Table 1

Contingency table comparing smoking incidence in symptomatic and non-symptomatic LHON individuals at two designated critical ages using two different smoking classifications

Group	Designated critical age	Pack year cut off		Symptomatic	Non-symptomatic	Total	Fisher’s exact p value
M, F	25	0.5 pack years (smoking classification 1)	Smoke	10	23	33	0.0009
			No smoke	0	32	32
			Total	10	55	65
M, F	25	3.5 pack years (smoking classification 2)	Smoke	10	17	27	0.0001
			No smoke	0	38	38
			Total	10	55	65
Males	25	0.5 pack years (smoking classification 1)	Smoke	9	14	23	0.0146
			No smoke	0	12	12
			Total	9	26	35
Males	25	3.5 pack years (smoking classification 2)	Smoke	9	9	18	0.001
			No smoke	0	17	17
			Total	9	26	35
M, F	35	3.75 pack years (smoking classification 1)	Smoke	10	16	26	0.0001
			No smoke	0	32	32
			Total	10	48	58
M, F	35	8.5 pack years (smoking classification 2)	Smoke	10	12	22	0.0001
			No smoke	0	36	36
			Total	10	48	58
Males	35	3.75 pack years (smoking classification 1)	Smoke	9	10	19	0.0051
			No smoke	0	12	12
			Total	9	22	31
Males	35	8.5 pack years (smoking classification 2)	Smoke	9	7	16	0.0008
			No smoke	0	15	15
			Total	9	22	31