Fibre-supplemented tube feeding in the hospitalised elderly

Transcription

1 Age and Ageing 2005; 34: Age and Ageing Vol. 34 No. 2 British Geriatrics Society 2005; all rights reserved doi: /ageing/afh242 Published electronically 29 November 2004 Fibre-supplemented tube feeding in the hospitalised elderly MAURITS F. J. VANDEWOUDE, KATHLEEN M. J. PARIDAENS, RAYMONDA A. L. SUY, MIREILLE A. A. BOONE, HEIDI STROBBE UCG (Universitair Centrum Geriatrie), ZNA, Campus Elisabeth, Leopoldstraat 26, 2000, Antwerpen, Belgium Address correspondence to: M. F. J. Vandewoude, Floralienlaan 38, 2600 Berchem, Belgium. maurits.vandewoude@ua.ac.be Abstract Objectives: to evaluate the effect of fibre supplementation in enteral feeding on bowel function in hospitalised geriatric patients, and to assess its metabolic and nutritional efficiency. Design: prospective randomised controlled trial with stratification for diabetes. Setting: Department of Geriatrics at the University of Antwerp. Subjects: during 30 months (January 2000 June 2002) every hospitalised patient requiring tube feeding was assessed for eligibility (n = 183). Finally 172 patients (19% diabetics) were randomised. Methods: an enteral nutritional regimen consisting of 30 kcal/kg in 2000 ml with a calorie/nitrogen ratio of 156 with or without fibre was instituted. At weekly intervals, stool output was qualitatively evaluated by recording frequency, volume (small <1/2 cup, large >1/2 cup) and consistency (solid-formed, soft-pasty or liquid-watery). Nutritional and metabolic effects were evaluated through laboratory analysis. Results: overall mortality was 24% with a trend for excess mortality in diabetic patients (33.3% versus 21.6% in non-diabetics; P = 0.176). There was no difference in duration of feeding between the fibre group (27.5 days; 95% CI = ) and the no fibre group (27.9 days; 95% CI = ). In the fibre-supplemented group, stool frequency was lower (4.1 per week; 95% CI = ) than in controls (6.3 per week; 95% CI = ). Qualitatively, stool consistency was higher (P<0.001) but no difference in volume was noted. There were no differences in final laboratory parameters between groups. Conclusions: fibre supplementation improved bowel function with reduced stool frequency and more solid stool consistency. It did not affect the nutritional efficiency of enteral feeding in hospitalised geriatric patients. Diabetes may be a risk factor for mortality in malnourished patients requiring tube feeding. Keywords: fibre, elderly, tube feeding, enteral nutrition, bowel function Introduction Fibre supplementation has been recommended to normalise bowel function, improve feeding tolerance and reduce diarrhoea in enteral nutrition [1 4]. Diarrhoea is often reported as the most common complication of enteral tube feeding in the acute care setting [5]. The true incidence of diarrhoea, however, is difficult to define owing to the lack of a universally accepted definition [6]. Fibre-free enteral feeding provokes an abnormal secretion of water and electrolytes in the ascending colon [7]. This colonic secretion of fluid and electrolytes can be reversed by an infusion of shortchain fatty acids in the right colon [8]. Because short-chain fatty acids are produced by fermentation of fibre in the colon [9], the addition of fibre may improve salt and water absorption and overcome the diarrhoea associated with tube feeding. In addition to controlling salt and water absorption, other effects of fibre may influence intestinal transit. Lin et al. showed that fibre-supplemented nutrition slowed intestinal transit by intensifying inhibitory feedback from the distal gut [10]. Conversely, in patients requiring longer-term enteral feeding, faecal impaction and constipation are the most commonly cited gastrointestinal problems [11]. This is particularly the case in a chronically sick, disabled and bedridden population [12]. Since fibre addition is recommended for treating constipation, the provision of fibre could also benefit patients receiving long-term enteral feeding [13]. Furthermore fibre addition may also have favourable metabolic effects. Increasing soluble fibre can contribute to cholesterol lowering [14] and fibre-rich diets can improve glucose tolerance [15]. Most clinical studies addressing the effect of fibresupplemented enteral nutrition used fibre from a single source, mostly derived from soy polysaccharide. Indeed, of the single fibre sources, soy polysaccharide seemed to show most benefit, although consistent and significant improvements were not demonstrated unequivocally. Recently, new 120

