Evaluation (Validation and Verification) - Medical Device Design: Innovation from Concept to Market - page 234

“A hypothesis (from Greek) consists either of a suggested explanation for a phenomenon
or of a reasoned proposal suggesting a possible correlation between multiple phenomena.
The term derives from the Greek, hypotithenai meaning 'to put under' or 'to suppose.'”
(Wikipedia, 2011)

“An unproved theory. Proposition, etc.”

(Collins, 2009)

For medical devices the hypothesis is the clinical beneit that your device produces and the
trial is trying to prove it is real . The clinical benefit need not be positive, it can be neutral or
even negative. But the wording is quite specific and you, as the designer, need to have a good
idea of what it should be. To go back to our design methodology, you are in fact designing
your study and hence use the same methodology that we have seen throughout. Therefore,
for the study the hypothesis is your statement of need. For example Table 9.9 illustrates some
benefits and a typical hypothesis.

Note that the hypothesis is a statement that is either true or false ( null ). Hopefully you are
trying to prove that your hypothesis is true - therefore enabling you to make a statement
about the clinical benefit.

Where a trial deviates from a study is in the examination of side effects; that is, a thing going
awry. If you have conducted you design correctly failures should be avoided. However, you
can never escape the unexpected long-term effects that will only occur after long-term use. In
essence, and before you can release your product, you must have tested the hypothesis “This
device is safe to use.”

If you cannot test this hypothesis and obtain an emphatic “true” result then you need a clinical
trial to test it. If all of the precedents, design work, and evaluations you have undertaken make
the answer a “true,” then a clinical trial is probably unnecessary. Unfortunately there is an
exception to this rule; under current EC rules “ All devices of classification class III require
clinical trials ” (EC, 2010).

Table 9.9: Clinical Benefit Hypotheses

Example Clinical Benefit Example Hypothesis to Be Tested

Positive The rate of non-intervention has

increased

The use of device A for the treatment of B results in an
increase in the rate of non-intervention when compared
with traditional methods.

Neutral The infection rate is no worse

compared with others

The use of device C for the treatment of D results in
infection rates that are no different than those observed
when device(s) E (F and G) is (are) used.

Negative The amount of antibiotics taken

is reduced

When treating X, the amount of antibiotics used is lower
when device Y is used compared with common practice.