Canadian health care managers, clinicians and other health professionals face the increasingly difficult challenge of reducing costs while maintaining or improving quality of care and access.
In this environment, the importance of the information that decision-makers use to help manage health care facilities and regional health authorities has never been greater. That’s why we’ve taken a lead role in developing and implementing case-mix methodologies. These methodologies categorize patients into statistically and clinically homogeneous groups based on the collection of clinical and administrative data.
Sorting Out Case Mix: This video explains how sorting information about each person into similar categories - or case mix groupings - can help us better understand the populations we're caring for and meet their individual needs.
Case Mix in Action: This video explains how CIHI’s case-mix methodologies are used by hospitals, health regions and ministries of health to help monitor and improve the care and services provided.
Understanding the different care requirements of patients and clients forms the basis for comparing health care organizations and case mix–adjusted resource use.
Who uses case mix?
Health care facilities use these grouping methodologies and their accompanying resource indicators to effectively plan, monitor and manage the services they provide.
We welcome your feedback and questions
Case mix information
Case-mix products, such as Case Mix Group+ (CMG+) and the Comprehensive Ambulatory Classification System (CACS), are methodologies for grouping acute care episodes captured in CIHI’s databases.
Population Grouping Methodology
- The population grouping methodology assigns clinical profiles and resource utilization indicators to all persons in the population. The methodology uses inpatient, day surgery, physician billing and long-term care data.
Acute inpatient grouping methodology
- CMG+—A refinement of the Case Mix Groups methodology. It aggregates acute care inpatients with similar clinical and resource utilization characteristics.
- Resource Intensity Weights (RIWs) and Expected Length of Stay (ELOS)—ELOS is the average acute length of stay in hospital for patients with the same CMG, age category, comorbidity level and intervention factors. RIW is a relative value measuring total patient resource use compared with average typical acute inpatients.
- Case Mix Decision-Support Guide: CMG+—A summary of the CMG+ grouping and indicator methodology. It also includes guidelines for using case-mix information for decision support as well as analytical techniques for using case-mix data.
- Assigning HIG Weights and ELOS Values to Ontario Inpatient DAD Cases—Provides an explanation of the ELOS calculation and the Health Based Allocation Model (HBAM) Inpatient Group (HIG) Weight calculation for typical and atypical acute care inpatient cases.
Acute ambulatory care grouping methodologies
- Comprehensive Ambulatory Classification System (CACS)—A national grouping methodology for ambulatory care patients
Continuing and specialized care grouping methodologies
Case mix also supports grouping methodologies for continuing and specialized care.
Continuing Care Reporting System (CCRS)
- RUG-III Grouping and Weighting Methodology (information sheet) (February 2014) (PDF)
- Differences Between RUG-III 44-Group and 34-Group Methodologies (information sheet) (February 2014) (PDF)
- Continuing Care Reporting System: Case Mix Resource Utilization Groups version 3 and RUG Weighted Patient Days—Resource Materials and FAQ, 2014–2015 (April 2014) (PDF)
Resource Utilization Group, version III (RUG-III)—Grouping methodology applied to RAI-MDS 2.0 Canadian version assessment data submitted to CCRS. Effective 2011, the CCRS RUG-III (44-group) Case Mix Index (CMI) values will no longer be a separate product; they are available only with the complete CCRS RUG-III grouper product.
- CCRS RUG-III (44-Group) Grouping Methodology
- CCRS RUG-III (34-Group) Grouping Methodology
- How RUG-III (44-Group) CMI Values Are Calculated (CCRS technical document) (PDF)
RUG Weighted Patient Day (RWPD) reports—Resource summary reports produced for complex continuing care and long-term care at the resident level.
- RWPD Reports Moving to CCRS eReports FAQ (July 2014) (PDF)
- CCRS Technical Document for RWPD Methodology (April 2014) (PDF)
- Continuing Care Reporting System: Interpreting RUG Weighted Patient Day Reports (June 2014) (PDF)
- RUG Weighted Patient Day (RWPD) Reports Quick Reference Guide (June 2014) (PDF)
Home Care Reporting System (HCRS)
Resource Utilization Group, version III, Home Care (RUG-III-HC)—Grouping methodology applied to RAI-HC Canadian version assessment data submitted to HCRS.
National Rehabilitation Reporting System (NRS)
Rehabilitation Patient Groups (RPGs)—Grouping methodology applied to episodes based on the FIM® instrument data submitted to the NRS.
