The Medline literature searches resulted in 191 eligible publications that were scrutinized for predetermined inclusion
and exclusion criteria of this study. In addition, 137 studies were identified by hand-searching reference lists of
the publications obtained. Fifteen publications fulfilled the inclusion criteria and remained throughout the assessments
(Table 1). The studies included were published during 1996 to 2006, in 10 scientific journals and originated from six
countries (Table 1).