Table 2.

Influence of possible confounders

Confounders	Global oscillatory activity			Confounder
	HR	CI	P-value	HR	CI	P-value
Age (≤ 40)	2.40	1.33–4.36	0.004**	2.20	0.78–3.22	0.138
Age (years continuous)	2.33	1.31–4.13	0.004**	0.97	0.93–1.02	0.210
Gender	2.49	1.35–4.61	0.004**	0.44	0.13–1.47	0.183
KPS (≤ 80)	2.04	1.17–3.58	0.013*	0.49	0.06–3.88	0.497
WHO grade	2.05	1.17–3.59	0.013*	1.23	0.39–3.93	0.723
Histology	2.37	1.32–4.25	0.004**	2.23	1.03–4.82	0.041*
IDH1 mutation status (N = 18)	2.13	1.14–3.97	0.018*	2.10	0.66–6.69	0.209
IDH1 mutation status combined with 1p/19q codeletion (N = 18)	2.88	1.14–7.28	0.025*	2.33	0.99–5.51	0.054
Adjuvant treatment	2.09	1.17–3.74	0.013*	1.02	0.52–2.00	0.958
Tumor volume (cm3)	2.29	1.33–3.93	0.003**	1.02	1.00–1.04	0.019*
Tumor diameter (< 6 cm)	2.02	1.16–3.51	0.013*	0.68	0.26–1.82	0.445
Non-eloquent area	2.28	1.28–4.06	0.005**	0.52	0.17–1.60	0.256
Head size	2.23	1.24–4.01	0.007**	1.16	0.69–1.93	0.580

Results of Cox proportional hazard models for the thirteen separate multivariate analyses using global oscillatory activity combined with each of the confounders

CI 95% confidence interval, HR hazard ratio, KPS Karnofsky performance status, WHO World Health Organization

*P < 0.05; ** P < 0.01