Subanesthetic ketamine infusions for the treatment of children and adolescents with chronic pain: a longitudinal study

Table 4 Predictors of pain score reduction after sub-anesthetic doses of ketamine infusions in children and adolescents with chronic pain syndromes treated in an outpatient tertiary care pediatric center ^a

Variable	P value	Beta
Multivariate analysis after each infusion
Older age	0.004	−0.1
Chemotherapy neuropathy	0.006	−3.1
Complex regional pain syndrome	0.018	−0.7
Multivariate analysis after each treatment
Older age	<0.001	−0.2
Chemotherapy neuropathy	<0.001	−7.3
Complex regional pain syndrome	<0.001	−2.1

^aIn the multivariate model, the P value for interaction represents the heterogeneity of ketamine effect by subgroup and the beta value indicates its direction. That is, a significant P value for interaction between ketamine effect and complex regional pain syndrome (CRPS) indicated that effect of ketamine in pain reduction is different in CRPS than other chronic pain syndromes. A negative beta value indicates that ketamine caused greater pain reductions in patients in the CRPS group compared to other chronic pain syndromes. When analyzing each ketamine treatment (one to three infusions), the pain score after the last infusion was compared with the one before the first infusion

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