Introduction

This concept provides a working definition of hepatitis B, describes the method used at MCHP to investigate hepatitis B in the administrative data held in the Manitoba Population Research Data Repository, and lists the codes that are used in laboratory tests to investigate its presence in the population.

Definition of Hepatitis B

Hepatitis B is a sexually transmitted and blood-borne infection (STBBI) of the liver caused by the hepatitis B virus (HBV) belonging to the Hepadnaviridae family. As an infectious disease, hepatitis B is transmitted from one individual to another through percutaneous or mucosal contact with infectious bodily fluids (Public Health Agency of Canada Website - Canadian Immunization Guide - Hepatitis B Vaccine), such as unprotected sexual contact, sharing of contaminated needles and drug-using equipment, sharing personal care articles (e.g., razors, scissors, nail clippers or toothbrush), or from mother-to-child transmission during childbirth (Public Health Agency of Canada Website - Hepatitis B). In Manitoba, the most common method of transmission is unprotected sexual activity (Manitoba Health - Communicable Disease Control Unit - Communicable Disease Management Protocol - Hepatitis B). Those acquiring HBV sexually are at high risk for other sexually transmitted infections (STIs), such as HIV, gonorrhea, chlamydia, and syphilis, and should be tested accordingly (Public Health Agency of Canada Website - Hepatitis B).

Approximately 90% of adults will expel HBV on their own within six months of becoming infected (acute hepatitis B) and develop lifelong immunity against the virus (Public Health Agency of Canada Website - Hepatitis B). Of those infected with acute hepatitis B, 50 - 70% are asymptomatic, and those presenting symptoms often have non-specific symptoms, such as fatigue, nausea, vomiting, anorexia, rash or arthralgia (Public Health Agency of Canada Website - Hepatitis B). The remaining 10%, who are unable to clear the virus, are said to be chronically infected and infectious and may experience serious health implications, such as scarring of the liver or liver cancer (Public Health Agency of Canada Website - Hepatitis B).

Because of the significant public health implications, hepatitis B is a notifiable disease in Canada since 1969 (Lix et al. 2012) . All positive laboratory-confirmed cases of hepatitis B are reportable to Manitoba Health, Public Health Surveillance Unit. However, unlike other STIs hepatitis B can be prevented through vaccination (Public Health Agency of Canada Website - Hepatitis B). For more information on hepatitis B, see the Public Health Agency of Canada Website - Notifiable Diseases On-Line - Hepatitis B and the Government of Manitoba Public Health Website - Hepatitis B (HBV).

MCHP Hepatitis B Algorithms

The following method has been used at MCHP to determine testing and to identify individuals with hepatitis B.

1. Brownell et al. (2012)

The number of cases of hepatitis B for Manitoban youths was not reported in Brownell et al. (2012). Information from the Manitoba Monthly Surveillance Unit reports for the year 2010 (Manitoba Health - Epidemiology and Surveillance - Reports) was examined but could not be reported because the cases were not disaggregated by age groups. Without the disaggregation, identifying the number of cases was not possible.

Furthermore, data from the Cadham Provincial Laboratory (CPL) within the administrative records at the MCHP Population Health Repository was examined. However, because the counts for Manitoban youths were small, the data was not reported. In Manitoba, CPL is responsible for hepatitis B surface antibody (HBsAb) and hepatitis B surface antigen (HBsAg) testing (Manitoba Health - Communicable Disease Control Unit - Communicable Disease Management Protocol - Hepatitis B).

Table 1 lists the AUXCD5 codes used to identify hepatitis B testing in the Serology Section of CPL. For more information, see the CADHAM Provincial Laboratory (CPL) - Overview of Services and Data concept and the section titled Hepatitis B in Brownell et al. (2012) .

Table 1 - Hepatitis B: Serology Section

STARTDT 1	STOPDT 2	AUXCD5	DESCR40
01/01/90	03/18/02	AHBCG	ANTIBODY TO HEPATITIS B CORE IGG
01/01/90	01/01/99	AHBCM	ANTIBODY TO HEPATITIS B CORE IGM
03/18/02	01/01/99	AHBCT	ANTIBODY TO HEP. B CORE ANTIGEN (TOTAL)
01/01/90	01/01/99	AHBEA	HEPATITIS B "E" ANTIBODY
01/01/90	01/01/99	AHBS	ANTIBODY TO HEPATITIS B SURFACE ANTIGEN
01/01/90	01/01/99	HBEG	HEPATITIS B "E" ANTIGEN
01/01/90	01/01/99	HBSAG	HEPATITIS B SURFACE ANTIGEN
11/28/94	01/01/99	HBVD	HEPATITIS B DNA
07/20/07	01/01/99	HBVGT	HEPATITIS B VIRUS GENOTYPING
11/13/01	04/01/09	HBVL	HEPATITIS B VIRAL LOAD
07/15/94	01/01/99	HBVN	HBSAG CONFIRMATION
04/01/09	01/01/99	HBVVL	HEPATITIS B VIRAL LOAD
05/11/92	05/01/06	HPAHB	ANTIBODY TO HEPATITIS B SURFACE ANTIGEN
01/01/90	01/01/99	HPHBS	HEPATITIS B SURFACE ANTIGEN


¹ - The date that the code was created in the file.
² - The date that the code became inactive. Codes with stop dates recorded as "01/01/99" are still active as this is a default system date.

In the deliverable Long-Term Outcomes Of Manitoba's Insight Mentoring Program: A Comparative Statistical Analysis by Ruth et al. (2015), the same set of code values listed above were used to identify hepatitis B serology testing in first trimester.

Limitations /Cautious

• A value of P [Positive] to identify a positive test result in the POSNEG field [Positive-Negative] for specific AUXCD5 codes in the Cadham Provincial Laboratory (CPL) data was used to determine a positive test result.
  
  
• The AUXCD codes used to identify hepatitis B in the Serology Section should be verified at the beginning of each new study to ensure that the list of codes from the CPL data is up-to-date.