Table 4.

Correlation of VEP variables with age, duration of illness, pack-years, spirometric indices, and MMSE scores

VEP variables	Age	Duration of illness	Pack-years	PEFR	FEV1	FEV1/ FVC	MMSE score
Latency P100 (Right eye)	r	0.190	0.067	0.085	–0.241	–0.243	–0.358	–0.327
	P	0.240	0.680	0.844	0.134	0.130	0.023*	0.039*
Latency P100(Left eye)	r	0.097	0.083	0.049	–0.198	–0.163	–0.183	–0.178
	P	0.553	0.612	0.766	0.220	0.315	0.257	0.272
Amplitude P100 (Right eye)	r	0.012	0.154	0.085	0.084	–0.045	0.063	0.208
	P	0.943	0.342	0.588	0.377	0.332	0.381	0.197
Amplitude P100(Left eye)	r	–0.261	–0.025	–0.015	0.270	0.274	0.239	0.121
	P	0.104	0.879	0.926	0.092	0.087	0.137	0.459

FEV₁ = Forced expiratory volume in first second; FVC = Forced vital capacity; MMSE = Mini-mental state examination questionnaire; PEFR = Peak expiratory flow rate; VEP = Visual evoked potentials; r = Pearson’s coefficient; P = P value;

^*correlation was significant at the 0.05 level (2-tailed); an inverse correlation was noted