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Published on: May 30, 2017
Evaluation of three rapid diagnostic tests for cholera: does the skill level of the technician matter?
Pavani Kalluri1, Aliya Naheed, Saifur Rahman
1Centers for Disease Control and Prevention, Atlanta, GA, USA. pkram@buffalo.edu
Objective:
To evaluate SMART, Medicos Dip Stick and an Institut Pasteur (IP) cholera dipstick tests for accuracy and ease of use.
Method:
Every 50th patient presenting with diarrhoea at ICDDR,B between 1 April 2003 and 30 November 2003 was enrolled. The rapid diagnostic tests were performed by field and laboratory technicians, and sensitivity (Se), specificity (Sp), positive (PPV) and negative (NPV) predictive values calculated.
Results:
We isolated Vibrio cholerae O1 from 116 (38%) of 304 patients. The Se, Sp, PPV and NPV of the SMART test were 58%, 95%, 84% and 84% for field technicians, and 83%, 88%, 83% and 88% for laboratory technicians. The Se, Sp, PPV and NPV of the IP dipstick test were 93%, 67%, 63% and 94% for field technicians, and 94%, 76%, 70% and 95% for laboratory technicians. The Se, Sp, PPV and NPV of the Medicos test were 84%, 79%, 71% and 90% for field technicians, and 88%, 80%, 72% and 92% for laboratory technicians. A high proportion of indeterminates (30%) hampered the performance of the SMART test. The IP dipstick had the highest Se, irrespective of technician skill level.
Conclusion:
The IP dipstick is the most appropriate rapid diagnostic assay for the detection of V. cholerae O1 in locations where the skill level of personnel may be low, such as remote areas or refugee camp settings. High cost may limit the utility of any diagnostic test in the developing world.
Insights
The Institut Pasteur (IP) cholera dipstick test demonstrated the highest sensitivity for detecting Vibrio cholerae O1. This rapid diagnostic assay is recommended for use in low-skill settings, despite potential cost limitations.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Diagnostic Assays
Background:
- Cholera remains a significant public health concern, particularly in resource-limited settings.
- Accurate and rapid diagnostic tools are crucial for timely treatment and outbreak control of Vibrio cholerae O1 infections.
- Several rapid diagnostic tests (RDTs) exist, but their performance characteristics can vary.
Purpose of the Study:
- To evaluate the diagnostic accuracy and ease of use of three cholera rapid diagnostic tests: SMART, Medicos Dip Stick, and Institut Pasteur (IP) cholera dipstick.
- To compare the sensitivity, specificity, and predictive values of these tests when performed by technicians with different skill levels.
Main Methods:
- A cross-sectional study enrolled every 50th patient presenting with diarrhea at ICDDR,B between April and November 2003.
- Three rapid diagnostic tests (SMART, Medicos, IP) were performed by both field and laboratory technicians.
- Sensitivity (Se), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) were calculated for each test.
Main Results:
- Vibrio cholerae O1 was isolated from 38% of 304 patients.
- The IP dipstick test exhibited the highest sensitivity (93-94%) across both field and laboratory technicians.
- The SMART test's performance was hampered by a high proportion of indeterminate results (30%).
- The Medicos test showed moderate sensitivity and specificity, with PPV/NPV comparable to the IP test.
Conclusions:
- The Institut Pasteur (IP) cholera dipstick is the most suitable rapid diagnostic assay for Vibrio cholerae O1 detection, especially in settings with limited personnel expertise.
- The high sensitivity of the IP dipstick makes it valuable for remote areas and refugee camps.
- The cost of diagnostic tests may influence their widespread adoption in developing countries.
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