Impact and cost-effectiveness of short-course tuberculosis preventive treatment for household contacts and people with HIV in 29 high-incidence countries: a modelling analysis.

BACKGROUND: Guidelines and implementation of tuberculosis preventive treatment (TPT) vary by age and HIV status. Specifically, TPT is strongly recommended for people living with HIV/AIDS (PLWHA) and household contacts younger than 5 years but only conditionally recommended for older contacts. Cost remains a major barrier to implementation. The aim of this study was to evaluate the cost-effectiveness of TPT for household contacts and PLWHA. METHODS: We developed a state-transition model to simulate short-course TPT for household contacts and PLWHA in 29 high-incidence countries based on data from previous studies and public databases. Our primary outcome was the incremental cost-effectiveness ratio, expressed as incremental discounted costs (2020 US$, including contact investigation costs) per incremental discounted disability-adjusted life year (DALY) averted, compared with a scenario without any TPT or contact investigation. We propagated uncertainty in all model parameters using probabilistic sensitivity analysis and also evaluated the sensitivity of results to the screening algorithm used to rule out active disease, the choice of TPT regimen, the modelling time horizon, assumptions about TPT coverage, antiretroviral therapy discontinuation, and secondary transmission. FINDINGS: Between 2023 and 2035, scaling up TPT prevented 0·9 (95% uncertainty interval 0·4-1·6) people from developing tuberculosis and 0·13 (0·05-0·27) tuberculosis deaths per 100 PLWHA, at an incremental cost of $15 (9-21) per PLWHA. For household contacts, TPT (with contact investigation) averted 1·1 (0·5-2·0) cases and 0·7 (0·4-1·0) deaths per 100 contacts, at a cost of $21 (17-25) per contact. Cost-effectiveness was most favourable for household contacts younger than 5 years ($22 per DALY averted) and contacts aged 5-14 years ($104 per DALY averted) but also fell within conservative cost-effectiveness thresholds in many countries for PLWHA ($722 per DALY averted) and adult contacts ($309 per DALY averted). Costs per DALY averted tended to be lower when compared with a scenario with contact investigation but no TPT. The cost-effectiveness of TPT was not substantially altered in sensitivity analyses, except that TPT was more favourable in analysis that considered a longer time horizon or included secondary transmission benefits. INTERPRETATION: In many high-incidence countries, short-course TPT is likely to be cost-effective for PLWHA and household contacts of all ages, regardless of whether contact investigation is already in place. Failing to implement tuberculosis contact investigation and TPT will incur a large burden of avertable illness and mortality in the next decade. FUNDING: Unitaid.

Cost-effectiveness of 3-months isoniazid and rifapentine compared to 9-months isoniazid for latent tuberculosis infection: a systematic review.

BACKGROUND: We conducted a systematic review examining the cost effectiveness of a 3-month course of isoniazid and rifapentine, known as 3HP, given by directly observed treatment, compared to 9 months of isoniazid that is directly observed or self-administered, for latent tuberculosis infection. 3HP has shown to be effective in reducing progression to active tuberculosis and like other short-course regimens, has higher treatment completion rates compared to standard regimens such as 9 months of isoniazid. Decision makers would benefit from knowing if the higher up-front costs of rifapentine and of the human resources needed for directly observed treatment are worth the investment for improved outcomes. METHODS: We searched PubMed, Embase, CINAHL, LILACS, and Web of Science up to February 2022 with search concepts combining latent tuberculosis infection, directly observed treatment, and cost or cost-effectiveness. Studies included were in English or French, on human subjects, with latent tuberculosis infection, provided information on specified anti-tubercular therapy regimens, had a directly observed treatment arm, and described outcomes with some cost or economic data. We excluded posters and abstracts, treatment for multiple drug resistant tuberculosis, and combined testing and treatment strategies. We then restricted our findings to studies examining directly-observed 3HP for comparison. The primary outcome was the cost and cost-effectiveness of directly-observed 3HP. RESULTS: We identified 3 costing studies and 7 cost-effectiveness studies. The 3 costing studies compared directly-observed 3HP to directly-observed 9 months of isoniazid. Of the 7 cost-effectiveness studies, 4 were modelling studies based in high-income countries; one study was modelled on a high tuberculosis incidence population in the Canadian Arctic, using empiric costing data from that setting; and 2 studies were conducted in a low-income, high HIV-coinfection rate population. In five studies, directly-observed 3HP compared to self-administered isoniazid for 9 months in high-income countries, has incremental cost-effectiveness ratios that range from cost-saving to $5418 USD/QALY gained. While limited, existing evidence suggests 3HP may not be cost-effective in low-income, high HIV-coinfection settings. CONCLUSION: Cost-effectiveness should continue to be assessed for programmatic planning and scale-up, and may vary depending on existing systems and local context, including prevalence rates and patient expectations and preferences.

