Digestive symptoms in older adults : Prevalence and associations with institutionalization and mortality

1Division of Gastroenterology, University of Alberta, Edmonton, Alberta; 2Department of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia; 3Division of Geriatric Medicine, Dalhousie University, Halifax, Nova Scotia Correspondence: Dr Turki AlAmeel, Division of Gastroenterology, University of Alberta 2-39 Zeidler Ledcor Centre, 130 University Campus Northwest, Edmonton, Alberta T6G 2X8. Telephone 780-492-8243, fax 780-492-1455, e-mail talameel@gmail.com Received for publication March 29, 2012. Acccepted June 5, 2012 Digestive symptoms are common, affecting more than 60% of adults (1,2). Most symptomatic individuals do not seek medical attention (2-6). Despite this, digestive symptoms constitute a significant burden on the health care system. In 2004, a primary diagnosis of a digestive disease led to 72 million outpatient visits in the United States; the majority of those patients were >65 years of age (7). There is a paucity of data regarding the prevalence of digestive symptoms in older Canadians, although studies performed in other countries have revealed that this is a common problem, the impact of which is difficult to gauge (8-10). However, some of these were referral-based studies and their findings may not be applicable to the general population. It also unclear whether older persons who report symptoms are more likely to experience worse outcomes, such as death or institutionalization, compared with asymptomatic subjects. We conducted the present study to determine the prevalence of digestive symptoms and their association with institutionalization and mortality in community-dwelling older adults.

To make population estimates, sample weights were derived to correct for the different populations in each sampling area and for the oversampling of the older groups (12).
The full CSHA study involved 9008 individuals from the community and 1255 from long-term care institutions.The same individuals were contacted again in 1996 (CSHA-2) and 2001 (CSHA-3).The community sampling frame was based on the Canadian provincial universal health insurance plans, with the exception of Ontario, where technical limitations with the health insurance plan list prevented its use at the time.Here, the Enumeration Composite Record was used, which was a composite list of all citizens in Ontario based on electoral lists, updated between elections from information such as property sales.The response rate in the community was 72.1%.The present study included the 8949 community dwellers who were administered the relevant section of the screening questionnaire.
The CSHA screening interview included questions regarding demographics, general health and psychometric tests for cognitive impairment.The interviewers were instructed to collect collateral information from family members or proxy respondents when recording the data, particularly in cases of cognitively impaired respondents in whom personal accounts may have been unreliable.
The question used to determine the presence of digestive symptoms was: "In the past year have you had troubles with your stomach or digestive system?You can just answer Yes or No." Cognitive function was based on the score from the Modified Mini-Mental Status (3MS) examination (13).The 3MS is a validated cognitive screening instrument with a possible score of 0 to 100 that tests orientation, immediate and remote memory, attention and concentration, language and naming, verbal fluency and executive function.The respondents were categorized as cognitively normal (3MS score ≥78) or impaired (3MS score <78).
Self-rated health was assessed using a 5-point scale ranging from very good to poor; this was taken from the Older American Resources Utilization Study (14).
For these analyses, self-rated health was dichotomized as either good (combining 'very good' or 'good' responses) or poor (in which 'fair', 'poor' and 'very poor' responses were combined).Self-rated health status was missing for 18 individuals (0.002%).
Functional status was based on self-report and was assessed using the activities of daily living (ADL) scale from the Older American Resources Utilization Study (14).For our analyses, each of five functional items (eating, dressing, grooming, bathing and toileting) was scored either as 1 (can perform without help) or 0 (needs assistance or unable to perform.) Participants were categorized according to the number of impairments they reported: no impairments in ADL, one impairment, and two or more impairments in ADL.Nineteen individuals were missing data for one of the five ADL; these individuals were included in the analysis according to the sum of their nonmissing impairments.
Marital status was classified as either married (subjects who were currently married or living in common-law relationships) or unmarried (widowed, divorced, separated and previously married).Marital status data were missing for two individuals.
The CSHA was approved by local ethics committees at all participating study sites.

