[Same year, different source: variability in prevalence estimates of exposure to secondhand smoke in Spain]

The aim of this study was to assess the variability in the prevalence of secondhand smoke (SHS) exposure in Spain estimated from different sources.

Study comparing the prevalence of exposure to SHS using survey data.

Spain, with specific analysis in Galicia and Catalonia.

General population aged 16 and over included in the following surveys: National Health Survey (NHS), Galicia Risk Behavior Information System (SICRI), and Health Survey of Catalonia (ESCA), corresponding to six editions of each.

Questions assessing exposure to SHS were selected from the NHS, SICRI and ESCA.

Prevalence of SHS exposure as estimated after homogenizing the definition of exposure. To compare the prevalences estimated with two sources, the absolute differences between them were calculated together with their 95% confidence interval (95%CI).

In Galicia, when comparing ENSE and SICRI, the absolute differences in SHS exposure prevalences exceeded 10 percentage points in five of six editions. In Catalonia, when comparing ENSE and ESCA, the differences ranged from 1.5 to 14.2 points. The 95%CI analysis of the absolute differences showed that for Galicia and Catalonia the differences were significant in four and five of the six years compared, respectively.

In Spain, large differences are observed in the estimation of SHS exposure prevalence depending on the data source. These differences are greater the less specific the area studied. The regional surveys reflect higher prevalences of exposure to SHS.