Baseline JC Virus Antibody Testing Before Natalizumab Start
Placeholder lead: every candidate is screened for anti-JCV antibodies first.
- ~54%: Seroprevalence (adults) (Placeholder short caption)
- ELISA: Test type (Placeholder short caption)
- 6 mo: Retest interval (Placeholder short caption)
- <0.1/1k: JC-negative PML risk (Placeholder short caption)
Why baseline serostatus anchors the whole risk model
Placeholder body text: seronegative patients carry near-zero baseline PML risk.
Placeholder body text: seroconversion can occur during therapy, so retesting matters.
Placeholder highlight: negative status can still convert positive over time.
JC Virus Antibody Index Level Refines Positive-Status Risk
Placeholder lead: index value splits positive patients into low vs high risk bands.
- ≤0.9: Low index cutoff (Placeholder short caption)
- >1.5: High index cutoff (Placeholder short caption)
- STRATIFY JCV: Index assay (Placeholder short caption)
- ~8×: Risk multiplier, high vs low (Placeholder short caption)
Index magnitude, not just positivity, drives stratification
Placeholder body text: higher index correlates with higher probable PML risk.
Placeholder body text: index is re-checked periodically alongside duration.
Placeholder highlight: a rising index over time signals escalating risk.
Cumulative Months on Natalizumab Sharply Shift Risk After Year Two
Placeholder lead: risk climbs notably once therapy passes 24 months.
- ~24 mo: Inflection point (Placeholder short caption)
- 25–48 mo: Peak risk window (Placeholder short caption)
- q4 weeks: Dosing interval (Placeholder short caption)
- q3–6 mo: MRI monitoring (Placeholder short caption)
Duration compounds with JC index rather than acting alone
Placeholder body text: longer exposure raises cumulative JC virus reactivation risk.
Placeholder body text: extended-interval dosing is one mitigation strategy studied.
Placeholder highlight: >24 months plus high index is the key inflection combo.
Prior Immunosuppressant Exposure Adds an Independent Risk Layer
Placeholder lead: history of immunosuppressive MS drugs further elevates risk.
- ~1.8×: Risk multiplier (Placeholder short caption)
- Mitoxantrone, azathioprine: Common priors (Placeholder short caption)
- Persists years: Washout relevance (Placeholder short caption)
- JC+ high, prior IS: Highest-risk subgroup (Placeholder short caption)
Immune history leaves a lasting mark on PML susceptibility
Placeholder body text: prior immunosuppressive therapy independently raises PML odds.
Placeholder body text: this factor is combined multiplicatively with index and duration.
Placeholder highlight: prior immunosuppression never lowers risk, only adds to it.
Combined Risk Score Guides Continue-Therapy vs Switch Decisions
Placeholder lead: JC index, duration, and prior immunosuppression multiply together.
- <0.1/1k: Lowest risk band (Placeholder short caption)
- ~10–13/1k: Highest risk band (Placeholder short caption)
- Recommended: Shared decision-making (Placeholder short caption)
- Consider switch: Alternative therapy (Placeholder short caption)
Turning three risk factors into one actionable stratum
Placeholder body text: the risk-matrix cell shows the patient's combined stratum.
Placeholder body text: very-high-risk strata prompt discussion of switching therapy.
Placeholder highlight: risk stratification informs, but does not replace, clinical judgment.