Table 8:

Summary of Subgroup Analyses for Pain-Related Outcomes, nVNS vs. Control, Acute Treatment, Chronic Cluster Headache

Pain outcome	Author, year (study)	Measurement, time	Participants, nVNS/control, n	Mean or proportion		Summary effect (95% CI or SE)	P
				nVNS	Control
Response	Silberstein et al, 201651 (ACT1)	Proportion after first attack, 15 min	22/26	13.6	23.1	RR 0.59 (0.17 to 2.09)b	.41b
	Goadsby et al, 201852 (ACT2)	Mean proportion treated of attacks per person, 30 min	34/31	36.6	28.5	Absolute difference: 8.1 (8.1)	.34
Response in ≥ 50% of attacks	Silberstein et al, 201651 (ACT1)	Proportion, 15 min	22/26	13.6	30.8	RR 0.44 (0.13 to 1.47)b	.18b
	Goadsby et al, 201852 (ACT2)	Proportion, 15 min	34/31	29.4	12.9	RR 2.28 (0.8 to 6.53)b	.12b
Sustained response	Silberstein et al, 201651 (ACT1)	Proportion, 15 min sustained to 60 min	22/26	13.6	15.4	RR 0.89 (0.22 to 3.54)b	.86b
Pain freedom	Goadsby et al, 201852 (ACT2)	Proportion, 30 min	34/31	19.2	17.9	Absolute difference: 1.3 (6.5)	.76
Pain freedom in ≥ 50% of attacks	Silberstein et al, 201651 (ACT1)	Proportion, 15 min	22/26	4.6	15.4	RR 0.30 (0.04 to 2.45)b	.26b
	Goadsby et al, 201852 (ACT2)	Proportion, 15 min	34/31	8.8	6.5	1.37 (0.24 to 7.65)b	.72b
Headache intensity	Silberstein et al, 201651 (ACT1)	Mean for all treated attacks, 15 min	22/26	2.3	1.9	Mean difference: 0.4 (-0.7 to 0.87)b	.09b
	Goadsby et al, 201852 (ACT2)	Mean change from attack onset to follow-up, 15 min	25/23	-1.2	-1.0	Mean difference: -0.2 (-0.75 to 0.35)	.48b
		Mean change from attack onset to follow-up, 30 min	25/23	-1.5	-1.3	Mean difference: -0.2	.5

Abbreviations: CI, confidence interval; nVNS, noninvasive vagus nerve stimulation, RR, relative risk; SE, standard error.

^aCalculated P values may differ from those in the published analyses due to varying statistical techniques and rounding.

^bCalculated using data provided.