Study	Reason for exclusion
Adan 1988	Insufficient data.
Bartels 1996	Compared two active interventions. No control group.
Bell 1992	Insufficient data.
Breakwell 2000	Insufficient data.
Dalrymple‐Hay 2001	Duplicate article.
Deramoudt 1991	Insufficient data.
Elawad 1992	Inappropriate control group.
Farrer 1997	Duplicate article.
Jacobi 1997	Insufficient data.
Kristensen 1992	Insufficient data.
Mac 1993	Insufficient data.
Mayer 1985	Insufficient data.
McShane 1987	Insufficient data.
Schaff 1978b	Duplicate article.
Schmidt 1997a	Duplicate article.
Schmidt 1997b	Duplicate article.
Skoura 1997	Insufficient data.
Thompson 1990	Insufficient data.
Trubel 1995	Compared two active interventions. No control group.
Vertrees 1996	Inappropriate control group.