Cost-effectiveness of scaling up short course preventive therapy for tuberculosis among children across 12 countries.

BACKGROUND: While household contact investigation is widely recommended as a means to reduce the burden of tuberculosis (TB) among children, only 27% of eligible pediatric household contacts globally received preventive treatment in 2018. We assessed the cost-effectiveness of household contact investigation for TB treatment and short-course preventive therapy provision for children under 15 years old across 12 high TB burden countries. METHODS: We used decision analysis to compare the costs and estimated effectiveness of three intervention scenarios: (a) status quo (existing levels of coverage with isoniazid preventive therapy), (b) contact investigation with treatment of active TB but no additional preventive therapy, and (c) contact investigation with TB treatment and provision of short-course preventive therapy. Using country-specific demographic, epidemiological and cost data from the literature, we estimated annual costs (in 2018 USD) and the number of TB cases and deaths averted across 12 countries. Incremental cost effectiveness ratios were assessed as cost per death and per disability-adjusted life year [DALY] averted. FINDINGS: Our model estimates that contact investigation with treatment of active TB and provision of preventive therapy could be highly cost-effective compared to the status quo (ranging from $100 per DALY averted in Malawi to $1,600 in Brazil; weighted average $383 per DALY averted [uncertainty range: $248 - $1,130]) and preferred to contact investigation without preventive therapy (weighted average $751 per DALY averted [uncertainty range: $250 - $1,306]). Key drivers of cost-effectiveness were TB prevalence, sensitivity of TB diagnosis, case fatality for untreated TB, and cost of household screening. INTERPRETATION: Based on this modeling analysis of available published data, household contact investigation with provision of short-course preventive therapy for TB has a value-for-money profile that compares favorably with other interventions. FUNDING: Unitaid (2017-20-IMPAACT4TB).

Risk of developing active tuberculosis following tuberculosis screening and preventive therapy for Tibetan refugee children and adolescents in India: An impact assessment.

BACKGROUND: Tuberculosis (TB) rates among Tibetan refugee children and adolescents attending boarding schools in India are extremely high. We undertook a comprehensive case finding and TB preventive treatment (TPT) program in 7 schools in the Zero TB Kids project. We aimed to measure the TB infection and disease burden and investigate the risk of TB disease in children and adults who did and did not receive TPT in the schools. METHODS AND FINDINGS: A mobile team annually screened children and staff for TB at the 7 boarding schools in Himachal Pradesh, India, using symptom criteria, radiography, molecular diagnostics, and tuberculin skin tests. TB infection (TBI) was treated with short-course regimens of isoniazid and rifampin or rifampin. TB disease was treated according to Tibetan and Indian guidelines. Between April 2017 and December 2019, 6,582 schoolchildren (median age 14 [IQR 11-16] years) and 807 staff (median age 40 [IQR 33-48] years) were enrolled. Fifty-one percent of the students and 58% of the staff were females. Over 13,161 person-years of follow-up in schoolchildren (median follow-up 2.3 years) and 1,800 person-years of follow-up in staff (median follow-up 2.5 years), 69 TB episodes occurred in schoolchildren and 4 TB episodes occurred in staff, yielding annual incidence rates of 524/100,000 (95% CI 414-663/100,000) person-years and 256/100,000 (95% CI 96-683/100,000) person-years, respectively. Of 1,412 schoolchildren diagnosed with TBI, 1,192 received TPT. Schoolchildren who received TPT had 79% lower risk of TB disease (adjusted hazard ratio [aHR] 0.21; 95% CI 0.07-0.69; p = 0.010) compared to non-recipients, the primary study outcome. Protection was greater in recent contacts (aHR 0.07; 95% CI 0.01-0.42; p = 0.004), the secondary study outcome. The prevalence of recent contacts was 28% (1,843/6,582). Two different TPT regimens were used (3HR and 4R), and both were apparently effective. No staff receiving TPT developed TB. Overall, between 2017 and 2019, TB disease incidence decreased by 87%, from 837/100,000 (95% CI 604-1,129/100,000) person-years to 110/100,000 (95% CI 36-255/100,000) person-years (p < 0.001), and TBI prevalence decreased by 42% from 19% (95% CI 18%-20%) to 11% (95% CI 10%-12%) (p < 0.001). A limitation of our study is that TB incidence could be influenced by secular trends during the study period. CONCLUSIONS: In this study, following implementation of a school-wide TB screening and preventive treatment program, we observed a significant reduction in the burden of TB disease and TBI in children and adolescents. The benefit of TPT was particularly marked for recent TB contacts. This initiative may serve as a model for TB detection and prevention in children and adolescents in other communities affected by TB.

