Relationship between estimated pretest probability and accuracy of automated Mycobacterium tuberculosis assay in smear-negative pulmonary tuberculosis

BACKGROUND: The AMPLICOR assay (Roche; Branchburg, NJ), a rapid direct amplification test for Mycobacterium tuberculosis, has only been licensed for use in smear-positive respiratory specimens. However, many patients with pulmonary tuberculosis (PTB) have smear-negative disease. The clinical utility of this test in patients with smear-negative PTB is unknown. OBJECTIVE: To evaluate the effect of pretest probability of PTB estimated by chest physicians on the accuracy of the AMPLICOR assay in patients with smear-negative PTB. Design and methods: A prospective study of consecutive patients suspected of having smear-negative PTB. Two chest physicians estimated the pretest probability of active disease (high, intermediate, and low categories). Respiratory specimens were examined with radiometric broth medium cultures and with the AMPLICOR assay for M tuberculosis. The decision on a final diagnosis of PTB was blinded to the AMPLICOR results. RESULTS: Active PTB was diagnosed in 25 of 441 patients (5.7%). The AMPLICOR assay had an overall sensitivity of 44% and a specificity of 99%. Results of the assay were negative in seven patients with culture-negative PTB. The proportions of patients in the high, intermediate, and low pretest groups were 4.5%, 19.7%, and 75.7%, respectively. The incidence of PTB for each group was 95%, 3.4%, and 0.9%, respectively. The sensitivities of the AMPLICOR assay in the three groups of patients were 47%, 33%, and 33%, respectively, while the specificities were 100%, 98%, and 99%, respectively. CONCLUSIONS: In patients suspected of having smear-negative PTB, the following conclusions were drawn: (1) the incidence of active PTB was low; (2) pretest estimates accurately discriminated between patients with high and low risk of PTB; (3) the risk of PTB was overestimated in the intermediate group; and (4) the utility of the AMPLICOR assay in the intermediate-risk group may be limited by the overestimation of disease prevalence and low test sensitivity. Further studies are needed on the role of the AMPLICOR assay in better selected patients with an intermediate risk of having smear-negative PTB.     

How can detection of infectious tuberculosis be improved? Experience in the Somali region of Ethiopia.

In early 1999, 48% of pulmonary tuberculosis (PTB) cases detected in the Somali region of Ethiopia were smear-positive. Actions at the laboratory level and peer-review of smear-negative PTB diagnoses were proposed. Clinicians knew, but did not adhere to, the algorithm recommended by the National Tuberculosis Programme for these diagnoses, partly due to the costs involved to patients. Challenging clinicians, in a non-threatening way, to become more clinically rigorous proved successful, and the proportion of smear-positive PTB increased to 65%. Operational research is needed to assess the feasibility of these widely-recommended smear-negative PTB diagnosis guidelines.     

Utility of nucleic acid amplification techniques for the diagnosis of pulmonary tuberculosis in sub-Saharan Africa.

SETTING: Lusaka, Zambia. OBJECTIVES: To investigate the utility of nucleic amplification tests for the diagnosis of pulmonary tuberculosis in a resource-poor setting with a high incidence of human immunodeficiency virus (HIV). DESIGN: Sputum specimens from suspects attending a referral chest clinic were examined by low-cost 'in-house' one-tube nested polymerase chain reaction (PCR), the enhanced Gen-Probe Amplified Mycobacterium Direct Test (AMTD), auramine smear and Lowenstein-Jensen culture. RESULTS: PCR and AMTD detected respectively 80% and 92% of smear-positive specimens and 40% and 60% of smear-negative, culture-positive specimens. AMTD was positive for 18 culture-negative suspects; subsequent investigation indicated these to be six confirmed tuberculosis patients, nine judged from radiological data and clinical follow-up studies to have pulmonary tuberculosis, and three non-tuberculosis patients. Sensitivity for smear, culture, PCR and AMTD, when compared to a gold standard incorporating both microbiological and clinical data, was respectively 29%, 69%, 55% and 81%. CONCLUSION: In this setting, the sensitivity of the low-cost PCR proved insufficient for its effective use as a tool for diagnosing pulmonary tuberculosis, while AMTD performed considerably better than the current laboratory methods for diagnosis of pulmonary tuberculosis. However, the high cost of this technology may limit its application in the public sector of low-income countries.     

