Comparing Diagnostic Performance of Pronto Dry Rapid Urease® and Culture to Histopathology among Endoscopy Patients at the Aga Khan University Hospital, Nairobi-Kenya
Stephen Njoroge *
Jomo Kenyatta University of Agriculture and Technology, P.O.Box 62000-00200, Nairobi, Kenya and Technical University of Kenya, P.O.Box 52428, Nairobi, Kenya.
Catherine Mwangi
Jomo Kenyatta University of Agriculture and Technology, P.O.Box 62000-00200, Nairobi, Kenya.
Kimang’a Nyerere
Jomo Kenyatta University of Agriculture and Technology, P.O.Box 62000-00200, Nairobi, Kenya.
Gunturu Revathi
Aga Khan Hospital University, P.O.Box 37002-00100, Nairobi, Kenya.
Smita Devani
Aga Khan Hospital University, P.O.Box 37002-00100, Nairobi, Kenya.
Allan Rajula
Aga Khan Hospital University, P.O.Box 37002-00100, Nairobi, Kenya.
Rose Kamenwa
Aga Khan Hospital University, P.O.Box 37002-00100, Nairobi, Kenya.
Nyamongo Onkoba
Technical University of Kenya, P.O.Box 52428, Nairobi, Kenya.
Fredrick Odhiambo
National Public Health Laboratory, P.O.Box 20750-00200, Nairobi, Kenya.
*Author to whom correspondence should be addressed.
Abstract
Aim: This study sought to evaluate Pronto dry rapid urease® diagnostic test and compare its performance with culture.
Study Design: Cross-sectional study.
Place and Duration: From September 2017 to July 2018, across-sectional study was conducted at the Aga Khan University Hospital.
Methodology: Patients attending endoscopy unit at the hospital were randomly sampled to provide gastric biopsy specimen. One specimen was tested for presence or absence of H. pylori using Pronto dry rapid urease® test and another specimen subjected to in vitro culture test which were then compared with histology reference results. Test validity and reliability was determined using Graph Pad Prism v5.01.
Results: Of 274 study specimens, 121(44%) were positive for histology. Ninety-one (33%) of the study specimen were positive for culture compared to 147(54%) for Pronto dry rapid urease®. Pronto dry rapid urease® test had sensitivity of 100% (97.5%-100%) against 73.6% (64.8%-81.3%) for culture. Specificity was 96.1% (91.1%-98.7%) for Pronto dry rapid urease® compared to 35.3% (95% CI 24.1%-47.8%) for culture. Positive predictive value was 96.7% (92.5-98.9%) for Pronto dry rapid urease® compared to 97.8% (92.3%-99.7%) for culture. Negative predictive value was 100% (97%-100%) for Pronto dry rapid urease® against 82.5% (76.2%-87.7%) for culture. There was significant difference between both Pronto dry rapid urease® and culture test performance with histology in all validity measures, P< 0.001. On the other hand, there was no significant difference between Pronto dry rapid urease® and culture in all validity measures due to overlapping confidence intervals.
Conclusion: Pronto dry rapid urease® out-performed culture in sensitivity and NPV. It would be the method of choice in H. pylori detection where histology is untenable and antimicrobial profiling which require culturing the bacterium is needless.
Keywords: Helicobacter pylori, diagnosis, pronto dry rapid® urease test, biopsy, rapid urease, diagnostic tests