Cost-effectiveness of one month of daily isoniazid and rifapentine versus three months of weekly isoniazid and rifapentine for prevention of tuberculosis among people receiving antiretroviral therapy in Uganda.

INTRODUCTION: Preventive therapy is essential for reducing tuberculosis (TB) burden among people living with HIV (PLWH) in high-burden settings. Short-course preventive therapy regimens, such as three-month weekly rifapentine and isoniazid (3HP) and one-month daily rifapentine and isoniazid (1HP), may help facilitate uptake of preventive therapy for latently infected patients, but the comparative cost-effectiveness of these regimens under different conditions is uncertain. METHODS: We used a Markov state-transition model to estimate the incremental costs and effectiveness of 1HP versus 3HP in a simulated cohort of patients attending an HIV clinic in Uganda, as an example of a low-income, high-burden setting in which TB preventive therapy might be prescribed to PLWH. Our primary outcome was the incremental cost-effectiveness ratio, expressed as 2019 US dollars per disability-adjusted life year (DALY) averted. We estimated cost-effectiveness under different conditions of treatment completion and efficacy of 1HP versus 3HP, latent TB prevalence and rifapentine price. RESULTS: Assuming equivalent clinical outcomes using 1HP and 3HP and a rifapentine price of $0.21 per 150 mg, 1HP would cost an additional $4.66 per patient treated. Assuming equivalent efficacy but 20% higher completion with 1HP versus 3HP, 1HP would cost $1,221 per DALY averted relative to 3HP. This could be reduced to $18 per DALY averted if 1HP had 5% greater efficacy than 3HP and the price of rifapentine were 50% lower. At a rifapentine price of $0.06 per 150 mg, 1HP would become cost-neutral relative to 3HP. CONCLUSIONS: 1HP has the potential to be cost-effective under many realistic circumstances. Cost-effectiveness depends on rifapentine price, relative completion and efficacy, prevalence of latent TB and local willingness-to-pay.

Cost-effectiveness of a 12 country-intervention to scale up short course TB preventive therapy among people living with HIV.

INTRODUCTION: In 2017, the Aurum Institute, with support from Unitaid, launched an initiative to expand short-course therapy for the prevention of tuberculosis (TB) in 12 high-burden countries. This study aimed to investigate the importance of "catalytic" effects beyond the original project timeframe when estimating cost-effectiveness of such large investments. METHODS: We estimated the cost-effectiveness of the IMPAACT4TB (I4TB) initiative from a health system perspective, using a 10-year time horizon. We first conservatively estimated costs using a "top-down" approach considering only the direct health benefits of providing TB preventive therapy to people initiating antiretroviral therapy (ART) through I4TB activities. We then re-estimated the incremental cost-effectiveness of I4TB incorporating the costs and health benefits of potential catalytic effects beyond the program itself. RESULTS: We estimated that TB preventive therapy through the I4TB initiative alone would prevent 14 201 cases of active TB and 1562 TB deaths over 10 years with an up-front investment of $52.5 million; the estimated incremental cost-effectiveness was $1580 per disability-adjusted life year (DALY) averted. If this initiative could achieve its desired catalytic effects, an additional 375 648 cases and 41 321 deaths could be averted, at an incremental cost of $546 million and cost-effectiveness of $713 per DALY averted. CONCLUSIONS: Our findings provide donors with reasonable evidence of value for money to support investment in short-course TB preventive therapy for people initiating ART in high-burden settings. Our study also illustrates the importance of considering long-term secondary ("catalytic") effects when evaluating the cost-effectiveness of large-scale initiatives designed to change a global policy landscape.

