Predicting the leakage performance of small bodyworn disposable incontinence pads using laboratory tests

An international multi-centre project (The ISO Pad Leakage Project) was conducted to study the leakage performance of large bodyworn incontinence pads for heavily incontinent users and to create international standards for measuring their absorption capacities in the laboratory. This was achieved by recruiting 13 user test centres through which over 100 incontinent subjects tested each of six different products (each in three different sizes) for a period of about a week to a common protocol. Over 10 000 used pads were collected and weighed and the severity of leakage from each of them recorded. Correlations were sought between these data and the results from some 50 technical tests performed in a total of 16 technical test centres in order to discover the impact of different technical parameters on clinical pad performance. It was found that at low urine weights (less than 50 g, say) pad shaping was the most important predictor of pad leakage performance: shaped pads leaked less. With increasing urine weight, absorption capacity and absorption time increased in importance until at 350 g of urine these two parameters and shaping were of about equal significance: shaped pads with high absorption capacity and fast absorption time leaked least. A second series of analyses identified two absorption capacity tests which produced data correlating well with the overall leakage performance of pads, considering all urine weights together. Both tests were checked for repeatability (precision within laboratories) and reproducibility (precision between laboratories) and have been written up as working draft standards. In due course, either or both of them should be adopted as International Standards for measuring the absorption capacity of pads for heavily incontinent users. A second, similar project (ISO Pad Leakage Project 2) has begun. It focuses on small pads for lightly incontinent ambulatory women.