May 18, 2011

Scientific Article Review

Problem: Secondary complications from SCI include loss of

lean body mass, increase in body fat, and loss of pulmonary function.

Hypothesis

Could anabolic steroids have a positive effect on body composition and pulmonary function following SCI?

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Prospective Going forward in time.

Repeated Measures The exact same measures are used at

multiple timepoints.

Longitudinal The same people are observed multiple

times over a designated period of time.

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Prospective • Eliminates sources of bias (i.e., recall). • Minimizes confounding. * Provided you measured possible sources

of confounding.

Repeated Measures • Comparability.

Longitudinal • Allows you to observe an effect that takes time to

develop. • Captures change over time.

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“Each individual served as his own control”

Improvement is assessed by making comparisons within individuals, not between groups.

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Pre Post Δ

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PROS CONS

Basis of comparison Expense

Eliminates confounding Difficult for rare groups

Flaws in randomization (unaccounted confounders) Ethics

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Sample (N=10) Male. Ages 18-65. At least 1 year post-injury. Motor complete tetraplegia (C4-C8). No chronic health problems (DM, CVD, liver disease). No lipid-lowering agents.

Limitations Homogeneous sample (gender, injury diagnosis). Small N = inability to assess group differences (age). Quite healthy.

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Confounders: • Any “other” unmeasured variables that are

potentially very influential in the observed relationship.

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X1 Y

??

Steroid use

Body Comp

X2

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Body composition (8 weeks) Total ▲ in percent change of LBM (x = 1.9, p = 0.02). ▼in percent change of BF, not significant.

Arms ▲ in percent change of LBM, not significant. ▲ in percent change of BF, not significant.

Pulmonary function (8 weeks) ▲ in percent change of FVC, not significant. ▲ in percent change of FEV, not significant. ▲ in percent change of LBM, not significant. ▼ in percent change of BF, not significant.

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Choice of a global 4 week mark was unclear and not justified! Body composition Reported at 8, 12, and 20 weeks. One modestly significant difference. Improvement in LBM and BF were not maintained. Pulmonary function Reported at 8 and 20 weeks. No significant changes Improvement in PF was not maintained.

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Lipid Profile Does appear to peak at 4 weeks. Reported as abnormal during the 8-week treatment; i.e., no “improvement.” Liver Function Appears to peak at 8 weeks. Trend was “abnormal.” Change was not significant.

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Purpose: To highlight the disparity between SCI and able-

bodied persons in body composition, implying elevated health risks.

Problem: Tabling this comparison conflates results of this

study with another, unrelated study. The point of a Discussion section is to tie your

findings into what has been reported by other researchers.

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Adverse effects of lipid metabolism. →Increases risk for metabolic and CVD.

Small and unsustained gains in body composition do not outweigh this risk.

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