Patient-incurred cost of inpatient treatment for Tuberculosis in rural Malawi.

OBJECTIVES: To mitigate the economic burden of tuberculosis (TB), it is important to fully understand the costs of TB treatment from the patient perspective. We therefore sought to quantify the patient-incurred cost of TB treatment in rural Malawi, with specific focus on costs borne by patients requiring inpatient hospitalisation. METHODS: We conducted a cross-sectional survey of 197 inpatients and 156 outpatients being treated for TB in rural Malawi. We collected data on out-of-pocket costs and lost wages, including costs to guardians. Costs for inpatient TB treatment were estimated and compared to costs for outpatient TB treatment. We then explored the equity distribution of inpatient TB treatment cost using concentration curves. RESULTS: Despite free government services, inpatients were estimated to incur a mean of $137 (standard deviation: $147) per initial TB episode, corresponding to >50% of annual household spending among patients in the lowest expenditure quintile. Non-medical hospitalisation costs accounted for 88% of this total. Patients treated entirely as outpatients incurred estimated costs of $25 (standard deviation: $15) per episode. The concentration curves showed that, among individuals hospitalised for an initial TB episode, poorer patients shouldered a much greater proportion of inpatient TB treatment costs than wealthier ones (concentration index: -0.279). CONCLUSION: Patients hospitalised for TB in resource-limited rural Malawi experience devastating costs of TB treatment. Earlier diagnosis and treatment must be prioritised if we are to meet goals of effective TB control, avoidance of catastrophic costs and provision of appropriate patient-centred care in such settings.

OBJECTIFS: Pour atténuer la charge économique de la tuberculose (TB), il est important de bien comprendre les coûts du traitement de la TB du point de vue du patient. Nous avons donc cherché à quantifier les coûts encourus par les patients pour le traitement de la TB dans les zones rurales du Malawi, en mettant l'accent sur les coûts supportés par les patients nécessitant une hospitalisation. MÉTHODES: Nous avons mené une enquête transversale auprès de 197 patients hospitalisés et 156 patients ambulatoires traités pour la TB dans les régions rurales du Malawi. Nous avons collecté des données sur les dépenses payées directement de la poche et les pertes de salaire, y compris les coûts pour les gardiens des malades. Les coûts du traitement anti-TB des patients hospitaliser ont été estimés et comparés aux ceux des patients ambulatoires. Nous avons ensuite exploré la répartition des équités propres au coût du traitement de la TB des patients hospitalisés en utilisant des courbes de concentration. RÉSULTATS: Malgré les services gratuits du gouvernement, les patients hospitalisés encouraient en moyenne estimée de 137 $ (écart-type: 147 $) par épisode initial de TB, ce qui correspond à >50% des dépenses annuelles des ménages chez les patients du quintile de dépenses le plus bas. Les frais d'hospitalisation non médicaux représentaient 88% de ce total. Les patients traités entièrement en ambulatoire encouraient des coûts estimés à 25 $ (écart type: 15 $) par épisode. Les courbes de concentration ont montré que, parmi les personnes hospitalisées pour un premier épisode de TB, les patients les plus pauvres supportaient une proportion beaucoup plus élevée des coûts de traitement de la TB en hospitalisation que les plus riches (indice de concentration: -0,279). CONCLUSION: Les patients hospitalisés pour la TB dans les régions rurales pauvres du Malawi connaissent des coûts dévastateurs pour le traitement de la TB. Le diagnostic et le traitement précoces doivent être priorisés si nous voulons atteindre des objectifs de contrôle efficace de la TB, d'évitement des coûts catastrophiques et de prestation de soins appropriés centrés sur le patient dans de tels contextes .

Addressing critical needs in the fight to end tuberculosis with innovative tools and strategies.

This month in PLOS Medicine we launched a Special Issue on New Tools and Strategies for Tuberculosis Diagnosis, Care, and Elimination. In this issue's Editorial, the Guest Editors Claudia Denkinger, Richard Chaisson, and Mark Hatherill highlight some of the research that will publish and how these studies focusing on discovery, clinical trials and implementation research collectively add to the prospects for reaching the EndTB targets of the WHO by 2035.

Screening for Tuberculosis Among Adults Newly Diagnosed With HIV in Sub-Saharan Africa: A Cost-Effectiveness Analysis.

