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. 2021 Mar 1;24(7):551–561. doi: 10.1093/ijnp/pyab009

Table 4.

Drug Effect Questionnaire Responses for N2O and Ketamine

Effect size (95% CI)
N2O Ketamine
Mean Pre (SD) Mean Peri (SD) Mean Post (SD) (current study) (Morgan et al., 2004)
Like
Medical air 18.34 (26.03) 14.72 (18.69) 6.72 (14.07)
N2O 15.34 (24.64) 50.06 (28.29) 27.44 (24.70) 1.46 (0.92, 2.02) 1.44 (0.73, 2.21)
Want more
Medical air - 4.03 (7.51) 0.69 (1.86)
N2O - 25.03 (23.34) 17.44 (17.87) 1.20 (0.67, 1.74) 1.06 (0.37, 1.78)
Feel
Medical air 0.09 (0.30) 3.47 (4.68) 1.44 (3.67)
N2O 0.00 (0.00) 63.38 (23.21) 20.84 (12.38) 3.53 (2.78, 4.37) 2.23 (1.42, 3.11)
High
Medical air 0.09 (0.30) 1.16 (2.24) 1.13 (2.66)
N2O 0.00 (0.00) 53.31 (27.51) 14.16 (14.03) 2.65 (2.00, 3.36) NR
Dislike
Medical air 0.97 (2.61) 5.53 (9.83) 0.84 (2.53)
N2O 0.06 (0.25) 18.53 (15.90) 12.31 (16.95) 0.97 (0.46, 1.50) NR

Abbreviations: Med, medical; NR, outcome not reported.

Pre, peri and post subjective ratings for “liking,” “wanting more,” “feeling [the effect],” “[feeling] high,” “disliking,” for medical air and N2O. Effect sizes are Hedges’ g based on peri-inhalation (trimmed) means (SDs) for medical air and N2O. For comparison, the right-hand column displays effect sizes for the same outcomes (where available) for ketamine (0.4 mg/kg) versus medical air, obtained 10 minutes after infusion began based on data extracted from graphs presented in Morgan et al (2004).