Data Notes

• In Ontario, the integrated Public Health Information System (iPHIS) is the information system used for reporting case information on all reportable communicable diseases for provincial and national surveillance, as described in the Health Protection and Promotion Act (HPPA) (1). Each public health unit is responsible for collecting case information on reportable communicable diseases occurring within their boundaries and entering information into iPHIS.  Minimum data requirements are outlined in disease-specific user guides available on the public health Ontario e-portal (2) in the "iPHIS" workspace in the "Disease-specific user guides" folder.
• Cases are classified in iPHIS according to the Ontario Ministry of Health and Long-Term Care (MOHLTC) case definitions.  Effective April 28, 2009, the MOHLTC released updated case definitions as an appendix to the Infectious Disease Protocol, 2009 (3).  The new case definitions replace those published in the 2005 iPHIS Manual.  Comparison of trends for specific diseases before and after 2009 must, therefore, be interpreted with caution.  The MOHLTC has created a "Case Definition Comparison Document" (publichealthontario.ca username and password required) outlining the most recent changes.  This document can be found on the public health Ontario e-portal (2) in the "iPHIS" workspace in the "Mandated Materials" folder and "Reclassifying Cases in iPHIS" sub-folder.  In their 2009 infectious disease report, Toronto Public Health has also summarized how the case definition changes may affect incidence rates (near the end of each section, there is a page entitled "Case Definitions").
• The Ontario Agency for Health Protection and Promotion (OAHPP) created a document comparing the provincial and national reportable disease case definitions. The document, "Case Definitions Comparison Table" (publichealthontario.ca username and password required) outlines any diseases for which the OAHPP identified differences between the provincial and national case definitions.
• iPHIS, and the associated reporting tool Cognos ReportNet, were implemented in all Ontario health units during a staged roll-out from April until November 2005. iPHIS replaced the Reportable Disease Information System (RDIS) and linked all Ontario health units into a common database. This was a major step in public health practice, as 36 stand alone systems were integrated into one central, provincially managed, database (4).
• RDIS contained duplicate records for clients who lived or were managed in multiple jurisdictions because it was a stand alone system.  All RDIS records were converted to iPHIS thus the duplicates persisted. 
• The MOHLTC has co-ordinated several data cleaning initiatives since 2005 to eliminate duplicates.  These initiatives apply to the following diseases:  TB, HIV/AIDS, chlamydia and hepatitis B.  Resources on how to merge duplicate clients can be found on the public health Ontario e-portal (2) in the “iPHIS” workspace in "Training Documentation" folder in the “Duplicate Records Management” sub-folder. 
• iPHIS and Cognos ReportNet are web-based applications that are accessed through a secure VPN connection.
• Upon implementation of the iPHIS system, each health unit converted select variables associated with each RDIS case into iPHIS (5).  Multiple issues with the quality of converted RDIS data, particularly for HIV/AIDS data, have been reported to the Ministry of Health and Long-Term Care through the iPHIS Help Desk.  A document titled “Summary Update of Cognos ReportNet (CRN) Issues” was written by CRN users in 2006.  The MOHLTC responded with a document titled “Update Report on Cognos ReportNet (CRN) Issues” in November 2006.  These documents can be found in the public health Ontario e-portal (2) under the “Public Health Commons” workspace in the “iPHIS and CRN” folder.  In the most recent version of Cognos ReportNet, a few issues have also been identified.  The MOHLTC has created a document called "CRN 2.0 Known Issues List" that can be found on the public health Ontario e-portal (2) in the "iPHIS Ontario" workspace in the "Training Documentation" folder and the "CRN User Documentation" sub-folder and the "CRN 2.0" sub sub-folder. A document has been created on the APHEO Wiki site to capture iPHIS fields reported as missing in CRN 2.0.
• Monthly and annual provincial summaries are compiled by the Ontario MOHLTC's Public Health Protection and Prevention Branch which allows comparisons of health unit rates with Ontario rates. These summaries are available on the public health portal (2) under “Public Health Commons” workspace in the “Infectious Disease Reports” folder.  Data prior to 2006 are found in the “Programs” section under “Health Surveillance”.  These MOHLTC reports include confirmed cases only.
• The most common source of case identification is through laboratory notification of confirmed test results (serology, microbiology cultures, etc.). Physicians are required to report cases that fulfill laboratory or clinical case definitions.
• There may be considerable under-reporting of actual cases for some diseases in iPHIS. For instance, when an infected person has mild clinical symptoms they may not seek medical care and/or laboratory testing may not be performed.
• Rates and proportions based on counts less than 5 may be suppressed at the discretion of the health unit. iPHIS data are not subject to provincial suppression rules because it is the health unit that collects the information. A health unit may want to report, for example, that it had only one case of measles over the past 5 years, without providing any identifiable information.

References and Resources

1. Health Protection and Promotion Act.  1990.  http://www.e-laws.gov.on.ca/DBLaws/Statutes/English/90h07_e.htm  
2. Public Health Ontario e-portal:  www.publichealthontario.ca.  MOHLTC.
3. Ontario Ministry of Health & Long-Term Care.  Ontario Public Health Standards: Infectious Diseases Protocol, 2009, Appendix B. 
4. Ontario Ministry of Health & Long-Term Care, Public Health Division.  iPHIS Manual.  April 2005.
5. Ontario Ministry of Health & Long-Term Care, Public Health Division.  iPHIS Conversion: RDIS Conversion User Manual.  April 2005.