OBJECTIVE: New tools, including light-emitting diode (LED) fluorescence microscopy and the molecular assay Xpert MTB/RIF, offer increased sensitivity for tuberculosis (TB) in persons with HIV but come with higher costs. Using operational data from rural Malawi, we explored the potential cost-effectiveness of on-demand screening for TB in low-income countries of Sub-Saharan Africa. DESIGN AND METHODS: Costs were empirically collected in 4 clinics and in 1 hospital using a microcosting approach, through direct interview and observation from the national TB program perspective. Using decision analysis, newly diagnosed persons with HIV were modeled as being screened by 1 of the 3 strategies: Xpert, LED, or standard of care (ie, at the discretion of the treating physician). RESULTS: Cost-effectiveness of TB screening among persons newly diagnosed with HIV was largely determined by 2 factors: prevalence of active TB among patients newly diagnosed with HIV and volume of testing. In facilities screening at least 50 people with a 6.5% prevalence of TB, or at least 500 people with a 2.5% TB prevalence, Xpert is likely to be cost-effective. At lower prevalence-including that observed in Malawi-LED microscopy may be the preferred strategy, whereas in settings of lower TB prevalence or small numbers of eligible patients, no screening may be reasonable (such that resources can be deployed elsewhere). CONCLUSIONS: TB screening at the point of HIV diagnosis may be cost-effective in low-income countries of Sub-Saharan Africa, but only if a relatively large population with high prevalence of TB can be identified for screening.

Mortality associated with delays between clinic entry and ART initiation in resource-limited settings: results of a transition-state model.

OBJECTIVE: To estimate the mortality impact of delay in antiretroviral therapy (ART) initiation from the time of entry into care. DESIGN: A state-transition Markov process model. This technique allows for assessing mortality before and after ART initiation associated with delays in ART initiation among a general population of ART-eligible patients without conducting a randomized trial. METHODS: We used patient-level data from 3 South African cohorts to determine transition probabilities for pre-ART CD4 count changes and pre-ART and on-ART mortality. For each parameter, we generated probabilities and distributions for Monte Carlo simulations with 1-week cycles to estimate mortality 52 weeks from clinic entry. RESULTS: We estimated an increase in mortality from 11.0% to 14.7% (relative increase of 34%) with a 10-week delay in ART for patients entering care with our pre-ART cohort CD4 distribution. When we examined low CD4 ranges, the relative increase in mortality delays remained similar; however, the absolute increase in mortality rose. For example, among patients entering with CD4 count 50-99 cells per cubic millimeter, 12-month mortality increased from 13.3% with no delay compared with 17.0% with a 10-week delay and 22.9% with a 6-month delay. CONCLUSIONS: Delays in ART initiation, common in routine HIV programs, can lead to important increases in mortality. Prompt ART initiation for patients entering clinical care and eligible for ART, especially those with lower CD4 counts, could be a relatively low-cost approach with a potential marked impact on mortality.

South African TB nurses' experiences of provider-initiated HIV counseling and testing in the Eastern Cape Province: a qualitative study.

This study addressed factors that played a role in the limited but effective implementation of provider-initiated HIV counseling in tuberculosis (TB) clinics in the Eastern Cape Province, South Africa, as part of a clinical trial. The Eastern Cape is a region with some of the highest TB and HIV rates in the world. The parent study was a pragmatic, cluster-randomized trial designed to measure the impact of provider-initiated ("opt-out") counseling on the uptake of HIV counseling and testing in newly registered TB patients. Key informants were interviewed and clinic nurses who participated in the study were invited to participate in focus group discussions (FGDs). Thematic content analysis of transcriptions was conducted on data collected during interviews and FGDs. Three major themes regarding nurse experiences were derived from analysis, indicating that multiple structural and personal factors influence the success of provider-initiated HIV counseling of TB patients in primary care settings: (1) chronic frustration with knowing what TB tasks need to be accomplished but not having the resources, including staff, to accomplish them; (2) conflict between the appreciation of the need and importance of HIV counseling and testing and the health system's recognition of their difficulties implementing it; and (3) ambivalence in their roles as care providers and educators in the context of HIV counseling and testing. Innovative and coordinated strategies are needed in this environment to facilitate greater number of patients receiving HIV counseling and testing services.

