Journal Article > ResearchFull Text
PLOS One. 2015 April 17; Volume 10 (Issue 4); DOI:10.1371/journal.pone.0122433
Kosack CS, de Kieviet W, Bayrak K, Milovic A, Page AL
PLOS One. 2015 April 17; Volume 10 (Issue 4); DOI:10.1371/journal.pone.0122433
Creatinine is a parameter that is required to monitor renal function and is important to follow in patients under treatment with potentially toxic renal drugs, such as the anti-HIV drug Tenofovir. A point of care instrument to measure creatinine would be useful for patients monitoring in resource-limited settings, where more instruments that are sophisticated are not available. The StatSensor Xpress Creatinine (Nova Biomedical Cooperation, Waltham, MA, USA) point of care analyzer was evaluated for its diagnostic performance in indicating drug therapy change. Creatinine was measured in parallel using the Nova StatSensor Xpress Creatinine analyzer and the Vitros 5,1FS (Ortho Clinical Diagnostics, Inc, Rochester, USA), which served as reference standard. The precision (i.e., repeatability and reproducibility) and accuracy of the StatSensor Xpress Creatinine analyzer were calculated using a panel of specimens with normal, low pathological and high pathological values. Two different Nova StatSensor Xpress Creatinine analyzers were used for the assessment of accuracy using repeated measurements. The coefficient of variation of the StatSensor Xpress Creatinine analyzers ranged from 2.3 to 5.9% for repeatability and from 4.2 to 9.0% for between-run reproducibility. The concordance correlation agreement was good except for high values (>600 µmol/L). The Bland-Altman analysis in high pathological specimens suggests that the Nova StatSensor Xpress Creatinine test tends to underestimate high creatinine values (i.e., >600 µmol/L). The Nova StatSensor Xpress Creatinine analyzers showed acceptable to good results in terms of repeatability, inter-device reproducibility and between-run reproducibility over time using quality control reagents. The analyzer was found sufficiently accurate for detecting pathological values in patients (age >10 year) and can be used with a moderate risk of misclassification.
Journal Article > ResearchFull Text
PLOS One. 2012 March 19; Volume 7 (Issue 3); DOI:10.1371/journal.pone.0033704
Kosack CS, Page AL, Van Hulsteijn LT, Lentjes EG
PLOS One. 2012 March 19; Volume 7 (Issue 3); DOI:10.1371/journal.pone.0033704
Thyroid-stimulating hormone (TSH) promotes expression of thyroid hormones which are essential for metabolism, growth, and development. Second-line drugs to treat tuberculosis (TB) can cause hypothyroidism by suppressing thyroid hormone synthesis. Therefore, TSH levels are routinely measured in TB patients receiving second-line drugs, and thyroxin treatment is initiated where indicated. However, standard TSH tests are technically demanding for many low-resource settings where TB is prevalent; a simple and inexpensive test is urgently needed.
Journal Article > ResearchFull Text
Trop Med Int Health. 2016 March 6; Volume 21 (Issue 5); 603-609.; DOI:10.1111/tmi.12688
Kosack CS, Nick S
Trop Med Int Health. 2016 March 6; Volume 21 (Issue 5); 603-609.; DOI:10.1111/tmi.12688
OBJECTIVE
To evaluate the diagnostic accuracy of the OraQuick HCV rapid antibody test from OraSure and the Multisure HCV antibody assay from MP Biomedicals.
METHODS
Five seropanels from patients, intravenous drug users and blood donors with and without HCV infection were used on the two rapid immunochromatographic tests. Sensitivity, specificity and predictive values were calculated. In addition, seropanels from 10 seroconverters were used to assess early identification of HCV infection. The study was undertaken in a laboratory at Paul Ehrlich Institute in Germany.
