- Research article
- Open Access
Risk factors associated with lower defecation frequency in hospitalized older adults: a case control study
BMC Geriatrics volume 15, Article number: 44 (2015)
Constipation is highly prevalent in older adults and may be associated with greater frequency of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). We investigated the prevalence of lower defecation frequency (DF) and risk factors (including AECOPD) associated with lower DF among hospitalized elderly patients.
We conducted a retrospective case–control study in a community hospital of Southeast Ohio. Adults aged 65 years or older admitted during 2004 and 2006 were reviewed (N = 1288). Patients were excluded (N = 212) if their length of stay was less than 3 days, discharge diagnosis of Clostridium difficile-associated diarrhea, death or ventilator- dependent respiratory failure during hospitalization. Lower DF was defined as either an average DF of 0.33 or less per day or no defecation in the first three days of hospitalization; cases (N = 406) and controls (N = 670) were included for the final analysis.
Approximately 38% had lower DF in this patient population. Fecal soiling/smearing of at least two episodes was documented in 7% of the patients. With the adjustment of confounders, AECOPD (adjusted odds ratio [AOR] =1.47, 95% confidence interval [CI] =1.01-2.13) and muscle relaxant use (AOR =2.94; 95% CI =1.29-6.69) were significantly associated with lower DF. Supplementation of potassium and antibiotic use prior to hospitalization was associated with lower risk of lower DF.
Approximately 38% of hospitalized older adults had lower DF. AECOPD and use of muscle relaxant were significantly associated with lower DF; while supplementation of potassium and antibiotic use were protective for lower DF risk after adjusting for other variables.
Constipation is highly prevalent in older adults [1-3]. It was estimated that up to 55% of nursing home residents received laxatives regularly , and 42% of patients admitted to two acute geriatric wards had fecal impaction . While the majority of constipated patients have a benign clinical course with their constipation being considered functional in nature, chronic constipation has been associated with poor quality of life and reduced survival .
There is evidence that gastrointestinal conditions such as constipation  and gastro-esophageal reflux disease  may be associated with acute exacerbations of chronic obstructive pulmonary disease (AECOPD). It was shown that 40% of patients with stable COPD reported constipation and abdominal distention symptoms . As COPD is highly prevalent and the third leading cause of death among older adults in the USA , its possible association with constipation raises a clinical need to explore efficacious prevention and therapeutic strategies to improve its clinical outcome.
Despite the high prevalence of constipation, little information is available on the patterns of bowel health and defecation frequency (DF) among hospitalized adults. The purpose of this study was to report the prevalence of lower DF and to analyze associated risk factors (including AECOPD) with lower DF of hospitalized elderly patients in a community hospital.
Patients and data
Data were retrieved from a local community hospital of Southeast Ohio. This dataset was previously described elsewhere . Briefly, adults aged 65 years or older admitted during 2004 and 2006 were reviewed (N = 1288). Only the first admission was reviewed for patients with readmission(s). Patients were excluded (N = 212) if their hospital stay was less than 3 days, stool was positive for Clostridium difficile toxin, hospitalization-related mortality, on ventilator, or records were incomplete. Written informed consent for participation in the study was not obtained (and not required) from participants. This study was approved by the Ohio University Institutional Review Board.
Data included the number of defecation during hospitalization as documented by nursing staff, demographics, smoking status, medical history, medication use, admission/discharge diagnoses, and laboratory results (serum albumin, calcium, and potassium levels – obtained from the first set of blood). Medication use prior to admission was recorded as current use vs. non-use. The diagnosis of AECOPD was based on clinical diagnosis with the confirmation of chest x-rays to avoid the overlapped diagnosis with pneumonia . The diagnosis of acute congestive heart failure (CHF), pneumonia, and AECOPD were discharge diagnoses with which patients were mainly treated for during the hospital stay.
Definition of cases
It is commonly agreed that fewer than three defecations per week is considered infrequent bowel movement and constitutes one element of the diagnostic criteria for functional constipation . Given the fact that not all patients stayed in the hospital for more than one week, we decided to use the average DF per day (as calculated by the number of total defecations divided by the number of hospitalization days) as an indicator of lower DF. Those with an average DF 0.33 or less per day (i.e., ≤ one defecation in three days) or having no defecation for the first three days of hospitalization were considered lower DF (Cases; N = 406); those without the above conditions were grouped as the controls (N = 670). Episodes of fecal soiling/smearing were also recorded and not considered as defecation.
