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Yield of close contact tracing using two different programmatic approaches from tuberculosis index cases: a retrospective quasi-experimental study.

Loredo C, Cailleaux-Cezar M, Efron A, de Mello FC, Conde MB - BMC Pulm Med (2014)

Bottom Line: From 2005-2008, 1,310 close contacts from 369 index cases were identified and the prevalence of active TB and LTBI were 2.7% (35/1,310) and 69% (877/1,275), respectively.There was not a statically significant difference in the detection of active TB (p = 0.3) between the 2 time periods, but the detection of LTBI was significant higher (p = 0.003).The number needed to screen (contacts/new cases) decreased from 50 to 37 and the number need to contact trace (index cases/new cases) decreased from 16 to 10 from 2001-2004 to 2005-2008.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Thoracic Diseases of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. marcusconde@hucff.ufrj.br.

ABSTRACT

Background: Being a contact of a pulmonary tuberculosis (TB) case is a risk factor for active and latent TB. The objective of this study is to determine the contact tracing yield using two different programmatic definitions of close contact in the city of Rio de Janeiro, Brazil.

Methods: This is a retrospective quasi-experimental study. Data were obtained by reviewing the medical records from TB index cases and their close contacts admitted to the Outpatient TB Clinic of the Institute of Thoracic Diseases, University of Rio de Janeiro. From January 2001 to December 2004, a close contact was defined as an individual who shared an enclosed space with a TB index case for a total period of ≥ 100 hours, whereas from January 2005 to December 2008 the definition of close contact was changed to an individual who shared an enclosed space with a TB index case ≥ 4 hours a week. The primary outcome of this study was newly diagnosed pulmonary TB cases and the secondary outcome was the prevalence of latent TB infection (LTBI) among close contacts during both periods.

Results: From 2001-2004, 810 close contacts from 257 index cases were evaluated and the prevalence of active TB and LTBI were 2% (16/810) and 62% (496/794), respectively. From 2005-2008, 1,310 close contacts from 369 index cases were identified and the prevalence of active TB and LTBI were 2.7% (35/1,310) and 69% (877/1,275), respectively. There was not a statically significant difference in the detection of active TB (p = 0.3) between the 2 time periods, but the detection of LTBI was significant higher (p = 0.003). The number needed to screen (contacts/new cases) decreased from 50 to 37 and the number need to contact trace (index cases/new cases) decreased from 16 to 10 from 2001-2004 to 2005-2008.

Conclusion: In conclusion, the findings of this study suggest that the less conservative definition of TB close contacts (sharing space ≥ 4 h/week) can be a helpful tool for increasing the rate of diagnosis for newly active pulmonary TB cases and for the detection of LTBI among contacts of active pulmonary TB cases.

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Contact evaluation of period 2001–2004.
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Figure 1: Contact evaluation of period 2001–2004.

Mentions: Over a 92-month period, 806 patients with active pulmonary TB were admitted to the Outpatient TB Clinic of IDT/UFRJ. All medical records were reviewed and 180 active TB cases were excluded because the AFB results were unknown (n = 13), the M.tb culture results were missing or contaminated (n = 45), HIV status was unknown (n = 25) or the culture for Mycobacterium tuberculosis was negative (n = 97). From 626 active TB index cases included in the analysis (257 from 2001–2004 and 369 from 2005–2008), 2,979 contacts (1,090 from 2001–2004 and 1,889 from 2005–2008) were identified. Flow-charts showing the evaluation of contacts stratified by the AFB of the index case in both periods of study are presented in Figures 1 and2. In the period from 2001–2004 (contacts shared ≥ 100 hours total) 810 contacts were evaluated. Two per cent (16/810) of those contacts were diagnosed as a newly active TB cases (detection rate of 1,975/100000) and 62% (496/794) as having LTBI. In the period from 2005–2008 (contacts shared ≥ 4 hours/week) 1,310 contacts were evaluated and 2.7% (35/1.310) had a diagnosis of active TB (detection rate of 2,442/100,000 habitants) and 69% (877/1,275) were diagnosed with LTBI. There was not a statically significant difference in the detection of active TB (16/810 or 2% versus 35/1310 or 2.7%, p = 0.3) between the 2 time periods, but the detection of LTBI was significant higher (496/794 or 62% versus 877/1275 or 69%, p = 0.003). However, the NNS for a newly diagnosed TB case decreased from 50 in the period from 2001–2004 to 37 in the period from 2005–2008. The same occurred with the NNCT, decreasing from 16 in the first period to 10 in the second. The characteristics of the study population are shown in Table 1. There were statistically significant differences between both samples in some variables, with slightly more males, household contacts, smokers and cases of diabetes in the first period (2001–2004). The association of different variables to the diagnosis of active TB and LTBI among contacts in both periods studied is presented in Tables 2 and3, respectively. There was a statistically significant association between smoking and newly diagnosed active TB in the sample during the second period as well as those living in poor areas (slums) (Table 2). There was an association between a positive AFB in the index case and the diagnosis of LTBI in samples from both time periods. Smoking and alcohol abuse were associated with the diagnosis of LTBI only in the second period.


