Changes

Long term trends in the efficacy data are important for many reasons. One of the most important is that we all have the occasional bad night where the AHI is much higher than normal or the leaks are awful. Occasional bad nights do not indicate that there's something wrong with the way the PAP therapy is going. (Well, a really awful night for leaks might indicate it's time to replace those nasal pillows or to check whether the mask was put together correctly.) Sleep docs tend to focus almost exclusively on the long term data---a small number of well understood summary numbers and graphs are easier to look at than a massive amount of daily data when you are meeting with large numbers of patients each month. In this post, we'll This section will focus on how Sleepy Head SleepyHead presents the long term summary data.

The idea behind the Statistics Page is to provide a quick numerical view of the most important numbers from the efficacy data. This is the data that most DMEs Durable Medical Equipment (DME) suppliers print out from the proprietary software if the sleep doctor or insurance company wants more than just usage data. The organization of the summary data in the proprietary software varies from brand to brand, and we won't look at how the proprietary software organizes this data.

* Until you have more than 7 days of data the numbers in all columns except '''Most Recent''' will be the same

The numbers for '''Average hours per night''' is a simple average: Add up the usage for each night in the time period and divide by the number of days in the time period. We can see that I the patient didn't get much sleep last night (July 4) and that I'm she is averaging about 6 hours of mask time (and bed time) over the last year. There's a bit of variation between the 7-day, 30-day, 6-month, and 1-year figures, but the variation is not significant.

Sleepy Head SleepyHead defines '''Compliance''' for a given night as "usage is at least four hours". The line for defining Compliance can be set in the Sleepy Head SleepyHead preferences if desired. The percentage in the '''Compliance''' column is simply the percentage of days in the time period where the usage was at least four hours. The fact that my 1-year compliance is listed as 96% means that I the patient used my her CPAP for at least 4 hours on roughly 350 or 351 days. (Both 350/365 and 351/365 round to 0.96). Of the 15 days where I she was not compliant, most of them are nights where I she got less than 4 hours of sleep. Notably, however, two nights were sleep tests that I did last performed during the past summer.

Therapy Efficiacy Efficacy data'''The Therapy Efficiacy Efficacy data are the numbers that measure the overall effectiveness of your PAP therapy. The whole point of PAPing is to get and keep the AHI below 5.0 long term while also having the leaks under control and getting enough sleep to feel well in the daytime. Hereare one patient's my Therapy Efficacy data:<br />

* PR System One users will see everything on my this list.

The long term indices are computed in the same way the nightly indices are computed: SH SleepyHead counts the number of events recorded during the time frame for the index and divides that by the total run time for the time frame. In other words the long term indices are long term averages.

As an example: My The patient's 6th month AHI = 1.79. This means that:

In other words, in the last 6 months, I've she had an average of 1.79 events each hour of sleeping with the machine. Some hours I've she had a lot more than that; other hours I've she had no events. But the expected number of events per hour of sleep would be 1-2 events each hour.

When we look at the numbers in aggregate, we can see some interesting things about my this patient's data:

* My Her '''Last Week''' numbers are quite a bit better than my her 6-month and 1-year numbers. That means that my her OSA has been better controlled this week than it has on average for the last 6 months. I know that my Her AHI numbers tend to be somewhat cyclic each month, and this week has seems to have been a "good" week.* The '''Last Month''' data is a bit better than the 6-month and 1-year data. So the last month has been a pretty good one in terms of PAP therapy. SH SleepyHead data cannot provide an explanation of why it's better. However I'm this patient is through my her spring allergy season and the summer allergies have not been that bad this year. And that That may be a partial explanation for why the 30-day numbers are a bit better than the 6-month and 1-year numbers. More than likely my her 30-day AHI will go back up once Ragweed starts to pollenate pollinate in the fall.* The '''Last 6 month''' numbers are a tiny bit better than the Last year. The difference is not statistically significant. And taken together, the 6-month and 1-year numbers say that my the machine is doing its job of preventing most of my her apneas and hypopneas from happening. A long term AHI < 2.0 is quite good. '''Leak Statistics'''

