Date Published: February 6, 2015
Publisher: Public Library of Science
Author(s): Juliet N. Sekandi, Kevin Dobbin, James Oloya, Alphonse Okwera, Christopher C. Whalen, Phaedra S. Corso.
Case detection by passive case finding (PCF) strategy alone is inadequate for detecting all tuberculosis (TB) cases in high burden settings especially Sub-Saharan Africa. Alternative case detection strategies such as community Active Case Finding (ACF) and Household Contact Investigations (HCI) are effective but empirical evidence of their cost-effectiveness is sparse. The objective of this study was to determine whether adding ACF or HCI compared with standard PCF alone represent cost-effective alternative TB case detection strategies in urban Africa.
A static decision modeling framework was used to examine the costs and effectiveness of three TB case detection strategies: PCF alone, PCF+ACF, and PCF+HCI. Probability and cost estimates were obtained from National TB program data, primary studies conducted in Uganda, published literature and expert opinions. The analysis was performed from the societal and provider perspectives over a 1.5 year time-frame. The main effectiveness measure was the number of true TB cases detected and the outcome was incremental cost-effectiveness ratios (ICERs) expressed as cost in 2013 US$ per additional true TB case detected.
Compared to PCF alone, the PCF+HCI strategy was cost-effective at US$443.62 per additional TB case detected. However, PCF+ACF was not cost-effective at US$1492.95 per additional TB case detected. Sensitivity analyses showed that PCF+ACF would be cost-effective if the prevalence of chronic cough in the population screened by ACF increased 10-fold from 4% to 40% and if the program costs for ACF were reduced by 50%.
Under our baseline assumptions, the addition of HCI to an existing PCF program presented a more cost-effective strategy than the addition of ACF in the context of an African city. Therefore, implementation of household contact investigations as a part of the recommended TB control strategy should be prioritized.
Tuberculosis (TB) disease continues to pose a serious public health threat despite decades of sustained control efforts worldwide. The World Health Organization (WHO) estimates that nearly 9 million new cases of TB occur while 2 million people die annually . Of the new cases, nearly 80% reside in the 22 high-burden countries including Uganda. In 2011, Uganda’s estimated annual TB incidence rate was 330/100,000 with a death rate of 5.3% . Deaths from TB disease are associated with a high economic burden as projected by a World Bank study on the economic benefit of TB control, that the cost of TB—related deaths (including HIV co-infection) in Sub-Saharan Africa from 2006 to 2015 would be US$ 519 billion when there is no effective TB treatment and control as prescribed by WHO’s Stop TB Strategy .
We conducted an incremental cost-effectiveness analysis to compare PCF+ACF and PCF+HCI with PCF alone in an African city context. The results indicate that PCF+HCI is cost-effective for detecting TB cases compared to PCF alone from both the societal and health provider perspectives. The cost per additional TB case detected was $443.62 and $416.35 for the PCF+HCI strategy from the societal and provider perspective respectively. The model conclusions were sensitive to changes in the probability of detecting one or more TB cases, a 10-fold increase in the prevalence of chronic cough in ACF, and to a 50% reduction in program costs in ACF from the set baseline values. A threshold point was reached when the probability of cough reached 0.305, such that the PCF+ACF strategy was even more cost-effective than PCF+HCI. When the probability of detecting a case from a true smear positive index case in HCI was set to its lowest plausible value of 0.06, PCF+HCI was no longer cost-effective. This is not surprising because the risk of a household contact becoming a TB cases is largely driven by the infectiousness of the index case [47,48]. It is important that in the context of Uganda and much of Africa, practical challenges such as the lack of well-organized public health systems, shortage of health care personnel and limited health resources to follow up index TB cases may make the effectiveness of the PCF+HCI less achievable.