Yield of close contact tracing using two different programmatic approaches from tuberculosis index cases: a retrospective quasi-experimental study.

Loredo C, Cailleaux-Cezar M, Efron A, de Mello FC, Conde MB - BMC Pulm Med (2014)

Contact evaluation of period 2001–2004.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4127044&req=5

Figure 1: Contact evaluation of period 2001–2004.
Mentions: Over a 92-month period, 806 patients with active pulmonary TB were admitted to the Outpatient TB Clinic of IDT/UFRJ. All medical records were reviewed and 180 active TB cases were excluded because the AFB results were unknown (n = 13), the M.tb culture results were missing or contaminated (n = 45), HIV status was unknown (n = 25) or the culture for Mycobacterium tuberculosis was negative (n = 97). From 626 active TB index cases included in the analysis (257 from 2001–2004 and 369 from 2005–2008), 2,979 contacts (1,090 from 2001–2004 and 1,889 from 2005–2008) were identified. Flow-charts showing the evaluation of contacts stratified by the AFB of the index case in both periods of study are presented in Figures 1 and2. In the period from 2001–2004 (contacts shared ≥ 100 hours total) 810 contacts were evaluated. Two per cent (16/810) of those contacts were diagnosed as a newly active TB cases (detection rate of 1,975/100000) and 62% (496/794) as having LTBI. In the period from 2005–2008 (contacts shared ≥ 4 hours/week) 1,310 contacts were evaluated and 2.7% (35/1.310) had a diagnosis of active TB (detection rate of 2,442/100,000 habitants) and 69% (877/1,275) were diagnosed with LTBI. There was not a statically significant difference in the detection of active TB (16/810 or 2% versus 35/1310 or 2.7%, p = 0.3) between the 2 time periods, but the detection of LTBI was significant higher (496/794 or 62% versus 877/1275 or 69%, p = 0.003). However, the NNS for a newly diagnosed TB case decreased from 50 in the period from 2001–2004 to 37 in the period from 2005–2008. The same occurred with the NNCT, decreasing from 16 in the first period to 10 in the second. The characteristics of the study population are shown in Table 1. There were statistically significant differences between both samples in some variables, with slightly more males, household contacts, smokers and cases of diabetes in the first period (2001–2004). The association of different variables to the diagnosis of active TB and LTBI among contacts in both periods studied is presented in Tables 2 and3, respectively. There was a statistically significant association between smoking and newly diagnosed active TB in the sample during the second period as well as those living in poor areas (slums) (Table 2). There was an association between a positive AFB in the index case and the diagnosis of LTBI in samples from both time periods. Smoking and alcohol abuse were associated with the diagnosis of LTBI only in the second period.

Bottom Line: From 2005-2008, 1,310 close contacts from 369 index cases were identified and the prevalence of active TB and LTBI were 2.7% (35/1,310) and 69% (877/1,275), respectively.There was not a statically significant difference in the detection of active TB (p = 0.3) between the 2 time periods, but the detection of LTBI was significant higher (p = 0.003).The number needed to screen (contacts/new cases) decreased from 50 to 37 and the number need to contact trace (index cases/new cases) decreased from 16 to 10 from 2001-2004 to 2005-2008.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Thoracic Diseases of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. marcusconde@hucff.ufrj.br.

ABSTRACT

Background: Being a contact of a pulmonary tuberculosis (TB) case is a risk factor for active and latent TB. The objective of this study is to determine the contact tracing yield using two different programmatic definitions of close contact in the city of Rio de Janeiro, Brazil.

Methods: This is a retrospective quasi-experimental study. Data were obtained by reviewing the medical records from TB index cases and their close contacts admitted to the Outpatient TB Clinic of the Institute of Thoracic Diseases, University of Rio de Janeiro. From January 2001 to December 2004, a close contact was defined as an individual who shared an enclosed space with a TB index case for a total period of ≥ 100 hours, whereas from January 2005 to December 2008 the definition of close contact was changed to an individual who shared an enclosed space with a TB index case ≥ 4 hours a week. The primary outcome of this study was newly diagnosed pulmonary TB cases and the secondary outcome was the prevalence of latent TB infection (LTBI) among close contacts during both periods.

Results: From 2001-2004, 810 close contacts from 257 index cases were evaluated and the prevalence of active TB and LTBI were 2% (16/810) and 62% (496/794), respectively. From 2005-2008, 1,310 close contacts from 369 index cases were identified and the prevalence of active TB and LTBI were 2.7% (35/1,310) and 69% (877/1,275), respectively. There was not a statically significant difference in the detection of active TB (p = 0.3) between the 2 time periods, but the detection of LTBI was significant higher (p = 0.003). The number needed to screen (contacts/new cases) decreased from 50 to 37 and the number need to contact trace (index cases/new cases) decreased from 16 to 10 from 2001-2004 to 2005-2008.

Conclusion: In conclusion, the findings of this study suggest that the less conservative definition of TB close contacts (sharing space ≥ 4 h/week) can be a helpful tool for increasing the rate of diagnosis for newly active pulmonary TB cases and for the detection of LTBI among contacts of active pulmonary TB cases.

Show MeSH
Related in: MedlinePlus