Chronic lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) are increasing in prevalence throughout the world and finding effective drug treatments to help sufferers is of great interest to many pharmaceutical companies.
Lung function measurements provide objective data that can demonstrate the effectiveness of these new therapies and measurements of either peak expiratory flow (PEF) and or forced expiratory volume in one second (FEV1) are often primary endpoint outcome measures. The collection of good quality data is therefore a critical factor to the success of most respiratory trials.
Symptom scores
Home collection of PEF and symptom scores in asthma studies has been widely practiced for many years but with the recent emergence of new treatments specifically for COPD there is an increasing need to focus on symptom scores and to replace PEF measurement with FEV1. COPD is a chronic condition with less demonstrable improvement in lung function and FEV1 is considered a more reproducible, accurate measure to show clinically significant changes.
Mechanical peak flow meters and paper diaries have been used to record daily PEF and symptom data, the accuracy of which has long been suspected as being inaccurate and indeed falsification of records has been clearly demonstrated in independent studies(1).
Such a mechanical meter is also limited to the measurement of peak flow, whilst FEV1 has been limited largely to clinic spirometry measurement.
The use of modern electronic spirometers specifically designed to provide an alternative to mechanical PEF meters and paper diary cards is therefore of great interest to pharmaceutical companies as a way to maximise objective data collection when monitoring drug responses at home. Such devices use different measurement sampling principles so that FEV1 as well as PEF can be accurately measured.
Acquisition of measurement points
Some of these devices have memory storage so that every recorded blow is electronically stored and date and time stamped and some also have the possibility to record symptom data responses in the same unit.
Every pharmaceutical company wants to reduce the length of time in getting a drug to market and increasingly electronic data transfer is seen as a possible solution to reducing this time, making devices such as these electronic spirometers very attractive to use.
The increased cost when using electronic spirometers over mechanical peak flow meters has often been prohibitive to using such devices in the past but it is now more widely accepted that the additional time saved in data transfer and the speedy presentation of clean data when using such devices can significantly reduce the overall cost of a clinical trial. Due to the array of electronic spirometers available, companies need to take into account some important factors when considering the choice of such a device.
Respiratory trials
Studies have shown ease of use to be an important factor in helping with compliance of home monitoring in respiratory trials(2) (Fig. 1). Modern technology can be perceived as difficult to use, particularly in elderly patients typical of the subject group being studied in COPD trials and a user-friendly device is of key importance. The ability to ask questions about symptoms that can be viewed in the patient's own language and answered in the same device is also very important in both COPD and asthma trials.
PEF and FEV1 are both effort dependant manoeuvres and in the case of FEV1, duration of blow is critical to get a good quality blow. The addition of quality check messages that can be viewed by patients when recording PEF and FEV1 unsupervised at home is particularly helpful in obtaining good quality data and some electronic spirometers also incorporate this feature (Fig.2).
The measuring technology for reproducible performance of electronic PEF/FEV1 meters should be proven to be stable(3) and accurate without the need for daily calibration, which is not practical in a home setting, and a turbine device is ideal in this situation.
Any spirometer that is chosen must be compliant to the 1994 ATS spirometry manufacture standards for monitoring and diagnosis in respiratory disease.
Finally, the method by which data is transferred from the device is of great importance to the overall success of any study using electronic data capture and should be easy for use investigators and monitors to use. In addition data managers must be happy that all uploaded data is secure and readily transferable into their study database. Spending time choosing an electronic PEF/FEV1 meter that meets all these needs and discussing the criteria for data transfer is time well spent in the initial planning stages.
Pharmaceutical companies should consider inviting companies who specialise in the manufacture of spirometers to partake in discussions with study managers and data managers at the protocol planning stage when a clear understanding of how these devices will work successfully in practice can be decided.
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Gill Rowe is New Business Development Manager, Micro Medical Ltd, Chatham Maritime, Kent, UK. www.micromedical.co.uk
References:1 Chowienczyk PJ, Parkin DH, Lawson CP, Cochrane GM: Do asthmatic patients correctly record home spirometry measurements?, BMJ, 1994;309:1618; 2 Reddel HK, Toelle BG, Marks GB, Ware SI, Jenkins CR, Wollcock AJ: Analysis of adherence to peak flow monitoring when recoding of data is electronic, BMJ, 2002;324:146-7; 3 Dirksen A, Madsen F, Pedersen OF, Vedel AM, Jenson AK: Long term performance of a hand held spirometer, Thorax, 1996;51:973-6.
