Six- and 12-month functional outcomes among patients with confirmed acute flaccid myelitis (AFM) with onset in 2018, United States.

Purpose: Acute flaccid myelitis (AFM), an uncommon but serious neurologic condition, primarily affects children, and can progress quickly to paralysis and respiratory failure. Data on long-term outcomes of patients with AFM are limited. This study reports on functional status through 12 months for AFM patients who became ill in 2018 in the United States.

Methods: Health departments collected information on outcomes at 6 and 12 months after onset of AFM using a standardized form that asked patients or their parents/guardians about functional status. Analyses were restricted to confirmed cases.

Results: Of the 238 confirmed AFM cases reported to CDC in 2018, 90 (38%) had assessments at 6 months, 82 (34%) at 12 months, and 49 (21%) at both 6 and 12 months. Among the 49 patients with data at both time points, the proportion of patients reporting significant or severe impairment at 6 months ranged from 2% to 59% depending on the outcome. Although proportions decreased by 12 months and ranged from 2% to 51%, most patients had some impairment at 12 months. No deaths were reported.

Conclusion: Six- and 12-month outcomes in patients with onset of AFM in 2018 span a wide range of functionality, particularly of upper and lower extremities. Importantly, improvement appears to occur over time in some patients.