“…Other studies, carried out after more than 10 years, documented a high incidence of uncontrolled and severe pain in hospitals (Donovan et al, 1987;Oden, 1989). The necessity to develop a precise strategy for pain management has been put in evidence later on, in a work by Kuhn et al (1990), and later stressed in several studies examined by systematic reviews such as Kitson (1993) and Brown (2004 Berry and Dahl, 2000;MacLellan, 2004). There is some evidence that extreme suffering from pain could weaken the patient's immune system, while the risk of addiction to pain medication has been shown to be extremely low in patients who received medications for post-operative pain.…”