Yield of tuberculosis among household contacts of tuberculosis patients in Accra, Ghana

Abstract

BackgroundThe End TB Strategy calls for systematic screening of selected high-risk groups including contacts of tuberculosis (TB) cases to facilitate early TB case detection. Contact investigation is not usually routinely practiced in low TB burden countries, such as Ghana, with consequent paucity of data on the yield of TB case detection from such interventions. This study’s objective was to document the outcomes and feasibility of implementing contact investigation activities under programmatic conditions in Ghana.MethodsRetrospective analyses were conducted of abstracted data from the National TB Program, following a contact investigation intervention for TB cases diagnosed in 10 facilities in Accra from June 2010 to December 2014. Various proportions and yield from number of contacts needed to screen (NNS) and number needed to test (NNT) to detect a TB case were assessed.ResultsOverall, out of the 8519 listed contacts of 3267 index cases, 8166 (96%) were screened and 614 (7.5%) were identified as presumptive TB. Out of these, 438 (71%) underwent sputum smear microscopy/evaluation and 53 TB cases were diagnosed. Of these, 56.6% were males, and 49% had sputum smear-positive TB, 38% had sputum smear-negative TB, and 7% had extra-pulmonary TB. The NNS and NNT to detect a TB case of all forms were 154 and 8, respectively. The proportion of TB cases with contacts listed and proportion of contacts screened annually were 88–96% and 83–100%, respectively. The proportion of presumptive TB cases tested and proportion of TB cases diagnosed among contacts tested that were 100% and 36%, respectively, in 2010 dropped to 40% and 14%, respectively, by 2014.ConclusionsThe study demonstrates that contact identification and prioritization components of a contact investigation were feasible, but overall yield of TB cases may have been lower due to the declining rate of clinical evaluation of presumptive TB contacts over time. Addressing barriers to accessing appropriate diagnostic tests may enhance yield from contact investigation in Ghana.Electronic supplementary materialThe online version of this article (10.1186/s40249-018-0396-5) contains supplementary material, which is available to authorized users.

Active household contact screening for tuberculosis and provision of isoniazid preventive therapy to under-five children in Afghanistan

“…TB was 1.8%, which is close to 10 times higher than the estimated national incidence of TB, at 189 per 100,000, and is closer to the 1.6% reported in another study in Afghanistan [9] and the 1.7% reported in Viet Nam [5]. Furthermore, the yield of 1.8% found in this study was higher than the 0.65% in Ghana [14], 0.17% in Viet Nam [5], and 0.9% in Peru [6], but lower than the 3.6% that WHO reported [3], lower than the 3.9% reported in South Africa [15] and lower than the 2.5% reported in Ethiopia [7]. In a 21-year retrospective study in Birmingham, UK, the TB yield among smear-positive contacts screened was 7.0 [16].…”

“…The NNS is lower than the NNS of 424 and 378 reported in the Afghanistan study [9]. In Ethiopia, the NNS and NNT were 40 and 2.4, respectively, and in Ghana, the NNS was 154 and the NNT was 8, respectively [7,14]. The NNT depends mainly on the incidence of the disease in a country, the quality of screening, and the screening tool used, so the differences among countries can be explained by these factors, but we do not know why the NNT in the other Afghanistan study was so high [9].…”

Prevalence of tuberculosis among mentally ill patients in conflict-stricken Afghanistan: A cross-sectional study

“…The contacts of people with TB have a higher risk of developing TB disease than persons having no contacts, and these countries (Uganda and Ethiopia) have a high HIV prevalence, while HIV prevalence in Afghanistan is very low, but the low NNS in our study shows that the risk of TB among the mentally ill is even higher than the risk reported for contacts in Uganda, Ethiopia, and Afghanistan. The NNT was also high, 6.1, which is close to the NNT reported in Ghana, 8 for contact screening (Ohene et al, 2018). The NNS and NNT also depend on the TB incidence of the country, and Afghanistan has a high TB incidence, at 189/100,000 population (WHO, 2018).…”

Yield of systematic household contact investigation for tuberculosis in a high-burden metropolitan district of South Africa

“…Thereupon non-targeted household contact investigation studies in sub-Saharan African countries tend to demonstrate a lower yield. For example, a study in the North West Province of South Africa among adult TB index cases produced a yield of only 1.3% [31] and a study in Ghana among adult TB index cases returned a yield of only 0.65% [32].…”