2 Fibre-supplemented tube feeding in the hospitalised elderly fibre-processing techniques have changed the soluble/insoluble fibre ratios in commercial formulae. This makes previous data about fibre addition more difficult to interpret. Different types of fibres may have different effects. A recent study with polymeric enteral formula containing a mixture of six fibres showed normalisation of the whole gut transit time and the maintenance of colonic motility in healthy volunteers [16]. Since malnutrition is a major risk factor for morbidity and mortality in the hospitalised geriatric patient, nutritional support is a cornerstone of management in geriatrics [17, 18]. Because data on tube feeding with additional soluble/ insoluble fibres are very sparse, a randomised controlled trial was started. It evaluates the clinical effects of fibresupplemented formulae on bowel function in a population of hospitalised elderly adults. Methods Patients From January 2000 until June 2002, patients at the Department of Geriatrics were considered eligible for the trial when they needed enteral nutrition support. Informed consent for the feeding protocol was given by the patient or their legal representative. In this prospective controlled trial, candidates were sequentially assigned by one of the dieticians (R.A.L.S., M.A.A.B., H.S.) to one of the two groups, stratified for the presence of diabetes mellitus (fasting glycaemia at admission >126 mg/dl) and for weight (<55 kg). The control group received standard enteral nutrition, the study group received the same enteral nutrition supplemented with fibre. Patients with inflammatory bowel disease, liver disease (transaminases >2 normal upper limit), renal dysfunction (creatinine >2 mg/dl), progressive malignant disease or metabolic instability were excluded. Parameters Before patients were included gender, age, and the presence of depression and dementia were recorded. Nutritional status was determined by anthropometric and laboratory values. Mid-arm circumference (MAC), triceps skin-fold thickness (TSF) and arm muscle circumference (AMC) were measured according to standardised techniques [19, 20] by one of the clinicians (M.F.J.V., K.M.J.P). Blood samples for blood cell count, biochemistry (glycaemia, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides) and nutritional parameters (albumin, pre-albumin, transferrin and total protein) were measured at initial and final visit. For patients who died during the trial, the last available laboratory values were carried forward on condition that the measurement was at least 14 days separate from baseline. At weekly intervals, stool output was qualitatively evaluated by the nursing staff, who were blinded to the nutritional regimen of the patient. For this purpose they used a validated tool for recording frequency, volume (small <1/2 cup, large >1/2 cup), and consistency (solid-formed, soft-pasty, or liquid-watery) [21]. To guarantee a uniform assessment, a visual scale to define the consistency of the stools was provided. Medication intake was also recorded on a weekly basis. Randomised patients who discontinued the tube feeding or died within 1 week were excluded from further analysis. Feeding formula The daily enteral nutritional regimen consisted of 30 kcal/kg in 2000 ml with a calorie/nitrogen ratio of 156. The fibresupplemented group received 30 g fibre with 33% insoluble (cellulose and hemicellulose A) and 67% soluble (pectin, hemicellulose B, inulin) fibre irrespective of the total caloric content of the regimen. Statistical analysis The t-test for independent samples was used to evaluate differences in means between groups after control of the normality assumption (F-test). If the condition of normality assumption was not fulfilled, the Mann Whitney U nonparametric test for comparisons of continuous variables was used. For comparisons of categorical variables, the Chisquare test was used. All tests were two-sided and a P value of <0.05 was considered to indicate statistical significance. Practical statistical analysis was performed using the Statistics Package for Social Scientists (SPSS) for Windows (11.0.1). Results During the 30-month inclusion period, 172 patients (mean age 81.3 ± 7.3 years) were randomised to receive enteral tube feeding with or without fibre supplementation. Baseline characteristics of both groups were comparable and are shown in Table 1. In the population under study, 19% had diabetes, 36% were demented and 13% fulfilled the criteria for depressive disorder. Overall mortality during the data collection period was 24%. There was a trend for excess mortality in the diabetic patients (33.3% versus 21.6% in non-diabetics; P = 0.176). There was no difference in mean Table 1. Baseline characteristics in groups with and without fibre supplementation Fibre No fibre P Number Age (years) 82.8 ± ± Men 16 (23) 26 (31) 0.59 Diabetes 14 (20) 16 (19) 0.36 Depression 14 (20) 7 (8) 0.07 Dementia 25 (36) 30 (35) 0.63 Nutritional parameters MAC (cm) Male 27.1 ± ± Female 26.1 ± ± TSF (% normal) Male 70 ± 9 65 ± Female 59 ± ± AMC (% normal) Male 96 ± 4 95 ± Female 98 ± ± Values are numbers, percentage in parentheses, or expressed as mean ± SD. MAC, mid-arm muscle circumference; TSF, triceps skin-fold thickness; AMC, arm muscle circumference. 121

