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Tumour Matching N.Ireland Experience. Colin Fox (IT Manager) Richard Middleton (Data Manager). Background to Approach 1. New Registry with a need to produce incidence figures QUICKLY!!
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Tumour MatchingN.Ireland Experience Colin Fox (IT Manager) Richard Middleton (Data Manager)
Background to Approach 1 • New Registry with a need to produce incidence figures QUICKLY!! • System implementation issues - problems with inherent code translations - switch to “Direct Mapping” approach • PAS - ICD10 coding from April 1996 • Pathology - SNOMED to ICD9/10 translation table • Small catchment area, manageable numbers - manual review possible
Background to Approach 2 • Bulk of incoming records from PAS and therefore already coded in ICD10 • Typical composition of selected tumour sites on NICR system (1998 reg.):SitePAS (max)Path (max)PAS (mean)Path (mean)No. %HiLung 29193.141.63923 67Breast 85 64.031.8292894Skin 38100.531.282274~93
Philosophy behind Matching Algorithm • Simple - use incoming raw data as much as possible to reduce complexity • Repeatable - consistent results • Fit for purpose - good enough to provide reasonable accuracy • Never be perfect - an understanding of the limitations and any additional countermeasures needed
Tumour Matching Rules 1 • NICR match tumours on ICD-10 • Receive most data in ICD10 (PAS) • Table coverts SNOMED into ICD10 • First 3 digits from SOURCE record S are compared to the first 3 digits of tumour registration D(i), where i is the number of tumour registrations for a matched patient • Match obtained when S=D(i) • Applies to most tumours with some exceptions
Tumour Matching Rules 2 Exceptions • Previous Rule applies except for Melanomas (C43), Colon (C18) and Skin (C44) • Match based on complete ICD10 code • Exception: skins (morphology considered)1 BCC + 1SCC per patient • Same site two tumour morphologies take highest morphologye.g. M80103, M81403 --> M81403on databaseExceptions • Skins (as above) and Leukaemias & Lymphomas
Tumour Matching Rules 3 Matched tumours are consolidated as follows: • If 4th digit in one of S or D(i) is 0-8 and the 4th digit of the other is “9” (NOS) the more specific sub-site is registerede.g. C50.4 & C50.9 –> C50.4 on database • If 4th digits in both of S or D(i) differ and are between 0-8 merge as “8”e.g. C15.5 & C15.4 –> C15.8 on database
Updating Date of Diagnosis • Preferred date is always “Date of first microscopic verification” – 80% cases in NICR have cytology or pathology • If no microscopic verification Manual Resolution (PAS only)“Date of procedure which leads to diagnosis”, we use a Hierarchy e.g. CT better than XR • This is different from UKACR & ENCR rules e.g. “Date treatment started” is before “Date of first microscopic verification”
Updating “Basis of Diagnosis” • Hierarchy of “Basis of Diagnosis” • Histopathology • Cytology • Clinical Investigation • Clinical Opinion • Death Certificate • Rules same as UKACR & ENCR
Consequences of Approach 1 • Loss of Multiple Primaries (currently <6% excluding NM skins) • Not the same as UKACR rules • ENCR Multiple Primary rules • Time does not matter • Laterality does not matter • Same family of tumour • Lose Clinical Statements e.g. “this is a new primary” • Cross-checks with “Customers” e.g. Breast Screening
Consequences 2Inaccurate Coding • Pathology report generally “dumb down” text description • Centroblastic centrocytic lymphoma gets coded as M95903 NHL • “Carcinoma” used fairly freely • TCC non invasive pTa coded as M81203 • Secondary tumours coded as primary • Adenocarcinoma of Liver M81403 should be M81406
Consequences 3Misleading Information • Site pathologist gives is not true site • Difference in clinician term and cancer registration • Cytology can give misleading information on site and behaviour of tumour • Secondary • Not very precise site • “Sputum” could be lung or elsewhere in respiratory system • Malignant cells from non-malignancy • “in situ” tumour (Breast) • “uncertain” tumour (Bladder)
How do you get round these problems? • Make sure computer system can identify them - source history/audit • Have access to full written pathology and cytology reports (may need hospital notes) • Always check multiple tumours manually • Checks on selected sites • Compare with other algorithms