“…Three studies reported using the WHO three-step ladder to guide the prescription of analgesics (Chen et al, 2007;Hu et al, 2010;Lu et al, 2006). Six studies specifically investigated the barriers of using opioids (Lai et al, 2002(Lai et al, , 2004Liang et al, 2008aLiang et al, , 2008bLiang et al, , 2012Liang et al, , 2013aLiang et al, , 2013bLiang et al, , 2015Pang et al, 2013), whereas the remaining 13 studies explored participants' perspectives on using analgesics.…”