Were encountered in the smoking history and laboratory results. Patients without documented data were excluded from data analysis.
Mean, standard deviation (SD), and percentage (%) with frequency were used to report continuous and discrete variables. Chi-square test and two-sample t-tests (two-sided) were used to assess if there was a significant association between two groups. Multiple logistic regression with odds ratio (OR) with a 95% confidence interval (CI) was used to measure the association between a risk factor and lower DF after adjusting for other variables in the model.
Potential confounders used in the multiple logistic regression model analysis included age, gender (Model 1), pneumonia, and acute congestive heart failure (Model 2), current smoking status, cognitive impairment, supplementation of potassium, calcium, and iron, anti-cholinergic drugs (including antipsychotics, H1 antihistamines, antimuscarinic receptor blocker, and antispasmodic drugs), diuretics, narcotics, muscle relaxants, and oral antibiotic use prior to admission (Model 3), and uses of β2 agonists and anti-cholinergic bronchodilators (Model 4, shown in Additional file 1).
Hosmer and Lemeshow goodness-of-fit test was used to assess the fit of the model to the data. Regression diagnostics were used to assess if a model is reasonable. Statistical significance was set at a level of .05. Statistical software package, PC SAS version 9.3 (SAS Institute, Inc., Cary, NC) was used to perform the statistical analyses.
Approximately 26% (281/1076) of patients had an average DF of 0.33 or less per day, and 26% (284/1076) had no defecation for the first three days of hospitalization; 38% (406/1076) had either one of the above. Fecal soiling/smearing of at least two episodes was documented in 7% (74/1076) of the study patients.
Both case and control groups were similar in the mean age (mean ± SD, 79.0 ± 8.2 vs. 79.9 ± 8.3 years), female gender (64% vs. 66%), current smoking status (13% vs. 11%), and mean blood levels of potassium, calcium and albumin on admission (all p values ≥0.10; Table 1). The case group was taking muscle relaxants more often (4% vs. 2%), but significantly less in the supplementation of potassium, calcium, and iron as well as the antibiotics prior to admission than the control group. Both case and control groups were similar in the use of anti-cholinergic drugs, calcium channel blockers, proton pump inhibitors, narcotics, and anti-cholinergic and β2 agonist bronchodilators (Table 1).
With the adjustment of age and gender (Model 1), and acute diagnosis of pneumonia and congestive heart failure (Model 2), AECOPD was not associated with lower DF (results shown in Additional file 1). With further adjustment of current smoking status, cognitive impairment, and supplementation as well as medication uses (Model 3), AECOPD (adjusted OR = 1.47, 95% CI = 1.01-2.13) and uses of muscle relaxants (AOR =2.94; 95% CI =1.29-6.69) were significantly associated with lower DF by the multiple logistic regression model (Table 2 and Additional file 1). On the other hand, supplementation of potassium and iron, and antibiotic use prior to hospitalization were significantly associated with lower risk of lower DF. The model was reasonable as regression diagnostics showed no collinearity among risk factors; no noticeable outlier or influential observations; and the model fit data very well (Chi-square =6.77, df = 8, p = 0.56, Hosmer and Lemeshow goodness-of-fit test). Similar results held if we further adjusted for uses of β2 agonists and anti-cholinergic bronchodilators (model 4 in Additional file 1).
Our study demonstrated that approximately 38% of hospitalized older adults had lower DF during their hospital stay. The risk factors that were associated with lower DF were the use of muscle relaxants and those with AECOPD after adjusting for confounders. On the other hand, supplementation of potassium and iron and antibiotic use were associated with a lower risk for lower DF.
This study found that AECOPD was associated with higher risk of lower DF during the hospital stay after adjusting for confounders that were listed in Table 2. The unadjusted OR for the association was 1.41 [95% CI = 0.99 - 2.01], which was very close to the significant level set at 0.05. As many conditions could alter defecation frequency, we adjusted for confounders in the multiple logistic regression models by including those risk factors that are known associated with constipation (e.g., supplementation of calcium, medications with anticholinergic effects, and narcotic drugs) as well as those that were significantly different between the case and control groups in this study (e.g., cognitive impairment, and supplementation of potassium and iron). With the adjustment of the above risk factors, patients with AECOPD had approximately 47% higher risk for lower DF (shown in Table 2). It is possible that the association may be further confounded by the anti-cholinergic side effects of bronchodilators which were commonly used during hospitalizations. With the inclusion of additional confounders for COPD (i.e., uses of β2 agonists and anti-cholinergic bronchodilators) into the model (model 4, results shown in Additional file 1), the association between lower DF and AECOPD remained significant (adjusted OR = 1.50, 95% CI = 1.01 - 2.22). Therefore, it was less likely that bronchodilator use accounted for the association.
