WIESNZ19 cost weights

Documentation and a cost weight table for the WIESNZ19 methodology.


The New Zealand Casemix Framework for Publicly Funded Hospitals provides the definitions for inclusion of hospital events in casemix funding together with information related to the calculation of cost weights for these events and the assignment of events to purchase units. WIESNZ19 is based on ICD-10-AM/ACHI Eighth Edition and AR-DRG v7.0.

ICD-10-AM/ACHI Eleventh Edition was implemented on 1 July 2019.  National Minimum Dataset (NMDS) events records coded in ICD-10-AM/ACHI Eleventh Edition will have their codes back-mapped to ICD-10-AM/ACHI Eighth Edition which are then used to derive AR-DRG7.0. Exclusion rules are based on ICD-10-AM/ACHI Eighth Edition coding and AR-DRG v7.0.  The framework associated with WIESNZ19 is the same as WIESNZ18 except for the following:

  • New NZ DRG B02W developed for Stroke Clot Retrieval
  • NZDRG A39W Pelvic Evisceration Surgery – the three pelvic exenteration procedure codes are valid for both female and male  
  • Retired co-payment for Endovascular Treatment of Cerebral Aneurysms and Clot Retrieval for Treatment of Strokes, as a NZ specific DRG has been developed for stroke clot retrieval cases, and following review of cerebral aneurysm costs it was found that they sit well within the wider portfolio of procedures possible for AR-DRG B02 Cranial Procedures
  • Revised Abdominal Aortic Aneurysm (AAA) co-payment value from 4.2336 to 3.8185
  • Revised Atrial Septal Defect (ASD) co-payment value from 1.1135 to 1.1882
  • Revised Scoliosis co-payment value from 5.5546 to 5.4629
  • Revised Live Donor Nephrectomy (LDN) co-payment value from 1.4133 to 1.4601
  • Revised Isolated Limb Infusion (ILI) co-payment value from 2.9784 to 1.9801
  • Revised Ventricular Assist Devices (VADs) for adults co-payment value from 24.8000 to 23.8461
  • Revised Complex Traumatic Limb co-payment value from 5.7934 to 3.5934
  • Revised Bilateral Mastectomy or Combined Mastectomy and Reconstruction co-payment values from 0.93 and 0.69 to 0.9697 and 0.9085
  • Revised Medical Termination of Pregnancy – added procedure code 9046100 [1330] Intra-amniotic injection
  • Revised Gastroenterology Procedure Codes used to Identify Excluded Events, Colonoscopy block – added procedure code 3209900 [933] Per anal excision of lesion or tissue of rectum
  • Revised weight values for NZ DRGs C03W and J11W
  • DRG I64A now flagged as hialosdrg in weight schedule.
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