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Understanding the TB Cohort Review Process: Instruction Guide 2006

What Is the Cohort Review Method?

3.  Timeline for Activities in the Cohort Review Process

A “cohort” is a group of TB patients who are being managed over a specific period of time, usually 3 months.  In order to evaluate treatment and contact investigation outcomes, the patients’ cases are reviewed approximately 6–9 months after initial case reporting.  This is after most patients with TB disease have had time to complete treatment and after most contacts have been identified, evaluated, and started on treatment for latent TB infection (LTBI), if indicated.  A review at 6–9 months allows the TB control team to evaluate the adequacy of treatment and correct any problem areas while there is still time for the patient to complete treatment within 365 days.  Most contacts infected with LTBI will not have completed therapy because of the time gap between patient reporting, testing of contacts, and the 9-month duration of standard isoniazid (INH) treatment.  Contacts on treatment for LTBI should be tracked through to completion by the case manager.  The data analyst reports treatment completion rate for contacts at the next review session.

The following timeline illustrates the cohort review process:

Table 8:  Cohort Review Timeline

1ST Quarter
Months 1–3

2ND Quarter
Months 4–6

3RD Quarter
Months 7–9

4TH Quarter
Months 10–12

Next Year 1ST Quarter
Months 1–3

  • TB cases counted
  • Treatment started
  • Contact investigation initiated
  • Ongoing treatment of patients with TB disease
  • Contacts evaluated and started on treatment, as necessary
  • Ongoing treatment of patients with TB disease
  • Contacts evaluated and started on treatment, as necessary
  • TB disease treatment completed
  • Infected contacts continue on treatment for LTBI
  • Contacts identified in previous year’s 1st quarter complete treatment
  • Cohort review process begins, ongoing case management, case review meetings, cohort review practice session

Cohort Review Session

  • Begin to follow up on suggestions from cohort review
  • Treatment completion rate presented for contacts of cases from previous 1st quarter
  • Continue to follow up on suggestions made during cohort review session

This cycle is repeated throughout the year.  Cohort review sessions take place each quarter so that every TB case and contact investigation receives a thorough review.  An example of a cohort review schedule is presented below.

Table 9:  Example of a Cohort Review Schedule

Quarter Case Reported

Quarter Case Reviewed

1st  (Jan-Mar 05)

4th  (Oct-Dec 05)

2nd  (Apr-Jun 05)

1st  (Jan-Mar 06)

3rd  (Jul-Sep 05)

2nd  (Apr-Jun 06)

4th  (Oct-Dec 05)

3rd  (Jul-Sep 06)


Released October 2008
Centers for Disease Control and Prevention
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Division of Tuberculosis Elimination -

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