RESULTS
Panel 1 contained of 55 positive and 25 negative samples. The OraQuick HCV test had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 100% (95% CI: 86.3-100). The Multisure HCV test had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 96% (95% CI: 79.6-99.9). Panel 2 consisted of 193 pre-characterised anti-HCV-positive patient samples. The OraQuick HCV test identified 191 samples correctly and the Multisure HCV 192. The sensitivity was 99.0% (95% CI: 96.3-99.9) for the OraQuick HCV test and 99.5% (95% CI: 97.1-100) for the Multisure HCV test. Panel 3 was composed of seroconversion samples of 10 patients. The OraQuick HCV test detected all of these 10 infections while the Multisure HCV test detected six and was indeterminate on 2. Panel 4 included 53 anti-HCV negative blood samples from blood donors. Both tests correctly identified all 53. Panel 5 consisted of 26 samples of HCV/HIV co-infected patients. The sensitivity of the OraQuick HCV test was 65.2% (95% CI: 42.8-82.8) after 20 min and 73.9% (95% CI: 51.3-88.9) after 40 min of incubation. The Multisure HCV test had a sensitivity of 96.2% (95% CI: 80.4-99.9).
CONCLUSION
This evaluation revealed good sensitivity for both rapid screening assays. The detection of seroconverters, however, was lower in the MutiSure HCV test. Therefore the MultiSure test should be used with hesitation in high incidence settings. The OraQuick gave HCV false-negative results in almost 25% of the HIV-positive sera. Therefore may the OraQuick be less suited in HIV prevalent areas.
To evaluate the diagnostic accuracy of the OraQuick HCV rapid antibody test from OraSure and the Multisure HCV antibody assay from MP Biomedicals.
METHODS
Five seropanels from patients, intravenous drug users and blood donors with and without HCV infection were used on the two rapid immunochromatographic tests. Sensitivity, specificity and predictive values were calculated. In addition, seropanels from 10 seroconverters were used to assess early identification of HCV infection. The study was undertaken in a laboratory at Paul Ehrlich Institute in Germany.
RESULTS
Panel 1 contained of 55 positive and 25 negative samples. The OraQuick HCV test had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 100% (95% CI: 86.3-100). The Multisure HCV test had a sensitivity of 100% (95% CI: 93.5-100) and a specificity of 96% (95% CI: 79.6-99.9). Panel 2 consisted of 193 pre-characterised anti-HCV-positive patient samples. The OraQuick HCV test identified 191 samples correctly and the Multisure HCV 192. The sensitivity was 99.0% (95% CI: 96.3-99.9) for the OraQuick HCV test and 99.5% (95% CI: 97.1-100) for the Multisure HCV test. Panel 3 was composed of seroconversion samples of 10 patients. The OraQuick HCV test detected all of these 10 infections while the Multisure HCV test detected six and was indeterminate on 2. Panel 4 included 53 anti-HCV negative blood samples from blood donors. Both tests correctly identified all 53. Panel 5 consisted of 26 samples of HCV/HIV co-infected patients. The sensitivity of the OraQuick HCV test was 65.2% (95% CI: 42.8-82.8) after 20 min and 73.9% (95% CI: 51.3-88.9) after 40 min of incubation. The Multisure HCV test had a sensitivity of 96.2% (95% CI: 80.4-99.9).
CONCLUSION
This evaluation revealed good sensitivity for both rapid screening assays. The detection of seroconverters, however, was lower in the MutiSure HCV test. Therefore the MultiSure test should be used with hesitation in high incidence settings. The OraQuick gave HCV false-negative results in almost 25% of the HIV-positive sera. Therefore may the OraQuick be less suited in HIV prevalent areas.
Protocol > Research Study
Kosack CS, Halton J, Greig J, Shanks L, Spijker S
2018 July 1
PRIMARY OBJECTIVE OF STUDY
• To demonstrate the extent of change in patient management through the availability of digital X-ray with teleradiology consultation.
SECONDARY OBJECTIVES OF STUDY
• To demonstrate the extent of change in patient diagnosis through the availability of digital X-ray with teleradiology consultation.
• To demonstrate the extent of change in patient diagnosis and management in the subgroup of patients with chest pathologies through the availability of digital X-ray with teleradiology consultation.
• To estimate if the extent of change in diagnosis and management is different in patients < 5 years of age versus ≥5 years of age.
