HYD: Assessing Hydration Status (2007)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To determine the validity of readily available clinical measures in the assessment of dehydration severity among elderly patients

Inclusion Criteria:
  • Stable, cooperative patients ages 60 years and over who were admitted to the emergency departments with suspected fluid and electrolyte imbalance.
  • Suspicion of dehydration was a clinical judgment made by the emergency department staff physicians on the basis of their initial clinical evaluation of the patient history and physical condition.
Exclusion Criteria:
  • Excluded were patients who were edematous, in renal failure, non-English speaking, or had reduced mentation.
  • It became apparent that to exclude patients with reduced mentation eliminated many dehydrated patients. Therefore, the mental status exclusion was dropped for the remainder of the study and an additional 40 patients meeting all other inclusion and exclusion criteria were enrolled.

 

Description of Study Protocol:

Recruitment

 This study was carried out in the emergency departments of 2 large metropolitan acute care hospitals, a 577-bed university hospital and a 427-bed county teaching hospital.

Design

  Study of sensitivity and specificity of a diagnostic test (prospective design)

Blinding used (if applicable)

 Physicians were blinded to the results of the standardized hydration.

Intervention (if applicable)

 N/A

Statistical Analysis

  •  Kendall's tau, a nonparametric correlation for the relationships between  the physician's dehydration ratings and most of the items in the hydration examination.
  • Pearson's correlation coefficient for the relationships between patients' age and vital signs.
  • Associations between dehydration ratings and binary or categorical data were evaluated using chi-square tests.
  • Multiple regression analyses were used to examine the combined explanatory power of a set of indicators to estimate dehydration severity ratings.
Data Collection Summary:

Timing of Measurements

Dehydration severity at time of initial presentation was rated by a physician at the completion of the hospital course, according to a scale developed by the investigators.

Dependent Variables

  • Physician Dehydration Rating Scale:
    • 0: Normally hydrated; vital signs and laboraty values are within normal range
    • +1: Suspected to have mild dehydration; blood pressure and laboratory values are usually within normal range, and serum sodium is <145 mEq/L.
    • +2: moderately dehydrated; several symptoms are present and some laboratory values are abnormal or nearly abnormal. BUN:Cr is 15:1 or above, serum Na, Osmolality, or BUN elevated.
    • +3: severely dehydrated; symptoms are present and some laboratory values are distinctly abnormal. BUN:Cr is at least 20:1 and usually over 25:1, Serum Na >145 mEq/L, osmolality >300, or BUN elevated.

Independent Variables

 Standardized hydration examination: 38 items, including vital signs, symptoms, and physical signs, performed independently by the study research nurse at the time of initial presentation in the emergency department.

Control Variables

 Age

Description of Actual Data Sample:

 

Initial N: 55 (35 women and 20 men)

Attrition (final N): 55

Age: 61 to 98 years old (median age 82 years)

Ethnicity: None

Other relevant demographics: living independently (50%); living in a skilled nursing home or board and care facility (50%)

Anthropometrics: No data

Primary diagnosis on admission to hospital: dehydration, cardiovascular disorders, and infections

Location: US

 

Summary of Results:
I. Physicians' dehydration ratings

 
Dehydrated (n=43, 78%)
Normally hydrated
(n=12, 22%)
Mild
Moderate
Severe
N
17
13
13
12

  • Laboratory results from samples drawn in the emergency department prior to or at the time of the hydration examination were available for all patients in the severe category, 77% of those in the moderate category, and 76% of those in the mild category. Only 17% of those judged normally hydrated had concurrent laboratory values.

II. Indicators of dehydration severity in elderly patients

  • Bivariate correlations were used to select a subset of the 38 items from the hydration examination that had the strongest correlations with dehydration severity and were not related to patient age. Using tau=0.35 as a cutoff point, 7 indicators were identified:
    • Upper body muscle weakness (tau=0.56, p<0.001)
    • Speech difficulty (tau=0.52, p<0.001)
    • Dry mucous membranes of nose and mouth (tau=0.44, p<0.001)
    • Longitudinal tongue furrows (tau=0.40, p<0.001)
    • Confusion (tau=0.39, p<0.001)
    • Sunken appearance of eyes in their sockets (tau=0.35, p<0.01)
  • Patients in the severe, moderate, mild, and no-dehydration categories had, on average, 5.7, 3.9, 2.7, and 1.3 of these 7 indicators, respectively, and there was a strong correlation between the number of indicators present and the dehydration rating (r=0.72, p<0.001)
  • Multiple regression analyses using all 7 indicators explained 56% of the variability in the physician's dehydration rating, while this simple sum of the number of indicators present performed almost as well, explianing 52%.
III. Inidcators that were not correlated with physician's rating of dehydration

Eyes' pupil reaction, skin appearance, turgor on forehead, skin turgor on sternum, axillary moisture, knees colder than thighs, capillary refill on patella, tremors, pallor, vein refill, hand, agitation, irritability, tingling, SBP, DBP, self-reported sensations of thirst and dryness

Contrary to expectations, orthostatic changes, as measured between supine and sitting blood pressures, were common to all hydration levels and therefore, did not correlate with dehydration severity.

The combination of orthostatic change with resting pulse was not more effective than pulse alone in distinguishing levels of dehydration.

Temperature and pulse both had weak, positive correlations with dehydration severity, but while tachycardia appeared to be a useful indicator of dehydration, fever was not.

Author Conclusion:

Physicians and other health care providers should be aware of those signs and symptoms that most specifically reflect severity of dehydration in elderly persons.

Further work is needed to develop combinations of these indicators that will be even more sensitive to degree of dehydration and to cross validate these on independent samples of elderly patients, including those in long-term care facilities.

Funding Source:
University/Hospital: University of Minnesota
Not-for-profit
0
Foundation associated with industry:
Reviewer Comments:

This research was private and univerity funding.

Bias and limitation: Laboratory results were not availble for all subjects. It appears that physicians did not use the same protocol to diagnose patients' hydration severity. Therefore, the "gold standard" may not be reliable.

Of interest was the negative finding that contrary to expectations, orthostatic changes, as measured between supine and sitting blood pressures, were common to all hydration levels and therefore, did not correlate with dehydration severity.

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? N/A
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) N/A
 
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? No
  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? Yes
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) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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")? Yes
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  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? Yes
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? N/A
  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? Yes
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? N/A
  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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? Yes
7. Were outcomes clearly defined and the measurements valid and reliable? No
  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? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? No
  7.5. Was the measurement of effect at an appropriate level of precision? No
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.7. Were the measurements conducted consistently across groups? No
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)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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