Several clinical trials have shown that maintenance treatment with azithromycin (a macrolide) significantly decreased the exacerbation rate of COPD and improved quality of life [11,12]. In addition to the immunomodulatory, anti-inflammatory, and antibacterial effects of azithromycin, it is also known that macrolides stimulate gastrointestinal motility  which may present as diarrhea . One of our speculations is that the benefit from azithromycin treatment on the reduction of COPD exacerbation rate may be exerted on the improvement of bowel motility and function in addition to its antibacterial effects. The clinical implication from our study may suggest that improving bowel motility (as shown by higher DF) may decrease the risk of AECOPD. It would require further studies to test the above hypothesis and the potential mechanism(s) that may explain the association between lower DF and AECOPD.
Medication’s side effects as the cause of constipation are also commonly encountered in the elderly population. Our study demonstrated that use of muscle relaxants was associated with lower DF, which was consistent with other reported findings [3,14,15]. Ueki et al. further extended this finding to the use of hypnotics conjecturing that mechanism of constipation may be induced by the myorelaxant effect of these medications during hospitalization .
Alternatively, our study revealed that use of potassium supplement and oral antibiotics prior to admission posed a lower risk for impaired DF. This was consistent with our current knowledge as potassium supplements improve bowel motility in the conditions of potassium deficiency  and may be associated with gastric irritation  which may increase bowel motility. The effect of oral antibiotics (particularly macrolide and penicillin) in increasing bowel motility (which may lead to diarrhea) is well known. In contrast, iron supplementation demonstrated a protective benefit for lower DF in our study. While iron supplement has been characteristically associated with chronic constipation , iron uses may also cause upset stomach, nausea, and diarrhea as side effects.
Although lower DF itself may not imply constipation status, infrequent bowel movement (i.e., fewer than three defecations per week) is one of the features defining constipation. Due to the lack of comprehensive subjective data, the case group may not have captured those patients who had normal DF but clinically felt constipated (i.e., straining, having lumpy or hard stool). Despite the limitation, DF was an objective feature that was readily available in our patients’ record for data analysis.
There were several limitations in our study. First, documentation of defecations depended on the reports from both nursing staff and patients. Second, patient-centered, subjective descriptions of constipation during the hospital stay were not available. Data of constipation history and laxative use were not readily available and thus, were not included for adjustment of confounders in the multiple logistic regression modeling. Furthermore, constipated patients often take over-the-counter laxatives for self-treatment, and it was not possible in capturing all the above information in a retrospective study. Third, potential confounders associated with lower DF including physical activity, functional status, and new medication use during the hospital stay were not available for data analysis. Lastly, the study patient population was mainly white and constituents of a single study site which precluded one from making generalizable conclusions.
This retrospective case–control study found that 38% of hospitalized older adults had lower DF and up to 7% of patients had fecal smearing during hospital stay in a rural community. AECOPD and use of muscle relaxants were significantly associated with lower DF; whereas supplementation of potassium and antibiotic use prior to hospitalization was protective for lower DF risk after adjusting for other confounders. Future studies focusing on the association between improving bowel health and reduction of COPD exacerbation may assist in forming more concrete hypothesis relating to how these two clinical entities inter-relate to one another.
Acute exacerbation of chronic obstructive pulmonary disease
Coronary artery disease
Congestive heart failure
Chronic obstructive pulmonary disease
Non-steroidal anti-inflammatory drugs
Talley NJ, Fleming KC, Evans JM, O’Keefe EA, Weaver AL, Zinsmeister AR, et al. Constipation in an elderly community: a study of prevalence and potential risk factors. Am J Gastroenterol. 1996;91:19–25.
Higgins PD, Johanson JF. Epidemiology of constipation in North America: a systemic review. Am J Gastroenterol. 2004;99:750–9.
Hosia-Randell H, Suominen M, Muurinen S, Pitkälä KH. Use of laxatives among older nursing home residents in Helsinki, Finland. Drugs Aging. 2007;24:147–54.
