TY - JOUR
T1 - Low diagnostic performance of thick blood smears of 50 µl in comparison with direct examination of 10 µl blood and the leukoconcentration technique of 5ml blood among loiasis-suspected patients with low microfilaremia in Gabon, Central Africa, using the STARD-BLCM guidelines
AU - M’Bondoukwé, Noé Patrick
AU - Owono-Medang, Matthieu
AU - Moussavou-Boussougou, Marie Noëlle
AU - Akoue, Yvan
AU - Migueba, Valentin
AU - Bulaev, Dmitry
AU - Neven, Anouk
AU - James, Luice Aurtin Joel
AU - Ntsame Ella, Sylvie Alberte
AU - Mawili-Mboumba, Denise Patricia
AU - Atsame, Julienne
AU - Vaillant, Michel
AU - Bouyou Akotet, Marielle Karine
N1 - This study was funded by the Department of Parasitology-Mycology-Tropical Medicine.
Publisher Copyright:
© The Author(s) 2024.
PY - 2024/3/15
Y1 - 2024/3/15
N2 - Background: The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies–Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques—direct examination of 10 µl blood and a leukoconcentration of 5 ml—for the diagnosis of microfilaremic loiasis. Methods: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM—the BLCM model I and alternative models II and III—for sensitivity analysis. Results: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7–14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2–18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3–90.2], specificity was 100.0% [97.8–100.0], the positive predictive value was 100.0% [81.5–100.0], and the negative predictive value was 96.5% [92.6–98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2–13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3–90.3], specificity of 100.0% [99.3–100.0], a positive predictive value of 99.1% [87.2–100.0], and a negative predictive value of 93.0% [87.3–97.7] for direct blood examination/TBS-50. Conclusions: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds. Graphical Abstract: (Figure presented.).
AB - Background: The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies–Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques—direct examination of 10 µl blood and a leukoconcentration of 5 ml—for the diagnosis of microfilaremic loiasis. Methods: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM—the BLCM model I and alternative models II and III—for sensitivity analysis. Results: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7–14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2–18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3–90.2], specificity was 100.0% [97.8–100.0], the positive predictive value was 100.0% [81.5–100.0], and the negative predictive value was 96.5% [92.6–98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2–13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3–90.3], specificity of 100.0% [99.3–100.0], a positive predictive value of 99.1% [87.2–100.0], and a negative predictive value of 93.0% [87.3–97.7] for direct blood examination/TBS-50. Conclusions: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds. Graphical Abstract: (Figure presented.).
KW - Diagnostic accuracy
KW - Direct blood examination of 10 µl
KW - Leukoconcentration technique of 5 ml
KW - Loiasis
KW - STARD-BLCM
KW - Thick blood smear of 50 µl
UR - http://www.scopus.com/inward/record.url?scp=85187919678&partnerID=8YFLogxK
UR - https://pubmed.ncbi.nlm.nih.gov/38491557
U2 - 10.1186/s13071-023-06089-1
DO - 10.1186/s13071-023-06089-1
M3 - Article
C2 - 38491557
AN - SCOPUS:85187919678
SN - 1756-3305
VL - 17
JO - Parasites and Vectors
JF - Parasites and Vectors
IS - 1
M1 - 138
ER -