Inadequately treated pain in children undergoing surgery is a major concern for health
providers. Recent evidence indicates that pain sensitivity differs among races and
ethnicities and genetic makeup. Catechol-O-methyltransferase (COMT) polymorphisms
(rs6269, rs4633, rs4818 and rs4680) which are inherited together in different phenotypes
influence clinical presentations and responses to pain.
A118G single-nucleotide polymorphism (SNP) in the mu-opioid receptor1 (OPRM1) gene is
associated with differences in pain perception and opioid requirements. The effect of
genome variations in the COMT gene and in the OPRM1 on postoperative pain perception and
morphine analgesia in children needs further exploration. The main objective of this
study was to investigate whether the OPRM1 and COMT SNPs influence postoperative pain
scores in children between the ages of 8 and 18 undergoing orthopedic, abdominal,
thoracic, and plastic surgeries. Secondary objective includes assessing whether OPRM1 and
COMT SNPs influence postoperative sedation score, intraoperative and postoperative opioid
requirements, length of stay in the post anesthesia care unit (PACU), and signs of
respiratory depression (RD) and postoperative nausea and vomiting (PONV).
Methodology: A prospective cohort genotype-blinded observational study will be conducted.
A convenience sample of 200 children between the ages of 8-18 undergoing orthopedic,
abdominal, thoracic, and plastic surgeries will be recruited from the American University
of Beirut Medical Center (AUBMC). The primary outcome of the study is the post operative
pain score in PACU.
Secondary outcomes include the postoperative sedation score, intraoperative and
postoperative opioid requirements, length of stay in the PACU, and signs of RD and PONV.
To test the hypothesis that COMT and OPRM1 SNPs are associated with postoperative
analgesia outcomes in children, SPSS version 29 will be used. Allelic and genotype
frequencies will be examined by the Hardy-Weinberg equilibrium (HWE) test. To analyze the
association between the different genetic variations and the outcomes, bivariate analysis
will be performed. Variables measured over time will be compared between the groups using
an exploratory mixed model analysis. Time to first post-operative opioid requirement will
be analyzed using the survival analysis Kaplan Meier curve. Such understanding will pave
the way for individual tailoring and optimization of pain assessment and management in
children undergoing orthopedic, abdominal, thoracic, and plastic surgical procedures.