Read NW, Abouzekry L, Read MG, Howell P, Ottewell D, Donnelly TC. Anorectal function in elderly patients with fecal impaction. Gastroenterology. 1985;89:959–66.
Chang JY, Locke 3rd GR, McNally MA, Halder SL, Schleck CD, Zinsmeister AR, et al. Impact of functional gastrointestinal disorders on survival in the community. Am J Gastroenterol. 2010;105:822–32.
Sun Y, Zheng F, Li Y, Wu R, Liu Y, Liu M, et al. Correlation between lower gastrointestinal tract symptoms and quality of life in patients with stable chronic obstructive pulmonary disease. J Tradit Chin Med. 2013;33:608–14.
Terada K, Muro S, Sato S, Ohara T, Haruna A, Marumo S, et al. Impact of gastro-oesophageal reflux disease symptoms on COPD exacerbation. Thorax. 2008;63:951–5.
Deaths: Final Data for 2013. Centers for disease control and prevention. Available at: http://www.cdc.gov/nchs/fastats/deaths.htm. Accessed on April 11, 2015.
Gau JT, Acharya U, Khan S, Heh V, Mody L, Kao T. Pharmacotherapy and the risk for community-acquired pneumonia: a case–control study of hospitalized older adults. BMC Geriatr. 2010;10:45.
Rome III diagnostic criteria for functional gastrointestinal disorders. Available at: http://www.romecriteria.org/assets/pdf/19_RomeIII_apA_885-898.pdf. Accessed March 20, 2015.
Albert RK, Connett J, Bailey WC, Casaburi R, Cooper Jr JA, Criner GJ, et al. Azithromycin for prevention of exacerbations of COPD. N Engl J Med. 2011;365:689–98.
Uzun S, Djamin RS, Kluytmans JA, Mulder PG, van’t Veer NE, Ermens AA, et al. Azithromycin maintenance treatment in patients with frequent exacerbations of chronic obstructive pulmonary disease (COLUMBUS): a randomised, double-blind, placebo-controlled trial. Lancet Respir Med. 2014;2:361–8.
Itoh Z, Suzuki T, Nakaya M, Inoue M, Mitsuhashi S. Gastrointestinal motor-stimulating activity of macrolide antibiotics and analysis of their side effects on the canine gut. Antimicrob Agents Chemother. 1984;26:863–9.
Talley NJ, Jones M, Nuyts G, Dubois D. Risk factors for chronic constipation based on a general practice sample. Am J Gastroenterol. 2003;98:1107–11.
Ueki T, Nagai K, Ooe N, Nakashima MN, Nishida K, Nakamura J, et al. Case-controlled study on risk factors for the development of constipation in hospitalized patients. Yakugaku Zasshi. 2011;131:469–76.
Webster DR, Henrikson HW, Currie DJ. The effect of potassium deficiency on intestinal motility and gastric secretion. Ann Surg. 1950;132:779–83.
McMahon FG, Ryan JR, Akdamar K, Ertan A. Upper gastrointestinal lesions after potassium chloride supplements: a controlled clinical trial. Lancet. 1982;2:1059–61.
The authors wish to express thanks to Ms. I-Ju Lu for the assistance in data collection. This research was partially supported by Ohio University Heritage College of Osteopathic Medicine Research and Scholarly Activity Committee research award and NIH grant 5R21DK096201-02 (with subcontract 000393678–001 of University of Alabama at Birmingham--to Dr. Gau). The content of this research article is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Department of Defense.
The authors declare that they have no competing interests.
JTG took a full responsibility for the integrity and the accuracy of this report, made substantial contributions to the study concept and design, review of data collection, analysis and interpretation of data, and preparation of this manuscript. UHA made substantial contributions to the acquisition and interpretation of data, and the drafting and revision of the manuscript. MSK made substantial contributions to the acquisition and analysis of data and revision of the manuscript. TCK made substantial contribution to the statistical analysis and report of the results. All authors read and approved the final manuscript.
About this article
Cite this article
Gau, JT., Acharya, U.H., Khan, M.S. et al. Risk factors associated with lower defecation frequency in hospitalized older adults: a case control study. BMC Geriatr 15, 44 (2015). https://doi.org/10.1186/s12877-015-0041-0
- Bowel movement
- Hospitalized elderly
- Acute exacerbation of COPD