Evaluation of routine Isoniazid Preventive Therapy among People Living with HIV for reducing Tuberculosis; a retrospective cohort study in Tanzania (2012-2016)

: Background: Isoniazid Preventive Therapy (IPT) reduced Tuberculosis (TB) among People Living with HIV (PLHIV). Despite this, uptake has been reported to be suboptimal . We describe characteristics of visits in which PLHIV were screened TB negative (as the main source for IPT initiation), determine characteristics of visits in which PLHIV were initiated on IPT as well as determined factors associated with IPT initiation to inform program scale up and improve quality of service. Methods : Retrospective cohort study design which involved PLHIV enrolled into care and treatment clinics in Dar es Salaam, Iringa and Njombe regions from January 2012 to December 2016. The study aimed at evaluating implementation of IPT among PLHIV. Data analysis was conducted using STATA. Our study documented low IPT initiation proportion among those who were enrolled in HIV care and eligible in the 3 regions during the study period. Variations in IPT initiation among regions signals different dynamics affecting IPT uptake in different regions and hence customized approaches in quality improvement. Implementation research is needed to understand health system as well as cultural barriers in the uptake of IPT intervention.


Sustainable Development Goals (SDG) and Joint United Nations Programme on
HIV/AIDS (UNAIDS) have laid goals and targets to end AIDS epidemic by 2030 (1). One of the targets to achieve 2030 HIV targets is to achieve HIV viral suppression among People Living on HIV (PLHIV) who are on Antiretroviral Therapy (ART) (1).Tuberculosis (TB) among PLHIV is still a public health concern(2) which despite wide coverage of ART and other interventions to reduce TB among PLHIV, cause increased ill-health and death (3), thus posing threats towards achieving SDG goals.
Worldwide, in 2018, 9% of individuals diagnosed with TB disease were HIV positive, 51% of those with HIV had Tuberculosis disease with84% on ART. Death among diagnosed TB was 1.3 million, among these 300,000 (23%) were HIV positive (2).
Isoniazid Preventive Therapy (IPT) which entails use of an anti-TB Drug called Isoniazid (INH) for at least 6 months, treats latent TB infection thus preventing the development of active TB disease in high risk population like PLHIV (4). IPT in PLHIV is one of the proven public health interventions to reduce TB disease among PLHIV(5)(6) (7).Following this, World Health Organization (WHO) recommends IPT be part of comprehensive HIV care and treatment package (8).
Despite available evidence on the benefits of IPT on PLHIV, use of this effective preventive tool is suboptimal(9)(10)(11) (12). Suboptimal implementation of IPT is equally present even in parts of the World hard-hit by both HIV and TB like in Sub-Saharan Africa (13) where service is needed most. In 2017, IPT among PLHIV Worldwide ranged from 1% in Eswatini to 53% in South Africa (2). Reasons for low IPT coverage ranges from health provider factors, client factors to general health system factors(9) (14).  (17).

Study Population and Data collection:
The study used retrospective data collected from PLHIV enrolled in HIV care and treatment clinics in the three regions enrolled in the specified study period. In Tanzania (28). High uptake among females could be due to more health information to women during medical encounter such as maternal and child health services (25). ART experience and good ARV adherence may increase confidence for IPT initiation among health care providers.
In our study IPT initiation was associated with advanced age above 50, being bedridden, WHO clinical stage II and enrolment into care in 2016. Other determinants were enrolment in hospitals, enrolment in public health facilities and having been in care for more than one year. IPT initiation among elder population was also reported in another study (24). Tendency to provide IPT to elderly population could be due to perceived risk of TB diseases by health care providers for elderly population. We found IPT initiation to be associated in visits involving health individuals (WHO clinical stage II). Our finding is agreement with what was found in Kenya (21). Reason for avoiding IPT in severely ill PLHIV can be attributed to fear of clinicians due to difficulty in ruling out TB disease in this population as speculated in the Kenyan study (21). High IPT initiation in hospitals and public health facilities could be explained by the fact that IPT was rolled out gradual starting with Hospitals. Higher initiation in public versus in private health facilities could be due to small pace of private health facilities in implementing new policies (29). Visits corresponding to being in care for more than one year had higher odds of IPT initiation than earlier visits. IPT initiation later after HIV care enrolment is also reported in Nepal (24). Lower IPT initiation associated with Iringa compared to Dar es Salaam and Njombe explains dynamics in IPT implementation which also differs from health facility to health facility as reported in another study (24). Lower IPT initiation in visits with good adherence is contrary to what is expected in normal program settings as good ARV adherence was one of the criteria for IPT initiation. We expected IPT to be initiated more readily in PLHIV with good ARV adherence than in those with poor adherence. This finding needs to be supplemented by qualitative evaluation.
Our study had several limitations. Firstly, the data used for the analysis is routinely collected from HIV program in Tanzania

CONCLUSION:
Our study which used routine HIV data from 315 clinics documented low IPT initiation proportion among those who were enrolled in HIV care and eligible for IPT in Dar es Salaam, Iringa and Njombe during the study period. Variations in IPT initiation among regions signal different dynamics affecting IPT uptake in different regions and hence require customized approaches in quality improvement. Implementation research is needed to understand health system as well as cultural barriers in the uptake of IPT intervention and design quality improvement initiative accordingly.

List of abbreviations:
ART-Antiretroviral Therapy

Declarations:
This article is an original research which is one of the required number of published articles for PhD training of the first author. We declare that this article has not been submitted to any other journal for publication.

Ethics approval and consent to participate:
The study used routine HIV data from Tanzania. Hence, the study did not have contact with human subjects. Approval for conducting the study was obtained from Kilimanjaro Christian Medical University College in Moshi Tanzania. Permission to use routine HIV data was obtained from Ministry of Health, Community Development, Gender, Elderly and Children (MoHCDGEC) Tanzania by signing Data Transfer Agreement (DTA).

Consent for publication:
Authors of the study collaboratively give permission to the publisher to publish the study findings as presented by the authors.

Availability of data and materials:
Data and other materials used for the study belong to the MoHCDGEC Tanzania.
Permission to access data and other materials used for the study can be obtained from the Permanent Secretary MoHCDGE in Tanzania.

Competing interests:
Authors of the study declare that there is no conflict of interest involved in conducting the study.

Funding:
The study was supported by the SEARCH (

Acknowledgements:
We would like to send our gratitude to Bill and Melinda Gates Foundation, PEPFAR and the Government of Tanzania for financial support. We also thank staff within National AIDS Control Program/MoHCDGEC Tanzania as well as staff from Regional, Council and health facility levels for their contribution in making sure that routine HIV data collected is of quality.