Survey of non-invasive ventilation use in ALS in Britain
- 1Department of Neurology, The Royal London Hospital, London, UK
- 2Queen Mary School of Medicine and Dentistry, Queen Mary University of London, London, UK
- Correspondence to Professor Michael Swash, Department of Neurology, The Royal London Hospital, London EC2Y 8BL, UK;
- Received 18 July 2011
- Accepted 25 July 2011
- Published Online First 2 September 2011
A group of neurologists and respiratory physicians from Sheffield, Tyneside and Newcastle1 report the results of a postal, questionnaire-based survey on the use of non-invasive ventilation (NIV) in motor neuron disease/amyotrophic lateral sclerosis (ALS) in Britain, suggesting that it represents ‘an update of current UK practice’ (see page XXX). Although this is the intent of the survey, responses were elicited from only 63% of UK neurologists, raising the spectre of sampling error.
There are several additional methodological problems in this survey. There was no check of the validity of the data submitted by those neurologists who replied; that is, none of the data was verified, or ‘cleaned’ to use clinical trial phraseology. We do not know how closely local or national guidelines for NIV were followed; although it is reasonable to suppose there was intent to do so, we have no reliable data. The seven neurologists with the biggest ALS practices said they referred for NIV a mean of 50 patients with ALS annually, versus only 8% for the others. As the authors show, there are therefore likely to be differences between the everyday practice patterns among ALS specialists and primary neurologists. However, there is no indication that this difference in practice (and possibly of expertise) implied any perceived benefit or hazard for patients or their families. No data on quality of life of those ventilated in different centres are presented. Importantly, no information is provided regarding patients who may have been offered NIV, but declined this management. And what were the non-responding neurologists doing? No information is available.
These criticisms aside, the survey does contain some hints of changing practice. However, it would be unwise to place too much reliance on these suggestions. Fewer responding neurologists said they were managing people with ALS, so UK practice in ALS, as in other areas of neurology, may be becoming more specialised. The absolute number of people with ALS referred for NIV increased, compared with a similar 2009 survey. All physicians managing people with ALS would surely agree that increased availability of NIV is to be welcomed.
The authors use their survey, which included questions concerning usual clinical practice, to highlight some possibly important aspects. They especially criticise the 26% of neurologists who stated that they used ‘uncontrolled oxygen prior to the end of life’ in patients who had not been assessed for NIV. Of course, no physician uses oxygen after the end of life, but leaving that solipsism aside, although there is an acknowledged theoretical risk associated with this practice, the authors do not consider the possible reasons for it. Perhaps these patients did not wish to use NIV? Perhaps they were truly near to death? We do not know, but this use of oxygen may well have been both humane and reasonable. They also emphasise that spirometry, used by many of the respondents in their clinics, is not a very reliable test of impending type 2 respiratory failure, and that sniff nasal inspiratory pressure and maximal inspiratory pressure are more reliable tests.
Chio and colleagues2 have recently addressed principles of good practice using epidemiological approaches. Ideally, such studies should be prospective, should use multiple sources of data, should include capture–recapture methodology when relevant, and must include ongoing diagnostic confirmation and accurate and complete follow-up when relevant. Case ascertainment must be complete. Only thus can selection bias, for example, of particular subsections of patients or in studies of clinical practice, be avoided. It is essential that these principles should be followed in future work.
Henry Barnet famously remarked, in relation to carotid endarterectomy, that ‘1000 anecdotes is not data'—let us have no more incomplete surveys, but rely on prospective studies or validated population-wide databases.
Competing interests None.
Provenance and peer review Commissioned; internally peer reviewed.