To What Extent Does JC Virus Status Influence Patient Decisions Regarding Treatment with Natalizumab?

Background: The stratify John Cunningham Virus [JCV] test started to be used at Salford Royal NHS Trust, a major tertiary neurology centre in the United Kingdom for patients on or being considered for treatment with Natalizumab. The JCV test is not mandatory at this time for patients prior to commencing, or on treatment at this centre as there was feeling that a positive test might put patients off treatment. This is due to the risk of developing progressive multifocal leukoencephalopathy increasing from 1 in 10,000 if JCV negative, to 1 in 1,429 if JCV positive in the first 2 years of treatment, increasing to 1 in 189 at 2 – 4 years. It was decided to audit the results of these tests to see if a positive test affects how they perceive the risk of treatment.

Objectives: To determine to what extent JC Virus status influences patients decisions regarding treatment with Natalizumab.

Methods: Retrospective case note analysis of these patients was undertaken to identify whether a decision to remain on or start treatment was affected by a positive test result. All patients who underwent JCV testing from the start of its use at the centre in August 2011 to the end of June 2014 were included in the audit (n=150). Demographics of the patient cohort was an average age of 37.9 (range 18 – 63), 68.7% female (n=105), with 54% (n=82) being DMT naïve. As at 25 September 2014 190 patients were being treated with Natalizumab.

Results: Of the patients tested n=55 were treated with Natalizumab and n=95 were tested prior to deciding whether or not to commence treatment. Out of the 150 tests performed at this centre all patients treated with Natalizumab (n=55) remained on treatment regardless of JCV status (positive n=21, negative n=34), additionally one patient who seroconverted from negative to positive elected to remain on treatment. In patients tested prior to treatment JCV Positivity (n=45) resulted in 9 who elected not to start treatment, in JCV negative patients (n=50) 6 elected not to start Natalizumab.

Conclusions: JCV positivity before treatment reduced the likelihood they would elect to be treated with Natalizumab by 11% (12% JCV negative vs 23% JCV positive).