SCI: Preventing Overweight (2007)

Citation:

Jones LM, Legge M, Goulding A. Healthy body mass index values often underestimate body fat in men with spinal cord injury. Arch Phys Med Rehabil 2003;84:1068-1071. 

PubMed ID: 12881836
 
Study Design:
Case-Control Study
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To examine the relation between body mass index (BMI) and adiposity in men with spinal cord injury (SCI) and controls.
Inclusion Criteria:
  • Males with SCI, injured more than 1 year before the study
  • Able-bodied controls, age, height and weight matched with SCI subjects
Exclusion Criteria:
  • Amputation
  • Heterotopic ossification or orthopedic pins in scan regions of interest
Description of Study Protocol:

Recruitment

SCI subjects recruited through university spinal unit; controls recruited by advertisement.

Design

 Comparison of total body and regional lean tissue mass and fat mass vs BMI in men with SCI and age, height, and weight matched controls.

Blinding used (if applicable):  Not applicable

Intervention (if applicable):  Not applicable

Statistical Analysis

  • Independent t-tests for significance between groups
  • Analysis of covariance (ANCOVA) to examine the influence of group (SCI or able-bodied controls) on body fat
Data Collection Summary:

Timing of Measurements

One time measurement.

Dependent Variables

  • Lean tissue mass by dual-energy x-ray absorptiometry (DXA) (Lunar DPX-L)
  • Fat mass (DXA as above)
  • Bone mineral (DXA as above)
  • BMI (kg/m2) with kg weight being the sum of total fat tissue, total lean tissue and total bone mineral content from the total body DXA scan

Independent Variables

  • SCI

Control Variables

  • Age (within 5 yrs)
  • Height (within 5 cm) from the electronic ruler function of the Lunar DPX-L scanner software
  • Weight (within 5 kg, when possible)

 

Description of Actual Data Sample:

Initial N: 20 men with SCI (13 with tetraplegia; 7 with paraplegia); 20 able-bodied controls

Attrition (final N): 19 men with SCI, 19 able-bodied controls. (Subject under 18 and his control dropped, being outside the age range for the WHO criteria for the BMI values used in this study).

Age: 16-52 yrs (see attrition note above); mean age 34 yrs

Ethnicity: not reported

Other relevant demographics: none reported

Anthropometrics: see results table

Location: University of Otago, Dunedin, New Zealand

 

Summary of Results:

Table 1:  BMI and body composition for men with SCI and able-bodied controls (values are mean ± SD)

Variables

SCI

n=19

Controls

n=19

Statistical Significance between groups

Height (cm)

180±6

179±6

ns

Weight (kg)

74.4±12.3

76.8±6.9

ns

BMI (kg/m2)

 23.1±3.9

24.1±1.8

p = 0.34

Total body lean mass (kg)

 50.4±7.3

 59.3±3.5

 p < 0.001

Total fat mass (kg)

 21.1±10.7

 14.1±6.0

 p < 0.02

Fat (%)

27.5±10.4

18.1±6.5

p < 0.01

Leg lean mass (kg)

14.3±3.1

21.3±1.7

p < 0.001

Leg fat mass (kg)

7.0±3.4

4.9±1.9

p < 0.05

Arm fat mass (kg)

2.1±1.1

1.3±0.7

p < 0.02

Trunk fat (kg)

11.0±6.0

7.3±3.5

p < 0.05

Other Findings

 

Author Conclusion:

BMI may underestimate body fat in men with SCI, compared to DXA, as body fat mass was greater for any given BMI in the SCI group vs the control group

While both groups had mean BMI values not considered to be overweight or obese, many subjects with SCI had fat percentages that would fall within the obese range; therefore, lower BMI cutoff points for overweight and obesity in SCI may be appropriate, compared to the currently used WHO definitions

SCI group had significantly increased centrally distributed fat mass compared to controls, perhaps an indication for increased risk of CHD and diabetes.

Funding Source:
Industry:
Lifescan (Johnson & Johnson)
Other:
Reviewer Comments:
  • sample size is small
  • women not included in the 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) ???
  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? 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? N/A
  2.3. Were health, demographics, and other characteristics of subjects described? ???
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? ???
  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? ???
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) 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? 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.) Yes
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? No
4. Was method of handling withdrawals described? Yes
  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%.) 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
  4.5. 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? 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? 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? N/A
  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)? N/A
  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