Evidence-Based Medicine

Sensitivity analysis
Analysis to test if results from meta-analysis are sensitive to restrictions on
the data included. Common examples are large trials only, higher quality trials
only, and more recent trials only. If results are consistent this provides stronger
evidence of an effect and of generalisability.
Sham treatment
An intervention given in the control group of a clinical trial, which is ideally
identical in appearance and feel to the experimental treatment and believed
to lack any disease specific effects (e.g. detuned ultrasound or random
biofeedback).
Placebo is used for pills, whereas sham treatment is used for devices,
psychological, and physical treatments. We always try and provide information
on the specific sham treatment regimen.
Significant
Significance comes in 2 varieties:
Statistical significance is when the p-value is small enough to reject the null
hypothesis of no effect; where clinical significance is when the effect size is large
enough to be potentially considered worthwhile by patients. By convention,
taken to mean statistically significant at the 5% level. This is the same as a 95%
confidence interval not including the value corresponding to no effect.
SnNout
When a sign/test has a high sensitivity, a negative result rules out the diagnosis;
e.g. the sensitivity of a history of ankle swelling for diagnosis ascites is 92
percent, therefore, is a person does not have a history of ankle swelling, it is
highly unlikely that the person has ascites.
Specificity (Sp)
Percentage of patients ( or the proportion of people) without (free of) disease
who have a negative test for the disease in question. See also SpPins and
SnNouts.
SpPin
When a sign / test / symptom has a high Specificity, a Positive result rules
in the diagnosis. For example, the specificity of Western plot test for HIV for
diagnosing HIV is 98% therefore if a person does have a positive western plot
test, it rules in the diagnosis of HIV.
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