Corticosteroids for Immune Reconstitution Inflammatory Syndrome (IRIS)

Time Course Change in Functional Status Based on Karnofsky Performance Status Index Through 6 Months Following Completion of Plasma Exchange (PLEX)

The Karnofsky Performance Status Index (KPSI) is an assessment tool intended to assist clinicians and caretakers in gauging a patient's functional status and ability to carry out activities of daily living. A KPSI of 100=normal, no complaints, no evidence of disease; 90=able to carry on normal activity, minor signs or symptoms of disease; 80=normal activity with effort, some signs or symptoms of disease; 70=cares for self, unable to carry on normal activity or do active work; 60=requires occasional assistance but is able to care for most personal needs; 50=requires considerable assistance and frequent medical care; 40=disabled, requires special care and assistance; 30=severely disabled, hospitalization is indicated, although death is not imminent; 20=very sick, hospitalization is necessary, active support treatment is necessary; 10=moribund, fatal processes progressing rapidly; 0=dead.

Time frame: Baseline up to 6 months

Number of Participants Who Survived at 6 Months Following Completion of Plasma Exchange (PLEX)

Following the completion of rapid removal of natalizumab using PLEX or equivalent.

Time frame: 6 months

Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs)

AE=any untoward medical occurrence in a participant administered a pharmaceutical product and that does not necessarily have a causal relationship with this treatment. SAE=any untoward medical occurrence that at any dose: results in death; in the view of the Investigator, places the participant at immediate risk of death (a life-threatening event); however, this does not include an event that, had it occurred in a more severe form, might have caused death; requires hospitalization or prolongation of existing hospitalization; results in persistent or significant disability/incapacity; or results in a congenital anomaly/birth defect. An SAE may also be any other medically important event that, in the opinion of the Investigator, may jeopardize the participant or may require intervention to prevent one of the other outcomes listed in the definition above.

Time frame: from the first dose of study treatment through the end of the treatment period (6 months) + a 4-week post-treatment period

Severity of AEs and SAEs

AEs and SAEs were categorized as mild, moderate or severe according to the following criteria: Mild=barely noticeable to participant or does not make participant uncomfortable; does not influence performance or functioning; prescription drug not ordinarily needed for relief of symptom(s) but may be given because of personality of participant. Moderate=of a sufficient severity to make participant uncomfortable; performance of daily activity is influenced; participant is able to continue in study; treatment for symptom(s) may be needed. Severe=symptoms cause severe discomfort; symptoms cause incapacity or significant impact on participant's daily life; severity may cause cessation of treatment with study treatment; treatment for symptom(s) may be given and/or participant hospitalized. Please see Outcome Measure 3 for AE and SAE definitions.

Time frame: from the first dose of study treatment through the end of the treatment period (6 months) + a 4-week post-treatment period

Time Course Change in the Global Clinical Impression of Improvement (GCI-I) Scale

The GCI-I scale is a 7-point scale that assesses how much the participant's illness has improved or worsened relative to a baseline state at the beginning of the intervention, and rates it as: 1=very much improved; 2=much improved; 3=minimally improved; 4=no change; 5=minimally worse; 6=much worse; 7=very much worse.

Time frame: Screening to 6 months following completion of PLEX (participants began treatment with intravenous methylprednisolone (IVMP) within 2 weeks after PLEX [or equivalent]).

Time Course Change in Cerebral Dysfunction Using the Symbol Digit Modalities Test (SDMT)

The SDMT measures the time to pair abstract symbols with specific numbers. The test requires elements of attention, visuoperceptual processing, working memory, and psychomotor speed. The score is the number of correctly coded items from 0-110 in 90 seconds. The total score provides a measure of the speed and accuracy of symbol-digit substitution.

Time frame: Screening to 6 months following completion of PLEX (participants began treatment with IVMP within 2 weeks after PLEX [or equivalent]).

Time Course Changes in Brain Magnetic Resonance Imaging (MRI)

The brain MRI data collected included: progressive multifocal leukoencephalopathy (PML) lesion localization, T2 hyperintense lesion volume, and signs of cerebral edema.

Time frame: Screening to 6 months following completion of PLEX (participants began treatment with IVMP within 2 weeks after PLEX [or equivalent]).

Time Course Change in Magnetoencephalography (MEG) Results

MEG was used to map brain activity.

Time frame: Screening to 6 months following completion of PLEX (participants began treatment with IVMP within 2 weeks after PLEX [or equivalent]).

Time Course Change in Clinical Laboratory Values

Clinical laboratory values included chemokines, cytokines, C-reactive protein (CRP), John Cunningham (JC) virus load, and cell count in cerebrospinal fluid.

Time frame: Screening to 6 months following completion of PLEX (participants began treatment with IVMP within 2 weeks after PLEX [or equivalent]).

Time Course Elimination of Serum Natalizumab Concentration Following Plasma Exchange (PLEX) or Equivalent

Time frame: Baseline up to 6 months