Impact and cost-effectiveness of culture for diagnosis of tuberculosis in HIV-infected Brazilian adults.

BACKGROUND: Culture of Mycobacterium tuberculosis currently represents the closest "gold standard" for diagnosis of tuberculosis (TB), but operational data are scant on the impact and cost-effectiveness of TB culture for human immunodeficiency (HIV-) infected individuals in resource-limited settings. METHODOLOGY/PRINCIPAL FINDINGS: We recorded costs, laboratory results, and dates of initiating TB therapy in a centralized TB culture program for HIV-infected patients in Rio de Janeiro, Brazil, constructing a decision-analysis model to estimate the incremental cost-effectiveness of TB culture from the perspective of a public-sector TB control program. Of 217 TB suspects presenting between January 2006 and March 2008, 33 (15%) had culture-confirmed active tuberculosis; 23 (70%) were smear-negative. Among smear-negative, culture-positive patients, 6 (26%) began TB therapy before culture results were available, 11 (48%) began TB therapy after culture result availability, and 6 (26%) did not begin TB therapy within 180 days of presentation. The cost per negative culture was US$17.52 (solid media)-$23.50 (liquid media). Per 1,000 TB suspects and compared with smear alone, TB culture with solid media would avert an estimated eight TB deaths (95% simulation interval [SI]: 4, 15) and 37 disability-adjusted life years (DALYs) (95% SI: 13, 76), at a cost of $36 (95% SI: $25, $50) per TB suspect or $962 (95% SI: $469, $2642) per DALY averted. Replacing solid media with automated liquid culture would avert one further death (95% SI: -1, 4) and eight DALYs (95% SI: -4, 23) at $2751 per DALY (95% SI: $680, dominated). The cost-effectiveness of TB culture was more sensitive to characteristics of the existing TB diagnostic system than to the accuracy or cost of TB culture. CONCLUSIONS/SIGNIFICANCE: TB culture is potentially effective and cost-effective for HIV-positive patients in resource-constrained settings. Reliable transmission of culture results to patients and integration with existing systems are essential.

Clinical evaluation of the microscopic-observation drug-susceptibility assay for detection of tuberculosis.

BACKGROUND: There is an urgent need for low-cost methods for rapid, accurate detection of Mycobacterium tuberculosis in clinical specimens. The microscopic-observation drug-susceptibility (MODS) assay is a relatively low-cost and simple liquid culture method that has been proposed for use in resource-limited environments. METHODS: This prospective study evaluated the performance of the MODS assay for detection of M. tuberculosis in persons undergoing evaluation for pulmonary tuberculosis in Brazil and Honduras. Respiratory specimens were evaluated using smear microscopy, culture on Lowenstein-Jensen medium, and culture using the MODS assay. A subset of specimens was also cultured using the Mycobacterial Growth Indicator Tube (MGIT) 960 automated system (Becton Dickinson). A study subject was considered to have tuberculosis if at least 1 culture on Lowenstein-Jensen medium was positive for M. tuberculosis. FINDINGS: A total of 1639 respiratory specimens obtained from 854 study subjects were analyzed. On a per-subject basis, MODS sensitivity was 97.5% (95% confidence interval [CI], 95.7-98.6), and specificity was 94.4% (95% CI, 93.1-95.2). Median times to detection were 21 days (interquartile range [IQR], 17-25 days) and 7 days (IQR, 5-10) for culture on Lowenstein-Jensen medium and for the MODS assay, respectively (P<.01). For 64 specimens cultured using the MGIT 960 automated system, median time to growth was similar for the MODS assay (7 days; IQR, 7-10 days) and the MGIT 960 automated system (8 days; IQR, 6-11.5 days; P=.16). The percentage of contaminated cultures was lower for the MODS assay than for culture on Lowenstein-Jensen medium (3.8% vs. 5.8%; P<.01). CONCLUSIONS: The MODS assay is a relatively simple test whose good performance characteristics for detection of pulmonary tuberculosis may make it suitable for resource-limited environments.

The potential impact of enhanced diagnostic techniques for tuberculosis driven by HIV: a mathematical model.