全国初治涂阴肺结核病例登记现状分析

目的分析全国各省初治涂阴肺结核病例登记现状,为评价初治涂阴肺结核病例诊断质量提供依据。方法根据2004—2005年全国结核病防治规划报表中初治涂阴和初治涂阳肺结核病例登记资料,分析各省2年初治涂阴肺结核病例登记率变化和增长幅度;统计各省及不同地区初治涂阴与初治涂阳肺结核病例登记率;对各省初治涂阴与初治涂阳肺结核病例登记率进行直线回归分析。结果2005年全国登记初治涂阴肺结核病例316 405例,登记率为24.27/10万,各省登记率在6.01/10万72.17/10万;2005年登记初治涂阴病例数比2004年增加了19.9%,其中2个省登记数呈负增长,其余各省登记数增长了0.5%62.3%;2005年全国初治涂阳病例登记率是涂阴病例登记率的1.5倍,其中23个省初治涂阳病例登记率高于涂阴病例登记率,8个省相反;初治涂阴病例占初治涂阳病人登记率的比例,京津沪地区为149.28%,非项目地区为83.6%,项目地区为50.3%;对涂阳和涂阴病例登记率进行直线回归分析,回归方程y=22.342+0.563 6x。结论对初治涂阴肺结核患者实行免费政策后,全国涂阴肺结核病例登记率提高。但各省初治涂阴病例登记率和增长幅度以及涂阴病例登记率与涂阳病例登记率的比例悬殊。由于涂阴病例诊断困难,对于涂阴病例登记率高或增长幅度大的地区,特别在DOTS执行时间短和人力资源有限的地区,应对涂阴病例诊断质量予以进一步检查和评价。     

The diagnosis of smear-negative pulmonary tuberculosis: the practice of sputum smear examination in Malawi.

SETTING: Forty hospitals in Malawi (3 central, 22 district and 15 mission) performing smear microscopy and registering tuberculosis patients. OBJECTIVE: To determine, in patients aged 15 years or above, 1) the proportion with smear-negative pulmonary tuberculosis (PTB) who had sputum smears examined, 2) the number of sputum smears examined per patient, and 3) the proportion of patients registered with smear-positive and smear-negative PTB. DESIGN: Data collection during three 6-month periods, from January 1997 to June 1998, using tuberculosis registers, laboratory sputum registers and quarterly reports. RESULTS: Of 6301 smear-negative PTB patients, 84% had sputum smears examined, the rate increasing from 76% in January-June 1997, to 85% in July-December 1997, to 89% in January-June 1998. Of patients who submitted sputum (where the number of smears was recorded), 99% had two or more smears examined and 93% had three smears examined. In district and mission hospitals performance improved over time, while in central hospitals results were more variable. During the same 18-month period 21 422 patients aged 15 years or more were registered with PTB: 59% with smear-positive PTB and 41% with smear-negative PTB; this pattern was similar in each 6-month period. CONCLUSION: The study suggests that it is reasonable to aim for a target of 90% or more of smear-negative PTB patients having sputum smears examined.     

Useful clues to the presence of smear-negative pulmonary tuberculosis in a West African city.

