Date	Event	Description
16 March 2004	New search has been performed	November 2003 Further search. Addition of two excluded trials (Hakim 1984; Isaka 1990). Minor changes to text January 1998 Further search Addition of an excluded trial (Zhao 1991) Exclusion of the trial of Mizushima (Mizushima 1994) since no data have been made available by the authors January 1996 Further information on the trial of Hsu et al (Hsu 1986) obtained from an internal Upjohn Company report Data from the trial of Pokrupa and colleagues (Pokrupa 1986) made available as individual patient data and from an unpublished manuscript NOTE: This review covers an area where no active research is taking place. It will be updated if relevant information becomes available, e.g. on completion of an appropriate study.