Catechol-O-methyltransferase (COMT) gene polymorphisms are associated with baseline disability but not long-term treatment outcome in patients with chronic low back pain

Purpose:
To examine the association between COMT and OPRM1 gene polymorphisms and pain and disability at baseline and long-term follow-up in patients treated for chronic low back pain (LBP).
Methods:
371 of 767 unrelated European patients recruited from four randomised trials underwent genetic analyses at mean 11.4 years follow-up. 274 patients had fusion and 97 had non-operative treatment. Association analyses included disability, pain, five single nucleotide polymorphisms (SNPs) in the COMT gene, and one SNP in the OPRM1 gene. Analyses were adjusted for age, gender, smoking, analgesics and treatment.
Results:
Disability at baseline was significantly associated with COMT SNPs rs4818 (p = 0.02), rs6269 (p = 0.007), rs4633 (p = 0.04) rs2075507 (p = 0.009), two haplotypes (p < 0.002), age, gender and smoking (p ≤ 0.002). No significant associations with clinical variables were observed for OPRM1, or for COMT at long-term follow-up. Conclusions: Results suggest that genetic factors are partly responsible for the variation in disability levels in patients presenting with chronic LBP being considered for surgery; in contrast, genetics has no influence on the long-term outcome of treatment.