OBJECTIVE: To explore the potential impact of enhanced tuberculosis (TB) diagnostic techniques as a TB control strategy in an adult population with high HIV prevalence. DESIGN: A compartmental difference-equation model of TB/HIV was developed using parameter estimates from the literature. METHODS: The impact of five TB control interventions (rapid molecular testing, mycobacterial culture, community-wide and HIV-targeted active case finding, and highly active antiretroviral therapy) on TB incidence, prevalence, and mortality was modeled in a steady-state population with an HIV prevalence of 17% and annual TB incidence of 409 per 100 000. Sensitivity analyses assessed the influence of each model parameter on the interventions' mortality impact. RESULTS: Enhanced diagnostic techniques (rapid molecular testing or culture) are each projected to reduce TB prevalence and mortality by 20% or more, an impact similar to that of active case-finding in 33% of the general community and greater than the effect achievable by case-finding or antiretroviral treatment efforts in HIV-positive patients alone. The projected impact of enhanced diagnostics on TB incidence (< 10% reduction) is smaller. The impact of TB diagnostics is sensitive to the quality of existing diagnostic standards and the level of access to diagnostic services, but is robust across a wide range of population parameters including HIV and TB incidence. CONCLUSIONS: Enhanced TB diagnostic techniques may have substantial impact on TB morbidity and mortality in HIV-endemic regions. As TB rates continue to increase in these areas, enhanced diagnostic techniques merit further consideration as TB control strategies.

The effect of antiretroviral therapy on liver disease among adults with HIV and hepatitis C coinfection.

In the era of antiretroviral therapy (ART), liver disease has emerged as an important cause of death among persons with human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfection. The objective of this study was to estimate the burden of liver disease and evaluate determinants of liver fibrosis and necroinflammatory activity among HIV/HCV coinfected patients receiving ART. We studied 112 randomly selected and 98 referred HCV-infected patients undergoing care in the Johns Hopkins University HIV clinic. Liver disease was characterized clinically and histologically. Of the 210 individuals studied--64% of whom had received ART within 2 years of liver disease assessment--33% had no fibrosis (F0), and 26% had bridging fibrosis or cirrhosis (> or =F3). The median necroinflammatory activity score was 3 (range, 0-9 of 18). ART was not associated with fibrosis; however, significantly less hepatic necroinflammatory activity was observed among persons who had received highly active antiretroviral therapy longer (P = .02) and more effectively (defined by HIV RNA suppression; P < .01). Twelve percent of individuals had previous ART-associated liver enzyme elevations (grades 3-4), but liver fibrosis was not more severe if the liver enzyme elevation resolved. On the other hand, liver fibrosis was more severe in persons with persistent liver enzyme elevations (grades 1-4). In conclusion, despite widespread exposure to ART and documented instances of ART-related hepatitis, we found no evidence that ART caused serious histological liver disease. Recognition of bridging fibrosis and cirrhosis in some but not most patients underscores the importance of identifying and treating liver disease in HIV/HCV coinfected persons.

Longitudinal assessment of the effects of drug and alcohol abuse on HIV-1 treatment outcomes in an urban clinic.

OBJECTIVE: To assess the temporal association of changes in substance abuse with antiretroviral therapy use and adherence, HIV-1 RNA suppression, and CD4 cell count changes in patients attending an urban clinic. DESIGN: Prospective cohort study. METHODS: Six-hundred and ninety-five HIV-1-infected individuals, who completed two or more semi-annual standardized surveys and in whom antiretroviral therapy was indicated, were included in the analysis. Surveys addressed antiretroviral therapy use and adherence, and use of illicit drugs and alcohol. Substance abuse was defined as active heroin, cocaine, or heavy alcohol use in the 6 months preceding survey. The units of analysis were consecutive pairs of surveys (couplets) in individual participants. Couplets in which participants denied substance abuse in both surveys were compared to couplets in which participants switched from non-use to substance abuse, and couplets in which participants reported substance abuse in both surveys were compared to couplets where participants switched from substance abuse to non-use. RESULTS: Switching from non-use to substance abuse was strongly associated with worsening antiretroviral therapy use and adherence, less frequent HIV-1 RNA suppression, and blunted CD4 cell increases, compared to remaining free of substance abuse. Alternatively, switching from substance abuse to non-use was strongly associated with improvements in antiretroviral therapy use and adherence, and HIV-1 treatment outcomes, compared to persisting with substance abuse. CONCLUSIONS: This longitudinal study highlights the dynamic nature of substance abuse and its temporal association with the effectiveness of HIV-1 treatment in patients attending an inner-city clinic.