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Hydration

HYD: Assessing Hydration Status (2007)

Citation:

Wakefield B, Mentes J, Diggelmann L, Culp K. Monitoring hydration status in elderly veterans. West J Nurs Res 2002 Mar;24(2):132-42.

PubMed ID: 11858345
 
Study Design:
Observational Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To determine whether urine color, as measured by a urine color chart, accurately reflects hydration status, as measured by urine specific gravity and osmaolality in patients who fasted for ten hours.

Inclusion Criteria:
  • Patients hospitalized at both an acute care site and a skilled rehab unit. 
  • Patients age 65 years or older
  • Patients able to understand the research protocol, who agreed to eat nothing by mouth for ten hours overnight
Exclusion Criteria:

Excluded were patients who were:

  • Terminally ill,
  • Incontinent,
  • Had conditions affecting water and electrolyte balance including uncontrolled diabetes, NG or G-tube feeding tubes, severe renal failure necessitating fluid restriction or dialysis, or severe CHF
Description of Study Protocol:

Recruitment: Consecutively admitted patients to the acute care and rehab units of two VA hospitals. Patients were paid $5.00 for participating in the study. Written informed consent was obtained from each participant.

Design: First of all, inter-rater reliability in assessment of the urine color was established prior to data collection.  Environmental adjustments were made to promote the most accuracy.  After all the adjustments in protocol were made, the two raters agreed on 19 of 20 samples, with the remaining sample having a difference of one.  Age, diagnoses and body mass index was collected for each patient.  At 9:00pm a baseline non-fasting midstream urine sample was obtained and rated using the color chart within 30 minutes of collection.   Patients were told not to eat between 9:00pm and 7:00am, when a fasting second-void urine sample was obtained and analyzed for color in the same manner. Both urine samples were refrigerated and tested the next morning for specific gravity and osmolality.  For the acute care patients only, if blood was being collected on the morning of the second urine sample collection, the lab was requested to run the blood for hematocrit, sodium, BUN, creatinine and osmolality.  Medication data was also collected to evaluate the effect of medication on urine color. A 24-hour food intake recall from each patient was also collected prior to the first urine test to assess the effects of food on urine color.

Blinding used (if applicable) NA

Intervention (if applicable) NA

Statistical Analysis: Spearman rank-order correlation coefficient was used to analyze the cross-sectional relationship between urine color scores and baseline and fasting urine specific gravity and osmoloality and between urine color scores and the hematological data.  Pearson product-moment coefficients were used to analyze the relationship between the urine specific gravity and osmolality and hematological indices.

Data Collection Summary:

Timing of Measurements: At 9:00pm a baseline non-fasting midstream urine sample was obtained and rated using the color chart within 30 minutes of collection.   Patients were told not to eat between 9:00pm and 7:00am, when a fasting second-void urine sample was obtained and analyzed for color in the same manner. Both urine samples were refrigerated and tested the next morning for specific gravity and osmolality.

Dependent Variables: Increasing urine color scores

Independent Variables: urine specific gravity and osmolality, hematocrit, serum sodium, BUN, creatinine and serum osmolality

Control Variables: NA 

Description of Actual Data Sample:

Initial N: 47 from the acute care and 42 from the rehab unit for a total of 89.

Attrition (final N):  None

Age: Mean age for the acute care setting was 74 years ± 5 yrs and for the rehab unit 73 years ± 4.7 yrs.

Gender: All patients are male

Other relevant demographics: NONE

Anthropometrics:  Mean body mass index (BMI) for the acute care was 26.8 ± 4.3 and for the rehab unit was 26.6 ± 6.8.

Location: 2 different Veterans' Administration Medical Centers. Specific location unspecified.

Summary of Results:

Relatively few medications with the potential to color the urine were used. Mean number of medications used in acute care and rehab unit were 2 and 1 respectively.  Very few foods known to affect urine color were consumed by patients in this study so it was concluded that neither medication or food significantly affected urine color.

98% of the patients (n=87 of 89) met the criteria for being well hydrated based on urine color and 100% were well hydrated according to specific gravity (< 1.029) and urine osmolality (< 1.052mOsm).

Correlations between urine color and specific gravity and osmolality for both urine samples are shown in Table 1. The results were moderate and significant to <0.01.

Table 1: Correlation Between Urine Color Chart and Urine Specific Gravity and Osmolality

 

Baseline Color Chart

Fasting Color Chart

Statistical Significance of Spearman rank-order correlation

Baseline Specific Gravity

           0.57            p<0.01
Baseline Urine Osm

           0.56

 

         p<0.01

Fasting Specific Gravity

 

             0.59

         p<0.01

Fasting Urine Osm                0.56          p<0.01

Significant correlations were found between urine osmolality and serum sodium (r=0.37, p<0.05) and BUN-Creatinine Ratio (r=0.39, p<0.05).  Data found below in Table 2.

Table 2: Correlations Between Fasting Hematologic Values and Urine Specific Gravity, Urine Osmoloality and Urine Color

Hematologic Tests Specific Gravity Urine Osmolality Urine Color
Sodium  (n=43)          0.25             0.37           0.13
BUN-Creatinine Ratio (n=43)

         0.28

          0.39 

         0.05

 

Author Conclusion:

Limitations of Study per Authors:

  • No range of hydration status was used; in other words, patients were all well hydrated. Would the color charts have demonstrated the same correlations in patients who were underhydrated or severely dehydrated?
  • 10 of the patients (11%) received fluids during the night either via IV or orally with meds. This could have affected the urine color ratings.
  • 33% of patients had a urine osmolality of under 400mOsm, indicating they were in renal failure.  Since BUN and Creatinine were only measure in the acute care setting, the authors had no idea how many of the total patients may have been in renal failure and to what extent the renal impairment may have affected the results.
  • The study did not test for blood in the urine, which may have affected the color results.
  • No females were studied.

 Conclusions:

  • Increasing scores on the urine color chart are moderately and positively correlated with urine specific gravity and osmolality. 

Urine osmoloality was significantly correlated with serum sodium and BUN-Creatinine Ratio, but only moderately.

Funding Source:
Government: Dept. of Veterans Affairs, National Institute for Nursing Research
Reviewer Comments:
The limitations in this study severely weakened the relatively moderate positive correlates between urine color change with other markers of hydration status.  Based on this one study, use of urine color charts was not clearly demonstrated to be a viable way of hydration testing in our elderly patients.
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) No
  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) No
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? 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
  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
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. 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
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? 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
  2.1. 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
  2.2. Were criteria applied equally to all study groups? No
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
  3. Were study groups comparable? N/A
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  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? No
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) 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? No
  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? No
  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.) No
  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.) No
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? 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. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? 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
  4.2. 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? N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  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
  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? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) 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.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  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
  5.4. 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
  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. 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
  6.1. 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? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  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
  6.4. 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? 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
  6.6. 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
  6.7. 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? N/A
  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. 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
  7.1. 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
  7.2. 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
  7.3. 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
  7.4. 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? ???
  7.5. Was the measurement of effect at an appropriate level of precision? ???
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.7. Were the measurements conducted consistently across groups? 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? ???
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? 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
  8.2. 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
  8.3. 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
  8.4. 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)? No
  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
  8.6. 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? No
  8.7. If negative findings, was a power calculation reported to address type 2 error? No
  9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
  10. Is bias due to study's funding or sponsorship unlikely? No
10. Is bias due to study's funding or sponsorship unlikely? No
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes
  10.2. Was the study free from apparent conflict of interest? Yes