• To demonstrate the extent of change in patient management through the availability of digital X-ray with teleradiology consultation.
SECONDARY OBJECTIVES OF STUDY
• To demonstrate the extent of change in patient diagnosis through the availability of digital X-ray with teleradiology consultation.
• To demonstrate the extent of change in patient diagnosis and management in the subgroup of patients with chest pathologies through the availability of digital X-ray with teleradiology consultation.
• To estimate if the extent of change in diagnosis and management is different in patients < 5 years of age versus ≥5 years of age.
Journal Article > ResearchFull Text
Bull World Health Organ. 2015 June 25; Volume 93 (Issue 9); 623-630.; DOI:10.2471/BLT.14.146480
Fajardo E, Metcalf CJ, Piriou E, Gueguen M, Maman D, et al.
Bull World Health Organ. 2015 June 25; Volume 93 (Issue 9); 623-630.; DOI:10.2471/BLT.14.146480
OBJECTIVE
To estimate the proportion of invalid results generated by a CD4+ T-lymphocyte analyser used by Médecins Sans Frontières (MSF) in field projects and identify factors associated with invalid results.
METHODS
We collated 25,616 CD4+ T-lymphocyte test results from 39 sites in nine countries for the years 2011 to 2013. Information about the setting, user, training, sampling technique and device repair history were obtained by questionnaire. The analyser performs a series of checks to ensure that all steps of the analysis are completed successfully; if not, an invalid result is reported. We calculated the proportion of invalid results by device and by operator. Regression analyses were used to investigate factors associated with invalid results.
FINDINGS
There were 3354 invalid test results (13.1%) across 39 sites, for 58 Alere PimaTM devices and 180 operators. The median proportion of errors per device and operator was 12.7% (interquartile range, IQR: 10.3-19.9) and 12.1% (IQR: 7.1-19.2), respectively. The proportion of invalid results varied widely by country, setting, user and device. Errors were not associated with settings, user experience or the number of users per device. Tests performed on capillary blood samples were significantly less likely to generate errors compared to venous whole blood.
CONCLUSION
The Alere Pima CD4+ analyser generated a high proportion of invalid test results, across different countries, settings and users. Most error codes could be attributed to the operator, but the exact causes proved difficult to identify. Invalid results need to be factored into the implementation and operational costs of routine CD4+ T-lymphocyte testing.
To estimate the proportion of invalid results generated by a CD4+ T-lymphocyte analyser used by Médecins Sans Frontières (MSF) in field projects and identify factors associated with invalid results.
METHODS
We collated 25,616 CD4+ T-lymphocyte test results from 39 sites in nine countries for the years 2011 to 2013. Information about the setting, user, training, sampling technique and device repair history were obtained by questionnaire. The analyser performs a series of checks to ensure that all steps of the analysis are completed successfully; if not, an invalid result is reported. We calculated the proportion of invalid results by device and by operator. Regression analyses were used to investigate factors associated with invalid results.
FINDINGS
There were 3354 invalid test results (13.1%) across 39 sites, for 58 Alere PimaTM devices and 180 operators. The median proportion of errors per device and operator was 12.7% (interquartile range, IQR: 10.3-19.9) and 12.1% (IQR: 7.1-19.2), respectively. The proportion of invalid results varied widely by country, setting, user and device. Errors were not associated with settings, user experience or the number of users per device. Tests performed on capillary blood samples were significantly less likely to generate errors compared to venous whole blood.
CONCLUSION
The Alere Pima CD4+ analyser generated a high proportion of invalid test results, across different countries, settings and users. Most error codes could be attributed to the operator, but the exact causes proved difficult to identify. Invalid results need to be factored into the implementation and operational costs of routine CD4+ T-lymphocyte testing.
Journal Article > ResearchFull Text
PLOS One. 2015 December 15; Volume 10 (Issue 12); e0144656.; DOI:10.1371/journal.pone.0144656
Ardizzoni E, Fajardo E, Saranchuk P, Casenghi M, Page AL, et al.
