A method comparison study to assess the reliability of urine collection pads as a means of obtaining urine specimens from non-toilet-trained children for microbiological examination
Background. In young, non-toilet-trained children, the collection of a urine sample for microbiology can be challenging, with the application of a urine bag being the main method of collection. However, recent research has shown that absorbent pads can be used yielding similar results to bag specimens. However, weaknesses in study design erode confidence in research findings. Therefore, improvements in research design are required to fully evaluate the reliability of pad collection.
Aims of the study. This pilot study sought to test the feasibility of a technique for the collection of concurrent bag/pad urine samples from non-toilet-trained children, and to assess the reliability of urine pads over bags as a collection method for urine specimens for microbiological evaluation.
Design. A pilot, method comparison study.
Methods. Twenty concurrent bag and pad specimens were collected from non-toilet-trained children, following parental consent. Urine specimens were analysed for presence or absence of white cell count (WBC), and bacterial growth, using standard laboratory methods.
Data analysis. The Kappa (κ) statistics and confidence interval (CI) estimation were used to assess agreement between the two collection methods.
Results. Despite concurrent samples there was a lack of agreement between bag and pad specimens on both main outcome measures. Agreement between bag and pad specimens for the presence of WBC yielded a κ=0·10 (95% CI: 0·19, 0·39), indicating poor agreement, while a κ of 0·5 (95% CI: 0·12, 0·88) was calculated for the degree of agreement in bacterial growth reflecting moderate agreement. Differences in proportions of the presence of WBC between bag and pad did not quite reach significance at the 5% level 0·2 (95% CI: 0·00, 0·42, P=0·062). For cultures the difference was calculated as 0·15 (95% CI: 0·05, 0·35, P=0·125).
Conclusion. The pilot study demonstrates that concurrent urine samples can be obtained without difficulty. Despite poor to moderate agreement on outcome measures the level of agreement is greater than reported in those other studies, that use non-current methods of urine collection, suggesting an advantage of the concurrent technique. It is recommended that larger scale studies be undertaken using the concurrent collection technique to assess reliability of these findings.