UNAIDS' "HIV this week" occasionally notes an important advance for people living in Myanmar. This is one. Here is a Southeast Asia-developed algorithm to help screen for and rule out TB in people with HIV disease. Should the algorithm be validated in Myanmar? Or should clinicians, people with HIV, and groups of people living with HIV be taught the algorithm right away?
[him] moderator
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An algorithm for tuberculosis screening and diagnosis in people with HIV.
Cain KP, McCarthy KD, Heilig CM, Monkongdee P, Tasaneeyapan T, Kanara N, Kimerling ME,
Chheng P, Thai S, Sar B, Phanuphak P, Teeratakulpisarn N, Phanuphak N, Nguyen HD, Hoang TQ, Le
HT, Varma JK. N Engl J Med. 2010;362:707-16.
Tuberculosis screening is recommended for people with human immunodeficiency virus (HIV)
infection to facilitate early diagnosis and safe initiation of antiretroviral therapy and isoniazid
preventive therapy. No internationally accepted, evidence-based guideline addresses the optimal
means of conducting such screening, although screening for chronic cough is common. The
authors consecutively enrolled people with HIV infection from eight outpatient clinics in
Cambodia, Thailand, and Vietnam. For each patient, three samples of sputum and one each of
urine, stool, blood, and lymph-node aspirate (for patients with lymphadenopathy) were obtained for
mycobacterial culture. They compared the characteristics of patients who received a diagnosis of
tuberculosis (on the basis of having one or more specimens that were culture-positive) with those
of patients who did not have tuberculosis to derive an algorithm for screening and diagnosis.
Tuberculosis was diagnosed in 267 (15%) of 1748 patients (median CD4+ T-lymphocyte count,
242 per cubic millimeter; interquartile range, 82 to 396). The presence of a cough for 2 or 3 weeks
or more during the preceding 4 weeks had a sensitivity of 22 to 33% for detecting tuberculosis.
The presence of cough of any duration, fever of any duration, or night sweats lasting 3 or
more weeks in the preceding 4 weeks was 93% sensitive and 36% specific for tuberculosis.
In the 1199 patients with any of these symptoms, a combination of two negative sputum smears, a
normal chest radiograph, and a CD4+ cell count of 350 or more per cubic millimeter helped to rule
out a diagnosis of tuberculosis, whereas a positive diagnosis could be made only for the 113
patients (9%) with one or more positive sputum smears; mycobacterial culture was required for
most other patients. In persons with HIV infection, screening for tuberculosis should include
asking questions about a combination of symptoms rather than only about chronic cough.
It is likely that antiretroviral therapy and isoniazid preventive therapy can be started safely in
people whose screening for all three symptoms is negative, whereas diagnosis in most others
will require mycobacterial culture.
For full text access click here:
http://content.nejm.org/cgi/content/full/362/8/707
Editors’ note: This simple algorithm of 3 predictors - cough of any duration, fever of any duration,
or night sweats lasting 3 weeks or more during the previous 4 weeks, accurately ruled out
tuberculosis in the majority of people living with HIV attending these clinics in Cambodia, Thailand,
and Viet Nam where the prevalence of TB among these patients was 15%. The number of false
negative results was reduced by 83% compared with the current WHO screening based on the
presence or absence of chronic cough. Compared to an approach that would see sputum smears
examined and chest X-rays performed for every person with HIV infection, this algorithm reduced
the number of false negative results by half while decreasing the number of patients requiring
sputum-smear microscopy and chest radiography. Testing this algorithm in populations of people
living with HIV in other settings would be very useful given the challenging balance in most places
between limited resources and the risk of false negative results for TB leading to delays in
treatment of TB, the major cause of death for people living with HIV.
