Inclusion Criteria:  ICD11 Medical diagnosis of chronic pain and its subcategories Treatment with intravenous lidocaine and ketamine infusions during the years of 2012 to May 2021 at our pain unit at the USB Patient is at least 18 years of age at the beginning of the first infusion treatment  Exclusion Criteria:  Patient is underage at the beginning of the first infusion treatment Documented written refusal of consent for research (general consent or specific study consent) Patients undergoing treatment with only lidocaine or ketamine respective