PSG not better than ambulatory testing: new study

From Medscape:

Polysomnography Offers No Benefit Over Ambulatory Testing to Diagnose OSA CME

News Author: Laurie Barclay, MD
CME Author: Désirée Lie, MD, MSEd


February 12, 2007 — Polysomnography offers no benefit over the ambulatory approach in diagnosis of patients with obstructive sleep apnea, according to the results of a randomized validation study reported in the February 6 issue of the Annals of Internal Medicine.

"Polysomnography (PSG), despite limited availability and high cost, is currently recommended for diagnosis of obstructive sleep apnea and titration of effective continuous positive airway pressure (CPAP)," write Alan T. Mulgrew, MB, of the University of British Columbia and Vancouver Coastal Health Research Institute in Vancouver, British Columbia, Canada, and colleagues.

The objective of this randomized, controlled, open-label trial was to test the utility of a diagnostic algorithm in conjunction with ambulatory CPAP titration in initial management of obstructive sleep apnea. The investigators compared standard PSG vs ambulatory CPAP titration in high-risk patients identified by the diagnostic algorithm.

At a tertiary referral sleep disorders program in Vancouver, 68 patients with a high pretest probability of moderate to severe obstructive sleep apnea (apnea-hypopnea index, >15 episodes/hour) were identified by sequential application of the Epworth Sleepiness Scale (ESS) score, Sleep Apnea Clinical Score, and overnight oximetry. These patients were randomized to PSG or ambulatory titration using a combination of auto-CPAP and overnight oximetry, and they were followed up for 3 months. Main outcomes included apnea-hypopnea index on CPAP, ESS score, quality of life, and CPAP adherence.

The PSG and ambulatory groups were similar in median body mass index (38 kg/m2), age (55 years), ESS score (14 points), and respiratory disturbance index (31 episodes of respiratory disturbance per hour). Each episode was determined by a computer algorithm based on analysis of oxygen saturation measured by pulse oximetry.

After 3 months, the PSG and ambulatory groups did not differ in the primary outcome, apnea-hypopnea index on CPAP (median, 3.2 vs 2.5; difference, 0.8/hour; 95% confidence interval [CI],
-0.9 to 2.3; P = 0.31), or in the secondary outcomes, ESS score, Sleep Apnea Quality of Life Index, and CPAP. Adherence to CPAP therapy was better in the ambulatory group compared with the PSG group (median, 5.4 vs 6.0; difference, -1.12 hour/night; 95% CI, -2.0 to 0.2; P = .021).

"In the initial management of patients with a high probability of obstructive sleep apnea, PSG confers no advantage over the ambulatory approach in terms of diagnosis and CPAP titration," the authors write. "The ambulatory approach may improve adherence to treatment. When access to PSG is inadequate, the ambulatory approach can be used to expedite management of patients most in need of treatment."

Study limitations include the design as a superiority trial, inability to blind the patients to treatment allocation, probably incorrect assumption regarding independence of the components of the diagnostic algorithm, variability in the characteristics of currently available oximeters and auto-titrating CPAP equipment, and lack of diagnostic PSG in patients in the ambulatory group precluding assessment of their baseline apnea-hypopnea index.

"Most patients with a probability of OSA [obstructive sleep apnea] of 90% or greater do not require polysomnography before starting CPAP," the editors write.

ResMed Corp, Poway, California; Vitalaire Canada, Inc, Mississauga, Ontario, Canada; a Michael Smith Foundation for Health Research Infrastructure; Sagatech Electronics, Inc, Calgary, Alberta, Canada; BC Lung Fellowship; the CIHR/HSFC IMPACT training program; Michael Smith Foundation for Health Research Scholar Award; a CIHR/BC Lung Association New Investigator Award; and a Departmental Scholar Award from the University of British Columbia supported this study. The authors have disclosed financial relationships with Respironics, Inc, ResMed Corp, and/or Vitalaire Canada, Inc.

Ann Intern Med. 2007;146:157-166.

Learning Objectives for This Educational Activity
Upon completion of this activity, participants will be able to:
Describe a diagnostic algorithm for the treatment of obstructive sleep apnea.
Compare the use of ambulatory CPAP titration with and without initial PSG in the management of obstructive sleep apnea.
Clinical Context
According to the American Academy of Sleep Medicine and the American Thoracic Society, supervised PSG is currently recommended as a first-line diagnostic tool followed by CPAP titration for management of obstructive sleep apnea. However, according to the current authors, PSG is expensive and time-consuming, requiring 2 nights in a sleep laboratory, and alternatives, such as overnight home monitoring with oximetry, have improved access to diagnostic testing. Access to ambulatory CPAP without requiring PSG would further enhance care for patients with obstructive sleep apnea, according to the current authors.

This is an open study to compare the use of CPAP with and without initial diagnostic PSG on clinical outcomes in patients with suspected moderate to severe obstructive sleep apnea.

