Table IV. Time from symptom onset to diagnosis of reported ALS patients by project areas.

	Combined areas		States		Metropolitan areas
	#	%	#	%	#	%
< 12 monthsa	2588	44.0	1623	44.8	965	42.6
12-17 months	1059	18.0	643	17.8	416	18.4
≥ 18 monthsb	1815	30.9	1061	29.3	754	33.3
Unknown	421	7.1	293	8.1	128	5.7
Total	5883	100.0	3620	100.0	2263	100.0

^aPatients with unknown month of diagnosis or month of symptom onset were included in the < 12 months category when the years were the same.

^bPatients with missing month of onset symptom but year was present and were three years or more apart were placed in the ≥ 18-month category.