Factors Associated With HIV Co-infection in Persons With History of Tuberculosis
Compared with HIV-uninfected persons with prior tuberculosis, those co-infected with HIV and tuberculosis were more likely to be women (OR = 2.1; 95% CI: 1.1 to 3.9) (Table 5). HIV-infected persons with prior tuberculosis were more likely to be urban residents than HIV-uninfected persons with such a history (OR = 2.4; 95% CI: 1.2 to 4.5) and were more likely to be from Nyanza region (compared to Nairobi region; OR = 3.1; 95% CI: 1.1 to 8.5). HIV co-infected persons were wealthier than HIV-uninfected persons with prior tuberculosis (P = 0.006).
The proportion of HIV-uninfected persons with history of tuberculosis peaked among persons aged 25–34 years, at 27.4%. In contrast, the proportion of HIV-infected persons with a history of tuberculosis peaked higher and later among persons aged 35–44 years (34.1%) and 45–54 years (33.8%). The latter distribution corresponded with the age distribution for HIV prevalence in the population, where HIV prevalence peaked among persons aged 35–54 years, at 9.4% (Fig. 1).
Awareness of HIV Serostatus and Access to HIV Care and ART
Overall, 47% of persons with HIV infection were aware of their infection.11 However, knowledge of HIV infection was significantly higher among persons with prior tuberculosis (77.2%) compared with persons without prior tuberculosis (42.9%) (Table 6). Among persons who were aware of their HIV infection, those with prior tuberculosis were more likely to be in HIV care (99.0%) than those without prior tuberculosis (89.8%) (P < 0.0001).
Among all HIV-infected persons, the proportion of those with and without prior tuberculosis who were on ART were 73.9% and 26.2%, respectively. Persons with prior tuberculosis therefore accounted for 28.8% (56/200) of all those taking ART. For persons who were aware of their HIV status, the respective proportions taking ART were 95.7% for those with prior tuberculosis and 61.2% for those without prior tuberculosis (P < 0.0001).
To estimate ART coverage for HIV-infected persons without prior tuberculosis who were in care, we examined persons with CD4 counts available and considered all persons on ART as treatment eligible, as well as those untreated who had a CD4 cell count ≤350 cells per microliter. The proportion of treatment-eligible persons without prior tuberculosis who were in care and receiving ART was 88.6%.
For both groups, ART coverage was lower when was assessed among all HIV-infected persons eligible for treatment, including those without knowledge of HIV serostatus. Overall coverage was 86.9% for persons with prior tuberculosis and 58.3% for those without prior tuberculosis (P < 0.0001). Approximately, three-quarters of HIV-infected persons on ART had achieved virologic suppression (76.6% among persons with prior tuberculosis and 74.5% among persons without prior tuberculosis).
KAIS 2012 gives insight into the epidemics of HIV and tuberculosis and their association in Kenya. Overall, 5.6% of adults and adolescents aged 15 to 64 years were infected with HIV in the survey,11 and 2% of those who had heard of tuberculosis reported ever having had tuberculosis. In 2011, the Kenya Ministry of Health's Division of Leprosy, Tuberculosis and Lung Disease reported a total of 103,981 cases of tuberculosis nationally.7 In KAIS 2012, almost one third of persons who reported prior tuberculosis were infected with HIV compared with 5.1% of persons without prior tuberculosis. In addition, 11.6% of persons with laboratory-diagnosed HIV infection reported having had tuberculosis previously. In contrast, only 1.4% of HIV-negative persons reported prior tuberculosis, indicative of the greatly increased relative risk for this disease that HIV infection confers at a population level. The association between HIV and tuberculosis was even stronger for the smaller group of persons self-reporting as HIV-positive, of whom 1 of 5 reported prior tuberculosis.
