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Evaluation of the diagnostic performance of the urine dipstick test for the detection of urinary tract infections in patients treated in Kenyan hospitals
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John Maina1
, John Mwaniki1, Franklin Mwiti1, Susan Kiiru1, Japhet Katana1, Fredrick Wanja2, Joel Mukaya3, Osborn Khasabuli2, Benon Asiimwe4, Stephen Gillespie5, John Stelling6, Stephen Mshana7, Matthew Holden5, Wilber Sabiiti5, John Kiiru1,8 and HATUA consortium
Abstract
Introduction. Culture is the gold-standard diagnosis for urinary tract infections (UTIs). However, most hospitals in low-resource countries lack adequately equipped laboratories and relevant expertise to perform culture and, therefore, rely heavily on dipstick tests for UTI diagnosis.
Research gap. In many Kenyan hospitals, routine evaluations are rarely done to assess the accuracy of popular screening tests such as the dipstick test. As such, there is a substantial risk of misdiagnosis emanating from inaccuracy in proxy screening tests. This may result in misuse, under-use or over-use of antimicrobials.
Aim. The present study aimed to assess the accuracy of the urine dipstick test as a proxy for the diagnosis of UTIs in selected Kenyan hospitals.
Methods. A hospital-based cross-sectional method was used. The utility of dipstick in the diagnosis of UTIs was assessed using midstream urine against culture as the gold standard.
Results. The dipstick test predicted 1416 positive UTIs, but only 1027 were confirmed positive by culture, translating to a prevalence of 54.1 %. The sensitivity of the dipstick test was better when leucocytes and nitrite tests were combined (63.1 %) than when the two tests were separate (62.6 and 50.7 %, respectively). Similarly, the two tests combined had a better positive predictive value (87.0 %) than either test alone. The nitrite test had the best specificity (89.8 %) and negative predictive value (97.4 %) than leucocytes esterase (L.E) or both tests combined. In addition, sensitivity in samples from inpatients (69.2 %) was higher than from outpatients (62.7 %). Furthermore, the dipstick test had a better sensitivity and positive predictive value among female (66.0 and 88.6 %) than male patients (44.3 and 73.9 %). Among the various patient age groups, the dipstick test’s sensitivity and positive predictive value were exceptionally high in patients ≥75 years old (87.5 and 93.3 %).
Conclusion. Discrepancies in prevalence from the urine dipstick test and culture, the gold standard, indicate dipstick test inadequacy for accurate UTI diagnosis. The finding also demonstrates the need for urine culture for accurate UTI diagnosis. However, considering it is not always possible to perform a culture, especially in low-resource settings, future studies are needed to combine specific UTI symptoms and dipstick results to assess possible increases in the test’s sensitivity. There is also a need to develop readily available and affordable algorithms that can detect UTIs where culture is not available.
- Received:
- Accepted:
- Published Online:
Keyword(s):
dipstick test
,
leucocytes esterase
,
nitrites
,
urinary tract infections
and
urine culture
Funding
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Medical Research Council - UK
(Award MR/S004785/1)
- Principal Award Recipient: MatthewHolden
© 2023 The Authors