CKD: MNT (2010)
Patients with progressive chronic renal failure, not yet on dialysis, with creatinine clearance <25 mL/min who attend a general hospital nephrology clinic.
Chronic dialysis, or patients found to have stable or improving renal function based on serial measures of creatinine clearance.
Recruitment: methods not described.
Design: nonrandomized pilot time series study.
Blinding Used: no
Intervention: Dietetic intervention with an experienced renal dietitian offered at entry, every 3 months at clinic visits, and as needed between visits by telephone. Emphasis placed on type, amount and frequency of food and liquids to maintain or achieve goals of BMI (20-25), protein intake (0.8-1.0 g/kg IBW/day), serum potassium (<6 mmol/L) and serum phosphorus (<1.5 mmol/L).
Data are compared with data from 2 other published studies. In these studies, predialysis subjects did not receive nutritional interventions, and these studies showed a correlation between decline in renal function and decline in nutritional status. There were 95 subjects in the MDRD feasibility study (1992) and 90 subjects from an Ikizler et al study (1995).
Statistical Analysis: Significance of mean changes tested using Wilcoxon signed rank test. Correlations between change in creatinine clearance and nutritional parameters using Spearman's rank correlation coefficients and significance.
Timing of Measurements: Baseline (0), 3 and 6 months.
Dependent Variables:
- Subjective Global Assessment (SGA)
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Anthropometrics: Height, Weight, triceps skinfold thickness (TST), mid arm muscle circumference (MAMC) calculated using mid upper arm circumference, grip strength.
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Biochemical: serum albumin, serum transferrin, insulin like growth factor-1 (IGF-1)
Independent Variables:
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Renal function assessed from serum creatinine to calculate creatinine clearance.
Control Variables:
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Dietary assessment, including routine diet history with energy and protein intakes assessed using 3-day diet diary.
Initial N: 11 subjects. Nutritional status compared with similar predialysis subjects: 96 subjects in MDRD feasibility study and 90 subjects from another study.
Attrition (Final N): 11 subjects
Age: mean age 63.9+14.5 yr
Ethnicity: not reported
Other Relevant Demographics: Gender: 64% male/36% female
Anthropometrics: see results section
Location: a nephrology clinic in Wales, UK
Changes from baseline to 6 months for several nutritional parameters are shown. Most remained stable or increased slightly. None of the changes were significant except increase in midarm muscle circumference (p<0.05).
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Baseline | End of study |
| Weight (kg) | 77.5+19.9 | 79.4+18.7 |
| BMI | 26.9+5.1 | 27.5+4.6 |
| TST (mm) | 13.5+6.3 | 14.9+5.5 |
| MAMC (cm) | 26.6+3.2 | 27.2+2.7 (p<0.05) |
| grip strength (kgf) |
33.2+10.7 |
33.4+12.6 |
| serum albumin (g/dL) | 4.25+0.29 | 4.2+0.24 |
| serum transferrin (mg/dL) | 215+31 | 228+41 |
| IGF-1 (ng/mL) | 204+108 | 222+118 |
| serum creatinine (mg/dL) | 4.6+0.9 | na |
| creatinine clearance (mL/min) | 17.3+6.0 | * |
*Mean creatinine clearance decreased by 3.5+2.3 mL/min over the 6 months.
No patients became malnourished, as assessed by Subjective Global Assessment.
| Subjective Global Assessment category | Number of patients at baseline | Number of patients at 6 months |
| A=well nourished | 8 | 10 |
| B=mild to moderately malnourished | 3 | 1 |
| C=severely malnourished | 0 | 0 |
Changes in energy intake (kcal/kg IBW/day) and protein (g/kg IBW/day) from baseline to 6 months are shown for the total group, and subdivided into groups instructed to either decrease or increase/maintain their intakes. Although none of the changes were statistically significant, they all changed in the expected direction, notably energy decrease (n=5) from 32.7+3.8 to 27.3+5.0.
No significant correlations were found between changes in creatinine clearance and changes in any of the nutritional parameters that were measured. This is in contrast to the other 2 studies that found significant positive correlations between decline in renal function and decline in nutritional parameters when nutrition intervention was not offered.
This study suggests that dietetic intervention may prevent decline in nutritional status in predialysis patients. A longer-term, randomized and control study is required to confirm this and to determine if there is an effect on quality of life, life expectancy, and cost savings by postponing dialysis.
It is recommended that all predialysis patients be screened for nutritional status and intervention be offered when appropriate to prevent deterioration of nutritional status, which is common in these patients.
| Government: | Whales Office of Research and Development |
| University/Hospital: | Gwynned Hospitals Health Service Trust |
The study sample was small and the duration of the study short. However, RD intervention appears to have prevented deterioration of nutritional status in these patients.
Only patients with declining creatinine clearance were included in this study. No recruitment details were provided, no details on data collection or analyses from diet records. Energy and protein intake assessed per kg IBW.
Numerous nutrition related parameters were measured. As the authors noted, there is no single absolute marker of nutritional status, so multiple considerations seems prudent.
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Quality Criteria Checklist: Primary Research
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| 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? | ??? | |
| 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? | ??? | |
| 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? | ??? | |
| 3. | Were study groups comparable? | No | |
| 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.) | 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? | 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? | 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? | N/A | |
| 5. | Was blinding used to prevent introduction of bias? | No | |
| 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.) | No | |
| 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? | ??? | |
| 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? | ??? | |
| 6.4. | Was the amount of exposure and, if relevant, subject/patient compliance measured? | ??? | |
| 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? | ??? | |
| 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? | ??? | |
| 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? | No | |
| 7.7. | Were the measurements conducted consistently across groups? | N/A | |
| 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? | ??? | |
| 8.2. | Were correct statistical tests used and assumptions of test not violated? | ??? | |
| 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)? | 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? | No | |
| 10.2. | Was the study free from apparent conflict of interest? | Yes | |