Suspicion Index for -4 years
NPC-SI for individuals under four years
The original NPC Suspicion Index (NPC-SI) has been redeveloped to include a second screening tool for individuals with suspected Niemann-Pick disease type C (NPC) under four years of age.
This early-onset NPC-SI was developed following a retrospective chart review of 200 patients under four years from nine expert centres in seven countries and included: 106 confirmed NPC cases; 31 NPC non-cases (confirmed negative for NPC) and 63 controls. Statistical analyses determined the strength of association between combinations of signs and symptoms and a diagnosis of NPC.1
This early-onset NPC-SI includes nine key signs and symptoms related to the central nervous system (CNS), spleen, liver, lungs, natal factors, and family history, as well as two modifier symptoms (ataxia and cognitive decline) that indicate an association with NPC when combined with other clinical features.
Each symptom has a score based on its strength of association with NPC, ranging from the highest score of four points to the lowest score of one. An overall risk prediction score (RPS) is then calculated.
How to use the NPC-SI for under four years
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Refer individual on for further testing as appropriate (see NPC Clinical Guidelines)2
The NPC-SI calculator
For individuals under four years
If you need further information about the symptoms included in the NPC-SI or how to assess these, see our Symptoms page.
Understanding the results
| Risk Prediction Score | Referral advice |
|---|---|
| <3 | LOW likelihood of NPC
Discount other possible causes |
| 3-5 | MODERATE likelihood of NPC
Contact your nearest NPC referral centre to discuss |
| ≥6 | HIGH likelihood of NPC
Refer the individual to an NPC referral centre for immediate testing |
For further information about diagnosis and management of NPC, please refer to the Clinical Management Guidelines for NPC.2 If your patient is subsequently diagnosed with NPC, please consider including them in the International Niemann-Pick Disease Registry (INPDR) (see Resources page for further information)
Other important symptoms
If any of the following symptoms are observed alongside a moderate level of suspicion, the likelihood of NPC should be considered elevated, and the individual should be referred to an NPC centre for testing: