Calculators & Tools

SILC Score (Lyme Carditis)

Suspicious Index in Lyme Carditis - pre-test probability in a patient with new high-degree AV block.

1 What is the SILC Score (Lyme Carditis)?

The SILC Score (Lyme Carditis) is a infectious scoring tool used in paediatric practice. Suspicious Index in Lyme Carditis - pre-test probability in a patient with new high-degree AV block. It scores 5 criteria and interprets the total across 3 bands, so the number always arrives with the severity it implies rather than on its own. In PediAid each criterion is shown as a labelled option with the weight it carries, so the total can be checked rather than taken on trust.

2 When to use it

  • Grading severity at the bedside in infectious
  • Recording an objective severity band in the case notes
  • Deciding when a total crosses the threshold for escalation
  • Re-scoring to track whether a child is improving or deteriorating
  • Checking the exact criteria of a score used infrequently

3 Formula & method

The score sums 5 criteria: Constitutional symptoms (fever, malaise, arthralgia, dyspnoea); Erythema migrans rash; Outdoor activity or residence in an endemic area; Male sex; Age < 50 years. Totals are then banded: any score - Low probability: score 0-2 - low probability of Lyme carditis. Investigate other causes of AV block; a permanent pacemaker may be appropriate; 3 points or more - Intermediate: score 3-6 - intermediate probability. Send Lyme serology and consider empirical antibiotics before committing to a permanent pacemaker; 7 points or more - High probability: score ≥7 - high probability of Lyme carditis. Treat with antibiotics; AV block is usually reversible, so avoid a permanent pacemaker until treated.
  • Purpose is to avoid unnecessary permanent pacemakers - Lyme-related AV block usually resolves with antibiotic therapy.
  • Source: Besant G et al. Suspicious index in Lyme carditis: systematic review and proposed new risk score. Clin Cardiol 2018;41:1611-1616.

4 Frequently asked questions

How many criteria does the SILC Score (Lyme Carditis) use?

5. They are Constitutional symptoms (fever, malaise, arthralgia, dyspnoea); Erythema migrans rash; Outdoor activity or residence in an endemic area; Male sex; Age < 50 years.

What do the bands of the SILC Score (Lyme Carditis) mean?

The total is interpreted as: any score - Low probability: score 0-2 - low probability of Lyme carditis. Investigate other causes of AV block; a permanent pacemaker may be appropriate; 3 points or more - Intermediate: score 3-6 - intermediate probability. Send Lyme serology and consider empirical antibiotics before committing to a permanent pacemaker; 7 points or more - High probability: score ≥7 - high probability of Lyme carditis. Treat with antibiotics; AV block is usually reversible, so avoid a permanent pacemaker until treated.

Does the score replace clinical judgement?

No. It is a structured way to record and communicate severity. A clinician concerned about a child should act on that concern regardless of the total.

Where does this score come from?

Purpose is to avoid unnecessary permanent pacemakers - Lyme-related AV block usually resolves with antibiotic therapy.

Does it work offline?

Yes. Score definitions are bundled with the PediAid app, so the score computes without a connection.

For qualified clinicians. This page and the PediAid app are a clinical aid only. Calculations and reference data must be verified against the patient's clinical context, the source guideline and your local protocols before any treatment decision is made.