EAL

COPD: Determination of Energy Needs (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To analyze the prognostic value of nutritional depletion in patients with COPD receiving long-term oxygen therapy with respect to survival and hospitalization rate.

Inclusion Criteria:

Diagnosis of chronic bronchitis or emphysema
FEV1/vital capacity ratio <60%
PaO2 < 8 kPa
Treatment with long-term oxygen therapy between 1984 and 1993
In a stable state, defined as pH between 7.35 - 7.45

Exclusion Criteria:

None specifically mentioned.

Description of Study Protocol:

Recruitment

Analysis of the ANTADIR database, the national nonprofit network for home treatment of patients with chronic respiratory insufficiency founded in France in the 1980s.

Design

Cohort Study.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Not applicable.

Statistical Analysis

Correlations between nutritional and functional data were studied by linear correlations and represented graphically by dividing BMI into classes of 5 kg/m2. Population survival was calculated from the onset of long-term oxygen therapy by the actuarial and Kaplan-Meier methods with the closing date of January 2, 1997. The study of prognostic factors was performed using the log-rank test and the Cox semiparametric model.

Data Collection Summary:

Timing of Measurements

Data derived from database.

Dependent Variables

Hospitalizations
Treatment withdrawal
Death

Independent Variables

COPD diagnosis
Arterial blood gas levels
Lung function test results
BMI

Control Variables

Age
Sex
Height

Description of Actual Data Sample:

Initial N: 4088 patients, 3517 men, 571 women

Attrition (final N): 4088

Age: mean age men: 68 +/- 9 years, women: 70 +/- 10 years

Ethnicity: not mentioned

Other relevant demographics:

Anthropometrics:

Location: France

Summary of Results:

Factors	RR of Death (95% CI)	t test	p Value
Age, by 10 years	1.54 (1.48 - 1.61)	19.3	<0.001
BMI, by 5 kg/m2	0.75 (0.72 - 0.79)	- 12.6	<0.001
PaO2, by 1 kPa	0.85 (0.80 - 0.89)	- 6.1	<0.001
FEV1 % predicted, by 10%	0.89 (0.86 - 0.93)	- 6.0	<0.001
Sex, female (vs male)	0.78 (0.69 - 0.87)	- 4.3	<0.001

Other Findings

The prevalence of malnutrition, as defined by BMI < 20, was 23% in men and 30% in women.

BMI was significantly correlated with FEV1 and FEV1/VC.

The mean follow-up duration was 7.5 years.

The 5-year survival rates were 24%, 34%, 44% and 59%, respectively, for patients with BMIs <20, 20 - 24, 25 - 29, and >30.

Effect of BMI on survival was independent of age, FEV1, PaO2, and sex.

Lower BMI was the most powerful predictor of duration and rate of hospitalization, independently of blood gas levels and respiratory function.

The mean annual time spent in the hospital was 29.6 +/- 40.4 days for patients with a BMI < 20 vs 17.5 +/- 30.1 days for patients wtih a BMI > 30.

Author Conclusion:

In conclusion, this study showed that nutritional depletion is an independent risk factor for mortality and hospitalization in patients with COPD treated with home oxygen. The best prognosis was observed in overweight and obese patients.

Funding Source:

Reviewer Comments:

Long-term follow up study.

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?	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?	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?		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?	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
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.)	N/A
	5.3.	In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded?	Yes
	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?		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?	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?	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?	N/A
	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