“…Ten articles were cross-sectional and included survey designs (Baeza-Velasco et al, 2012; Gerolimatos & Edelstein, 2012; Gianini et al, 2013; Karademas et al, 2011; Kravvariti et al, 2010; Messerli-Bürgy et al, 2012; Samar, 2001; Warmuz-Stangierska et al, 2010; Willard, 2006; Zijlstra et al, 2012). Three of these cross-sectional studies used healthy controls to compare with the illness population (Baeza-Velasco et al, 2012; Gerolimatos & Edelstein, 2012; Kravvariti et al, 2010), and one used matched controls (Zijlstra et al, 2012). Two studies used longitudinal surveys in a panel design (Kubzansky & Thurston, 2007; Vilchinsky et al, 2013).…”