WIESNZ21 cost weights

Documentation and a cost weight table for the WIESNZ21 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. WIESNZ21 is based on ICD-10-AM/ACHI Eighth Edition and AR-DRG v7.0.

 ICD-10-AM/ACHI Eleventh Edition was implemented 1 July 2019.  Events 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 WIESNZ21 is the same as WIESNZ20 except for the following:

  • New and revised same day/one day designations
  • Revised co-payment definitions:
    • Aortic Aneurysm (AAA) co-payment
    • Scoliosis
    • Electrophysiological Studies (EPS)
    • Complex Traumatic Limb (TLC)
    • Gender Affirming Surgery (GR)
  • Reinstated co-payment for Isolated Limb Infusion (ILI)
  • New co-payment for:
    • Peritonectomy with HIPEC (PH) 
    • Pelvic Evisceration (PE) Surgery for Waitemata DHB
  • Revised co-payment values for:
    • Atrial Septal Defect (ASD)
    • Ventricular Assist Devices (LVAD)
    • Bilateral Mastectomy or Combined Mastectomy and Reconstruction
    • Cardiac Lead Extraction (LE)
  • Revised costweight values for NZ DRGs C03W and J11W
  • Moved section ‘Note on anaesthesia coding’ to be sequenced before exclusion rules that have an anaesthesia criteria
  • Revised exclusion rules:
    • Same day pharmacotherapy for treatment of neoplasm
    • ERCP
    • Cystoscopies
    • Gastroscopy procedures
    • Bronchoscopy
  • Added three new facilities to the casemix eligible facilities list. The facilities are:
    • The Rutherford Clinic (9245)
    • East Bay Specialist Centre (9283)
    • Cambridge Specialist Centre (9284)
  • Updated cost weight schedule (Appendix 1) to include additional tabs (Legend and notes and Current co-payment values)
  • Updated ICD-10-AM/ACHI Mapping Table document (Appendix 8)
  • Updated SAS document (Appendix 2)
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