PLOS One. 2015 December 15; Volume 10 (Issue 12); e0144656.; DOI:10.1371/journal.pone.0144656
BACKGROUND
The Xpert® MTB/RIF (Xpert) is an automated molecular test for simultaneous detection of tuberculosis (TB) and rifampicin resistance, recommended by the World Health Organization as the preferred diagnostic method for individuals presumed to have multi-drug resistant TB (MDR-TB) or HIV-associated TB. We describe the performance of Xpert and key lessons learned during two years of implementation under routine conditions in 33 projects located in 18 countries supported by Médecins Sans Frontières across varied geographic, epidemiological and clinical settings.
METHODS
Xpert was used following three strategies: the first being as the initial test, with microscopy in parallel, for all presumptive TB cases; the second being only for patients at risk of MDR-TB, or with HIV- associated TB, or presumptive paediatric TB; and the third being as the initial test for these high-risk patients plus as an add-on test to microscopy in others. Routine laboratory data were collected, using laboratory registers. Qualitative data such as logistic aspects, human resources, and tool acceptance were collected using a questionnaire.
FINDINGS
In total, 52,863 samples underwent Xpert testing from April 2011 to December 2012. The average MTB detection rate was 18.5%, 22.3%, and 11.6% for the three different strategies respectively. Analysis of the results on samples tested in parallel showed that using Xpert as add-on test to microscopy would have increased laboratory TB confirmation by 49.7%, versus 42.3% for Xpert replacing microscopy. The main limitation of the test was the high rate of inconclusive results, which correlated with factors such as defective modules, cartridge version (G3 vs. G4) and staff experience. Operational and logistical hurdles included infrastructure renovation, basic computer training, regular instrument troubleshooting and maintenance, all of which required substantial and continuous support.
CONCLUSION
The implementation of Xpert was feasible and significantly increased TB detection compared to microscopy, despite the high rate of inconclusive results. Xpert implementation was accompanied by considerable operational and logistical challenges. To further decentralize diagnosis, simpler, low-cost TB technologies well-suited to low-resource settings are still urgently needed.
The Xpert® MTB/RIF (Xpert) is an automated molecular test for simultaneous detection of tuberculosis (TB) and rifampicin resistance, recommended by the World Health Organization as the preferred diagnostic method for individuals presumed to have multi-drug resistant TB (MDR-TB) or HIV-associated TB. We describe the performance of Xpert and key lessons learned during two years of implementation under routine conditions in 33 projects located in 18 countries supported by Médecins Sans Frontières across varied geographic, epidemiological and clinical settings.
METHODS
Xpert was used following three strategies: the first being as the initial test, with microscopy in parallel, for all presumptive TB cases; the second being only for patients at risk of MDR-TB, or with HIV- associated TB, or presumptive paediatric TB; and the third being as the initial test for these high-risk patients plus as an add-on test to microscopy in others. Routine laboratory data were collected, using laboratory registers. Qualitative data such as logistic aspects, human resources, and tool acceptance were collected using a questionnaire.
FINDINGS
In total, 52,863 samples underwent Xpert testing from April 2011 to December 2012. The average MTB detection rate was 18.5%, 22.3%, and 11.6% for the three different strategies respectively. Analysis of the results on samples tested in parallel showed that using Xpert as add-on test to microscopy would have increased laboratory TB confirmation by 49.7%, versus 42.3% for Xpert replacing microscopy. The main limitation of the test was the high rate of inconclusive results, which correlated with factors such as defective modules, cartridge version (G3 vs. G4) and staff experience. Operational and logistical hurdles included infrastructure renovation, basic computer training, regular instrument troubleshooting and maintenance, all of which required substantial and continuous support.
CONCLUSION
The implementation of Xpert was feasible and significantly increased TB detection compared to microscopy, despite the high rate of inconclusive results. Xpert implementation was accompanied by considerable operational and logistical challenges. To further decentralize diagnosis, simpler, low-cost TB technologies well-suited to low-resource settings are still urgently needed.
