At the time of my work with the National Commission on Sleep Disorders Research (NCSDR) in 1990 and 1991, I developed an intense concern for the lack of awareness about sleep disorders in America and throughout the world. Studies carried out by NCSDR showed a nearly complete failure to diagnose and treat victims of obstructive sleep apnea (OSA) not to mention all the other sleep disorders. There has been some progress in the ensuing decade, but I am afraid there is still a very long way to go.
Even today, most primary care sites that I visit around the country are doing little or nothing to identify, diagnose, and treat sleep disorders. One of my most compelling recent experiences in this regard was following my son’s 3 years of training in family medicine in a program that shall remain nameless. In spite of our joint effort to increase awareness in this program, the diagnosis and treatment of sleep disorders including OSA have remained close to zero.
The NCSDR estimated that there were 38,000 fatalities per year due to cardiovascular consequences of OSA. If we add an estimate for fatal accidents of all kinds, 50,000 unnecessary deaths per year is a reasonable figure. In its final report to the US Congress in 1992, NCSDR declared the lack of awareness about sleep disorders a national emergency and urged the Congress to fund an effective national awareness campaign. Unfortunately, this recommendation was not implemented. It boggles my mind to contemplate the needless deaths and disabilities in the United States alone, not to mention the rest of the world, that have occurred in the ensuing decade.
From the perspective of the foregoing, I would not discourage the home monitoring approach. We still need all possible resources to help victims of OSA. I know many patients who have received the “miracle of treatment” after being diagnosed and treated for OSA in a sleep disorders center. I also know many patients who have received the miracle of treatment after being diagnosed and treated for OSA by home monitoring. Until the two approaches have been adequately compared in a scientifically definitive manner including long-term outcomes, they should both be strongly encouraged and we should always ask for the highest quality in both.
William C. Dement, MD, PhD
Stanford Sleep Disorders Clinic and Research Center,
We found the article “Comparing Different Methodologies Used in Wrist Actigraphy,” which appeared in the Summer 2001 issue of Sleep Review, pg 40, by Stephen Gorny and Jennifer Spiro interesting because we know Gorny has served as a paid consultant for IM Systems Inc, Scottsdale, Ariz, a competing manufacturer of actigraphs. His face has been a familiar one at the IM Systems’ exhibit booth for many years. We wonder if your publication requires conflict of interest statements or if anyone was a bit curious why Gorny had such an interest in this topic.
We find that some of his statements regarding the typical sampling rates being 40 per second and the particular way digital integration is performed describe the technology and methodology provided by IM Systems. He demonstrates a limited scope of knowledge regarding activity recorders with these particulars. A sample rate of 40 Hz for a phenomenon that occurs predominantly in the 2-3 Hz range (as Redmond and Hegge showed, cited by Gorny) is superfluous. Digital integration, as presented, that does not first rectify the analog signal leaves half the signal unexamined. The proportional integrating measure of Ambulatory Monitoring Inc (AMI), Ardsley, NY, rectifies the curve (taking the absolute value of negative departures, see figure) and integrates at a much higher resolution than any other device on the market.
Further, he dismisses zero crossing and time-above-threshold modes since they do not characterize intensity of motion. This is true, but frequency and duration of movement are ignored in the digital integration mode. That is why all of AMI’s devices provide a TRI-mode capability that simultaneously captures frequency, duration, and intensity of movement.
Given these facts, we would like to see some sort of retraction/apology from Gorny and perhaps some equal time in your publication to further educate your readers in the finer points of actigraphic recording. We appreciate your consideration in this matter.
William Gruen, president
Thomas Kazlausky, vice president
Ambulatory Monitoring Inc