WIESNZ22 cost weights

Documentation and a cost weight table for the WIESNZ22 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. WIESNZ22 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 WIESNZ22 is the same as WIESNZ21 except for the following:

  • Removed section ‘Special Funding Arrangement for Temporomandibular Joint Replacement (TMJ)’
  • Revised Scoliosis co-payment definition to exclude DRG I06Z
  • Revised Live Donor Nephrectomy (LDN) co-payment value from 1.5817 to 1.3491
  • Revised Ventricular Assist Devices (VADs) for Adults co-payment definition to include both left or right VADs (unilateral) and BiVADs (bilateral).  Co-payment value revised for unilateral VAD from 21.0526 to 22.2877.  New co-payment for BiVADs 44.5754
  • Revised Gender Reaffirming Surgery (GR) definition to include procedure 3064101 [1184] Orchidectomy, bilateral
  • Revised patient’s age to be calculated as at date of admission
  • Revised Disability and Health of Older People exclusion rule to include the Waikato START program and allocate the appropriate excluded purchase unit codes
  • Revised excluded purchase unit code for Postnatal Early Intervention from W03012 to W03013
  • Removed ‘all [1910]’ from section 5.2.6 Note on Anaesthesia Coding
  • Added new excluded purchase unit code M86004 Nuclear Medicine – PRRT Treatment for Same Day Radiotherapy
  • Revised anaesthesia criteria to include sedation only for exclusion rules Lithotripsy and Same Day Transrectal Ultrasound (TRUS) Guided Biopsy of Prostate and Transperineal (TPA) Biopsy of Prostate
  • Added new facilities, Southern Cross Central Lakes Hospital (9297), South Island Plastic Surgery (9311), Mr Terrace Creagh (9312), Face Breast and Body (9313) and OneSixOne (9271) to the casemix eligible facilities list
  • Updated ICD-10-AM/ACHI Mapping Table document (Appendix 8)
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