OBJECTIVE: Tuberculosis suspects with negative sputum smears for acid-fast bacilli (AFB) may have either pulmonary tuberculosis (PTB) or some other pulmonary disease (non-PTB). The aim of this study was to improve the differentiation between PTB and non-PTB. DESIGN: We enrolled 396 tuberculosis suspects 15 years of age or older who had cough of 21 days or longer and three negative AFB smears. Non-PTB was diagnosed by clinical and radiographic responses to amoxicillin; smear-negative PTB was diagnosed by positive culture for Mycobacterium tuberculosis or response to antituberculosis chemotherapy. RESULTS: Multivariate analysis, without X-ray variables, of 79 patients with a final diagnosis of non-PTB and 110 patients with smear-negative PTB indicated that age less than 37 years, family contact with TB, never having been married, loss of weight, lack of expectoration, human immunodeficiency virus (HIV) seropositivity, and tuberculin reactivity were significantly associated with PTB. When the initial X-ray findings were included, age younger than 37 years, lack of expectoration, HIV seropositivity, and tuberculin reactivity remained in the model, and cavitation and patchy densities were significantly associated. CONCLUSION: The response to 10 days of amoxicillin and certain demographic, clinical and radiographic characteristics are useful in separating non-PTB from PTB in tuberculosis suspects with negative AFB smears.     

Benefit of amoxicillin in differentiating between TB suspects whose initial AFB sputum smears are negative.

SETTING: Out-patient dispensary in Conakry, Guinea, West Africa. OBJECTIVE: To differentiate between pulmonary tuberculosis (PTB) and non-PTB diseases among 204 acid-fast bacilli (AFB) smear-negative adult TB suspects. DESIGN: We derived scores from clinical, serological and radiological findings among PTB suspects aged > or = 15 years who, after having had three AFB-negative smears, were treated for 10 days with amoxicillin (AMX, 1.5 g/day). RESULTS: At the selected cut-off score from model 1 (clinical), sensitivity for PTB was 95%, specificity 40%, negative predictive value (NPV) 84%, and positive predictive value (PPV) 69%. Comparable values from model 2 (clinical + serological + radiological) were: sensitivity 99%, specificity 45%, NPV 97%, and PPV 71%. Results from AMX were better: sensitivity 92%, specificity 93%, NPV 94%, and PPV 91%. Of the 117 suspects who failed to respond clinically and radiographically to AMX and remained AFB smear-negative, 110 (94%) had PTB, confirmed either by positive culture (73 patients) or response to anti-tuberculosis treatment (37 patients). CONCLUSION: The clinical and radiographic response to AMX is better than derived scores at differentiating between PTB and non-PTB in TB suspects presenting to a dispensary in Guinea, a low HIV-seroprevalence country.     

Risk factors for death during tuberculosis treatment in Orel, Russia.

SETTING AND METHODS: In Orel, high tuberculosis (TB) case fatality rates have persisted despite successful implementation of the World Health Organization (WHO) global TB control strategy. We conducted a case control study to identify risk factors for mortality among Orel TB patients reported from October 1999 through June 2001. Cases were patients who died within 8 months of treatment initiation. We analyzed data abstracted from medical records using conditional logistic regression. RESULTS: Over the 21-month period, 63/1069 (5.9%) TB patients overall and 45/521 (8.6%) sputum smear-positive patients died during treatment. Compared to 192 controls, independent risk factors for death for both smear-positive and smear-negative patients included unemployment (adjusted odds ratio [AOR] 4.9, 95% confidence interval [CI] 1.9-12.9), homelessness (AOR 9.5, 95% CI 1.3-70.9), congestive heart failure (AOR 5.4, 95% CI 1.9-15.9), chronic lung disease (AOR 2.4, 95% CI 1.1-5.4), cancer (AOR 7.2, 95% CI 1.2-45.0), bilateral disease on chest X-ray (AOR 6.3, 95% CI 2.3-17.1), and hyperbilirubinemia (AOR 5.2, 95% CI 1.1-25.3). Among deaths, the median time from treatment initiation to death was 35 days. CONCLUSIONS: The diagnosis and treatment of TB in suspects with the observed comorbidities and risk factors should be aggressively pursued. The association of unemployment and homelessness with mortality suggests a contribution of poverty to death during TB treatment.     

