# For HIV-infected Adults with Positive PPD, TB Prophylaxis with Isoniazid for 36 Months Appears More Effective Than for 6 Months

 

 

      DynaMed Weekly Update - Volume 6, Issue 18 

Recommendations from the World Health Organization (WHO) call for at least 6 months of isoniazid therapy for tuberculosis (TB) prevention in adults who are HIV-positive and have either a positive or unknown tuberculin skin test (PPD) ([WHO 2011 PDF](http://whqlibdoc.who.int/publications/2011/9789241500708_eng.pdf)). A recent randomized trial compared isoniazid prophylaxis for 36 months vs. 6 months in 1,995 HIV-positive patients in Botswana. Following 6 months of open-label isoniazid treatment, patients received either continued isoniazid or placebo in blinded fashion for an additional 30 months. Patients with CD4 cell count <200 cells/mcL were given antiretroviral therapy. The primary outcome was any incident TB (definite, probable, or possible) defined as clinical presentation consistent with TB and response to anti-TB therapy. The 6-month open-label phase was completed by 83% of patients, and 78% of patients attended at least 80% of their monthly refill visits.

Isoniazid prophylaxis for 36 months was associated with significantly reduced incidence rates of TB (0.72 vs. 1.26 per 100 person-years in ITT analysis, p = 0.047) ([level 2 \[mid-level\] evidence](http://www.epnet.com/dynamed/levels.php)). This difference was primarily due to the effect of continued prophylaxis in patients with positive PPD at baseline. In subgroup analyses, incidence rates were 0.57 vs. 2.22 per 100 person-years (p = 0.02) for patients with positive PPD, and 0.75 vs. 1.01 (not significant) for patients with negative PPD. There were no significant differences in overall severe adverse events or mortality ([Lancet 2011 Apr 12 early online](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=21492926)).

For more information, see the [Tuberculosis in HIV-infected persons](http://search.ebscohost.com/login.aspx?direct=true&site=dynamed&id=AN+191726) topic in DynaMed.