An individual-patient-data meta-analysis of randomized controlled trials in people with drug-susceptible pulmonary TB on standard first-line therapy reported a TB relapse rate of 5.6%.28 Presence of cavitary disease on baseline x-ray and smear or culture positivity at 2 months increased the relapse rate to >10%. This is consistent with previous studies demonstrating an increased risk of relapse in people with extensive disease or cavitary disease and persistent sputum positivity at 2 months.28–30 In a separate meta-analysis, the relapse rate in people receiving RMP-containing regimens for 8 months or more was <1%.4 Despite the lack of direct randomized controlled trial data to support extension of therapy, we believe that extension of therapy is warranted in this population. Other factors to consider when deciding to prolong therapy include HIV status, diabetes mellitus, medical immune suppression, male sex, active smoking history and being <90% below ideal body weight (see Chapter 10: Treatment of Active Tuberculosis in Special Populations).1
Recommendation
We conditionally recommend, in people with drug-susceptible pulmonary TB and risk factors for relapse (i.e., extensive disease OR baseline cavitary disease on x-ray and smear or culture positive sputum at two months), extension of the continuation phase to seven months for a total of nine months of TB drug therapy (poor evidence).
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