Recurrent tuberculosis: definitions and treatment regimens.

Within the National Tuberculosis Control Programme of Malawi, misunderstandings sometimes occur about the diagnosis and management of recurrent tuberculosis (TB). Patients with smear-positive pulmonary tuberculosis (PTB) who have had a previous, treated episode of smear-negative TB may be registered as 'new cases' rather than relapse cases, and thus denied the benefits of a retreatment regimen. Patients with a recurrent episode of smear-negative PTB or extra-pulmonary TB (EPTB) may also be wrongly registered as 'new cases' rather than recurrent cases. International guidelines about the treatment of recurrent smear-negative PTB and EPTB are not explicit, resulting in confusion about how best to manage these cases. It is suggested that all such cases be considered for re-treatment regimen because of concerns about acquired drug resistance. WHO and IUATLD guidelines on the diagnosis and management of recurrent and relapse TB need to be improved, and operational research studies should be conducted to provide answers to some outstanding questions.     

Undiagnosed tuberculosis in a community with high HIV prevalence: implications for tuberculosis control

BACKGROUND: Although failure of tuberculosis (TB) control in sub-Saharan Africa is attributed to the HIV epidemic, it is unclear why the directly observed therapy short-course (DOTS) strategy is insufficient in this setting. We conducted a cross-sectional survey of pulmonary TB (PTB) and HIV infection in a community of 13,000 with high HIV prevalence and high TB notification rate and a well-functioning DOTS TB control program. METHODS: Active case finding for PTB was performed in 762 adults using sputum microscopy and Mycobacterium tuberculosis culture, testing for HIV, and a symptom and risk factor questionnaire. Survey findings were correlated with notification data extracted from the TB treatment register. RESULTS: Of those surveyed, 174 (23%) tested HIV positive, 11 (7 HIV positive) were receiving TB therapy, 6 (5 HIV positive) had previously undiagnosed smear-positive PTB, and 6 (4 HIV positive) had smear-negative/culture-positive PTB. Symptoms were not a useful screen for PTB. Among HIV-positive and -negative individuals, prevalence of notified smear-positive PTB was 1,563/100,000 and 352/100,000, undiagnosed smear-positive PTB prevalence was 2,837/100,000 and 175/100,000, and case-finding proportions were 37 and 67%, respectively. Estimated duration of infectiousness was similar for HIV-positive and HIV-negative individuals. However, 87% of total person-years of undiagnosed smear-positive TB in the community were among HIV-infected individuals. CONCLUSIONS: PTB was identified in 9% of HIV-infected individuals, with 5% being previously undiagnosed. Lack of symptoms suggestive of PTB may contribute to low case-finding rates. DOTS strategy based on passive case finding should be supplemented by active case finding targeting HIV-infected individuals.     

Additional risk of developing TB for household members with a TB case at home at intake: a 15-year study.

OBJECTIVE: To assess the additional risk to household contacts from an infectious case of tuberculosis (TB) at home in a rural community in south India. METHODS: In all, 3506 contacts of smear-positive (S+C+) and 2910 contacts of smear-negative TB cases (S-C+) and 246 845 persons with no TB case at home were followed for 15 years, with a repeat survey every 2.5 years consisting of radiographic and sputum examination, selective follow-up of high-risk individuals and passive surveillance. If a case developed during follow-up, all household members were subsequently considered as contacts. Cox's proportional hazards model (multivariate) was employed to compare incidences. RESULTS: The annual incidence of culture-positive TB was respectively 526 and 271 per 100000 population for contacts of smear-positive and smear-negative patients, and 198/100000 in non-contacts. The adjusted hazard rate was 3.4 for contacts of smear-positive patients (95% CI 3.0-3.9) and 1.7 for contacts of smear-negative patients (95% CI 1.4-2.0) as compared to non-contacts. Of 3942 incident cases, 337 (8.5%) came from households with a TB case. CONCLUSION: Although family contacts had a significantly higher incidence, their contribution to total new caseload was meagre. Contact chemoprophylaxis as a public health measure would therefore have limited impact on community TB incidence.     

