

Background: Numerous studies have assessed second-hand smoke (SHS) exposure but a gold standard remains to be established. This study aimed to review how SHS exposure has been assessed in adults in questionnaire-based epidemiological studies. Methods: A literature search of original papers in English, French, Italian or Spanish published from January 2000 to May 2011 was performed using PubMed. The variables recorded for each study included target population, sample size, validation of the SHS questions, study design and phrasing of every question used to assess SHS exposure. For each item, information such as the setting where exposure was assessed or the indicator used to ascertain SHS exposure was extracted. Results: We retrieved 977 articles, of which 335 matched the inclusion criteria. The main objective of 75.8% of the studies was to assess SHS exposure.The proportion of validated questions aiming to ascertain SHS exposure was 17.9%. Most studies collected data only for one (40.3%) or two settings (33.4%), most frequently the home (83.9%) and workplace (57%). The most commonly used indicator to ascertain exposure was the presence of smokers and 68.9% of the studies included an item to assess the intensity of SHS exposure. Conclusions: The variability in the indicators and items used to ascertain SHS exposure is very high, whereas the use of items derived from validated studies remains low. Identifying the diverse settings where SHS exposure may occur is essential to accurately assess exposure over time. A standard set of items to identify SHS exposure in distinct settings is needed.