Determinants of isoniazid preventive therapy completion among people living with HIV attending care and treatment clinics from 2013 to 2017 in Dar es Salaam Region, Tanzania. A cross-sectional analytical study.

BACKGROUND: Tuberculosis (TB) disease is a common opportunistic infection among people living with HIV (PLHIV). WHO recommends at least 6 months of isoniazid Preventive Therapy (IPT) to reduce the risk of active TB. It is important to monitor the six-month IPT completion since a suboptimal dose may not protect PLHIV from TB infection. This study determined the six-month IPT completion and factors associated with six-month IPT completion among PLHIV aged 15 years or more in Dar es Salaam region, Tanzania. METHODS: Secondary analysis of routine data from PLHIV attending 58 care and treatment clinics in Dar es Salaam region was used. PLHIV, aged 15 years and above, who screened negative for TB symptoms and initiated IPT from January, 2013 to June, 2017 were recruited. Modified Poisson regression with robust standard errors was used to estimate prevalence ratios (PR) and 95% confidence interval (CI) for factors associated with IPT completion. Multilevel analysis was used to account for health facility random effects in order to estimate adjusted PR (APR) for factors associated with IPT six-month completion. RESULTS: A total of 29,382 PLHIV were initiated IPT, with 21,808 (74%) female. Overall 17,092 (58%) six-month IPT completion, increasing from 42% (773/1857) in year 2013 to 76% (2929/3856) in 2017. Multilevel multivariable model accounting for health facilities as clusters, showed PLHIV who were not on ART had 46% lower IPT completion compared to those were on ART (APR: 0.54: 95%CI: 0.45-0.64). There was 37% lower IPT completion among PLHIV who transferred from another clinic (APR: 0.63: 95% CI (0.54-0.74) compared to those who did not transfer. PLHIV aged 25-34 years had a 6% lower prevalence of IPT completion as compared to those aged 15 to 24 years (APR:0.94 95%CI:0.89-0.98). CONCLUSION: The IPT completion rate in PLHIV increased over time, but there was lower IPT completion in PLHIV who transferred from other clinics, who were aged 25 to 34 years and those not on ART. Interventions to support IPT in these groups are urgently needed.

Effect of isoniazid preventive therapy on tuberculosis incidence and associated risk factors among HIV infected adults in Tanzania: a retrospective cohort study.

BACKGROUND: Tuberculosis (TB) continues to be the leading cause of morbidity and mortality among human immunodeficiency virus (HIV) infected individuals in Sub Saharan Africa including Tanzania. Provision of isoniazid preventive therapy (IPT) is one of the public health interventions to reduce the burden of TB among HIV infected persons. However there is limited information about the influence of IPT on TB incidence in Tanzania. This study aimed at ascertaining the effect of IPT on TB incidence and to determine risk factors for TB among HIV positive adults in Dar es Salaam region. METHODS: A retrospective cohort study was conducted using secondary data of HIV positive adults receiving care and treatment services in Dar es Salaam region from 2011 to 2014. TB incidence rate among HIV positive adults on IPT was compared to those who were not on IPT during the follow up period. Risk factors for incident TB were estimated using multivariate Cox proportional hazards regression model. RESULTS: A total of 68,378 HIV positive adults were studied. The median follow up time was 3.4 (IQR = 1.9-3.8) years for patients who ever received IPT and 1.3 (IQR = 0.3-1.3) years among those who never received IPT. A total of 3124 TB cases occurred during 114,926 total person-years of follow up. The overall TB incidence rate was 2.7/100 person-years (95%CI; 2.6-2.8). Patients on IPT had 48% lower TB incidence rate compared to patients who were not on IPT (IRR = 0.52, 95%CI; 0.46-0.59). Factors associated with higher risk for incident TB included; being male (aHR = 1.8, 95% CI; 1.6-2.0), WHO stage III (aHR = 2.7, 95% CI; 2.3-3.3) and IV (aHR = 2.4, 95% CI; 1.9-3.1),being underweight (aHR = 1.7, 95% CI; 1.5-1.9) while overweight (aHR = 0.7, 95% CI; 0.6-0.8), obese (aHR = 0.5, 95% CI; 0.4-0.7), having baseline CD4 cell count between 200 and 350 cells/µl (aHR = 0.7, 95% CI; 0.6-0.8) and CD4 count above 350 cells/µl (aHR = 0.5, 95% CI; 0.4-0.6) were associated with lower risk of developing TB. CONCLUSION: Isoniazid preventive therapy (IPT) has shown to be effective in reducing TB incidence among HIV infected adults in Dar es Salaam. More efforts are needed to increase the provision and coverage of IPT.