Defining and assessing the maximum number of visits patients should make to a health facility to obtain a diagnosis of pulmonary tuberculosis.

SETTING: All non-private hospitals in Malawi. OBJECTIVES: To determine 1) how many patients with pulmonary tuberculosis (PTB) exceed the maximum number of visits needed for registration as defined by the National Tuberculosis Control Programme, and 2) the factors associated with this delay. DESIGN: Cross-sectional study interviewing hospitalised patients with new smear-positive and smear-negative PTB. RESULTS: Of 380 patients with PTB admitted to the 44 hospitals visited between April and June 2002, 329 (212 smear-positive and 117 smear-negative PTB) were interviewed: 64 (30%) smear-positive PTB patients needed more than five visits, and 44 (37%) smear-negative PTB patients needed more than six visits before being registered and started on treatment. Factors associated with exceeding the maximum number of visits were the first visit being to a health centre, submission of > 1 set of sputum specimens, and > 1 course of antibiotics. The main consequence of exceeding the maximum number of visits was increased duration of cough and increased time spent at health facilities. CONCLUSION: One third of patients exceed the maximum number of visits for registration of PTB. The main consequence of this is an increased duration of cough and an increased time spent at health facilities. Ways to reduce this delay need to be found.     

涂阳肺结核患者抗结核药物不良反应发生影响因素分析

目的 探讨涂阳肺结核患者接受抗结核药物治疗的不良反应发生情况及其影响因素,为制定结核病防治策略提供参考。方法 选择2008—2010年我国8个省(市、自治区)结核病定点医疗机构治疗诊治的涂阳肺结核患者共2 142例,根据是否发生不良反应将其分为两组,运用卡方检验单因素及logistic多因素回归对不良反应发生的危险因素进行分析。结果 2 142例涂阳肺结核患者中536例患者出现不良反应,不良反应发生率为25.0%。经单因素分析结果表明年龄(χ²=23.815, P<0.001)、吸烟情况(χ²=12.040, P=0.024)及结果差异均有统计学意义。多因素非条件logistic回归结果显示, 45~64岁和≥65岁年龄组及吸烟是不良反应发生的独立危险因素,OR(95%CI)值分别为1.524(1.159~2.422)和1.756(1.200~2.570)及1.620(1.194~2.198)。结论 涂阳肺结核患者中吸烟及中老年人是发生不良反应的危险因素,在患者诊治过程中,应及时对这类高危人群进行监测和主动干预,对发现和降低不良反应的发生率有着重要意义。     

Direct observation of tuberculosis treatment by supervised family members in Yasothorn Province, Thailand.

SETTING: Yasothorn Province, Thailand. OBJECTIVE: To evaluate the effectiveness of a programme offering the option of direct observation of treatment (DOT) by a supervised family member. METHODS: Review of patient records and district registers in Yasothorn Province after implementation of the revised tuberculosis control strategy. RESULTS: From 1 October 1996 to 30 September 1997, the programme registered 779 patients: 366 smear-positive pulmonary, 357 smear-negative pulmonary, and 56 extra-pulmonary. DOT was given in 243 (66%) smear-positive, 83 (23%) smear-negative, and in 21 (38%) extra-pulmonary cases; the observer was a family member in 299 (86.2%) of the 347 cases. By December 1998, treatment outcomes were determined for the 695 new patients (326 smear-positive, 321 smear-negative, 48 extra-pulmonary) of the 779 registered during the period under study. In new smear-positive patients, cure rates were 184/216 (85.2%, 95% confidence interval [CI] 80.5-89.9) with DOT versus 78/110 (70.9%, 95% CI 62.4-79.4) with self-administration. CONCLUSION: The overall cure rate was 80.4% in a programme in which trained and supervised family members directly observed the treatment of two-thirds of sputum smear-positive patients. Supervised family members may contribute to more widespread effective implementation of the revised tuberculosis strategy in Thailand.     