Study Highlights
Patients with suspected moderate to severe obstructive sleep apnea were recruited from one sleep center.
Inclusion criteria were high pretest probability of moderate to severe obstructive sleep apnea, medically stable, and not using sedatives.
Exclusion criteria were pregnancy, abnormal spirometry, psychiatric disorder, known cause of daytime sleepiness, or chronic medical condition.
High probability patients were identified by the ESS, Sleep Apnea Clinical Score, and overnight home oximetry.
The ESS has a maximum score of 24.
The Sleep Apnea Clinical Score is based on snoring, observed episodes of apnea, neck circumference, and systemic hypertension, with score of 15 or higher indicating moderate to severe obstructive sleep apnea.
The respiratory disturbance index is a device measuring oxygen saturation, and a score higher than 15 per hour that indicates moderate to severe sleep apnea.
A diagnostic algorithm was used in the PSG group to diagnose moderate to severe sleep apnea.
The combined likelihood ratio conditional on a Sleep Apnea Clinical Score of 15 or higher and an oximetry respiratory disturbance index of 15 per hour or more yielded a pretest probability of moderate to severe sleep apnea greater than 95%.
All patients completed the Sleep Apnea Quality of Life Index and received 1-on-1 orientation to CPAP with mask fitting and a trial of CPAP.
Mean age was 53 years, 75% were men, mean body mass index was 38 kg/m2, median baseline ESS score was 14, and Sleep Apnea Clinical Score was 32.
Of 68 patients screened and considered eligible, 35 were assigned to the PSG followed by ambulatory CPAP and 33 to ambulatory CPAP without PSG.
PSG was supervised by a trained technician, and obstructive sleep apnea was confirmed during a scheduled PSG in a sleep laboratory at the hospital.
Once obstructive sleep apnea was diagnosed, CPAP titration followed with no subsequent adjustment.
The ambulatory group received CPAP with the AutoSet Spirit (ResMed, Inc, Sydney, Australia) set to pressures of 4 to 20 cm for 1 week. After 1 week, the 95th percentile pressure was taken as the initial effective pressure if no residual sleep-disordered breathing was identified.
Continued CPAP mode was offered and overnight oximetry was performed on days 6 and 13.
At baseline and after 3 months, all patients completed the ESS (decreasing score indicated less sleepiness) and the Sleep Apnea Quality of Life Index (higher score indicated better quality of life).
Overall compliance was better in the ambulatory CPAP compared with the PSG group (median, 6 vs 5.4 hours/night).
After 3 months, there was no difference in the apnea-hypopnea index on CPAP between the 2 groups.
ESS, Sleep Apnea Clinical Score, and Sleep Apnea Quality of Life Index scores were similar.
ESS and Sleep Apnea Quality of Life Index improved for more than 3 months in both groups, except in 1 person with Cheyne-Stokes respiration.
There was no difference in CPAP between the PSG and ambulatory groups.
62% of patients in the PSG reported a preference for home management vs 6% of those in the ambulatory group preferring laboratory management.
The authors recommended using a clinical algorithm for patients with high probability of obstructive sleep apnea and PSG for those who do not respond to CPAP or do not meet criteria for high probability.
Pearls for Practice
A diagnostic algorithm may be used for obstructive sleep apnea using ESS, respiratory disturbance index, and Sleep Apnea Clinical Score.
Use of PSG before initiating ambulatory CPAP is not associated with better outcomes during 3 months on the ESS, Sleep Apnea Clinical Score, or Sleep Apnea Quality of Life Index.

Bet the sleep lab and sleep doc community are putting their spin on this.
This is GREAT and tells me a pcp can do a history on a suspected osa patient and send the patient home with an APAP to diagnose him/her,

Saves the patient a zillion bucks and outcome is the same.

no surprises here,
tomjax

Since so many people around here redo their titrations anyway, big shock.

Just a word of caution: apap is the absolute worst thing for complex sleep disordered breathing (CSDB). So if a person doing a home titration feels awful, they definitely need to take the next step to a PSG. At least until a more full assessment can be done at home. CO2 monitoring needs to be included along with the oximetry.

Thank you, frequenseeker.

[quote="frequenseeker"]Just a word of caution: apap is the absolute worst thing for complex sleep disordered breathing (CSDB). So if a person doing a home titration feels awful, they definitely need to take the next step to a PSG. At least until a more full assessment can be done at home. CO2 monitoring needs to be included along with the oximetry.

In support of the ESS, my original (local) sleep doctor noticed that my ESS scores kept getting worse despite my use of and progression through plain vanilla cpap, simple bipap, and VPAP bipap. She gave this alot of credibility, which translated into alot of emotional support and validation as well as medical support in the search for better methods.

No one is going to admit they nap at stoplights, but just the process one does in taking the ESS may result in admitting at least to oneself that it has been possibly tempting, or more, realizing it is not okay, and getting more motivated to do something about it.

I didn't need a sleep study to tell me I had OSA either. Unfortunately it's hard to get the machine without a prescription, so we have to go along with this arcane (and expensive) requirement.