The primary objective is to obtain pilot prospective data to explore whether sensory symptom cluster analysis is useful for predicting treatment response in PHN. - Phenotype PHN subjects entering study with sensory symptom clustering using the PainPREDICT, PainDETECT and NPSI questionnaires, “baseline pain interference with sleep”, Patient Health Questionnaire 8 (PHQ-8), Generalized Anxiety Disorder 7-item (GAD-7), as well as Pain Catastrophizing Scale (PCS) questionnaire. - Find “responders” and “non-responders” to treatment (pregabalin). - Compare distribution of phenotypes within “responder” and “non-responder” groups.