Specific objectives for the study at large will be to: 1) Identify the influence of demographic, environmental/societal and clinical factors on the risk of developing and maintenance of NP. 2) To apply modern genomics to validate (using a targeted approach) and find novel (using genome wide association) genetic risk factors for NP. 3) To determine if patient stratification using physiological (sensory profile, endogenous analgesic mechanisms and nerve excitability) and psychological factors can predict NP risk and progression. 4) Development of a risk model/algorithm for (severe) NP, combining measurable genetic and environmental factors. The desired impact is to provide a firm platform to improve diagnosis and stratify patients according to risk profile, employ preventive strategies and ultimately develop novel therapeutics.