Does Isoniazid Preventive Therapy Provide Better Treatment Outcomes in HIV-Infected Individuals in Northern Ethiopia? A Retrospective Cohort Study

Isoniazid Preventive Therapy for Prevention of Tuberculosis among People Living with HIV in Ethiopia: A Systematic Review of Implementation and Impacts

BACKGROUND

Tuberculosis (TB) is a major cause of morbidity and mortality in people living with HIV (PLWHIV). Isoniazid preventive therapy (IPT) prevents TB in PLWHIV, but estimates of its effects and actual implementation vary across countries. We reviewed studies that examined the impact of IPT on PLHIV and the factors influencing its implementation in Ethiopia.

METHODS

We searched PubMed/MEDLINE, Embase, and the Cochrane Central Register of Clinical Controlled Trials from their inception to 1 April 2021 for studies of any design that examined the impact of IPT on PLHIV and the factors influencing its implementation. The protocol was registered in PROSPERO, ID: CRD42021256579.

RESULT

Of the initial 546 studies identified, 13 of which enrolled 12,426 participants, 15,640 PLHIV and 62 HIV clinical care providers were included. PLHIV who were on IPT, independently or simultaneously with ART, were less likely to develop TB than those without IPT. IPT interventions had a significant association with improved CD4 count and reduced all-cause mortality. IPT was less effective in people with advanced HIV infection. The major factors influencing IPT implementation and uptake were stock-outs, fear of developing isoniazid-resistant TB, patient's refusal and non-adherence, and improper counseling and low commitment of HIV clinical care providers.

CONCLUSION

IPT alone or in combination with ART significantly reduces the incidence of TB and mortality in PLHIV in Ethiopia than those without IPT. More research on safety is needed, especially on women with HIV who receive a combination of IPT and ART. Additionally, studies need to be conducted to investigate the efficacy and safety of the new TPT (3 months combination of isoniazid and rifapentine) in children and people living with HIV.

Impact of Isoniazid Preventive Therapy on Tuberculosis incidence among people living with HIV: A secondary data analysis using Inverse Probability Weighting of individuals attending HIV care and treatment clinics in Tanzania

BACKGROUND

Information on how well Isoniazid Preventive Therapy (IPT) works on reducing TB incidence among people living with HIV (PLHIV) in routine settings using robust statistical methods to establish causality in observational studies is scarce.

OBJECTIVES

To evaluate the effectiveness of IPT in routine clinical settings by comparing TB incidence between IPT and non-IPT groups.

METHODS

We used data from PLHIV enrolled in 315 HIV care and treatment clinic from January 2012 to December 2016. We used Inverse Probability of Treatment Weighting to adjust for the probability of receiving IPT; balancing the baseline covariates between IPT and non-IPT groups. The effectiveness of IPT on TB incidence was estimated using Cox regression using the weighted sample.

RESULTS

Of 171,743 PLHIV enrolled in the clinics over the five years, 10,326 (6.01%) were excluded leaving 161,417 available for the analysis. Of the 24,800 who received IPT, 1.00% developed TB disease whereas of the 136,617 who never received IPT 6,085 (4.98%) developed TB disease. In 278,545.90 person-years of follow up, a total 7,052 new TB cases were diagnosed. Using the weighted sample, the overall TB incidence was 11.57 (95% CI: 11.09-12.07) per 1,000 person-years. The TB incidence among PLHIV who received IPT was 10.49 (95% CI: 9.11-12.15) per 1,000 person-years and 12.00 (95% CI: 11.69-12.33) per 1,000 person-years in those who never received IPT. After adjusting for other covariates there was 52% lower risk of developing TB disease among those who received IPT compared to those who never received IPT: aHR = 0.48 (95% CI: 0.40-0.58, P<0.001).

CONCLUSION

IPT reduced TB incidence by 52% in PLHIV attending routine CTC in Tanzania. IPTW adjusted the groups for imbalances in the covariates associated with receiving IPT to achieve comparable groups of IPT and non-IPT. This study has added evidence on the effectiveness of IPT in routine clinical settings and on the use of IPTW to determine impact of interventions in observational studies.