While it’s tempting for clinicians to do immunization clinical decision support (CDS) “by hand,” they can really benefit from computer-assisted CDS software to support the administration of the right vaccines at the right times, especially given the complexity of immunization recommendations. HLN provides its open source Immunization Calculation Engine (ICE) software for just this purpose.
As part of our support for ICE we encourage clinical users to send us instances where they believe our algorithm may not be evaluating the patient’s clinical history accurately, or may not be forecasting their needed doses correctly. Whether they are currently using ICE in their own systems, or testing ICE using our web-based simulator, we have talented analysts who examine these examples to document how ICE’s conclusions are accurate, or occasionally to identify corrections that we need to make in its rules.
Recently, we received a question from a clinician who believed, for a particular scenario, that the patient should receive a fourth (and last) pneumococcal immunization even though ICE did not recommend it. We did our usual deep-dive to analyze the scenario, by starting with the entry of the test patient’s record in our simulator:
We then reviewed the scenario against the ICE rules to determine why ICE considers this patient complete for the pneumococcal series, with a recommendation of “Not Recommended/ COMPLETE_HIGH_RISK.” In this case, ICE is using the Pneumococcal Child Series to provide the evaluation and forecast. According to this ICE series, a child is complete after 4 doses, unless an exception applies.
In this case, the Pneumococcal Child Series Exception 2B rule applied, where two doses at age < 12 months plus a dose at age >= 12 months completes the series.
At first glance, it may not appear that Exception 2B should be triggered because all 3 shots were given at less than 12 months old. But upon further inspection, we see the 3rd shot is counted as the final dose in the series because it was administered within an allowable grace period before the routinely recommended age of 12 months. With the 3rd dose given on 1/30/2020 (at age 1 year minus 1 day), this meets the absolute minimum age requirement for dose 4 (age 1 year – 4 days). With this valid dose, the patient has completed their series and therefore ICE recommends Not Recommended / COMPLETE_HIGH_RISK.
This ICE recommendation is in line with the CDC Catch Up Guidance for PCV and ACIP General Best Practice Guidelines for Immunization. The Catch Up Guidance for PCV indicates for a child of this age, with 3 previous doses of PCV (with one given at age 12 months or older), no additional doses are needed. The ACIP General Best Practice Guidelines indicate that vaccines given <= 4 days before the minimum interval or age are considered valid. In this case, the 3rd dose of PCV is counted as given at age 12 months or older because it was administered within the grace period.
This is a pretty complex example, but the benefits of computer-assisted CDS come through strong: adherence to rigorously-tested, consistently-applied complex rules. ICE rules are documented on a public wiki that increases access for individuals interested enough and capable of following them. Because they are presented in a structured manner they are easier to follow, but only by using them in a software implementation can you be sure that they are being used correctly. Note, as immunization recommendations evolve so do the ICE rules. This example is provided for illustrative purposes only, for the latest ICE rules, see the ICE public wiki.
If you have questions about ICE evaluation and forecasting or would like more information about ICE, please reach out to the HLN ICE team at email@example.com.
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