Reading an NHI pre-check rule in CQL

The library

The guide currently holds 77 libraries: 66 reimbursement rules for breast, colorectal, lung, liver and prostate cancer, one code set and one shared module per cancer type, and FHIRHelpers for type conversion. This page reads LCPembrAtezoRule1, a lung cancer rule.

We chose it because this one library uses most of the patterns in the guide: two drugs share one rule, first use and continued use are judged separately, the criteria cover diagnosis, gene tests, PD-L1, lab values, imaging reports and a treatment plan document, and the library ends by producing a text report. The original runs to just over 900 lines and more than 100 defines. This page covers the structure, so keep the official page open for the line-by-line detail.

Library

LCPembrAtezoRule1

Title

Pembrolizumab、Atezolizumab給付規定(鱗狀、非鱗狀非小細胞肺癌第一線用藥(單用))Pembrolizumab and atezolizumab criteria: first-line monotherapy for squamous and non-squamous non-small cell lung cancer

Version

1.0.0, status Draft

Includes

FHIRHelpers 4.0.1, LCCodeConcept 1.0.0 (lung cancer code set), LCReusable 1.0.0 (lung cancer shared module)

Official page

build.fhir.org/ig/TWNHIFHIR/cql/Library-LCPembrAtezoRule1.html

What the rule reads

The rules read request data as TWPAS defines it. Under TWPAS, a hospital packages each prior authorization request as a Bundle: the claim (Claim) plus resources for the patient, medications, tests and reports. This library’s data requirements (dataRequirement) list five resource types, and it reads the patient through context Patient:

TWPAS also has a Condition profile, but this rule reads every diagnosis from Claim.diagnosis and never queries Condition. When you read an official rule, check which resource and field it actually queries rather than guessing from the criteria text.

Header: what it includes

The rules we opened all start with the same few lines; only the name and the cancer type of the includes change:

Besides this lung cancer rule, we opened one rule each for colorectal, breast, liver and prostate cancer, and their headers follow the same structure. There is no parameter in the header: everything the rule needs is queried from the request data.

Code sets: the codes a rule uses

LCCodeConcept has no context and no logic. It only holds codes, in three groups:

• Code systems: the international SNOMED CT, LOINC and HL7 observation interpretation codes; the NHI code systems defined by TWPAS, such as line of therapy, NHI drugs, order type, continuation flag, response assessment, supporting information type and reimbursement indication; and TW Core’s Taiwan editions of ICD-10-CM and ICD-10-PCS (2014 and 2023).
• Lab and test codes, listed as strings with define: the LOINC codes for EGFR, ALK, ROS1 and the PD-L1 assays, the LOINC codes for GOT, GPT, T-bilirubin, creatinine and eGFR, and the ICD-10-PCS codes for imaging.
• Drug codes: each list is named by its ATC code and holds NHI drug codes. L01FF02 is pembrolizumab and L01FF05 is atezolizumab.

// Code set library: declare code systems, then list the codes
codesystem "LOINC": 'http://loinc.org'
codesystem "NHILOT": 'https://nhicore.nhi.gov.tw/pas/CodeSystem/nhi-line-of-therapy'

define "Some gene test": { 'code-A', 'code-B' }

The code set has no valueset declarations. The code lists sit in the library itself, so nothing needs to expand a FHIR ValueSet at run time. When a rule says CodeConcept followed by a name, look up the define with that name on the code set page to see which codes it covers.

Pulling data from the request

A rule uses a retrieve (the resource type in square brackets, such as [Observation]) to get this patient’s resources of one type, then filters them with where. Four patterns come up again and again in this rule:

// Pattern 1: a lab value below a threshold
define "Some lab below threshold":
  exists (
    [Observation] O
      where Reusable."IsTestObservation"(O)        // category is "lab test"
        and exists (
          O.code.coding C
            where C in CodeConcept.LOINC             // code system is LOINC
              and C.code in CodeConcept."Some lab"   // code is in the list
        )
        and O.value is FHIR.Quantity
        and (O.value as FHIR.Quantity).value < 2.0   // value below the threshold
  )

The criteria: defines in layers

The hierarchy of the reimbursement criteria becomes the hierarchy of defines: conditions make up rules, and rules make up main rules. Official define names put the number and the wording of the clause together, such as 1規則1-3=成人 (rule 1-3 = adult), which makes them easy to match against the criteria text.

// Conditions make up rules, rules make up main rules, joined with and / or
define "Rule 1":
  "Rule 1-1" and "Rule 1-2" and "Rule 1-3"

// The same rule checks a different condition depending on the drug requested
define "Rule 3":
  if "Drug A requested" then "Drug A PD-L1 condition"
  else if "Drug B requested" then "Drug B PD-L1 condition"
  else false

define "Main rule 1":
  "Rule 1" and "Rule 2" and "Rule 3" and "Rule 4"

The rule has three main rules. Main rule 1 (first use) is made of four rules:

Main rule 2 (continued use) requires a continuation flag of 2 and a response on i-RECIST, or stable disease (SD) as long as the current and previous assessments are not both SD; no confirmed progression (iCPD), no moderate, severe or life-threatening adverse drug reaction, and no break in treatment longer than 24 weeks; and the patient must still pass the performance status and organ function checks of 1規則2 and have imaging within 12 weeks.