3 M. F. J. Vandewoude et al. duration of feeding between groups ( fibre 27.5 ± 4.3 days versus no fibre 27.9 ± 4.0 days). In the fibre-supplemented group, stool frequency was lower than in the control group (4.1 ± 2.6 per week versus 6.3 ± 4.7 per week; P < 0.001). Furthermore, stool consistency was higher in this group (P < 0.001) than in patients without fibre supplementation, though no qualitative difference in volume was noted (Table 2). At the end of the feeding period there were no differences in glycaemia, lipid profile (Table 3) and nutritional parameters between groups (Table 4). Total cholesterol decreased in both groups. Visceral protein parameters remained stable. Thirty-two per cent of the patients in the control group and 20% of the patients in the fibre-supplemented group received antibiotics (P = 0.92) with a mean duration of 11.7 ± 5.6 days and 9.4 ± 5.7 days, respectively (P = 0.83). Laxative use was significantly higher in the control group: 28% of the controls versus 13% in the fibre-supplemented group (P < 0.02). The duration of laxative use was not significantly different between groups with medians of 34 versus 40.5 days (P = 0.52). The use of other medication classes (anticholinergic, antidepressant and gastrokinetic agents) was too limited to draw a meaningful conclusion. Table 2. Feeding period and stool characteristics with and without fibre supplementation Fibre No fibre P Duration feeding period (days) 27.5 ± ± Stool frequency (times/week) 4.1 ± ± Stool consistency Solid-formed 38 (31) 41 (21) Soft-pasty 84 (68) 130 (66) Liquid-watery 2 (2) 26 (13) Stool volume <1/2 cup 56 (46) 101 (51) 0.55 >1/2 cup 66 (54) 96 (49) Values are numbers, percentages in parentheses, or expressed as mean ± SD. Table 3. Glycaemia and lipid parameters before and after enteral feeding with or without fibre Before After P Fibre Glycaemia (mg/dl) Non-diabetics 102 ± ± Glycaemia (mg/dl) Diabetics 143 ± ± Total cholesterol (mg/dl) 194 ± ± HDL-cholesterol (mg/dl) 50 ± ± LDL-cholesterol (mg/dl) 113 ± ± Triglycerides (mg/dl) 119 ± ± No fibre Glycaemia (mg/dl) Non-diabetics 91 ± ± Glycaemia (mg/dl) Diabetics 156 ± ± Total cholesterol (mg/dl) 188 ± ± HDL-cholesterol (mg/dl) 48 ± ± LDL-cholesterol (mg/dl) 111 ± ± Triglycerides (mg/dl) 128 ± ± Values are expressed as mean ± SD. 122 Table 4. Nutritional parameters before and after enteral feeding with or without fibre Before After P Fibre Albumin (g/l) 29.3 ± ± Pre-albumin (mg/dl) 14.6 ± ± Transferrin (mg/dl) 172 ± ± Total protein (g/l) 61 ± 8 57 ± No fibre Albumin (g/l) 28.3 ± ± Pre-albumin (mg/dl) 16.1 ± ± Transferrin (mg/dl) 176 ± ± Total protein (g/l) 62 ± 8 60 ± Values are expressed as mean ± SD. Discussion Fibre supplementation in enteral tube feeding remains controversial [22]. This randomised controlled trial evaluated the clinical effect of fibre addition in frail, hospitalised geriatric patients. Fibre supplementation improved bowel function. The addition of fibre did not compromise nutritional efficiency compared with fibre-free formulae. However, neither did it seem to offer a clinically evident metabolic advantage. Baseline characteristics show that this population has global protein-calorie malnutrition with a reduction in both anthropometric and visceral protein parameters. Also, there was a substantial prevalence of diabetes, dementia and depression. The observed overall mortality of 24% during the trial clearly underscores the high risk for developing complications. Although not statistically significant, there was a trend for increased mortality in diabetes. This suggests that diabetes is a specific risk factor in this population. Nutritional support is intended to improve clinical outcome in older patients. It does so by providing energy and protein, but the absorption of substrate may be influenced by the presence of dietary fibre. Increased faecal excretion of nitrogen and fat has been reported during consumption of a high-fibre diet [23, 24]. Others do not find a major effect of fibre addition on macronutrient absorption in healthy volunteers [25] or hospitalised patients [26]. Adaptive mechanisms with prolonged use of fibre and contribution of fibre fermentation