EAL

CKD: Nutrition Assessment and Best Predictors of CKD (2001)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

The purpose of this study was to identify factors associated with mortality at the onset of dialysis and to estimate the impact of these deaths on survival and incidence rates. This is important because typically, patients who die within the first 90 days of dialysis treatment are excluded from U.S. national ESRD mortality rates and can be missing from incidence counts.

Inclusion Criteria:

All patients starting dialysis treatment between Jan 1, 1989 and Dec 31, 1992 in Georgia, North Carolina and South Carolina, identified through an ESRD registry.
Subjects were limited to those of black or white race.

Exclusion Criteria:

Patients in ethnic/race categories other than black or white.

Description of Study Protocol:

Recruitment: all patients beginning hemodialysis during duration of study recruitment, ie 4 years.

Design: Prospective cohort to compare characteristics of those patients who died within the first 90 days of dialysis treatment to all new patients, followed for 365 days, death, transfer, or transplant.

Blinding Used: Not applicable

Intervention: Not applicable

Statistical Analysis:

Chi-squared tests to compare characteristics of those patients who died within 90 days of beginning dialysis to all new patients.
Univariate analyses stratified individually for age, race and gender to examine associations between patient characteristics and death.
Unconditional logistic regression to identify characteristics independently associated with death within first 90 days.
Log-likelihood ratio tests to assess significance of terms for statistical interactions as identified in stratified analyses.
Most parsimonious risk model obtained by eliminating nonsignificant interactions and removing main effect variables not associated with outcome (0.05 significance) one at a time.
Actuarial survival analysis to assess distribution of death (deaths per patient month).
Incidence rates based on 1990 Census of states.
First year mortality rates as reported here conform to U.S. Renal Data System convention. Death rates are age adjusted.

Data Collection Summary:

Timing of Measurements:

Data collection performed at onset of treatment by dialysis facility staff.
Follow up began at first reported dialysis date and continued until death, transfer out of network, renal transplant or 365 days (1 year follow up time).

Dependent Variables: Death within 90 days of initiation of dialysis.

Independent Variables:

Demographics: age, gender, 1° cause of renal disease (diabetic or other), years of education, student or employment status, type of housing, whether patient lived alone, with family or others.
Most recent serum albumin
Physical activity level (modified Karnofsky scale).
Medical records for comorbid conditions: alcoholism, angina, blindness, cancer, comorbid diabetes (not diabetic nephropathy), CHF, MI, PVD, clinical depression, hypertension, peripheral neuropathy, renal osteodystrophy, smoking, and substance abuse.
Dialysis modality: hemodialysis (HD), continuous ambulatory peritoneal dialysis (CAPD), continuous cycling peritoneal dialysis (CCPD), and intermittent peritoneal dialysis (IPD).

Control Variables: patient characteristics were stratified by age, race and gender.

Description of Actual Data Sample:

Initial N: 15,245 patients starting dialysis.

Attrition (Final N): 922 (6%) deaths within the first 90 days of treatment.

Age: 56.8 + 16.2 years.

Ethnicity: white or black race.

Other Relevant Characteristics:

Anthropometrics:

Location: Georgia, North Carolina, and South Carolina.

Summary of Results:

Compared with all new patients, those who died within the first 90 days were older (65.4±13.2 years), white, male, poorly educated, without social support, were more physically impaired, had lower serum albumin, and had a higher proportion of cancer or history of MI.

Characteristics independently associated with increased risk of early death included:

history of MI (<45 years old, odds ratio: 8.8; 45-64, odds ratio: 1.4; 65-74, odds ratio: 1.2),
older age (>75 years, odds ratio: 5.0; 65-74 years, odds ratio: 4.3; 45-64 years, odds ratio: 2.1),
low serum albumin (10-30 g/L, odds ratio: 4.4; 31-34 g/L, odds ratio: 2.4; 35-40 g/L, odds ratio: 1.4),
impaired activity level (severe, odds ratio: 2.3; moderate, odds ratio: 1.5),
white race or male gender (both odds ratios:1.6),
comorbidities of cancer or CHF (both odds ratios: 1.5),
smoking or clinical depression (both odds ratios: 1.3).

During the first year of treatment, the death rate was not constant. During the first 3 months of treatment, 32% of all deaths occurred. The monthly hazard rate increased slightly from 0.24 deaths per patient month in the first month of treatment to 0.27 in the second month, then declined until the seventh month, thereafter leveling off.

Excluding those patients who died within the first 90 days of treatment changed the incidence rates. Incidence rates for dialysis treated ESRD were between 4.5-8.8% higher when all patients were considered. Discrepancies in incidence rates were greater for white than black patients, causing underestimates in relative risk for white deaths.

Age-adjusted first-year mortality rates based on this cohort were underestimated by 3-12% when patients who died early were excluded from death rates. White compared to black mortality was underestimated by almost 7%.


	All new patients	Deaths <91days
Age, yr	56.8±16.2	65.4±13.2
<45 yr, %	24	9
45-64 yr,%	39	30
65-74 yr, %	25	39
75 + yr, %	12	22
(P<0.001)
Activity Level
Normal, %	13	5
Mildly impaired, %	37	18
Moderately Impaired, %	31	36
Severely Impaired, %	18	40
(P<0.001)
Serum albumin (g/L)
41-50, %	15	6
35-40,%	43	29
31-34	23	28
10-30	18	38
(P<0.001)

Author Conclusion:

The authors found that new ESRD patients experienced declining rates of mortality during the first year of treatment. The risk factors for early mortality were similar to those associated with overall mortality. Mortality rates that fail to account for early deaths may lead to biased estimates of risk among certain groups, particularly whites, older individuals, and men.

These results suggest that certain patient characteristics—some potentially modifiable, confer increased risk of early death, and that systematic exclusion of patients who die early from the US national registry substantially influences ESRD mortality rates.

Funding Source:

Government:

HCFA

University/Hospital:

Emory University School of Medicine, Emory University School of Public Health

Not-for-profit

Foundation associated with industry:

Reviewer Comments:

The term "nutritional impairment" in this study refers to serum albumin levels.

Based on the data presented in this study, the RD should note the variety of characteristics associated with early death when dialysis is initiated, with particular attention to history of MI at early age, older patients, low serum albumin, and severely impaired activity levels.

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)	N/A
	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)	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?	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?		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?	Yes
	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?		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
	5.3.	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?	N/A
	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
	6.4.	Was the amount of exposure and, if relevant, subject/patient compliance measured?	No
	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)?	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