EAL

CI: Body Weight and Outcomes: Cardiovascular Surgery Patients (2007)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To determine the impact of obesity on mortality and specific morbidity after elective coronary revascularization.

Inclusion Criteria:

All patients undergoing elective coronary revascularization at the authors' institution in a 2-month period were consecutively enrolled into this prospective trial.

Exclusion Criteria:

Exclusion criteria were urgent/emergent operations and combined operations.

Description of Study Protocol:

Recruitment All patients undergoing elective coronary revascularization with cardiopulmonary bypass and without associated procedures at the authors' institution in a 2-month period were consecutively enrolled into this prospective trial. A preliminary power analysis established that with regard to the variables to be evaluated, 300 patients, with at least 100 obese patients were required. The authors' determined with the usual number of coronary operations and the prevalence of obesity in this population, the 300 N would take a 2-month recruitment period.

Design Prospective, clinical study

Blinding used (if applicable) No blinding described

Intervention (if applicable) Patients were assigned to the Obese group (O) if their body mass index was greater than 30 for men and 28.6 for women (according to the World Health Organization indications).

Statistical Analysis Preoperative and intraoperative variables were checked for between-group hemogeneity using an unpaired t-test for continuous variables and a Mann-Whitney test for discrete variables; categoric variables were tested with Pearson's chi-squared test. Postoperative continuous and discrete variables were tested with an unpaired t-test and Mann-Whitney. The incidence of mortality and adverse events was tested using a relative risk (with 95% confidence intervals) analysis.

In addition, adverse events significantly (p < 0.05) differing between the two groups were subsequently analyzed looking for other possible preoperative and intraoperative predisposing factors. All factors correlated with a p of 0.1 or less were entered into a multivariate logistic regression analysis (the output of this analysis is an odds ratio presented with 95% confidence interval). Continuous variables significantly related to the outcome indicators were plotted using a locally weighted scatterplot technique.

Data Collection Summary:

Timing of Measurements Preoperative, intraoperative, post-operative

Dependent Variables

Variable 1: Mortality
Variable 2: Intubation Time
Variable 3: ICU duration
Variable 4: Postoperative hospital stay times
Additional Variables: specific organ complications and organ dysfunctions were assessed for the presense of: 1) need for blood products, 2) reopening, 3) perioperative myocardial infarction, 4) low-output syndrome defined as the need for inotropes for more thatn 48 hours and/or need for mechanical assistance, 5) minor neurologic dysfunction defined as transient severely altered mental status, 6) major neurologic dysfunction defined as transient severely altered mental status, 7) minor pulmonary dysfunction defined on the basis of arterial blood gas results after extubation and in room air, 8) major pulmonary dysfunction defined as the need for prolonged (>24 hour) intubation because of arterial blood gas values not satisfying the extubation criteria or the need for reintubation because of respiratory dysfunction, 9) renal dysfunction defined as an increase in postoperative serum creatinine level to twice the baseline value, 10) superficial infections affection either the sternal or the leg wounds, 11) mediastinitis.

Independent Variables Obesity defined as body mass index greater than 30 for men and 28.6 for women (according to the World Health Organization indications).

Control Variables

Description of Actual Data Sample:

Initial N: N = 345 with 116 in Obesity Group and 229 patients in Control Group. Obesity Group had 31.9 women; control group 13.9 women.

Attrition (final N): no attrition described

Age: Obesity Group - mean (standard deviation) age 61.6±7.5; Control Group 64.8±8.7; p=0.001

Ethnicity: no information given

Other relevant demographics: no information given

Anthropometrics Weight and Body Mass Index were significantly greater in the Obesity Group - mean 87.1 kg±11.7 and Control Group 70.7±9.4 kg. p = 0.001

Location: Cardiovascular Center E. Malan, San Donato Hospital, Milan, Italy

Summary of Results:

Variables	Obesity Group N =116	Control group N = 229	Statistical Significance of Group Difference
Mortality	N = 3	N = 8	Relative Risk (95% confidence interval)0.81 (0.3-2.17) NS
Intubation Time	Median = 14 hours (range = 1 to 94 hours)	Median = 15 hours (range = 4-720 hours)	NS
ICU duration	Median = 2 days (range=1-12 days)	Median = 2 days (range=1-14 days)	NS
Postoperative hosptial duration	Median = 7 days (range=6-27 days)	Median = 8 days (range=4-26 days)	NS
Need for Blood Products	N = 32	N = 98	Relative Risk (95% confidence interval) 0.64 (0.45-0.90) P = 0.009
Minor Pulmonary dysfunction	N = 28	N - 17	Relative Risk (95% confidence interval) 2.14 (1.6-2.85) p = 0.001
Superficial Infections Leg wounds Sternal wound infection	Leg wounds N = 10 Sternal wound infection N = 9	Leg wounds N = 9 Sternal wound infection N = 8	Relative Risk (95% confidence interval) Leg wound 1.62 (1.03-2.55) p=0.045 Sternal wound 1.62 (1.01-2.61) p=0.048

Other Findings

1) reopening, 2) perioperative myocardial infarction, 3) low-output syndrome defined as the need for inotropes for more than 48 hours and/or need for mechanical assistance, 4) minor neurologic dysfunction defined as transient severely altered mental status, 5) major neurologic dysfunction defined as transient severely altered mental status, 6) major pulmonary dysfunction defined as the need for prolonged (>24 hour) intubation because of arterial blood gas values not satisfying the extubation criteria or the need for reintubation because of respiratory dysfunction, 7) renal dysfunction defined as an increase in postoperative serum creatinine level to twice the baseline value, 8) mediastinitis.
all were NS
Also, in multivariate logistic regression models, obesity remains an independent risk factor for minor pulmonary dysfunction and a protective factor against blood product use.

Author Conclusion:

The authors state, in conclusion, obese patients undergoing coronary revascularization should be considered as "big adults," definitively experiencing minor complications, but not at greater risk for major morbidity or mortality and at lower risk for transfusion.

Funding Source:

University/Hospital:

University of Milan, San Donato Hospital (Italy)

Reviewer Comments:

World Health Organization indications (article published in 1999) were used to determine obesity; 30 for men and 28.6 for women.

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
	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
	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)	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.	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?	Yes
	2.2.	Were criteria applied equally to all study groups?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.3.	Were health, demographics, and other characteristics of subjects described?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
	2.4.	Were the subjects/patients a representative sample of the relevant population?	Yes
	3.	Were study groups comparable?	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
	3.1.	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?	Yes
	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.)	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.)	Yes
	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?	Yes
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	4.4.	Were reasons for withdrawals similar across groups?	Yes
	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?	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?	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.)	Yes
	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?	Yes
	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
	5.4.	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?	Yes
	6.5.	Were co-interventions (e.g., ancillary treatments, other therapies) described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	6.6.	Were extra or unplanned treatments described?	Yes
	6.7.	Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?	Yes
	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
	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?	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
	7.6.	Were other factors accounted for (measured) that could affect outcomes?	Yes
	7.7.	Were the measurements conducted consistently across groups?	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.	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
	8.1.	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)?	Yes
	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
	8.6.	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
	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.	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?	???
	9.2.	Are biases and study limitations identified and discussed?	???
	10.	Is bias due to study's funding or sponsorship unlikely?	Yes
10.	Is bias due to study's funding or sponsorship unlikely?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.1.	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