outcome measures
For participants who died during the 10-year follow-up, survival time was calculated as the time between the baseline interview at CSHA-1 and the date of death.Ten-year mortality was coded as either 1 (deceased by the end of CSHA-3) or 0 (alive by the end of CSHA-3).Similarly, institutionalization was coded as 1 (institutionalized by the end of CSHA-3) or 0 (remained in the community).In Canada, it is very rare for institutionalized elderly people to return to the community.

statistical methods
All subjects for whom complete data were available were included in the analysis.In all analyses, proportional weights were used to account for sampling methodology (15).
The baseline characteristics of the subjects with digestive symptoms and the asymptomatic group were compared using the χ 2 test for proportions and Student's t test for continuous variables.In all analyses, having digestive symptoms was specified as the independent variable, with mortality or institutionalization as dependent variables.The potential confounders (age, sex, self-rated health, ADL dependence and cognitive impairment) were included as covariates in the regression models.

survival analyses
Cox proportional hazard regression was used to investigate whether having digestive symptoms was associated with survival, adjusting for potential confounding factors including age, sex, 3MS score, self-rated health and number of impairments in ADL.The results of the Cox regression were reported as HRs with 95% CIs.

institutionalization analyses
Multivariable logistic regression models were used to control for potential confounding variables and to determine the independent association between digestive symptoms and incident institutionalization.
All analyses were performed using STATA version 8.1 (Stata Corp, USA) and were weighted to account for the sampling methodology.

results
Data regarding digestive symptoms of 25 subjects were missing and were necessarily excluded from the analysis.Because of their small number, their exclusion is unlikely to have significantly affected the results.
Of the 8949 participants included, 2288 (25.6%) reported having difficulty with their stomach or digestive system in the past year.More women (28.4%) complained of digestive symptoms than men (20.3%;P<0.001).Participants >75 years of age were more likely to report symptoms (P=0.04) and the mean age of subjects with digestive symptoms was six months older than those without symptoms (P=0.007).
The percentage of subjects complaining of digestive symptoms was similar between those who were single (25.9%) at the time of the survey and those who were married (24.2%).
Digestive symptoms were found more frequently among subjects with cognitive impairment as defined by a 3MS score <78, those with poor self-reported health and patients with an increased number of impairments in ADLs (all P<0.001 [χ 2 test]) (Table 1).
The presence of digestive symptoms was associated with higher mortality (unadjusted HR 1.19 [95 % CI 1.06 to 1.34]).The relationship between mortality and digestive symptoms remained statistically significant after adjusting for age, sex, cognitive function and ADL impairment (HR 1.15 [95% CI 1.05 to 1.25]).However, after adjusting for self-reported health, mortality was similar between those with and without digestive symptoms (HR 1.05 [95% CI 0.96 to 1.15]) (Table 2).
There was no association between digestive symptoms and institutionalization.

