Development of the instrument
We developed a five question questionnaire to gather information about self-reported episodes of faecal impaction, their frequency, and therapeutic actions to remove them (manual removal, retrograde lavage –enema-, and anterograde lavage -intensive laxative use), with a recall period of one year, including two questions for evaluating understandability and need of a proxy.
Prior to validation in the desired setting (nursing home), we undertook a face validity and feasibility process. The questionnaire was presented to ten gastroenterologists and ten doctors specifically dedicated to medical care in nursing homes to test its face validity. They were asked to provide their opinion about the questions and their suggestions for improvement. Feasibility was pre-tested with ten non institutionalized subjects older than 80 years-old, without significant cognitive impairment. They were asked to complete the questionnaire and afterwards one of the investigators revisited questions and answers with each patient, obtaining feedback about their ability to understand each question and the appropriateness of the answers given.
Validation of the questionnaire
The study sample was recruited in a single nursing home (Centro “Valdeluz”, Madrid). The quality of care in this nursing home has been certified by the regional authority (“Madrid excellence” certification) and AENOR (ISO 9001:2000). It has the capacity to accommodate 244 residents. All residents were considered eligible and the only exclusion criteria were the definitive inability to answer the questionnaire even with the aid of a proxy (in the opinion of one investigator), and not providing consent to participate.
Participants were asked to complete the final version of the questionnaire. Two questions were added to recall if they completely understood the questionnaire by themselves and whether they needed the assistance of a proxy to complete it. The subjects themselves decided whether or not a proxy was required, as well as who was asked to be the proxy.
The medical and nursing records of the subjects were abstracted by a physician with no knowledge of subjects’ answers to the questions. Using a structured form, information was collected regarding the subjects’ history of faecal impaction, frequency and methods of removal. In addition, information on physical functional and cognitive impairment was recorded. As part of the clinical protocol, at admission and every 6 months thereafter, all residents underwent a Barthel’s test to evaluate physical function [
23,
24] and the mini-cognitive exam MEC-35 [
25], a Spanish validated version of the Folstein´s mini-mental test [
26]. A score of 19 to 23 was classified as mild, a score of 14 to 18 as moderate, and less than 14 as severe cognitive impairment [
27].
Analysis
In the literature, definition of Fecal Impaction is elusive, even in the best review published in the literature [
28]. Definition was review by Creason and Sparks [
18] and among those definitions provided by the literature, we chose the more restrictive which, was considered appropriate by gastroenterologists and nursing homes’ doctors, according to the first part of the design of the questionnaire. Thus, faecal impaction was defined as an accumulation of hard faeces in the rectum that the subject was unable to evacuate themself, occurring at least once in the last year. Level of education was categorized as either primary (school or just able to read and write) or secondary or higher (including high school, professional education and university education).
Feasibility was evaluated in the institutionalized sample of residents by the subjects self-reporting whether they could, or could not, understand all questions. We analyzed to what extent this led to the use of a proxy, and explored whether age, gender, time in the institution, cognitive impairment and level of education were associated with not understanding all of the questions using a regression model.
For the reproducibility test, twenty-eight subjects that were participating in the concurrent validity study were asked to answer the questionnaire on two occasions, 7–10 days apart. They were selected at random (the first 28 participants) from all participants. Concurrent validity was analyzed comparing the agreement between faecal impaction in the last year, as reported in the questionnaire by the subject, and the history of faecal impaction in the last year according to medical records.
Reproducibility and concurrent validity were analyzed by simple agreement and weighted kappa statistics.
We analyzed the factors associated with the decision to use a proxy, including the impact of cognitive and functional impairment and the understandability of the questionnaire as the key influencing variables, adjusting for age, gender, time in residence, and level of education. In addition, we explored whether using a proxy was associated with disagreement between self-reported faecal impaction in the previous year and medical/nurse diagnosis. This was examined using a logistic regression model, adjusting for age, gender, time in residence, level of education, cognitive impairment and functional abilities (Barthel’s score).
Ethical aspects
This study was approved by the Ethics Committee of the Hospital Clinico San Carlos (CEIC- Code: 10/014-E) and all data were treated confidentially by the researchers, according to law 15/99 on protection of personal data.
All participants signed the document of informed consent for participation in the study.