- Rehabilitation Patient Group (RPG) Grouping Methodology and Weights
- National Rehabilitation Reporting System: Case Mix Rehabilitation Patient Group Resource Materials and Frequently Asked Questions, 2013-2014 (PDF)
- RPG Grouping Methodology and Rehabilitation Cost Weights (information sheet) (PDF)
Ontario Mental Health Reporting System (OMHRS)
System for Classification of In-Patient Psychiatry (SCIPP)—Grouping methodology applied to MDS-MH assessment data submitted to OMHRS.
- SCIPP Grouping Methodology and CMI Values for SWPD Methodology
- SCIPP Grouping and Weighting Methodology (information sheet) (PDF)
OHMRS SCIPP Weighted Patient Day (SWPD) Reports—Resource summary reports produced at the patient level.
- Ontario Mental Health Reporting System (OMHRS) Interpreting SWPD Reports, 2016–2017
- Ontario Mental Health Reporting System: Case Mix System for Classification of In-Patient Psychiatry and SCIPP Weighted Patient Days Resource Materials and Frequently Asked Questions, 2011 to 2012 (PDF)
Canadian MIS Database
The Canadian MIS Database (CMDB) is the national data source for financial and statistical information about hospitals and health regions. The day-to-day health service operations data is collected according to a standardized framework known as the Standards for Management Information Systems in Canadian Health Service Organizations (MIS Standards).
Continuing Care Reporting System
The Continuing Care Reporting System (CCRS) contains demographic, clinical, functional and resource utilization information on individuals receiving continuing care services in hospitals or long-term care homes in Canada. Participating organizations also provide information on facility characteristics to support comparative reporting and benchmarking.
Discharge Abstract Database
The Discharge Abstract Database (DAD) contains demographic, administrative and clinical data on inpatient hospital discharges. Facilities in all provinces and territories except Quebec are required to report to the DAD. Quebec acute inpatient records are submitted to CIHI through a different process and are included in the Hospital Morbidity Database.
Home Care Reporting System
The Home Care Reporting System (HCRS) contains demographic, clinical, functional and resource utilization information on clients served by publicly funded home care programs in Canada.
National Ambulatory Care Reporting System
The National Ambulatory Care Reporting System (NACRS) contains data for all hospital-based and community-based ambulatory care: day surgery, outpatient clinics and emergency departments. Client visit data is collected at the time of service in participating facilities.
National Rehabilitation Reporting System
The National Rehabilitation Reporting System (NRS) contains client data collected from participating adult inpatient rehabilitation facilities and programs across Canada, including specialized facilities and hospital rehabilitation units, programs and designated rehabilitation beds.
Ontario Mental Health Reporting System
The Ontario Mental Health Reporting System (OMHRS) contains data about individuals admitted to adult mental health beds in the province of Ontario. It includes information about their mental and physical health, as well as which social supports and services they use. The data is collected at admission, discharge and every three months for patients with extended stays.
Listed below you’ll find a sample of CIHI’s education courses on case mix. You can register for any of these, or learn more about CIHI’s other courses, by visiting our Learning Centre.
- Classifications, DAD, NACRS and Case Mix Education Roadmap
- Introduction to Case Mix for DAD and NACRS
- Introduction to CMG+
- Introduction to Resource Indicators (RIW and ELOS) for DAD and NACRS
- An Introduction to Comprehensive Ambulatory Classification System (CACS)
Continuing and specialized care
- CCRS Case Mix Fundamentals of RUG-III and RWPD
- Calculating RUG-III (44-Group)
- Introduction to the Rehabilitation Patient Group (RPG) Methodology for NRS
- Introduction to RUG Weighted Patient Days for Ontario CCRS
- OMHRS SCIPP Methodology and SCIPP Weighted Patient Day (SWPD) Report Interpretation
Regrouping historical data
Regrouping historical data is the process of assigning the most recent grouping methodology and resource indicators to historical data. The Regrouped Historical Data—CIHI Reference Document provides information about this regrouped historical data process.
- HBAM Inpatient Group Methodology and Reports at CIHI—How Are HIGs Assigned to Ontario Inpatient Cases? (February 2015) (PDF)
- Regrouped Historical Data Dissemination: HIG and Ontario-Specific CACS (April 2016) (PDF)
- Regrouped Historical Data: Dissemination (April 2016) (PDF)
- Release of HIG Weights/ELOS 2016 + Ontario Client Tables (April 2016) (PDF)
- Regrouped Historical Data Dissemination: HIG and Ontario-Specific CACS (May 2015) (PDF)
- Regrouped Historical Data: Dissemination (May 2015) (PDF)
- Release of HIG Weights/ELOS 2015 + Ontario Client Tables (April 2015) (PDF)