Reflective of the distribution of HIV infection itself,6 persons with a history of HIV-associated tuberculosis were more likely than those with HIV-negative tuberculosis to be female, older, and residents of urban settings and Nyanza region, where HIV prevalence is high. They also were slightly wealthier. Just over one-quarter of all HIV-infected persons taking ART had a history of prior tuberculosis, which for many was likely the indicator disease leading to HIV diagnosis and care, including ART. Since tuberculosis frequently occurs relatively early in the natural history of HIV infection,2 tuberculosis services may be playing an analogous role to those for the prevention of mother-to-child transmission of HIV, which are a frequent entry point for HIV care among women.
Although awareness of tuberculosis in the general population in Kenya was high, less than half of study participants knew that tuberculosis was curable in persons living with HIV. The finding that HIV-infected people, especially those reporting their own HIV infection, had significantly higher levels of knowledge suggests that many may have acquired this understanding from their own disease experience. Nonetheless, as only about two-thirds to three-quarters of persons with HIV knew that HIV-associated tuberculosis was curable, education about tuberculosis should constitute an important element of HIV/AIDS treatment literacy.
KAIS 2012 provided insight into access to treatment and care for HIV and tuberculosis. More than 95% of participants with self-reported prior tuberculosis reported receiving anti-tuberculosis therapy, and more than 80% of the latter reported completing it. HIV treatment programs would benefit from emulating tuberculosis programs' approach to cohort analysis of outcomes for all persons diagnosed with HIV.12 Although the process would be more complex because of the need for lifelong ART, analogous treatment outcomes can be defined and viral load suppression (or lack of it) could replace cure (or failure) in tuberculosis treatment as an outcome measure of HIV therapy.
KAIS 2012 reinforced observations from KAIS 2007 concerning the importance of individuals knowing their HIV serostatus.6 Provided people were aware of their HIV infection, access to HIV care and uptake of ART for those eligible were high. For persons who reported that they were infected with HIV, all persons with prior tuberculosis and approximately 90% without prior tuberculosis were in HIV care, and a similar proportion of such persons who were eligible for treatment were receiving ART. However, taking into account undiagnosed HIV infection, only about three-quarters of all HIV-infected persons with prior tuberculosis were in care compared to about 40% of HIV-infected persons without prior tuberculosis. Taking ART eligibility into account for all HIV-infected persons, including those undiagnosed and not in care, ART coverage was higher at 87% for persons with and 56% for persons without prior tuberculosis. In the broader KAIS sample, ART coverage regardless of tuberculosis knowledge fell in between these 2 estimates, at 61%.13 Among persons who accessed ART, more than 70% were virally suppressed. These estimates show progress over a few years but are lower than coverage estimates from programmatic data or modeling efforts and fall short of universal access.14
In this analysis, approximately half of persons living with HIV were unaware of their HIV infection and thus unable to access potentially life-saving services.14 HIV testing is the essential entry into HIV care and treatment,15 but our data suggest that for many people tuberculosis disease may have been the reason for HIV diagnosis. If ART is to prevent morbidity including tuberculosis, HIV testing and ART provision must occur before people develop immunodeficiency-associated disease.16,17 WHO issued new guidelines in 2013 advocating ART for all HIV-infected persons with CD4 cell counts of 500 cells per microliter or below. Considerable prevention and therapeutic benefit occur at the population level with scale-up of ART initiated at the lower CD4 cell count thresholds still applied in most countries.18,19 Whatever future policy decisions are made,4 the critical requirements are widespread HIV testing, greatly increased knowledge of HIV serostatus, and timely implementation of ART, especially for those most immunosuppressed.
There were several limitations to the present study. History of tuberculosis was self-reported, and different clinical categories, such as new cases, recurrences, treatment failures, and drug-resistant cases, could not be explored. Self-reports of HIV infection were not necessarily accurate, and recall bias could have influenced participants' reporting of previously received testing, treatment and care services, and results. Despite its public health importance, tuberculosis is still a relatively rare event and numbers were small for further analyses. Cross-sectional surveys like KAIS 2012 have intrinsic biases because participants likely differ from nonparticipants who may have been excluded because of factors relevant to both HIV infection and tuberculosis, including through hospitalization or death, resulting in potential underestimation of the true burden of tuberculosis and HIV in the population. North Eastern region, the region of the country with the lowest HIV prevalence and a relatively small population, was excluded for reasons of insecurity, so the study was not perfectly representative of the whole country. Despite these and other limitations, this national survey has given a unique assessment of the tuberculosis and HIV situation in Kenya not available through routine surveillance or program evaluations.
