Table 1

Biological challenge response and subsequent panic attacks

Analysis group	Author (year)	n	Challenge	Response index	Median follow-up (years)	Effect size (r) (95% CI)
Panic attack symptoms	Coryell et al (2006)19	87	35% CO₂	Dichotomised panic attack symptoms	4.0	0.005 (−0.277 to 0.286)
	Harrington et al (1996)21	62	35% CO₂	Dichotomised panic attack symptoms	1.0	0.159 (−0.236 to 0.508)
	Schmidt (2007)15	295	20% CO₂	Panic attack symptom severity	1.5	0.470 (0.376 to 0.554)
Subjective anxiety or distress	Coryell et al (2006)19	87	35% CO₂	VAS-A change prechallenge to postchallenge	4.0	−0.093 (−0.294 to 0.115)
	Perna et al (1999)22	31	35% CO₂	Dichotomised VAS-A % change prechallenge to postchallenge	3.5	0.006 (−0.328 to 0.338)
	Schmidt (2007)16	295	20% CO₂	Subjective units of distress prechallenge to postchallenge	1.5	0.550 (0.465 to 0.625)
Objective physiological response	Coryell et al (2006)19	81	5% CO₂	Dichotomised abnormal minute ventilation slope	4.0	0.211 (−0.066 to 0.457)