Studies by Buchanan, Meng & Marks (1996), Castle et al. (1994), De Araujo, Ito & Marks (1996) and Keijsers, Hoogduin & Schaap (1994) have looked at variables predicting outcome. They found poor outcome was associated with depression, longer duration of illness, poorer motivation and dissatisfaction with the therapeutic relationship. De Araujo, Ito & Marks (1996) found that initial severity did not predict outcome, whereas the other studies found higher initial severity was associated with poorer outcome. The studies found that good outcome was associated with early adherence to exposure homework, employment, living with one's family, no previous treatment, having fear of contamination, overt ritualistic behaviour and the absence of depression. Castle et al. (1994) also found that having a co-therapist was positive for women.
Lelliot et al. (1998) found bizzarreness and rigidity of beliefs did not affect compliance with treatment or outcome following ERP. However Foa et al. (1999) found worse treatment outcome in those with fixed beliefs about the consequences of stopping compulsions and avoidance behaviours.
Beliefs that are part of an elaborate belief system, for example social or religious, can be resistant to change, and can be sanctioned and reinforced by others. Ciarrocchi (1998) presents some ideas about their treatment, including involving religious advisors to approve planned exposures. The aim may be to try to change the response to intrusions and learn to avoid sustained neutralising rather than to challenge the beliefs about obsessions.