The '''Leak Statistics''' are based on the Sleepy Head SleepyHead '''Leak''' data. Sleepy Head SleepyHead uses '''Leak''' to represent the excess or ''unintentional'' leak rate. In other words, for machines that record '''Total Leak Rate''' data, it's important to understand that

SleepyHead uses a statistical analysis to estimate the intentional leak rate from the Total Leak Rate data and uses that to compute the Leak Rate. For more details about how SleepyHead handles Leak Rate and Total Leak Rate data see [http://www.apneaboard.com/wiki/index.php?title=Beginner%27s_Guide_to_SleepyHead#Leaks 8. Leaks].

My The patient's summary Leak Statistics data looks like this:<br />

NOTE: IWe've changed my the patient's "top percentile" calculations to the 90% instead of the 95% because Encore reports 90% figures instead of 95%. Most SH SleepyHead users will see 95% numbers where my this patient's data shows 90% numbers.

The ''average'' and ''90%'' leak rates must be interpreted in terms of the statistical meanings of the words average and 90% (90th percentile) of a data set. For those who do not remember any about averages or percentiles, I suggest that you may wish to read [http://adventures-in-hosehead-land.blogspot.com/2012/03/average-median-95-numbers-guide-to.html Average, Median, 95% numbers: A guide to those who don't remember their introductory stats].

The 90% leak rates for 30-day, 6-month, and 1-year are found the same way: We line up all the data points for leak rate for the entire time period in increasing order. If there are n points on the entire list, we first find the integer '''k ''' that is equal to or just barely bigger than 0.9*n and then we find the kth '''k'''th number on the list.

The meaning of the long term 90% leak rate is the same as the meaning of the daily 90% leak rate in the Detailed Daily data. The fact that my 90% 6-month leak rate equals 3.0 means that for 90% of the time my the patient's BiPAP has been on in the last 6 months, the unintentional leak rate has been AT or LESS than 3.0 L/min. We can also say that my unintenional the patient's unintentional leak rate was ABOVE 3.0 for no more than 10% of the time my her machine was running in the last 6 months. Which means that long term I have , she has no serious leak problems to worry about.

'''Note:''' Because of the way weighted averages are computed, we cannot conclude anything about how long the leak rate was AT or BELOW the 7-day, 30-day, 6-month, or 1-year average leak rates.

The '''Pressure Statistics''' are not very interesting if you are using a fixed pressure PAP machine, ; your max pressure and 90% or 95% pressure levels should equal your pressure setting. Your minimum pressure level and your average pressure level will be less than your pressure setting if you use the Ramp feature. The minimum pressure level will most likely be the starting Ramp pressure.

My A sample patient's summary Pressure Statistics data looks like this:<br />

Two things need to be pointed out about my this patient's Pressure data:

* Most people will have either "Pressure" data and no IPAP/EPAP data OR they'll have IPAP/EPAP data and no "Pressure" data. IIt'm s not sure certain as to why I have this patient has both. It's probably could be a SleepyHead bug.* IWe've changed my this patient's "top percentile" calculations to the 90% instead of the 95% because Encore reports 90% figures instead of 95%. Most SH SleepyHead users will see 95% numbers where my this patient's data shows 90% numbers<br />

* Users of DeVilbiss IntelliPAP CPAP/APAPs, F&P Icon CPAP/APAPs, and PR System One CPAP/APAPs will have Pressure data.

There are some bugs in the CPAP Statistics numbers. So if a number obviously does not make sense, its best to disregard the numberit. ResMed S9 summary data has been particularly challenging for JediMark to work with if no detailed daily data is available for some days. The summary data stored for a day with multiple sessions is not sufficient to compute the long term percentiles and averages when only the summary data is available.