An investigation of laboratory test methods for predicting the in-use leakage performance of urine-absorbing aids in nursing homes.

The absorption before leakage method for measuring the absorption capacity of urine-absorbing aids was investigated. Along with the existing international standard (ISO 11948-1:1996, the Rothwell method), it was run on 12 experimental products whose in-use leakage performance was established by 55 incontinent nursing home residents. Methods were evaluated by considering their simplicity, their repeatability within - and their reproducibility between - six laboratories, and their correlation with in-use product performance. ISO 11948-1:1996 - which measures the absorption capacity of products under simple conditions - showed good repeatability and reproducibility, and reasonable correlation with in-use data. However, it proved blind to the effects of leg cuffs that conferred measurable benefits in real use. It should, therefore, be used with caution. The absorption before leakage method - which measures how much a product will hold before leakage when it is mounted on a manikin and standard aliquots of liquid are applied - is more complex and had poorer repeatability and reproducibility. However, it had stronger correlations with in-use data and successfully detected the benefits of leg cuffs on insert products. It is concluded that it holds potential as a new international standard to replace or complement ISO 11948-1:1996, and the necessary refinement work has been ongoing since the 2007 project described here. Two other laboratory methods were run opportunistically. A rewet method (Spanish national standard UNE 153601-2:2008) - for measuring the escape of fluid from a product under pressure - showed poor repeatability and reproducibility. Finally, an acquisition method was used to measure how quickly products absorbed two successive standard aliquots of liquid. It proved robust, showing good repeatability and reproducibility. Although measurements generally correlated well with in-use leakage performance, a direct causal link is unlikely. Products with high absorption capacity tend also to absorb quickly.