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U.S. Department of Health and Human Services


Understanding the TB Cohort Review Process: Instruction Guide 2006

What Is the Cohort Review Method?

Cohort review has been an integral part of the TB control approach advocated by the International Union Against Tuberculosis and Lung Disease (IUATLD). Dr. Karel Styblo, who pioneered the approach in Tanzania, proposed the idea of a local management unit that would have the staff and resources necessary to diagnose disease, initiate treatment, monitor adherence, and report patient treatment progress. After Dr. Styblo visited and reviewed the New York City TB Program, the Medical Director of the program implemented a cohort review process in which the Medical Director himself personally reviewed every one of the thousands of cases for treatment details and completion. The implementation of cohort review in conjunction with other TB control measures resulted in a steep increase in completion rates and, beginning in 1993, a steep decline in the number of reported TB cases. More impressive was the even sharper decline in the number of reported cases of multidrug-resistant TB (MDR TB), from 441 cases in 1992 to just 38 cases in 1998.

The cohort review process can take many forms.  In its most simplified form, TB control staff at the local level meet to review the treatment outcomes of every patient listed in a chronological patient register.  Today, with computerized TB registries, multimedia projection, and cheaper long-distance communications, it can be adapted to a variety of settings. 

“The fundamental concept of a cohort review is accountability.  Staff are accountable to supervisors and to the program for how well they are caring for patients...and the program is accountable to patients and to the public for controlling tuberculosis.”

Thomas Frieden, MD, MPH, New York City Commissioner of Health

Cohort review is a systematic review of the management of patients with TB disease and their contacts.  A “cohort” is a group of TB cases counted over a specific period of time, usually 3 months.  The cases are reviewed approximately 6–9 months after they are counted; therefore, many of the patients have completed treatment or are nearing the end of treatment.  Details regarding the management and outcomes of TB cases are reviewed in a group setting with the following information presented on each case by the case manager:

  • Patient’s clinical status
  • Patient’s treatment outcome
  • Adequacy of the medication regimen
  • Treatment adherence or completion
  • Results of contact investigation
  • Percentage of patients who did, or are likely to, complete treatment.

All TB patients should be assigned a case manager, whether they receive TB care in one of the health department clinics or from a private provider.  During the cohort review, case managers present the TB cases for which they are responsible, often assisted by staff involved in contact investigation, directly observed therapy, and initial patient evaluation.  TB case managers know that their day-to-day case management efforts will be reflected in the cohort review several months later and that they are accountable for the services they provide.  Information reported on each case at the cohort review session is found in Table 1. 

Table 1:  Case Information Reported in a Cohort Review

  • Patient’s initials and case number
  • Age
  • Sex
  • Country of birth
  • HIV status
  • Smear and culture results
  • Chest radiograph (CXR) results
  • Drug susceptibility results
  • Status of treatment (completed therapy, currently taking TB medications, lost, died, moved, or case reported at death)
  • Directly observed therapy status
  • Results of the source case investigation, if the patient is a child
  • Number of contacts identified
  • Number of contacts evaluated
  • Number of contacts infected, but without disease
  • Number of contacts infected and having disease
  • Number of contacts started on treatment for latent TB infection (LTBI)
  • Number of contacts completing treatment for LTBI

The presentation of cases allows staff to detect potential problems in the way the case is being managed, such as the use of an inappropriate regimen or an inadequate number of contacts tested.  It also allows clinicians, managers, and public health advisors to consult on difficult cases, especially those in which the patient is nonadherent, has MDR TB, or has numerous contacts in a congregate setting.  Finally, it allows senior staff and managers to recognize the intensive efforts of staff in managing TB cases and contacts.

Overall, the cohort review process can benefit the TB program by

  • Increasing staff accountability for patient outcomes,
  • Improving TB case management and the identification of contacts,
  • Motivating staff,
  • Revealing program strengths and weaknesses, and
  • Indicating staff training and education needs.
adopting cohort review, and highlights the roles of the cohort review team members.  Quotes from TB cohort review experts appearing in the video are presented in this document to provide testimony about their experiences with implementing the cohort review process.

After you have read this guide and completed the exercises, you will be able to

  • Define the cohort review approach
  • Discuss the roles key TB control staff play in the cohort review process
  • List the three essential elements of the cohort review process
  • Plan how to adapt and implement the cohort review method in your program area

The document is organized into the following sections:

  • Definition of the cohort review approach, its context, and its history
  • Roles of key TB control staff in a cohort review
  • Timeline for conducting cohort reviews
  • Three key elements in the process
  • Guidance on tailoring the cohort review to your program area
  • Glossary, Bibliography, and Resources

Many of the tools and processes in this guide are modeled on the highly successful program at the New York City Department of Health and Mental Hygiene, Bureau of Tuberculosis Control (BTBC).  It is recognized that each program area is different, in its TB epidemiology as well as in its TB control and prevention efforts.  It is not true that one size fits all.  However, in any setting the principles of systematic review and accountability that are fostered by the cohort review method can help improve overall program performance.


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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