Comparative cost and performance of light-emitting diode microscopy in HIV–tuberculosis-co-infected patients

Abstract

Light-emitting diode (LED) microscopy has recently been endorsed by the World Health Organization (WHO). However, it is unclear whether LED is as accurate and cost-effective as Ziehl–Neelsen (ZN) microscopy or mercury vapour fluorescence microscopy (MVFM) in tuberculosis (TB)–HIV-co-infected subjects. Direct and concentrated sputum smears from TB suspects were evaluated using combinations of LED microscopy, ZN microscopy and MVFM. Median reading time per slide was recorded and a cost analysis performed. Mycobacterial culture served as the reference standard. 647 sputum samples were obtained from 354 patients (88 (29.8%) were HIV-infected and 161 (26%) were culture-positive for Mycobacterium tuberculosis). Although overall sensitivity of LED compared with ZN microscopy or MVFM was similar, sensitivity of all three modalities was lower in HIV-infected patients. In the HIV-infected group, the sensitivity of LED microscopy was higher than ZN microscopy using samples that were not concentrated (46 versus 39%; p=0.25), and better than MVFM using concentrated samples (56 versus 44; p=0.5). A similar trend was seen in the CD4 count <200 cells mL−1 subgroup. Median (interquartile range) reading time was quicker with LED compared with ZN microscopy (1.8 (1.7–1.9) versus 2.5 (2.2–2.7) min; p ≤0.001). Average cost per slide read was less for LED microscopy (US$1.63) compared with ZN microscopy (US$2.10). Among HIV–TB-co-infected patients, LED microscopy was cheaper and performed as well as ZN microscopy or MVFM independent of the staining (ZN or auramine O) or processing methods used.

Light-emitting diode fluorescence microscopy for tuberculosis diagnosis: a meta-analysis

“…Nonetheless, SROC plots suggested that liquid culture reference standard was associated with higher diagnostic accuracy of LED-FM (see online supplementary material). Studies using culture on one specimen (n=7) [14-17, 19, 22, 23] had a lower pooled specificity (94.7%) and a higher sensitivity (70.0%) compared with studies using more than one specimen (n=6) [13,15,18,20,21,24] (98.5% and 61.1%, respectively), although the differences were not statistically significant. SROC plots suggested that culture reference based on more than one specimen improved the diagnostic accuracy of LED-FM, although associated with increasing heterogeneity in both sensitivity and specificity estimates of the LED-FM (see online supplementary material).…”

“…Lumin™ (LW Scientific, Lawrenceville, GA, USA), evaluated in five studies [13,18,[20][21][22], was the most commonly used device and displayed the best diagnostic performance on the SROC plots (see online supplementary material). Performance evaluations of all the other devices were based on fewer than four studies.…”

“…12 articles [13][14][15][16][17][18][19][20][21][22][23][24], reporting 12 independent studies, were included in the meta-analysis. One study [15] had two different patient groups (group 1: unlikely HIV-infected; group 2: HIV-infected) with separately analysed data.…”

“…The 12 prospective studies [13][14][15][16][17][18][19][20][21][22][23][24] were conducted across 11 countries and assessed six commercial LED-FM systems (table 1). All studies were located in middle-or low-income countries [25] and 11 recruited sites in WHO-recognised, high-TB-burden countries [1].…”

Point-of-Care Diagnostics for Tuberculosis: Are we there?

“…It can be performed on un-centrifuged specimens at the point of care. The introduction of the low cost light-emitting diode (LED) microscopy with the benefit of fluorescence microscopy without the associated operational requirements, has offered a new tool for POCT-TB [1]. More recently, the processing of serial sputum specimen examinations in the front-loaded microscopy approach focuses on collecting several specimens during one visit [2].…”