Ontoserver Postman

FHIR🔥 API Extensions

Boosting

The Extension URI http://ontoserver.csiro.au/profiles/boost can be added to the ValueSet.compose.include element to adjust the ranking up (value > 1.0) or down (value < 1.0) of codes when performing an $expand with filter.

For example, consider the following example ValueSet which includes AMT codes for “Trade Product Packs”, “Medicinal Product Packs”, and “Trade Products” - ie branded medications, unbranded medications, and simple brands.

{
   "resourceType" : "ValueSet",
   "url" : "http://csiro.au/example/ValueSet/drugs",
   "compose" : {
      "include" : [ {
         "system" : "http://snomed.info/sct",
         "filter" : [
            { "property" : "concept", "op" : "is-a", "value" : "30560011000036108" }
         ]
      }, {
         "system" : "http://snomed.info/sct",
         "filter" : [
            { "property" : "concept", "op" : "is-a", "value" : "30404011000036106" }
         ]
      }, {
         "valueSet": [ "http://snomed.info/sct?fhir_vs=refset/30513011000036104" ]
      } ]
   }
}

Now, we really want people to be as specific as possible when recording medication, so we prefer branded things over unbranded things over brands. This means we'd like this preference to be accounted for when ranking the matching codes in a ValueSet/$expand?filter=... operation. (The value for the filter parameter would be a search string entered by the user.)

We can achieve this by adding the following “boost” extension to the ValueSet.compose.include clauses. Then after Ontoserver has computed a ranking score for each concept, it is scaled by the appropriate factor depending on which clause matched the concept.

Note that the scaling factors here are somewhat arbitrary. In this case they are large, so have a big impact on scoring to the extent that the three clauses are likely scored in completely disjoint ranges. For boost values closer to 1, the effect is more subtle. Determining the best values is somewhat of an experiemental art.

{
   "resourceType" : "ValueSet",
   "url" : "http://csiro.au/example/ValueSet/boost1",
   "compose" : {
      "include" : [ {
         "system" : "http://snomed.info/sct",
         "filter" : [
            { "property" : "concept", "op" : "is-a", "value" : "30560011000036108" }
         ]
         // Reduce the significance of codes matching this filter
         "extension" : [ {
            "url" : "http://ontoserver.csiro.au/profiles/boost",
            "valueDecimal" : 0.01
         } ]
      }, {
         "system" : "http://snomed.info/sct",
         "filter" : [
            { "property" : "concept", "op" : "is-a", "value" : "30404011000036106" }
         ]
         "extension" : [ {
            // Increase the significance of codes matching this filter
            "url" : "http://ontoserver.csiro.au/profiles/boost",
            "valueDecimal" : 10.0
         } ]
      }, {
         "valueSet": [ "http://snomed.info/sct?fhir_vs=refset/30513011000036104" ],
         "extension" : [ {
            // Increase the significance of codes in the imported ValueSet, but not by as much as the above
            "url" : "http://ontoserver.csiro.au/profiles/boost",
            "valueDecimal" : 5.0
         } ]
      } ]
   }
}