13C-methacetin breath test reproducibility study reveals persistent CYP1A2 stimulation on repeat examinations

Table 1 Reproducibility of the ¹³C-methacetin breath test

	Dmax		Tmax		AUC0-60
	S_term	M_term	S_term	M_term	S_term	M_term
CVp	16.23%	16.46%	30.57%	32.49%	10.00%	10.00%
RC	15.55% dose/h	16.80% dose/h	16.86 min	16.73 min	5.84% dose	5.86% dose
Bias proportional	N	N	N	Y	N	N
Bias fixed	N	Y	N	N	N	Y
Delta0.05	3.80% dose/h	3.51% dose/h	4.0 min	3.8 min	1.43% dose	1.26% dose

T_max: Time to reach the maximum momentary ¹³C elimination; D_max: Maximum momentary ¹³C elimination; AUC_{0-60 :} 60-min cumulative ¹³C elimination in expiratory air, respectively; S_term: Short term reproducibility assessment on the basis of 20 pairs of ¹³C-methacetin breath tests separated by a median 2-d break; M_term: Medium-term reproducibility evaluation involved 20 pairs of examinations accomplished at a median interval of 18 d. CV_p: Coefficient of variation for paired examinations; RC: Repeatability coefficient. Delta_0.05: The least difference detectable at P = 0.05 level, two-tailed in the case of 20 paired examinations.