EGFR and Pleural effusion: However, in the multivariate analysis, the presence of the EGFR gene mutation was independently associated with female sex (OR: 3.873; 95% CI 1.084–13.836, p = 0.04) and the absence of smoking (OR: 5.105; 95% CI 1.363–19.120, p = 0.02), but not with the presence of pleural effusion.