Despite substantial progress since KAIS 2007,6 KAIS 2012 highlights important areas for improvement. Without universal knowledge of HIV serostatus in this country with a generalized HIV epidemic, the full benefit of ART for prevention of HIV transmission as well as of morbidity and death, including from tuberculosis, will not be realized.20,21 Much greater emphasis on preventing tuberculosis among persons living with HIV is required.
National surveys of tuberculosis itself, for assessment of prevalence, evaluation of case finding, and tracking of anti-tuberculous drug resistance, must also be supported in high burden countries, such as Kenya. The inclusion of tuberculosis-specific data in KAIS 2012 should lead to increased understanding, enhanced commitment to policy setting and planning for both HIV and tuberculosis, and improved services for both diseases, which remain among the most important health challenges in Kenya and on the African continent.
The authors thank the interviewers, counselors, phlebotomists, and their supervisors for their work during KAIS data collection. The authors also gratefully acknowledge all persons who participated in this national survey. The authors would also like to thank George Rutherford, Lucy Ng'ang'a, Anthony Waruru, and Mike Grasso for discussing and reviewing the manuscript, and the KAIS Study Group for their contribution to the design of the survey and collection of the data set: Willis Akhwale, Sehin Birhanu, John Bore, Angela Broad, Robert Buluma, Thomas Gachuki, Jennifer Galbraith, Anthony Gichangi, Beth Gikonyo, Margaret Gitau, Joshua Gitonga, Mike Grasso, Malayah Harper, Andrew Imbwaga, Muthoni Junghae, Mutua Kakinyi, Samuel Mwangi Kamiru, Nicholas Owenje Kandege, Lucy Kanyara, Yasuyo Kawamura, Timothy Kellogg, George Kichamu, Andrea Kim, Lucy Kimondo, Davies Kimanga, Elija Kinyanjui, Stephen Kipkerich, Danson Kimutai Koske, Boniface O. K'Oyugi, Veronica Lee, Serenita Lewis, William Maina, Ernest Makokha, Agneta Mbithi, Joy Mirjahangir, Ibrahim Mohamed, Rex Mpazanje, Silas Mulwa, Nicolas Muraguri, Patrick Murithi, Lilly Muthoni, James Muttunga, Jane Mwangi, Mary Mwangi, Sophie Mwanyumba, Francis Ndichu, Anne Ng'ang'a, James Ng'ang'a, John Gitahi Ng'ang'a, Lucy Ng'ang'a, Carol Ngare, Bernadette Ng'eno, Inviolata Njeri, David Njogu, Bernard Obasi, Macdonald Obudho, Edwin Ochieng, Linus Odawo, Jacob Odhiambo, Caleb Ogada, Samuel Ogola, David Ojakaa, James Kwach Ojwang, George Okumu, Patricia Oluoch, Tom Oluoch, Kenneth Ochieng Omondi, Osborn Otieno, Yakubu Owolabi, Bharat Parekh, George Rutherford, Sandra Schwarcz, Shanaaz Sharrif, Victor Ssempijja, Yuko Takanaka, Mamo Umuro, Brian Eugene Wakhutu, Wanjiru Waruiru, Celia Wandera, John Wanyungu, Paul Waweru, Larry Westerman, Anthony Waruru, and Kelly Winter.
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Keywords:© 2014 by Lippincott Williams & Wilkins
tuberculosis; HIV; co-infection; AIDS indicator survey; HIV/AIDS; HIV/TB