Therapeutic Effects of 7- to 14-Day Subanesthetic Ketamine Infusions for Chronic Pain on Standardized Psychiatric Measures

Figures & data

Table 1. Patient demographics and pain syndrome diagnosis.

Patient characteristics	n or mean	% or SD
Total patients	61
Sex
Male	12	20%
Female	49	80%
Age (years)	46.8	8.2
Treatment duration (days)	10.2	3.1
Condition
Fibromyalgia/central sensitization syndrome	40	66%
CRPS	9	15%
Chronic headache	7	11%
Chronic neuropathic pain	5	8%
Comorbidity
Anxiety	23	38%
Depression	14	23%
PTSD	7	11%
ADHD	3	4%

ADHD: Attention deficit hyperactivity disorder; CRPS: Chronic regional pain syndrome; PTSD: Post-traumatic stress disorder.

Table 2. Patient pain scores before and after treatment.

Patient pain scores	Pain severity		Pain interference
	Mean	SD	Mean	SD
All patients
Before treatment	7.6	0.8	6.2	0.7
After treatment	3.7^†	1.0	4.1^†	0.6
Fibromyalgia/central sensitization syndrome
Before treatment	7.8	0.9	6.2	0.8
After treatment	3.8^†	1.1	4.1^†	0.6
CRPS
Before treatment	7.8	0.7	6.2	0.3
After treatment	3.8^†	1.0	4.1^†	0.6
Chronic headache
Before treatment	7.5	0.6	5.9	0.9
After treatment	3.9^‡	0.8	3.8^‡	0.5
Chronic neuropathic pain
Before treatment	7.6	0.5	5.9	0.9
After treatment	3.2^‡	0.9	4.7^‡	0.6

† Indicates the difference in pain score before compared with after treatment is p < 0.0001.

‡ Indicates the difference in pain score before compared with after treatment is p < 0.05.

CRPS: Chronic regional pain syndrome.

Figure 1. Average patient pain scores before treatment, after treatment and at follow ups.

Error bars are standard deviation.

*Indicates that the difference in pain score from baseline levels is significantly reduced (p < 0.0001).

Table 3. Patient mood and anxiety scores before and after treatment.

Patient pain scores	PHQ-9		GAD-7
	Mean	SD	Mean	SD
All patients
Before treatment	22.2	3.2	14.6	3.1
After treatment	16.1^†	3.2	9.4^†	3.1
Fibromyalgia/central sensitization syndrome
Before treatment	22.0	3.3	14.7	3.0
After treatment	15.9^†	3.4	9.6^†	3.2
CRPS
Before treatment	22.1	4.0	14.7	3.3
After treatment	15.8^‡	3.4	9.6^‡	2.8
Chronic headache
Before treatment	23.4	1.9	15	2.8
After treatment	15.4^‡	3.5	6.6^‡	2.4
Chronic neuropathic pain
Before treatment	21.0	1.6	12.6	4.0
After treatment	16.8^‡	1.6	8.4	1.5

† Indicates the difference in score before compared with after treatment is p < 0.0001.

‡ Indicates the difference in score before compared with after treatment is p < 0.05.

CRPS: Chronic regional pain syndrome; GAD-7: Generalised Anxiety and Depression Assessment; PHQ-9: Patient Health Questionnaire.

Table 4. Correlation between baseline and post-treatment scores and changes in pain, anxiety and mood scores.

Variables compared		Baseline scores (r-value)	Post-treatment scores (r-value)	Change in scores (r-value)
Pain severity	PHQ-9	-0.05	-0.04	0.09
Pain severity	GAD-7	-0.05	-0.12	-0.05
Pain interference	PHQ-9	0.03	0.11	0.04
Pain interference	GAD-7	0.15	-0.03	0.01
GAD-7	PHQ-9	0.56^†	0.14	0.25^‡

† Indicates the correlation between scores is p < 0.0001.

‡ Indicates the correlation between scores is p < 0.05.

GAD-7: Generalised Anxiety and Depression Assessment; PHQ-9: Patient Health Questionnaire.

Table 5. Correlation between treatment duration and changes in pain, anxiety and mood scores.

Standardized score change	Correlation with treatment duration	p-value
Pain severity	-0.03	0.83
Pain interference	-0.10	0.46
PHQ-9	-0.31	0.01^†
GAD-7	-0.02	0.87

† Indicates the correlation between the score and treatment duration is p < 0.05.

GAD-7: Generalised Anxiety and Depression Assessment; PHQ-9: Patient Health Questionnaire.

Table 6. Change in pain, anxiety and mood scores for 7- or 14-day ketamine infusions.

Standardized score change	Reduction in patients with 7-day treatments	Reduction in patients with 14-day treatments	p-value
Pain severity	4.0	4.4	0.38
Pain interference	1.9	2.1	0.38
PHQ-9	4.8	8.8	0.004^†
GAD-7	5.1	5.9	0.49

† Indicates the difference in the changes in the score between the two time points is p < 0.05.

GAD-7: Generalised Anxiety and Depression Assessment; PHQ-9: Patient Health Questionnaire.