Modelling studies have estimated that the implementation of
Modelling studies have estimated that the implementation of Xpert MTB/RIF, either in addition to or as a replacement to smear microscopy, will be cost-effective for the diagnosis of tuberculosis and mutidrug-resistant (MDR) tuberculosis in countries with a high burden. The incremental cost of each disability-associated life-year averted by Xpert implementation (the incremental cost-effectiveness ratio [ICER]) is below the WHO-defined “willingness to pay” threshold for all settings modelled by Vassal and colleagues, and the findings of Menzies and colleagues suggest that Xpert implementation could, through improved case-finding and treatment, substantially reduce tuberculosis illness and death.
However, these studies differed in their assumptions about disease transmission, rates of MDR tuberculosis, duration and effect of future disease burden, downstream effects of antiretroviral therapy, and how the relevant health-care system models were constructed. Thus, further data are required about the cost-effectiveness of different algorithmic strategies on health-care systems in Africa. In this issue of , Ivor Langley and colleagues assess the cost-effectiveness of different diagnostic strategies on cost-effectiveness within the context of the Tanzanian health-care system. These strategies included a combination of conventional smear microscopy (Ziehl Nielson staining), LED microscopy (conventional versus same day), full roll-out of Xpert MTB/RIF, and LED microscopy followed by targeted Xpert in smear-negative cases (the latter two strategies in either all HIV-infected persons or only those known be HIV-infected). They found, using an integrated modelling approach, that full roll-out of Xpert MTB/RIF was the most cost-effective option with the potential to substantially reduce national tuberculosis burden, and that targeted use of Xpert MTB/RIF after microscopy in HIV-infected people was a less cost-effective approach. The latter was less cost-effective because of the reduced likelihood of preventing death and reductase enzyme in the potential gain in life-years owing to the shortened lifespan in HIV-infected people.
However, there are several limitations to these findings. Current diagnostic practice, especially the frequency, timing, and accuracy of clinical diagnoses or empirical tuberculosis treatment, is highly setting-specific, dependent on adherence to the WHO algorithm for smear-negative tuberculosis, and can reduce the cost-effectiveness of diagnostic interventions. Langley and colleagues\' estimated sensitivity of smear-negative tuberculosis in Tanzania (52%) is lower than that from a recent meta-analysis, and the authors also assumed excellent specificity (95%). In South Africa, for example, most smear-negative patients seem to be “detected” through empirical treatment, and, as seen in Uganda and Kenya, less than half of notified cases are microbiologically confirmed, suggesting that significant overtreatment is occurring.
Furthermore, patient-level costs were not included and these are known to be substantial and influence default, particular in tuberculosis-endemic countries. The targeted use of Xpert MTB/RIF after smear microscopy was only explored in HIV-infected participants and not HIV-uninfected people. The ICER also differed substantially from other studies. However, pollen tube must be understood within the context of different assumptions about transmission, future disease burden, and antiretroviral therapy, among other factors. MDR tuberculosis was not considered in the transmission component and therefore one wonders about applicability to other settings with high rates of MDR tuberculosis, such as South Africa. However, the higher rates of MDR tuberculosis would probably have made the Xpert MTB/RIF strategy even more cost-effective in this context.
In 2010, opioid use and dependence made the largest contribution to morbidity and mortality from illicit drug use, contributing to premature death from drug overdose and suicide, and in those who inject these drugs, infection with HIV and other blood-borne viruses. Dependence also produced considerable disability. Afghanistan has a tradition of opium smoking, and has long been a major source of illegal opiates for eastern and western Europe. In the past decade, Afghans have also reportedly begun to inject heroin and use pharmaceutical opioids. These developments have been attributed to increased heroin availability, civil disruption from insurgency, and the crowding of displaced Afghans into urban areas where heroin and pharmaceutical opioids are readily available.