PSG Concordance Project

Measures of sleep and breathing from polysomnography (PSG) are used in diagnosing sleep disorders, but Australian researchers Rob Pierce and Peter Rochford in Melbourne and Andrew Thornton in Adelaide have reported large inter-scorer variation for many of these measures. The chart at right shows the ranges of apnea-hypopnea index values when a set of 10 sleep studies was scored by different technologists. For example, AHI values for the first sleep study ranged from 26 to 66 events per hour.

This level of variation would be a major problem for ASTN multicentre trials relying on PSG, so the Network has sponsored a project led by Rob, Peter and Andrew. Fifteen participating laboratories, each with two scorers, will be randomised to one of three groups. One group will receive no intervention, another group will receive feedback about their performance, and the third group will receive feedback and will participate in active sessions aimed at improving scoring agreement. This will be the first time that the effect of such a program has been tested and the results will be used in the design of future multicentre studies. The project is being conducted between October 2006 and July 2007 with results presented at Worldsleep07 in October.

Investigators added the following update in October 2007:

The ASTN supported project to look at inter-scorer reliability in sleep laboratories in Australia and New Zealand completed the data collection phase in August. Statistical analysis of the huge data set is ongoing with a publication planned for submission later this year. The project generated a number of well received presentations at WorldSleep07 in Cairns. There was a very well attended symposium entitled "Quality and Reliability in Polysomnography Scoring" and two poster presentations which were the direct result of the project. The presentations received very positive feedback from a number of international visitors including those involved in AASM reference groups. The data set is a unique and highly valuable resource which once again puts Australasian sleep science at the forefront of this important area.

Although data analysis is not complete at this stage it is clear that the project has once again highlighted the issues with the reliability of scoring in different laboratories and even between scorers in the same laboratory. The preliminary analysis suggests that the effect of the intervention to improve scoring consistency is likely to be modest but nevertheless important in assisting individuals to measure their performance against other scorers. A scoring manual which clarifies a number of ambiguous or problematic issues in the Chicago criteria has been produced and scorers in the intervention group have provided positive feedback about the usefulness of the program. At this time an extension phase is being offered to all laboratories which participated so that they may, if they wish, receive the same feedback as those in the intervention group.

As a spin off from the project the proposed AASM changes to the scoring criteria have been examined. At WorldSleep07 Warren Ruehland presented a "late breaking" paper on the effect of the new AASM rules for scoring hypopnea. This has highlighted that the Australasian sleep community needs to be fully aware of the changes that adopting these new rules will make, particularly to the measurement of apnea-hypopnea index. It is anticipated that they will improve the inter-scorer variability but will also significantly reduce the AHI.

Whilst the Austin and Royal Adelaide groups have worked very hard to complete this project on time and within the allocated budget, the contributions of all scorers and laboratories who took part must be acknowledged. Each batch of PSG fragments added to their workloads and it is a credit to the individuals concerned that they managed to complete the scoring and comply with the tight time lines. Without this professional approach by the scorers and laboratories involved, the project would not have been possible.

Andrew Thornton, Peter Rochford, Warren Ruehland, Pam Singh and Rob Pierce.
10 October 2007

Sleep Apnoea CardioVascular Endpoints study (SAVE)

Planning is now being stepped up for the Sleep Apnea cardioVascular Endpoints (SAVE) trial, an international trial with Network representation which is providing valuable experience for the Network in the organisation of large-scale trials.

SAVE is designed to definitively address one of the most important questions remaining in the field of sleep medicine - namely, whether OSA causes cardiovascular events, and, if so, what level of risk reduction is achieved by OSA treatment. The Principal Investigator, ASTN CI Doug McEvoy is joined by an international investigator group to develop and implement SAVE.

Some industry sponsors are already in place, including Platinum sponsorship from Respironics Inc, and additional industry and government partnerships are currently being sought to enlarge this important trial.

View the SAVE website

Study development groups in 2008

All four ASTN steering groups set up in 2007, in the fields of insomnia, shiftwork, non-invasive ventilation and paediatric sleep health, initiated multi-centre clinical trials protocols which were submitted early this year for NHMRC grant funding. Facilitation and specialist expertise and was provided by the ASTN but credit for the development of these studies goes largely to the skills, hard work and collegiality of the steering and investigator groups themselves. Read more about the studies in the item below on the Melbourne Open Forum.

The groups will continue during 2008, to further develop the first round of studies but also to explore further study ideas. Steering group leaders are keen to hear from people who would like to contribute to the development of new studies in 2008. Contact people for the groups are:

• Insomnia group, Simon Smith
• Shiftwork group, Shantha Rajaratnam
• Non-invasive ventilation group, Amanda Piper
• Paediatrics group, Gillian Nixon

Get in touch with a steering group via ASTN National Research Manager Melanie Harris.