Richard H Epstein - Comment

In the Guidance, Appendix A - Examples of mobile medical apps, included are applications using "formulae or a processing algorithm" to "..output a patient-specific result.." Examples provided include calculations of eGFR, A-A gradient, scores or scales. There are thousands of such formulas currently available on-line and millions of delployed instances. For example, a Google search on "BMI calculator" returns over 9,000,000 hits. It is not conceivable that the FDA will ever have sufficient resources to deal with this area of the Guidance as currently written. As stated in the Guidance, FDA is claiming jurisdiction over server software which is accessible via mobile devices. Such regulation will dilute the ability of the FDA to regulate more critical areas covered in the Guidance. I just cannot get that excited about a BMI calculator. For a device that will be calculating chemotherapy or therapeutic radiation doses, there is much more concern. I suggest that the FDA adopts some reasonable measure of what will fall under this area of the Guidance and provide appropriate advice. For example, the FDA could supply on-line the formulas that are approved for exempt use (e.g, BMI = (wt in kg)/(ht in meters)^2). The alternative to using a tool to automatically perform such calculations will be that the user has to do the math either by hand or by entering the values manually into the equation. The unintended consequence of the FDA Guidance may be to increase patient risk, rather than decrease it, as the likelihood of calculation errors is considerable.