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).