Diagnosis pathway for patients with amyotrophic lateral sclerosis: retrospective analysis of the US Medicare longitudinal claims database

Table 5 Diagnostic testing frequency and median time to diagnosis

Diagnostic test	Total ALS cohort*		Limb-onset subgroup		Bulbar-onset subgroup
	Percent with test^†	Median time to diagnosis, years^‡	Percent with test^†	Median time to diagnosis, years^‡	Percent with test^†	Median time to diagnosis, years^‡
Nerve conduction testing
Sensory nerve conduction test	38	2.75	41	2.75	30	2.50
Motor nerve conduction test with F-wave	26	2.75	30	2.75	18	0.25
Motor nerve conduction test without F-wave	23	2.75	24	2.88	18	0.50
Imaging studies
MRI of neck and spine without dye	25	2.50	29	2.75	15	2.50
CT scans (head or brain) with/without contrast material	39	2.50	43	2.75	19	1.25
MRI of brain with/without dye	28	2.75	29	2.75	28	0.25
Electromyography
Limb electromyography (2 extremities and related paraspinal areas)	19	2.75	22	2.50	12	ND
Limb electromyography (1 extremity and related paraspinal areas)	16	2.50	18	2.75	10	ND
Other
Exam of throat and/or upper gastrointestinal tract	22	2.50	15	3.00	48	2.50

ALS, amyotrophic lateral sclerosis; CT, computed tomography; MRI, magnetic resonance imaging, ND, not determined, frequency of testing < 15%.
*n = 399.
^†In the eight quarters before ALS diagnosis, not including the quarter of diagnosis.
^‡In the time to diagnosis cohort (n = 272).

ISSN: 1471-2377