Comment
Measuring the effect of tuberculosis control: a step forward expected to occur. The cure rate (ie, the proportion of cured cases of those initiating tuberculosis treatment) is routinely calculated in all tuberculosis programmes and is of reliable quality.2 Unfortunately, the case detection rate (ie, the proportion of new tuberculosis cases detected out of those actually existing within the community) needs to be estimated. With the failure of Styblo’s model to predict the true incidence through tuberculin surveys,12 other approaches have been proposed.2 Such methods include improvement in the quality of data from the surveillance system (in terms of completeness, duplication, misclassification, and internal or external consistency), the evaluation of incidence and mortality trends (time-changes in notifications and deaths alongside changes in case-finding, case-definitions, HIV prevalence, and other determinants), and adhoc studies ensuring that all cases and deaths are captured by surveillance. These studies include socalled onion, inventory, capture–recapture studies, and prevalence surveys.2 In countries with a high burden of tuberculosis (ie, of the order of 100 cases per 100 000 population), the prevalence of bacteriologically confirmed pulmonary tuberculosis can be directly measured in nationwide population-based surveys with sample sizes of around 50 000 people, with a cost usually ranging from US$1 to US$4 million13 (potentially higher in larger countries). Repeat surveys done about every 10 years allow the effect
www.thelancet.com Published online March 18, 2014 http://dx.doi.org/10.1016/S0140-6736(14)60032-5
Published Online March 18, 2014 http://dx.doi.org/10.1016/ S0140-6736(14)60032-5 See Online/Articles http://dx.doi.org/10.1016/ S0140-6736(13)62639-2
Staff/Reuters/Corbis
Tuberculosis is an age old disease. Remarkably, although the DNA of Mycobacterium tuberculosis was found in mammoth’s bones and lesions in Egyptian mummies, the pandemic continues to exist and must be a public health priority in the third millennium.1,2 Although tuberculosis control poses a myriad of challenges to clinicians and public health authorities, the disease is potentially preventable and curable. Efforts to produce more efficient vaccines3 have been less than successful to date, but effective diagnostics4 and drugs5–8 are nevertheless currently available,8 and control and elimination strategies have been recently developed.2,9 The tuberculosis research community has pioneered prevention trials with new vaccines, and clinical trials on new drugs and combination regimens, attempting to evaluate their cost-effectiveness at a programmatic level.2 Reducing transmission of M tuberculosis by rapid detection and cure of infectious tuberculosis patients living in the community has represented the main pillar of national tuberculosis programmes for decades, for example in the Tanzania pilot project in the 1980s, subsequently implemented through WHO’s DOTS (directly observed treatment, short-course) and later Stop TB Strategy, approaches.2,10 However, because existing strategies have not significantly accelerated the decline in incidence towards elimination9 (ie,
Measuring the effect of tuberculosis control: a step forward expected to occur. The cure rate (ie, the proportion of cured cases of those initiating tuberculosis treatment) is routinely calculated in all tuberculosis programmes and is of reliable quality.2 Unfortunately, the case detection rate (ie, the proportion of new tuberculosis cases detected out of those actually existing within the community) needs to be estimated. With the failure of Styblo’s model to predict the true incidence through tuberculin surveys,12 other approaches have been proposed.2 Such methods include improvement in the quality of data from the surveillance system (in terms of completeness, duplication, misclassification, and internal or external consistency), the evaluation of incidence and mortality trends (time-changes in notifications and deaths alongside changes in case-finding, case-definitions, HIV prevalence, and other determinants), and adhoc studies ensuring that all cases and deaths are captured by surveillance. These studies include socalled onion, inventory, capture–recapture studies, and prevalence surveys.2 In countries with a high burden of tuberculosis (ie, of the order of 100 cases per 100 000 population), the prevalence of bacteriologically confirmed pulmonary tuberculosis can be directly measured in nationwide population-based surveys with sample sizes of around 50 000 people, with a cost usually ranging from US$1 to US$4 million13 (potentially higher in larger countries). Repeat surveys done about every 10 years allow the effect
www.thelancet.com Published online March 18, 2014 http://dx.doi.org/10.1016/S0140-6736(14)60032-5
Published Online March 18, 2014 http://dx.doi.org/10.1016/ S0140-6736(14)60032-5 See Online/Articles http://dx.doi.org/10.1016/ S0140-6736(13)62639-2
Staff/Reuters/Corbis
Tuberculosis is an age old disease. Remarkably, although the DNA of Mycobacterium tuberculosis was found in mammoth’s bones and lesions in Egyptian mummies, the pandemic continues to exist and must be a public health priority in the third millennium.1,2 Although tuberculosis control poses a myriad of challenges to clinicians and public health authorities, the disease is potentially preventable and curable. Efforts to produce more efficient vaccines3 have been less than successful to date, but effective diagnostics4 and drugs5–8 are nevertheless currently available,8 and control and elimination strategies have been recently developed.2,9 The tuberculosis research community has pioneered prevention trials with new vaccines, and clinical trials on new drugs and combination regimens, attempting to evaluate their cost-effectiveness at a programmatic level.2 Reducing transmission of M tuberculosis by rapid detection and cure of infectious tuberculosis patients living in the community has represented the main pillar of national tuberculosis programmes for decades, for example in the Tanzania pilot project in the 1980s, subsequently implemented through WHO’s DOTS (directly observed treatment, short-course) and later Stop TB Strategy, approaches.2,10 However, because existing strategies have not significantly accelerated the decline in incidence towards elimination9 (ie,
