<qa>  What is the ratio of participants to group based ACT?One hundred and twenty participants will be recruited from a list of patients referred to the Multidisciplinary Pain Department at the University Hospital of North Norway. Those who meet the defined criteria, are invited to participate. The study has a randomized, semi-crossover design. The participants are allocated to group based ACT or treatment in a primary care setting with a gender stratified, block randomization with a ratio of 1: 1. This means that half of the participants intervention group, n: 60 get early group based ACT, while the other half control group, n: 60 will be treated in a primary health care setting. Those of the control group who still meet the criteria, will be offered ACT afterwards. 