disCussion
The present study was one of the first to report on the prevalence of gastrointestinal symptoms in community-dwelling elderly Canadians.More than 25% of Canadians ≥65 years of age complained of digestive symptoms.At the time of CSHA data collection, this corresponded to more than 740,000 affected individuals in Canada.Digestive symptoms were more prevalent among subjects with advanced age and functional or cognitive impairments.
The prevalence of gastrointestinal symptoms in our study (25%) was similar to what has been reported in previously published studies.In a general population study conducted in Canada (1), the prevalence of upper gastrointestinal symptoms was 28.6%.Abdominal pain in the preceding year was reported by 25.2% of subjects in a British elderly population (9) and 24.3% of seniors living in Olmsted County, Minnesota (USA) (10).Upper dyspeptic symptoms, defined as epigastric pain, heart burn or acid reflux, was found in 25.7% of men and 32.5% of women in a Danish elderly population (8).
In the present study, women reported more digestive symptoms than men, a finding shared by other epidemiological studies involving elderly populations (8) and adults in general (10,16).In a previous Canadian study, patients were surveyed and their symptoms were classified based on Rome II classification: more women reported functional abdominal pain, bowel and anorectal disorders, while functional esophageal and gastroduodenal disorders were more prevalent in men (17).Several lines of inquiry have attempted to explain this sexrelated difference in functional gastrointestinal disorders on the basis of behavioural, hormonal, psychological or motility factors.However, the exact reason for the difference remains elusive (18,19).
In population-based studies of seniors, few have examined the differences in the prevalence of digestive symptoms among different age groups.Our results showed that subjects >75 years of age were more likely to report having digestive symptoms.Others have reported different results.Data from the United States revealed that the prevalence of dyspepsia in the elderly was similar among age groups (20).This variability may have been due to the difference in the question asked or due to the smaller number of subjects in that study (n=1375), which made it more difficult to detect difference in prevalence according to age.
To our knowledge, the present study was the first to examine the association between digestive symptoms and other important aspects of assessing older adults such as cognitive function and ability to perform ADLs.Impairment in cognitive function was associated with a greater prevalence of digestive symptoms, as were poor self-reported health and impairments in ADLs.
In the present study, we found that the presence of digestive symptoms was associated with higher mortality even after adjusting for age, sex, and cognitive function and ADL impairment.Nevertheless, the increased mortality was statistically insignificant after adjusting for self-reported health.This suggests that the presence of digestive symptoms may be a marker of deterioration in health, cognitive and/or functional status rather than a risk factor for mortality in itself.Another possibility is that digestive symptoms contribute importantly  to people's self-perception of their health status.Marital status at the time of the survey had no effect on the prevalence of digestive symptoms and digestive symptoms did not predict institutionalization.
The major strength of the present study is that the data were derived from a population-based survey generating a large representative sample of community-dwelling elderly people with 10-year follow-up of individual subjects and robust measures of cognition and function.One of the advantages of an epidemiological approach to digestive symptoms is the ability to study patients with variable symptom severity including those who had not sought medical advice (21).Other studies have shown that, in elderly populations, only 18% to 23% had sought health care for their gastrointestinal complaints in the previous year (10).The decision to consult health care providers is probably affected by the frequency and severity of symptoms (9).
Nevertheless, our study has limitations.Our survey was based on self-reported data, which can be affected by recall bias and may underestimate the prevalence of digestive symptoms (22).Another concern is misreporting if the subject was very cognitively impaired, although collateral information from proxy respondents was taken into account as much as possible in such cases.The state of health was also selfreported and its reflection of the patient's true health status is subject to personal subjective judgement.Accordingly, self-assessed health has been shown to correlate well with objective measures of health and mortality, and is a commonly used and well-validated measure (23).We relied on the subject's own assessment of severity by asking about "troubles with digestive system or stomach".Other epidemiological studies have used a similar approach (21).There is considerable variability in the type of question subjects were asked to investigate dyspepsia among different epidemiological studies.Among the most commonly used criteria in the functional gastrointestinal disorders literature are the Rome criteria (24).At the time of our baseline survey in 1991, the Rome criteria were not widely used.The elderly bowel symptom questionnaire (25) is another validated score that was published after our survey was conducted.The definition chosen for the present study, based on a broad self-report question, was designed to be as inclusive as possible of any symptoms suggestive of dyspepsia.

TAble 2 Outcomes (mortality and institutionalization) in individuals with digestive symptoms compared with those without Digestive symptoms model 1 (Unadjusted) 2 (Adjusted for age, sex) 3 (Adjusted for age, sex and cognition 4 (Adjusted for age, sex, cognition and ADls 5 (Adjusted for age, sex, cognition, ADls and SRH
Digestive symptoms (Yes/No), age (years),sex, number of basic activity of daily living (ADL) impairments, and self-rated health (SRH, good versus not good).Mortality was modelled using Cox regression.Results are presented as HRs, and OR with logistic regression.ORs for institutionalization were derived from logistic regression models