Pain management after surgery is not optimal, partly due to great interindividual variability in pain perception and coping. This can lead to persistent pain beyond the healing period and disability. Up to two-thirds of the inter-individual variability results from genetic variations in pain perception as well as response to the pain medicine. The investigators aim to identify genomic (genetic/epigenetic), psychological and drug profiles contributing to this variability. Opioids are the mainstay for treatment of postoperative pain in children. Experience dictates that opioids have narrow therapeutic indices and large inter-patient variability in response. This leads to serious side effects like respiratory depression in up to 50% of children undergoing invasive surgery, which can be fatal. It is evident that there are particular children who are more susceptible to suffering side effects and having inadequate pain relief from opioids. It is hypothesized that much of the genetic variability can be explained by gene function which is modulated by a) Single Nucleotide Polymorphisms (SNPs) in genes that encode proteins involved in pain perception, opioid transport/metabolism (pharmacokinetics), and opioid receptor signaling (pharmacodynamics); b) epigenetics which modify gene expression without structural changes to the DNA, and c) genes that influence psychological factors. The purpose of this research study is to identify factors and genes that may be associated with acute and chronic post-surgical pain, and to develop pharmacometric models for response to opioids, like morphine and hydromorphone. While children undergoing different surgeries will be recruited for acute outcomes, children undergoing spine fusion will be followed for 10-12 months for evaluation of psychological and genomic factors affecting chronic post-surgical pain, with a goal of identifying genetic and epigenetic risk models for prediction of acute and chronic post-surgical pain. Although opioids are used every day, some children have bad reactions from their use, like breathing problems, sedation, etc. The investigators want to study factors that may be associated with pain sensitivity, opioid requirements after surgery, their metabolism, efficacy and their side-effects. The investigators expect that the information obtained in this research study will help to develop effective, safer, and tailored treatment options in the future.

Genomics of Opioid Pharmacogenomics and Acute/Chronic Postsurgical Pain after Major Surgery in Children