High sensitivity of chest radiograph reading by clinical officers in a tuberculosis prevalence survey.

BACKGROUND: Chest radiographs (CXRs) are used in tuberculosis (TB) prevalence surveys to identify participants for bacteriological examination. Expert readers are rare in most African countries. In our survey, clinical officers scored CXRs of 19 216 participants once. We assessed to what extent missed CXR abnormalities affected our TB prevalence estimate. METHODS: Two experts, a radiologist and pulmonologist, independently reviewed 1031 randomly selected CXRs, mixed with lms of confirmed TB cases. CXRs with disagreement on 'any abnormality' or 'abnormality consistent with TB' were jointly reviewed during a consensus panel. We compared the nal expert and clinical of cer classifications with bacteriologically confirmed TB as the gold standard. RESULTS: After the panel, 199 (19%) randomly selected CXRs were considered abnormal by both expert reviewers and another 82 (8%) by one reviewer. Agreement was good among the experts (κ 0.78, 95%CI 0.73-0.82) and moderate between the clinical officers and experts (κ range 0.50-0.62). The sensitivity of 'any abnormality' was 95% for the clinical officers and 83% and 81% for the respective experts. The specificities were respectively 73%, 74% and 80%. TB prevalence was underestimated by 1.5-5.0%. CONCLUSIONS: Acceptable CXR screening can be achieved with clinical officers. Reviewing a sample of CXRs by two experts allows an assessment of prevalence underestimation.

Isolation of multidrug-resistant tuberculosis strains in patients from private and public health care facilities in Nairobi, Kenya.

SETTING: Health care facilities in Nairobi, Kenya. OBJECTIVE: To document the presence of multidrug-resistant tuberculosis (MDR-TB) strains in patients from Nairobi between September 1999 and October 2001. DESIGN: Descriptive study. RESULTS: Of the 983 referred patients who submitted sputum for culture and drug susceptibility testing (DST), 59% were males. Two hundred and nine (21.3%) patients had a positive culture, of whom 15.2% had a request for DST against isoniazid, rifampicin, streptomycin and ethambutol. Of these, 65 (43.6%) had an isolate resistant to one or more drugs, while 17 (11.4%) had MDR-TB. Ten (59.0%) cases were referred from public health care facilities while seven (41%) were from the private sector. Sixteen isolates were resistant to all four drugs. All MDR-TB cases but one were from Nairobi. CONCLUSION: The emergence of MDR-TB in Nairobi is a cause for concern. An outbreak would be catastrophic, creating not only increased morbidity and mortality but also a tremendous strain on already limited health care resources. Lack of policies for the treatment and management of MDR-TB and the unavailability of appropriate diagnostic facilities may increase its spread. Efforts to prevent outbreaks of MDR-TB should be emphasised.

Isoniazid preventive therapy for tuberculosis in HIV-1-infected adults: results of a randomized controlled trial.

OBJECTIVES: To determine the efficacy of isoniazid 300 mg daily for 6 months in the prevention of tuberculosis in HIV-1-infected adults and to determine whether tuberculosis preventive therapy prolongs survival in HIV-1-infected adults. DESIGN AND SETTING: Randomized, double-blind, placebo-controlled trial in Nairobi, Kenya. SUBJECTS: Six hundred and eighty-four HIV-1-infected adults. MAIN OUTCOME MEASURES: Development of tuberculosis and death. RESULTS: Three hundred and forty-two subjects received isoniazid and 342 received placebo. The median CD4 lymphocyte counts at enrolment were 322 and 346 x 10(6)/l in the isoniazid and placebo groups, respectively. The overall median follow-up from enrolment was 1.83 years (range, 0-3.4 years). The incidence of tuberculosis in the isoniazid group was 4.29 per 100 person-years (PY) of observation [95% confidence interval (CI) 2.78-6.33] and 3.86 per 100 PY of observation (95% CI, 2.45-5.79) in the placebo group, giving an adjusted rate ratio for isoniazid versus placebo of 0.92 (95% CI, 0.49-1.71). The adjusted rate ratio for tuberculosis for isoniazid versus placebo for tuberculin skin test (TST)-positive subjects was 0.60 (95% CI, 0.23-1.60) and for the TST-negative subjects, 1.23 (95% CI, 0.55-2.76). The overall adjusted mortality rate ratio for isoniazid versus placebo was 1.18 (95% CI, 0.79-1.75). Stratifying by TST reactivity gave an adjusted mortality rate ratio in those who were TST-positive of 0.33 (95% CI, 0.09-1.23) and for TST-negative subjects, 1.39 (95% CI, 0.90-2.12). CONCLUSIONS: Overall there was no statistically significant protective effect of daily isoniazid for 6 months in the prevention of tuberculosis. In the TST-positive subjects, where reactivation is likely to be the more important pathogenetic mechanism, there was some protection and some reduction in mortality, although this was not statistically significant. The small number of individuals in this subgroup made the power to detect a statistically significant difference in this subgroup low. Other influences that may have diluted the efficacy of isoniazid include a high rate of transmission of new infection and rapid progression to disease or insufficient duration of isoniazid in subjects with relatively advanced immunosuppression. The rate of drug resistance observed in subjects who received isoniazid and subsequently developed tuberculosis was low.