Disease related factors Exp. studies evaluating the factor Experimental studies reporting significant effects
Progress, duration, and severity of the condition and its symptomatology 8 n = 2 (Nieuwkerk et al., 2012; Al-Haj Mohd et al., 2016)
Level of disability caused by the condition at the physical, psychological, social, and vocational levels 6 n = 3 (Crowley et al., 2012; Nascimento et al., 2016; Laba et al., 2018)
Existence of co-morbidities (including depression) 15 n = 3 (Grigoryan et al., 2012; Park et al., 2015; Shankari et al., 2020)