Main rule 3 (drug use rules) holds four limits: one immune checkpoint inhibitor per patient per indication, with no switching; no concurrent use of the listed targeted drugs during treatment; no more than 2 years in total; and at most 12 weeks per request. The report labels these four as reference information (參考資訊), and they do not affect the final result.

The final decision

The last few defines turn everything above into output:

Request type

The shared module reads the continuation flag on the claim: 1 is first use and 2 is continued use (the TWPAS code table calls it a repeat request). With neither, the type cannot be determined.

Boolean result

Its name ends in _布林 (Boolean). First use is judged on main rule 1, continued use on main rule 2, and an undetermined request type gives false.

Text result

Pass or fail, together with the request type.

Report summary (報告總結)

A text report: request type, items met, items not met, and finally the result. Items not met are split into two groups: required data missing, and conditions or codes not met.

// The request type decides which main rule applies; an unknown type fails
define "Result (Boolean)":
  case
    when Reusable."First use" then "Main rule 1"
    when Reusable."Continued use" then "Main rule 2"
    else false
  end

How does the report tell “not provided” apart from “provided but not met”? The rule has a separate set of defines that check whether each piece of data was provided, named “… data exists” (…資料存在), such as ECOG資料存在. The conditions themselves mostly ask whether matching data can be found, so missing data makes them false, not null. Looking only at the Boolean result, missing data and unmet criteria both fail; these extra defines are what let the report tell the hospital which item is missing.

Compared with the workbench

The CQL the workbench exports handles the same kind of question as the official rules, but it is written differently:

For why the workbench uses parameters, see Parameter-based CQL in Core concepts; for how parameters and three-valued logic work, see Parameters and Three-valued logic in the CQL primer; for how the two fit together, see Where the workbench fits on the Taiwan guidance page.

To compare, treat each official condition define as one atomic condition. For example, 1規則1-3=成人 corresponds to the condition “18 or older at the time of the request”. Going through them one by one shows whether the conditions the workbench extracted miss anything or add anything. Also watch the details of the official checks, such as age being calculated at the current treatment start date and imaging having to fall within 12 weeks: both the conditions you split out in the workbench and the parameters the adapter fills in need to match them.

Reading checklist

Whichever rule in the guide you open, you can read it in this order:

1. Check the metadata at the top of the page: official URL, version, status, and the code set and shared module listed under Dependency.
2. Read the title and the opening comment to confirm the cancer type, the drug and the indication. Look up the reimbursement indication code (such as P013) in the TWPAS indication code table.
3. Read the includes. For CodeConcept followed by a name, find the define with that name on the code set page for that cancer type; for Reusable followed by a name, look on the shared module page.
4. Use the comment dividers to find each main rule, then match the rule and condition numbers to the reimbursement criteria text.
5. Go through the condition defines one by one: which resource and field each reads, and which codes or thresholds it uses. Pay particular attention to conditions that match text with Matches.
6. Find the defines that check whether data was provided (in this rule, the ones ending in 資料存在) to see what counts as missing data.
7. Finish with the results: the Boolean result, the text result and the report. Items marked as reference information (參考資訊) do not affect the result.
8. Note the date you checked. The guide is still a draft, and the same library may have changed the next time you open it.

Version and status

As checked on 2026-10-28, consistent with the Taiwan guidance page:

• The guide is a continuous integration (CI) build, 0.0.1, marked as a draft. Its header says it is not an authorized publication and changes regularly.
• This library is version 1.0.0, status Draft.
• The official URLs the guide declares, under the NHI Administration’s nhicore.nhi.gov.tw/cql/, were not live when we checked. For now you read it on build.fhir.org, and the guide’s download page offers the whole package as package.tgz.
• The guide’s dependencies list TWPAS 1.2.4, while the NHI Administration currently publishes TWPAS 1.2.7. Before testing with real request data, check what changed in fields and codes between the two.

Official pages

Read the official pages for the full CQL. All links were checked on 2026-10-28.

1. Taiwan NHI Clinical Quality Language Implementation Guide (臺灣健保預檢規則實作指引)
2. Library list, grouped by cancer type
3. LCPembrAtezoRule1: the lung cancer rule read on this page
4. LCReusable: lung cancer shared module
5. LCCodeConcept: lung cancer code set
6. FHIRHelpers
7. Taiwan NHI Prior Authorization Support Implementation Guide (TWPAS) (臺灣健保事前審查實作指引)
8. The TWPAS Claim profile
9. The TWPAS reimbursement indication code table