Journal Article > CommentaryFull Text
J Int AIDS Soc. 2017 July 19; Volume 20 (Issue 1); DOI:10.7448/IAS.20.1.22098
Kosack CS, Page AL, Beelaert G, Benson TT, Savane A, et al.
J Int AIDS Soc. 2017 July 19; Volume 20 (Issue 1); DOI:10.7448/IAS.20.1.22098
Journal Article > ResearchFull Text
J Int AIDS Soc. 2017 March 22 (Issue 1)
Kosack CS, Page AL, Beelaert G, Benson TT, Savane A, et al.
J Int AIDS Soc. 2017 March 22 (Issue 1)
Although individual HIV rapid diagnostic tests (RDTs) show good performance in evaluations conducted by WHO, reports from several African countries highlight potentially significant performance issues. Despite widespread use of RDTs for HIV diagnosis in resource-constrained settings, there has been no systematic, head-to-head evaluation of their accuracy with specimens from diverse settings across sub-Saharan Africa. We conducted a standardized, centralized evaluation of eight HIV RDTs and two simple confirmatory assays at a WHO collaborating centre for evaluation of HIV diagnostics using specimens from six sites in five sub-Saharan African countries.
Journal Article > ResearchFull Text
Trop Med Int Health. 2004 April 1; Volume 9 (Issue 4); DOI:10.1111/j.1365-3156.2004.01217.x
Checchi F, Piola P, Kosack CS, Ardizzoni E, Klarkowski DB, et al.
Trop Med Int Health. 2004 April 1; Volume 9 (Issue 4); DOI:10.1111/j.1365-3156.2004.01217.x
We report below an in vivo antimalarial efficacy study conducted in 2002 in Bundi Bugyo, a district of western Uganda housing a large displaced population. We tested sulfadoxine-pyrimethamine (SP), amodiaquine (AQ) and the combination chloroquine plus SP (CQ + SP). A total of 268 children with uncomplicated Plasmodium falciparum malaria were followed-up for 28 days according to WHO recommendations, with PCR genotyping to distinguish late recrudescences from re-infections. PCR-adjusted failure proportions at day 28 were 37.0% (34/92, 95% CI 27.1-47.7) in the SP group, 20.6% (14/68, 95% CI 11.7-32.1) in the AQ group and 22.8% (18/79, 95% CI 14.1-33.6) in the CQ + SP group. Early failures were particularly frequent in the SP group (15.2%). Clearance of gametocytes was slower in the SP and CQ + SP groups than in the AQ group. This study suggests that, in Bundi Bugyo, CQ + SP (Uganda's first-line regimen) will need to be replaced by a more efficacious regimen. Across Uganda, the deployment of SP containing combinations may not be a feasible long-term strategy. For Bundi Bugyo, we recommend a combination of artesunate and AQ. Our study also confirms previous findings that resistance is considerably underestimated by 14-day follow-ups. Antimalarial policy decisions should therefore be based on 28-day studies, with PCR adjustment to distinguish re-infections.
Journal Article > ReviewFull Text
Clin Chem Lab Med. 2012 March 16; Volume 50 (Issue 7); 1221-1227.; DOI:10.1515/cclm-2011-0618
Kosack CS
Clin Chem Lab Med. 2012 March 16; Volume 50 (Issue 7); 1221-1227.; DOI:10.1515/cclm-2011-0618
In medical humanitarian assistance, the diagnosis of diseases plays a crucial role. Laboratory investigations are one of the main diagnostic tools utilized in Médecins Sans Frontières' (MSF) programs. Currently MSF supports and/or operates more than 130 laboratories in approximately 45 countries. The variety of analysis offered depends largely on the context of the program and the availability of context adapted tools and ranges from sophisticated laboratories specializing in tuberculosis culture to small laboratories within a primary health care program or operating as mobile clinics. The largest laboratories in MSF are found in programs with the main objective to diagnose, treat and monitor patients with tuberculosis and/or human immunodeficiency virus. Other MSF programs are either disease-specific (e.g., malaria, Chagas, kala azar or visceral leishmaniasis, sleeping sickness, malnutrition, sexually transmitted infections) or are integrated in primary or secondary health care structures.