The diagnostic accuracy of the point-of-care urine dipstick test in detecting urinary tract infection among symptomatic patients in Nairobi County, Kenya

Background Urinary tract infections (UTIs) are among the most frequently diagnosed bacterial infections and constitute a large proportion of workload in clinical microbiology laboratories. Urine culture is the confirmatory test for UTI. However, most primary care settings routinely use the more rapid, less labour-intensive dipstick. This study assesses the characteristics of a urine dipstick test in predicting a positive urine culture and how best it can be used in resource constrained settings despite its limitations. Method A cross-sectional study was conducted at two level-V health facilities in Nairobi County, Kenya. Adults and children presenting with clinical symptoms of UTI were enrolled after obtaining written informed consent. Midstream urine samples were collected. Urinary dipstick was used to identify Nitrites (NIT) and leucocyte esterase (LE) production. Urine was cultured on Cystine Lactose Electrolyte Deficient agar, blood agar and MacConkey agar; and incubated at 37C for 24 hours. Urine cultures with pure bacterial colony counts of ≥104 cfu/ml were classified as “positive” for UTI. Results Of a total of 552 participants enrolled into the study, 124 (23%) were urine culture positive. Prior medication use was associated with culture negativity. With urine culture as the reference standard, urinary dipstick sensitivity was poor overall (using either LE+ or NIT+ to confer a positive dipstick result still only achieved sensitivity of 66.9%). Using combined NIT+ and LE+ to confer a positive dipstick result had the highest specificity (99.2%), alongside a positive predictive value of 91.1%, and a positive likelihood ratio of 35.6. A NIT+ test alone showed highest concordance with urine culture results (percentage agreement: 86%) but still had a Cohen’s Kappa value of only 0.5, conferring weak agreement overall. Conclusion Dipstick test is a poor surrogate of urine culture. However, the test may be suitable as a ‘rule-out’ test to exclude UTI, and avoid antibiotic prescription, when both NIT and LE are negative. Although dipstick continues to be in use in resource constrained settings, poor concordance with urine culture results highlights a need for better near patient tests to diagnose UTI and guide antibiotic decision-making. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Yes ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the University of St. Andrews Teaching and Research Ethics Committee (UTREC), [Approval code. MD15749] Jomo Kenyatta University of Agriculture and Technology Institutional Ethics Review Board (JKUAT-IERB) [Approval no. JKU/IERC/02316/0166] National Commission for Science Technology and Innovation (NACOSTI) [Approval no. P/21/12520]. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All relevant data are within the manuscript and its supporting information files