My Screening Test for Screening Tests

Wednesday, December 07, 2011

Bringing a screening test to market is a good news / bad news situation.

For folks hoping to market a screening test, the good news is they don't have to worry about regulatory uncertainty. The bad news is, they can be virtually certain that their screening test will face the highest regulatory hurdles of just about any type of product. I've been known to refer to screening as the S-Word.

Few IVDs end up as screening tests, but an awful lot of them start out with that endpoint in mind. As a result, I often find myself helping clients understand whether they are ready to take on the regulatory burdens involved.

Is your test a good candidate for a screening application? The following screening test may help identify hidden regulatory risks that could develop into a full-blown case of project failure.

A screening test should produce an aggressively low level of false positives and false negatives. Your exact thresholds will vary according to your use, but it’s not unusual for screening tests to be held to 99% sensitivity and specificity (such as an HIV test) or have extremely high negative predictive value (i.e., no false negatives) such as HPV. Score 10 points each if your test has:

  • Very high sensitivity and/or
  • Very high specificity

The test will need to be incredibly well-developed. Deduct 1,000 points each of your test is:

  • Still an early version
  • Lacks design control
  • Showing problems with interfering substances

Still have a positive score? Add another 10 points each if you are prepared to:

  • Demonstrate that laboratories can set up and deliver the test as accurately as you can
  • Invest the time and expense necessary to file a PMA
  • Withstand a pre-approval FDA inspection

Minimum score to proceed at this point is 40 points.

And now the test gets difficult:

  • Be prepared to discuss whether a well-designed test that produces accurate results is actually producing clinically useful results.

By the time most of our clients work through the implications of the above, many of them are calling screening the S-Word too.

FDA sets high standards for screening tests and recent news helps show why. Even when a test is presumed accurate and well-developed, it's still a thorny question whether the risk profile changes when you use it on a truly large population. The cost of getting this wrong is measured in lives not saved or debilitating procedures needlessly endured.

It’s been said that all screening tests cause harm, some also do good. That might be an overly grim assessment, but understanding the basis of that statement will help you appreciate where FDA is coming from.

I don't mean to be a complete bummer. Those who truly are ready for the regulatory burden could reap outsize rewards and enjoy significant insulation from competition.

Just don't expect it to be easy. If screening tests were easy, everyone would offer them.

Tags: 510(k), FDA, FDA 101, HPV, IVD, PMA

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