Provider-initiated sympton screening for tuberculosis in Zimbabwe: diagnostic value and the effect of HIV status

Abstract

Objective To assess the diagnostic value of provider-initiated symptom screening for tuberculosis (TB) and how HIV status affects it. Methods We performed a secondary analysis of randomly selected participants in a community-based TB-HIV prevalence survey in Harare, Zimbabwe. All completed a five-symptom questionnaire and underwent sputum TB culture and HIV testing. We calculated the sensitivity, specificity, and positive and negative predictive values of various symptoms and used regression analysis to investigate the relationship between symptoms and TB disease. Findings We found one or more symptoms of TB in 21.2% of 1858 HIV-positive (HIV+) and 9.9% of 7121 HIV-negative (HIV−) participants (P < 0.001). TB was subsequently diagnosed in 48 HIV+ and 31 HIV− participants. TB was asymptomatic in 18 culture-positive individuals, 8 of whom (4 in each HIV status group) had positive sputum smears. Cough of any duration, weight loss and, for HIV+ participants only, drenching night sweats were independent predictors of TB. In HIV+ participants, cough of ³ 2 weeks' duration, any symptom and a positive sputum culture had sensitivities of 48%, 81% and 65%, respectively; in HIV− participants, the sensitivities were 45%, 71% and 74%, respectively. Symptoms had a similar sensitivity and specificity in HIV+ and HIV− participants, but in HIV+ participants they had a higher positive and a lower negative predictive value. Conclusion Even smear-positive TB may be missed by provider-initiated symptom screening, especially in HIV+ individuals. Symptom screening is useful for ruling out TB, but better TB diagnostics are urgently needed for resource-poor settings.Une traduction en français de ce résumé figure à la fin de l'article. Al final del artículo se facilita una traducción al español. ‫املقالة.‬ ‫لهذه‬ ‫الكامل‬ ‫النص‬ ‫نهاية‬ ‫يف‬ ‫الخالصة‬ ‫لهذه‬ ‫العربية‬ ‫الرتجمة‬

HIV Infection Does Not Affect Active Case Finding of Tuberculosis in South African Gold Miners

“…Another possible, but highly speculative, explanation is that the selective pressure of approximately 50 years of radiological screening in this population has pushed the circulating tuberculosis strains toward ones that are less readily detectable by radiological screening. The sensitivity of symptom screening for active tuberculosis case finding varies markedly in different communities, workplace settings, and in HIV clinic patients (Table 6) (20,21). The explanation for the large differences in sensitivity and specificity of symptom screening seen in these studies, all based in Southern Africa, is likely to be multifactorial and may include: differences in study populations, such as mining versus general populations and the proportion HIV-infected; the screening algorithms used; and the case definitions of tuberculosis used.…”

HIV and Tuberculosis: a Deadly Human Syndemic

“…In this study population from Cambodia, Thailand, and Vietnam, combination symptom screening was found to have 93% sensitivity and 36% specificity, with a 97% negative predictive value and a 21% positive predictive value for culture-positive pulmonary TB. Similarly, Corbett et al assessed the efficacy of provider-initiated symptom screening for TB in HIV-infected patients in Zimbabwe and found that assessing for the presence of any cough, drenching night sweats, or weight loss yielded a sensitivity of 75% and a specificity of 82%, with a 99.2% negative predictive value and a 10.2% positive predictive value for TB (both culture-positive and culture-negative TB) (63). The use of a combination of symptoms to screen for TB appears to be an effective and practical method to rule out active TB in HIV-infected patients.…”

Do Xpert MTB/Rif Cycle Threshold Values Provide Information About Patient Delays for Tuberculosis Diagnosis?

“…Alternatively, or in addition, it may imply that the reported duration of symptoms does not reflect the duration of disease. This may be due to poor recall by patients and/or relatively long and variable periods of subclinical disease before symptoms arise [25], although subclinical disease is more likely to be missed in routine than in providerinitiated symptom screening for tuberculosis [26]. We investigated other predictors of patient delay for TB diagnosis and found rural residence and being HIV-negative to predict patient delay for TB diagnosis.…”