“…Studies include between 20 [ 19 ] and 1531 [ 15 ] patients and are conducted in Australia [ 19 , 28 ], Denmark [ 14 , 34 ], France [ 31 ], GB [ 17 , 22 ], Germany [ 21 , 23 , 27 , 29 , 32 , 33 ], Italy [ 24 ], Netherlands [ 35 ], Norway [ 18 ], Switzerland [ 30 ], and the USA [ 15 , 16 , 20 , 25 , 26 ]. Five studies focus on patients with chronic pain [ 21 , 23 , 30 , 32 , 33 ], four studies on patients undergoing palliative care [ 16 , 19 , 20 , 26 ], and two studies on patients with neurological diseases (Parkinson’s disease (PD) [ 24 ], multiple sclerosis [ 14 ]), cancer [ 27 , 31 ], or severe mental illness [ 34 , 35 ].…”