to some digestible energy could compensate at least partially for possible losses. In our study there was no clear effect of the fibre addition on nutritional parameters between groups. So, the addition of fibre constitutes no disadvantage for the nutritional efficacy of the regimen. A secondary effect of fibre on nutrient absorption could be an improvement of the lipid profile in general, or of glycaemia in diabetic patients [15]. However, overall glycaemic control was not different between our study groups. A subgroup analysis of the diabetic patients in the sample was equally unable to show a difference. The enteral nutrition regimen reduced total cholesterol but it did so in both groups equally. Our findings do not support the claim that fibre strongly influences intestinal absorption of nutrients or has a favourable effect on glycaemia and

4 Fibre-supplemented tube feeding in the hospitalised elderly cholesterol level. Others too have concluded that addition of soluble fibre only had a minor effect on serum cholesterol [14], and that there was only a minimal effect on absorption of minerals [27]. The same limited effects of fibre on nutrient absorption have been seen in animal studies [28]. Separate from the metabolic effects of enteral nutrition, avoiding diarrhoea and constipation is particularly important in a functionally compromised and often bedridden patient population such as the frail hospitalised elderly. To judge the clinically important effects of fibre addition on bowel function, an analysis of faecal production and bowel movements is necessary. In routine practice it is difficult to measure stool weight. Therefore, clinical definitions tend to be used and quantitative measurements should be replaced by qualitative measurements. Guenter et al. developed a stool output assessment tool for this purpose and tested it for validity and reliability [21]. Stool output scores were determined by using a 24-hour output form that assessed stool size, consistency and frequency. Using this qualitative stool output tool we found that fibre has a regulatory effect on bowel function in older patients. Stool consistency improves, with less watery diarrhoea and with bowel movements that follow a more regular scheme. This was confirmed by the observation that the use of laxatives was considerably higher in the group without fibre, even though watery diarrhoea was more prevalent among them. This may be the result of improved absorption of salt and water in the colon owing to the increased availability of shortchain fatty acids in the fibre group [8, 29]. It confirms the results in trials in post-operative and intensive care units [30], and those in a small trial in elderly patients where Nakao et al. [4] found favourable effects on bowel function. Our findings should be interpreted within the context of the data that we analysed in a qualitative manner rather than with quantitative methods. On the other hand, qualitative methods do estimate differences that can be considered more easily as clinically significant. In conclusion, this randomised trial suggests that fibreenriched enteral nutrition improves bowel function in a frail, hospitalised geriatric population. Fibre addition does not compromise nutritional efficiency nor does it seem to offer a clinically evident metabolic advantage. Since control of symptoms is very important in geriatric care, it seems justifiable to recommend fibre-supplemented feedings as the standard tube-feeding formulae. This advice should be based on the clinically perceptible positive effects of regulating colonic function rather than on claimed nutritional and metabolic advantages, which remain to be proven. Key points The addition of fibre to enteral feeding regimens improves bowel function. Fibre has no clinically significant metabolic effect in geriatric patients receiving tube feeding. Fibre addition does not compromise the nutritional efficiency of enteral feeding. Acknowledgements We would like to thank the staff of the Geriatric Units (University of Antwerp) for their involvement in this study, and John Weil for the helpful suggestions regarding the final manuscript. Conflict of interest There are no conflicts of interest to declare. References 1. American Gastroenterological Association. American Gastroenterological Association technical review on tube feeding for enteral nutrition. Gastroenterology 1995; 108: Scheppach W, Burghardt W, Bartram P, Kasper H. Addition of dietary fiber to liquid formula diets: the pros and cons. JPEN J Parenter Enteral Nutr 1990; 14: Spapen H, Diltoer M, Van Malderen C, Opdenacker G, Suys E, Huyghens L. 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