Collecting information from the elderly is a difficult task, especially when self-reported information is required. Although some instruments to evaluate self-reported information on digestive symptoms have been specifically tested in the elderly
, faecal impaction was not included; moreover, faecal impaction is likely to be associated with cognitive impairment
, so any study on faecal impaction should take this limitation into account.
So far we did not have a validated questionnaire to collect information from fecal impaction, so studies were based on the information contained in the medical record or the patient’s response to a single question about fecal impaction history in recent months
Our study shows that a simple questionnaire is reliable for collecting information on faecal impaction in the elderly and the limitations imposed by cognitive impairment are minimized by using a proxy.
Feasibility is one major concern with self-reported questionnaires in the elderly. The ability to understand the questions and answer them appropriately is markedly influenced by cognitive impairment
 and, depending on the complexity of the questions
, level of education. Our questionnaire is simple enough to be understood even by subjects with a primary level of education. Nonetheless, the feasibility is remarkably influenced, as would be expected, by cognitive impairment.
The best way to overcome the limitation imposed by cognitive impairment in the use of self-reported questionnaires is using the help of proxies. In general, proxies are considered useful and reliable
. In our study, we do not limit or direct the use of proxies, and subjects were allowed to choose whether they needed a proxy or not and who participated as their proxy. Obviously, not understanding all of the questions were a primary reason to elect to use the help of a proxy, but among those who did understand the questions, driving factors to choose a proxy were primary level of education, and cognitive and physical limitations. We have shown that the aid of a proxy overcomes the limitations inherent to our population, and specifically cognitive impairment. There is a fairly good agreement between subjects’ answers and medical and nursing records and, remarkably, lack of agreement is not related to education, cognitive impairment or the use of a proxy.
The main strength of our study is that the validation process was performed in a high quality of care nursing home since this is the best way to recruit a sample of elderly subjects with varying degrees of cognitive impairment. In fact, only subjects totally unable to complete the questionnaire were excluded, and a relevant proportion of the sample had moderate to severe cognitive impairment, allowing us to consider the questionnaire to be applicable for virtually all purposes. We should acknowledge some limitations. Firstly, we did not evaluate the agreement between self-reported and proxy-reported information. Since testing self-reported information against proxy-reported information is difficult and its value debatable
, we tested the final effect directly, by comparing subject derived information (either self-reported or proxy-reported) to medical and nursing records. This can be considered a true gold standard in a nursing home, where all events occur inside the institution and are recorded, especially in a center like ours, with the highest external certifications of the quality of care and processes. Secondly, although reproducibility of the main question is fairly good, reproducibility of some items is relatively low, especially items regarding the use of anterograde and retrograde lavage. This may be due simply to difficulties inherent in discriminating whether they were used just for constipation (a usual event in nursing homes) or specifically for faecal impaction, as suggested by the high reproducibility of the question regarding manual removal, which is used only for faecal impaction.