# CareScience Risk Assessment Model - Hospital Performance Measurement

## Appendix C — Select Practice Formulas

- Determine case-weighted arithmetic means by disease (3-digit ICD-9 code, k) for
- mortality (T
_{k}) - morbidity (B
_{k}) - complications (C
_{k})

Note: Records without a risk score are excluded.

- mortality (T
- Compute risk-adjusted rate for each facility (h) for each adverse outcome:
- T
_{kh}= T_{k}+ ΔT_{kh}, where Δ indicates mean deviation (actual - risk) - B
_{kh}= B_{k}+ ΔB_{kh} - C
_{kh}= C_{k}+ ΔC_{kh}

Note: T_{kh}, B_{kh}, and C_{kh}can never be negative.

- T
- Compute quality indicator by disease k for each facility (h) based on CHRP weights:
- Q
_{kh}= 0. 46(T_{kh})^{0.96}+ 0.29(B_{kh})^{0.91}+ 0. 25(C_{kh})^{0.94}

Note: Smaller Q_{kh}denotes higher quality.

- Q
- Compute efficiency ratio for length of stay by disease k for each hospital h:
- RL
_{kh}= exp{(logLOS)_{kh}- (logLOSrisk)_{kh}} for hxk level means

Note: Smaller RL_{kh}denotes higher efficiency.

- RL
- Cross tabulate Q
_{kh}and RL_{kh}by quintile across facilities for each disease k.

Note: This is a 5 x 5 cross-tabulation matrix.

Small facilities with less than 100 cases for disease K were excluded from the tabulation.

No matrix is constructed with fewer than 200 qualifying facilities. - Identify the select practice facilities for each disease k (set H*
_{k}) by choosing facilities falling into the top 2x2 cells in the 5x5 cross-tabulation matrix.

Note: Select practice represents roughly 16% (4/25) of cases for each disease k. The reason for the imprecision is that select practice is a facility characteristic, requiring all cases from a given facility be sorted into one quintile only.

For the 50 highest-volume diseases, the correlations between quality (Q_{kh}) and efficiency (RL_{kh}) are weak. - Compute select practice risk for each disease k as
- T*
_{k}= case-weighted mean T_{kh}for all h Î H*_{k} - B*
_{k}= case-weighted mean B_{kh}for all h Î H*_{k} - C*
_{k}= case-weighted mean C_{kh}for all h Î H*_{k} - RL*
_{k}= case-weighted geometric mean RL_{kh}for all h Î H*_{k} - R$*
_{k}= case-weighted geometric mean R$_{kh}for all h Î H*_{k}

Note: Compute ratio for total costs by disease k for each hospital h:

R$_{kh}= exp{(logCost)_{kh}- (logCostRisk)_{kh}} for hxk level means

- T*
- Compute the scaling factor for each outcome as the ratio of select practice to mean:
- R
_{tk}= T*_{k}/T_{k}for all k - R
_{bk}= B*_{k}/ B_{k}for all k - R
_{ck}= C*_{k}/ C_{k}for all k - R
_{lk}= RL*_{k}for all k, where l indicates LOS - R
_{$K}= R$*_{k}for all k, where $ indicates Total Costs

- R
- ICD-9 codes that fail to pass Step 5 are rolled up into one of 18 major diagnosis groupings (Dx_Groups) of the ICD-9-CM classification system. For example, ICD-9 codes 460 to 519 (excluding the six codes that could stand alone) are rolled up into Dx_Group 8, which represents the diseases of the respiratory system. The scaling factor for each Dx_Group is computed as outlined by Steps 5 to 8. ICD-9 codes rolled up into a broader Dx_Group share the same scaling factor.

### C.1 Applying the Scaling Factors

The purpose of the scaling factors is to generate risk scores based on Select Practice hospitals. Deviation (Actual - Risk) and significance flag can then be computed on the new risk scores. The deviation and significance flags indicate the facility's performance level compared to the nation's Select Practice facilities for the particular disease group.

1. Compute risk score and stderr of Select Practice at patient level:

Ln_los_risk_select = Ln_Rlk + Ln_length_of_stay_risk

Ln_los_risk_stderr_select = Ln_Rlk + Ln_length_of_stay_risk_stderr

Ln_cost_risk_select = Ln_R$k + Ln_cost_risk

Ln_cost_risk_stderr_select = Ln_R$k + Ln_cost_risk_stderr

comp_risk_select = comp_risk * Rck

comp_risk_stderr_select = comp_risk_stderr * Rck

mort_risk_select = mort_risk * Rtk

mort_risk_stderr_ select = mort_risk_stderr * Rtk

comp_morb_risk_select = comp_morb_risk * Rbk

comp_morb_risk_stderr_select = comp_morb_risk_stderr * Rbk

**(R: Scaling Ratio; k: 3-digit ICD-9 code; L: LOS; $: cost; c: complication; t: mortality; b: morbidity)**

2. Report the Select Practice deviation and significance flag at the aggregate level:

Use the same method as the standard-practice report.

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Proceed to Appendix D