The Comprehensive Ambulatory Classification System (CACS) is a national grouping methodology for ambulatory care patient data submitted to either the Discharge Abstract Database (DAD) or the National Ambulatory Care Reporting System (NACRS). Specific groupings include emergency visits, ambulatory interventions, rehabilitation and clinic visits as well as grouping exception cases such as telephone visits and direct diagnostic imaging. Patients are grouped according to a number of data elements including diagnosis or intervention for DAD as well as emergency visit indicator, mode of visit, visit disposition, ambulatory care type or program area for NACRS. DAD CACS groups represent a subset of the broader range of CACS groups available for NACRS clients. The redeveloped methodology uses age, anaesthetic technique and investigative technology to enhance the calculation of the Resource Intensity Weights (RIW).

On April 1, 2018, CIHI will release a new version of CACS.

Product Overview

CACS places client visits into groups that are clinically and resource homogenous. Variables that assign clients to groups are diagnosis or, intervention for DAD clients while emergency visit indicator, visit disposition, mode of visit, ambulatory care type and program area are also used for NACRS clients. Anaesthetic, age and investigative technology are used in the factor overlay methodology to assist in the assignment of resources.


Client visit data collected via NACRS and grouped by CACS can be used to support:

  • Management decision-making at the facility level;
  • Resource allocation decisions at a global and facility level;
  • Provincial and national comparisons; and
  • The effective analysis of ambulatory care services.


Before downloading read about requirements for downloading files.