SleepyHead Trend Plots

This question is for the medical community right now than the software developer later. I would like to evaluate trends in the AHI graph and am plotting my results using a linear regression line on a spreadsheet and would like to have trend information from SleepyHead directly. My respiratory therapist told me to expect that the AHI would get lower in the near future and my graph of three weeks data shows that.

For the MD's and RT's monitoring this board, what would be useful to plot long term and what should trigger an alert to the patient that a concerning trend is developing? I am thinking of parameters such as a maximum value of the plot slope in conjunction with an AHI greater than some value.

Phrasing the question differently, what constitutes a statistically significant and medically significant adverse trend?