High early death rate in tuberculosis patients in Malawi.

SETTING: Thirty-eight district and mission hospitals in Malawi. OBJECTIVES: In patients registered with all types of tuberculosis (TB) in 1997 to determine 1) treatment outcomes, and 2) when in the course of anti-tuberculosis treatment TB deaths occurred. DESIGN: A retrospective study using information from TB registers, health centre registers, TB treatment cards and TB ward admission books. RESULTS: A total of 16,004 patients were registered with all types of TB, 6471 with smear-positive pulmonary tuberculosis (PTB), 5305 with smear-negative PTB and 4228 with extra-pulmonary tuberculosis (EPTB). Of patients with all types of TB, 3720 (23%) died: death rates were 22% in smear-positive PTB, 26% in smear-negative PTB and 22% in EPTB. Month of death was known in 3371 patients (91% of those who died) and day of death in 3326 patients (89% of those who died). In patients who died, 19% of deaths occurred by day 7 and 41% by the end of the first month of treatment. A higher proportion of early deaths occurred in patients with smear-negative PTB and EPTB and in relation to increasing age. CONCLUSIONS: There was a high overall death rate in TB patients registered in 1997, with 40% of deaths occurring in the first month of treatment. Strategies to combat this problem are needed.     

加强转诊和追踪以提高结核病发现率的实施性研究

目的通过加强综合医院与结核病防治所之间合作和病例转诊与追踪,探讨提高结核病人的发现水平方法。方法采取非概率抽样法抽取湖南省邵阳、常德和怀化3市所辖的38个县(区)作为研究现场。结合全省实际,制订切实可行的结核病人转诊追踪实施规范并组织实施。比较项目前后1年及覆盖地区与非覆盖地区间结核病转诊率、追踪率,新涂阳病人发现率和登记率。结果在38个实施县(区)的126家县级综合性医疗机构中,124家平均每月转诊10例结核病可疑症状者或结核病患者到结核病防治机构。与项目前1年比较,病人的登记率增长了102.1%;综合医院疑似结核病例或结核病人转诊率增加了5倍;新涂阳肺结核患者登记率从27.12/10万增加到57.71/10万,且明显高于非项目县(38.77/10万)。结论加强结核病转诊和追踪是提高病人发现率的有效措施。行政干预和激励机制是这一有效措施得以实施的保证。     

Clinical diagnosis of smear-negative pulmonary tuberculosis: an audit of diagnostic practice in hospitals in Malawi.

SETTING: Thirty-seven hospitals in Malawi. OBJECTIVE: To audit the hospital practice of clinically diagnosing adults with smear-negative pulmonary tuberculosis (PTB). DESIGN: A cross-sectional survey of adults aged 15 years or above who were registered and receiving inpatient treatment for smear-negative PTB. An assessment of each patient was carried out to determine 1) the number of recommended diagnostic guidelines (cough >3 weeks, no response to antibiotics, negative sputum smears and a chest radiograph compatible with PTB) used by hospital staff in making the diagnosis of PTB, and 2) whether the clinical diagnosis of smear-negative PTB was correct according to criteria set by the study. RESULTS: There were 259 patients, 127 men and 132 women, with a mean age of 37 years; 93% had a cough >3 weeks, 95% had received one or more courses of antibiotics, 92% had submitted sputum samples for smear examination and 97% had chest radiographs performed. In 148 (57%) patients, all four diagnostic guidelines were used, and in 238 (92%) patients three or more were used. The diagnosis of smear-negative PTB was considered correct by study criteria in 203 (78%) patients. In the remainder, 22 (8%) were considered to have extrapulmonary TB and 34 (14%) another diagnosis. CONCLUSION: Hospital practices in the diagnosis of smear-negative PTB are reasonable, although there is room for improvement with in-service training and regular audits of practice.     

