🧠 Natalizumab PML Risk Stratification Simulator

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.