(1) Each case mix classification group shall be assigned a case mix weight. The case mix weight for each resident of a nursing facility for each calendar quarter or six-month period during a calendar year shall be based on data from resident assessment instruments completed for the resident and weighted by the number of days the resident was in each case mix classification group. Days shall be counted as provided in this section.

(2) The case mix weights shall be based on the average minutes per registered nurse, licensed practical nurse, and certified nurse aide, for each case mix group, and using the United States department of health and human services nursing facility staff time measurement study. Those minutes shall be weighted by statewide ratios of registered nurse to certified nurse aide, and licensed practical nurse to certified nurse aide, wages, including salaries and benefits, which shall be based on cost report data for this state.

(3) The case mix weights shall be determined as follows:

(a) Set the certified nurse aide wage weight at 1.000 and calculate wage weights for registered nurse and licensed practical nurse average wages by dividing the certified nurse aide average wage into the registered nurse average wage and licensed practical nurse average wage;

(b) Calculate the total weighted minutes for each case mix group in the resource utilization group classification system by multiplying the wage weight for each worker classification by the average number of minutes that classification of worker spends caring for a resident in that resource utilization group classification group, and summing the products;

(c) Assign the lowest case mix weight to the resource utilization group with the lowest total weighted minutes and calculate case mix weights by dividing the lowest group's total weighted minutes into each group's total weighted minutes and rounding weight calculations to the third decimal place.

(4) The case mix weights in this state may be revised if the United States department of health and human services updates its nursing facility staff time measurement studies. The case mix weights shall be revised, but only when direct care component rates are cost-rebased as provided in subsection (5) of this section, to be effective on the July 1st effective date of each cost-rebased direct care component rate. However, the department may revise case mix weights more frequently if, and only if, significant variances in wage ratios occur among direct care staff in the different caregiver classifications identified in this section.

(5) Case mix weights shall be revised when direct care component rates are cost-rebased as provided in *RCW 74.46.431(4).

*Reviser's note: RCW 74.46.431 was repealed by 2015 2nd sp.s. c 2 § 9, effective June 30, 2016.

Purpose—Findings—Intent—Severability—Effective date—2011 1st sp.s. c 7: See RCW 74.48.005, 74.48.900, and 74.48.901.

Analysis—2011 1st sp.s. c 7: See note following RCW 74.46.485.

Effective date—2010 1st sp.s. c 34: See note following RCW 74.46.010.

Effective date—2006 c 258: See note following RCW 74.46.020.