Table 3. l-[1-¹³C]tryptophan breath test results in patients with major depressive disorder and healthy controls.

Parameter	Patients (n = 18) Mean ± SD	Controls (n = 24) Mean ± SD	t–test/Mann–Whitney U test	ANCOVAa
Cmax	14.5 ± 4.3	10.9 ± 3.1	p = 0.003 Cohen’s d = 0.99	p = 0.002 partial η2 = 0.23
AUC	1596.2 ± 405.3	1320.0 ± 350.2	p = 0.023 Cohen’s d = 0.74	p = 0.008 partial η2 = 0.18
CRR0-180	20.4 ± 3.8	17.2 ± 3.7	p = 0.009 Cohen’s d = 0.86	p = 0.004 partial η2 = 0.21
Tmaxb	30	45	p = 0.068c r = 0.28

Abbreviations: C_max, the maximal Δ¹³CO₂ (%); T_max, time to reach the C_max (min); AUC, area under the Δ¹³CO₂-time curve (min %); CRR_0-180, the cumulative recovery rate during the 180 min test (%); r, the effect size of the Mann–Whitney U test.

^aHealthy controls versus patients with major depressive disorder in analysis of covariance controlled for sex, age, and body weight.

^bMedian.

^cHealthy controls versus patients with major depressive disorder by the Mann–Whitney U test.