Evaluation of a unified treatment regimen for all new cases of tuberculosis using guardian-based supervision.

SETTING: Ntcheu District, Malawi, using an oral antituberculosis treatment regimen. OBJECTIVE: To determine whether directly observed treatment (DOT) during the initial phase of treatment supervised either in hospital, at health centres or by guardians in the community, was associated with 1) satisfactory 2-month and 8-month treatment outcomes, and 2) with a reduction of in-patient hospital-bed days. DESIGN: Prospective data collection of all tuberculosis (TB) patients registered between 1 April 1996 and 30 June 1997, with 2-month and 8-month treatment outcomes, sputum smear conversion in smear-positive pulmonary TB patients (PTB) and in-patient hospital-bed days. RESULTS: Among the 600 new patients, 302 had smear-positive PTB, 150 smear-negative PTB and 148 extrapulmonary TB (EPTB). Eight-month treatment completion was 65% for smear-positive PTB patients, which was significantly higher than in patients with smear-negative PTB (45%) and EPTB (54%), due mainly to high 8-month mortality rates. The site of the intensive phase was determined in 596 patients: 178 (30%) received DOT from guardians, 115 (19%) from a health centre and 303 (51%) in hospital. At 2 months, mortality rates were significantly higher in hospitalised patients. Two-month treatment outcomes (including sputum smear conversion rates in smear-positive PTB patients) were similar between patients receiving DOT at health centres or from guardians. Decentralised DOT resulted in a 25% reduction in hospital-bed days in patients alive at 2 months compared with that predicted using the old regimens. CONCLUSION: Decentralising DOT to health centres and to guardians during the intensive phase is associated with satisfactory treatment outcomes.     

The Incremental Cost-Effectiveness of Engaging Private Practitioners to Refer Tuberculosis Suspects to DOTS Services in Jogjakarta,Indonesia

We aimed to evaluate the incremental cost-effectiveness of engaging private practitioners (PPs) to refer tuberculosis (TB) suspects to public health centers in Jogjakarta, Indonesia. Effectiveness was assessed for TB suspects notified between May 2004 and April 2005. Private practitioners referred 1,064 TB suspects, of which 57.5% failed to reach a health center. The smear-positive rate among patients reaching a health center was 61.8%. Two hundred eighty (280) out of a total of 1,306 (21.4%) new smear-positive cases were enrolled through the PPs strategy. The incremental cost-effectiveness ratio per smear-positive case successfully treated for the PPs strategy was US$351.66 (95% CI 322.84–601.33). On the basis of an acceptability curve using the National TB control program''s willingness-to-pay threshold (US$448.61), we estimate the probability that the PPs strategy is cost-effective at 66.8%. The strategy of engaging PPs was incrementally cost-effective, although under specific conditions, most importantly a well-functioning public directly observed treatment, short-course (DOTS) program.     

Potential utility of BCG test in excluding tuberculosis in adults

In developing countries, many sputum-negative suspects of pulmonary tuberculosis (PTB) are given antituberculous medication just because tuberculosis (TB) could not be excluded in them. Many studies have shown that BCG test is nearly 100% sensitive, except in those with severe malnutrition, steroid therapy and other causes of immunosuppression. The aim of the present study was to find out the proportion of PTB suspects in whom BCG test may be useful in excluding diagnosis of TB. The study was carried out on adult subjects attending District Tuberculosis Clinic (DTC), Pali, Rajasthan, India. Out of 104 subjects studied, all 18 sputum-positive subjects showed a positive BCG test indicating 100% sensitivity of the test. The result of BCG test was negative in 16.28% of 86 sputum-negative suspects of TB. The BCG test did not show any adverse reactions among these cases except for adenitis of axillary or cervical lymph nodes in 6.7% subjects. The study raises the possibility that BCG test may be useful in excluding diagnosis of tuberculosis in a proportion of adult sputum negative-suspects of PTB in developing countries like India. More studies are needed in this direction.