HYD: Effect of Thickened Beverages on Fluid Intake (2007)

Whelan K. Inadequate Fluid Intakes in Dysphagic Acute Stroke. Clin Nutr. 2000; 20 (5): 423-428. PubMed ID: 11534937
Study Design:
Randomized controlled trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • To investigate the fluid intakes of patients with dysphagic acute stroke
  • To evaluate the effect of disability, ward specialty and the type of fluid given on oral intake
  • To monitor the incidence of the clinical sequelae of dehydration
  • To measure the frequency of reports for biochemical parameters of hydration.
Inclusion Criteria:
  • Newly diagnosed acute stroke and dysphagia requiring thickened fluids
  • Diagnosis of acute stroke was taken from symptomology, computed tomography scan or magnetic resonance imaging scan
  • Dysphasia was diagnosed by a speech and language therapist or videofluroscopy.
Exclusion Criteria:
In order to maximize numbers eligible, no exclusion criteria (patients diagnosed with dysphagia using only a screening tool were not included).
Description of Study Protocol:


Twenty-four patients at St. George’s Hospital, U.K. with dysphagic acute stroke requiring thickened fluids were recruited between May 1999 and December 1999.


Patients were randomly assigned (using a two-way randomization table before any clinical details had been taken).

Blinding Used

No blinding was used in order to ensure compliance in recording on the charts. Staff were informed of the aim of the study and to which group the patient had been randomly assigned.


  • Control subjects received fluids thickened with powder thickener (made from modified maize starch)
  • Intervention subjects received pre-thickened drinks (apple- and orange-flavored with a syrup consistency)
  • Patients in the intervention group were also allowed hot drinks thickened with powder thickener as requested
  • All fluid intakes and outputs were recorded hourly on fluid balance charts provided by the hospital staff
  • Patients were provided with a cup that was calibrated in 10-ml increments from which to drink all thickened liquids
  • Intakes of parenteral and enteral fluids were taken from the content of the fluid containers, the rate of the infusion pump and the length of infusion period, and recorded on the same balance chart
  • Urine output was recorded for all patients with a urinary catheter in situ, using calibrated collection bags
  • Patients receiving diuretics and patients without a urinary catheter did not have output data collected
  • The incidence of chest infections and urinary tract infections (UTI) was monitored to indicate the clinical sequelae of aspiration and dehydration, respectively
  • Data was collected for 14 days or until the patient no longer required thickened fluids.

Statistical Analysis

  • Mean and standard error of the mean were calculated for fluid intakes and urine outputs using Microsoft Excel
  • Inter-group means were compared using Student’s T-test for unpaired data
  • Fisher's exact test was used to compare the incidence of UTI between groups using Stata statistical analysis package.
Data Collection Summary:
Timing of Measurements
  • Staff recorded all fluid intakes and outputs hourly on fluid balance charts provided
  • Data was collected for 14 days or until patient no longer required thickened fluids
  • Data collected represented a total of 240 patient-days.

Dependent Variables

Fluid intake as well as incidence of chest infections and UTI to indicate clinical sequelae of aspiration and dehydration, respectively.

Independent Variables

  • Fruit-flavored, ready-made, pre-thickened drinks
  • Ward specialty.

Control Variables

Powder thickener made from modified maize starch.

Description of Actual Data Sample:
  • Initial N: Twenty-four patients were recruited. No patient refused admission to the study.
  • Attrition (final N): Not indicated
  • Age: The mean age of the patients was 72.3 years (SD±13.4)
  • Ethnicity: Not described
  • Other relevant demographics: Mean Barthel score, 4.0±5.0 (Barthel score of zero indicates "fully dependent," 20 indicates "independent")
  • Anthropometrics: Mean body weight was 67.7kg (±12.7).
  • Location: St. George's Hospital, UK.
Summary of Results:

Number of Patients

Days they Received Supplementary Fluids±SEM (Percentage)

Mean Volume Infused (ml per Day)

Mean Volume Infused (Percentage of Requirements)

Mean Daily Fluid Intake ±SEM (ml)

Mean Daily Fluid Intake ±SEM (Percentage of Daily Requirements)

Total Oral







Total Enteral







Total Parenteral







Total non-oral







Total Fluid Intake








Sample Size (N)

Total Number Days Monitored

Mean Age in Years ±SD


Barthel Score

Weight (kg)

Mean Oral Fluid Intake


Acute Stroke Unit with Powder-Thickened Liquids (Control)









Acute Stroke Unit with Pre-Thickened Liquids (Intervention)









Non-Stroke Ward with powder thickened liquids (Control)









Non-Stroke Ward with pre-thickened liquids (Intervention)









Patients with Urinary Catheter in Situ

Mean Total Daily Fluid Intake (ml per Day) ±SEM

Mean Urine Output (ml per Day) ±SEM

Mean Fluid Balance (ml per Day) ±SEM





Other Findings

  • Of the 11 patients in the intervention group receiving pre-thickened fluids, 10 of them chose to have hot drinks thickened with powder thickener, which contributed to 32% (SEM±7) of their total fluid intake
  • A total of seven UTI were diagnosed in six different patients, all of whom were catheterized and only one patient was diagnosed with aspiration pneumonia
  • No significant difference in the incidence of chest infection or UTI between those receiving powder-thickened fluids or ready-made pre-thickened fluids
  • Biochemical parameters of hydration were requested at least once for every patient and repeated on average every 3.5 days (SD±2). Total number of samples requested came to 71 (excluding data for one patient with chronic renal failure).

Biochemical Parameters; Mean Results

  • Serum sodium: 137mmol per L (SD±5)
  • Urea: 7.6mmol per L (SD±3.7)
  • Creatinine: 80µmol per L (SD±22).

Biochemical Parameters; Other Results

  • Two patients with hypernatraemia (serum sodium over 145mmol per L)
  • Twelve patients with hyperuraemia (serum urea over eight mmol per L)
  • Three patients with hypercreatininaemia (serum creatinine over 120µmol per L).
Author Conclusion:
  • In the stroke population, oral intakes of thickened fluid are hugely inadequate and no patient was able to achieve his or her daily fluid requirement through oral intake alone, suggesting that dysphagia pre-disposes the patient to dehydration
  • The association between disability and lower oral fluid intakes supports an inverse relationship between nursing dependency and fluid intake
  • There was no difference in the oral fluid intake of the patients on the acute stroke ward, whether they received powder thickener or pre-thickened liquids. On the non-specialist stroke ward, there was almost a 100% increase in oral fluid intake for those patients receiving pre-thickened liquids, compared to those receiving powder thickener.
  • The results of this study show no correlation between the traditional biochemical markers of hydration and daily fluid intake or fluid balance.
Funding Source:
Novartis Consumer Health (UK)
Pharmaceutical/Dietary Supplement Company:
Reviewer Comments:
As noted in the discussion, using fluid balance charts does not measure fluid output from feces, respiration and perspiration and therefore cannot represent absolute fluid output.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? No
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? Yes
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? No
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes