Concept: Tuberculosis (TB) - Method of Identification

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Concept Description

Last Updated: 2019-01-17

Introduction
    This concept provides a working definition of tuberculosis (TB) and describes the methods used at MCHP to investigate TB in the administrative data held in the Manitoba Population Research Data Repository. The concept lists the ICD-9-CM and ICD-10-CA diagnostic codes to identify TB in the hospital abstracts data and the medical services data, and lists the codes that are used in laboratory tests to investigate its presence in the population. SAS code (internal access only) is also available for working with the laboratory data.
Definition of Tuberculosis
    Tuberculosis (TB) is a disease that is acquired through an infection from a Mycobacterium, specifically Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium canetti, and Mycobacterium bovis (Lix et al., 2012).

    TB is highly contagious: it is spread through the air by individuals with infected lungs or throats when they cough, sneeze, or talk. An individual with a spreading TB disease will become sick; and if left untreated, the individual may die (Martens et al. 2010). Because of its significant public health implications, TB is a notifiable disease in Canada since 1924. All clinical and laboratory-confirmed cases are reportable to the Canadian Tuberculosis Reporting System (CTBRS). For more information on TB, see the Public Health Agency of Canada Website - Tuberculosis.
MCHP Tuberculosis Algorithms
    The following methods have been used at MCHP to identify testing and to identify individuals with tuberculosis.
1. Martens et al. (2010) and Smith et al. (2013)
    In Martens et al. (2010) and Smith et al. (2013), the average annual hospital episode rates for TB per 100,000 residents for all ages were calculated. ICD-9-CM codes 011-018 and ICD-10-CA codes A15-A19 were used to identify TB cases recorded in the Hospital Abstracts data. All diagnosis fields were included. Only those who had a diagnosis of TB were counted for this indicator. Individuals with a code of "primary tuberculosis infection" (ICD-9-CM code 010.xx - skin test for TB) were excluded.

    In Martens et al., (2010) , hospital abstracts were reviewed from 1984 to 2008 and divided in five time periods. From the first time period (1984/85 - 1988/89) to the last time period (2004/05 - 2007/08), the average annual hospitalization for TB decreased from 16.67 per 100,000 residents to 12.81 per 100,000 residents.

    The rates of hospitalization due to TB by income quintiles were calculated for rural and urban residents. The disparity rate ratios (DRRs) were similar across time for the urban neighborhood income quintiles, but increased significantly over time in the rural neighborhood income quintiles. The socioeconomic gap in rates of hospitalization due to TB was very high in both rural and urban neighborhood income quintiles across time, however, the gap appeared to be widening over time for rural Manitoba. For more information, read the section Hospitalization due to Tuberculosis in Martens et al., (2010) and the section Hospitalizations due to Tuberculosis in Smith et al. (2013) .
2. Lix et al. (2012)
Table 1: Tuberculosis: Clinical Microbiology Section - Results
    NOTE: All records are RECTYPE=8

    AUXCD5 DESCR70
    AFB ACID FAST BACILLI DETECTED ON CULTURE
    AFBC ACID FAST BACILLI ON CULTURE. SEE PREVIOUS REPORT
    AFBCF A.F.B. NOT SEEN ON SPECIMEN(S) RECEIVED. CULTURE REPORT TO FOLLOW
    AFBNS ACID FAST BACILLI NOT SEEN
    AFG ACID FAST GROWTH DETECTED RADIOMETRICALLY
    AFIF ACID FAST BACILLI ISOLATED
    AFL ACID FAST-LIKE ORGANISM ISOLATED
    AFNI ACID FAST BACILLI NOT ISOLATED
    AFS ACID FAST-LIKE ORGANISMS SEEN
    FAFB FEW ACID FAST BACILLI SEEN
    FCFB FEW ACID FAST BACILLI SEEN
    MAFB MANY ACID FAST BACILLI SEEN
    MCC MYCOBACTERIAL CULTURE IS CONTAMINATED, PLEASE REPEAT
    NTMI NON TUBERCULOUS MYCOBACTERIA
    ODR ORGANISMS DETECTED RADIOMETRICALLY ARE NOT ACID FAST BACILLI
    OGNT ORANGE GROWTH. NOT LIKELY M. TUBERCULOSIS
    ONT ORANGE GROWTH. NOT LIKELY M. TUBERCULOSIS
    SAFB SCREEN FOR AFB NEGATIVE, CULTURE REPORT TO FOLLOW
    SCOMB 10 ML. REQ. FOR TB INVEST. SPECIMENS FROM THIS PATIENT WERE COMBINED

Table 2: Tuberculosis: Clinical Microbiology Section - Organisms
    NOTE: All records are RECTYPE=9

    AUXCD5 DESCR40
    MYC4 MYCOBACTERIUM BOVIS
    MYC20 MYCOBACTERIUM TUBERCULOSIS
Comparison of Lab Data to Hospital Discharge Abstracts and Medical Services Data
SAS Code
  • SAS code for identifying TB tests in the Cadham Provincial Laboratory is available in the SAS code and formats section below (internal access only).
Limitations / Cautions
  • The CPL data files do not contain all laboratory tests for TB. Prior to 2001/02 approximately half of the TB tests were conducted by CPL. In subsequent years, all TB testing was conducted by Diagnostic Services of Manitoba (DSM).

  • A value of P [Positive] to identify a positive test result in the POSNEG field [Positive-Negative] for specific codes in the CPL data was used to determine a positive test result.

  • In the Medical Services / Physician Claims data, the diagnosis recorded is limited to one, 3-digit ICD-9-CM code. In some cases, the 3-digit code is not specific enough to uniquely identify conditions and if used, may over report certain conditions. NOTE: In December 2018, a 5-digit diagnosis code variable was added to the Medical Services data. If recorded, the first 3-digits of both the 3-digit and 5-digit diagnosis code variables will match exactly. The 5-digit diagnosis code variable applies to records from 2015/16 forward.

  • The codes used to identify Tuberculosis (TB) in the Clinical Microbiology Section should be verified at the beginning of each new study to ensure they are up-to-date.

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References 

  • Lix L, Smith M, Azimaee M, Dahl M, Nicol P, Burchill C, Burland E, Goh C, Schultz J, Bailly A. A Systematic Investigation of Manitoba's Provincial Laboratory Data. Winnipeg, MB: Manitoba Centre for Health Policy, 2012. [Summary] [Full Report] (View)
  • Martens P, Brownell M, Au W, MacWiliam L, Prior H, Schultz J, Guenette W, Elliott L, Buchan S, Anderson M, Caetano P, Metge C, Santos R, Serwonka K. Health Inequities in Manitoba: Is the Socioeconomic Gap in Health Widening or Narrowing Over Time? Winnipeg, MB: Manitoba Centre for Health Policy, 2010. [Summary] [Full Report] [Data extras] [Errata] (View)
  • Smith M, Finlayson G, Martens P, Dunn J, Prior H, Taylor C, Soodeen RA, Burchill C, Guenette W, Hinds A. Social Housing in Manitoba. Part II: Social Housing and Health in Manitoba: A First Look. Winnipeg, MB: Manitoba Centre for Health Policy, 2013. [Summary] [Full Report] (View)