Quality of Home Spirometry Data in Asthmatic Patients

Introduction

Spirometry requires maximum patient effort in order to achieve acceptable and repeatable results. Coaching patients on the correct technique and providing feedback can improve the quality of spirometry data. This is provided by trained medical staff in the clinic and is centred on the ATS/ERS 2005 criteria1 on acceptability and repeatability, which is widely used in clinical trials to determine the quality of spirometry results. At home, sophisticated spirometers are needed to provide feedback to the patient on test performance and repeatability, in order to obtain good quality data in the absence of a trained coach.

In respiratory clinical trials, home measurements of lung function (including PEF and FEV1) are of particular importance, since they are frequently used as endpoints for efficacy and safety. Thus, the ability of patients to provide high quality data is crucial.

Electronic Spirometry e-Diaries are often used in clinical trials to record home measurements. In a previous clinical trial where 113,098 Home Pulmonary Function Tests (PFTs), sessions were recorded using the previous model of the Vitalograph e-Diary, where limited feedback was given to the patient on test quality. 85% of the PEF measurements and only 63% of the FEV1 measurements met the ATS/ERS 2005 repeatability criteria2,3.

The new Vitalograph In2itive e-diary provides even more accurate feedback regarding patient technique and repeatability; this has the potential to improve the quality of home spirometry data.

Aim

To determine the repeatability of home PEF and FEV1 data collected using the Vitalograph In2itive e-Diary in an international multi-centre, double blind, placebo-controlled clinical trial with adolescent and adult patients with asthma.

Method

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During this study 174 patients were each provided with a Vitalograph In2itive e-Diary at the screening visit and
were instructed by the trained site staff to use the e-Diary twice a day to record asthma symptoms and PFTs,
first in the morning between 6am-11am and then again in the evening between 6pm-11pm. The data collected
on the e-Diary in the morning and evening were treated as separate sessions.

Clinic Visits

The total duration for patients that completed the trial was 14-20 weeks. For those patients who were not
randomised, maximum total duration for the screening and run-in period was up to 8 weeks.

Training and Feedback

At the screening visit, patients were trained on how to use the e-Diary and perform a correct PFT
manoeuvre by the site staff.

The e-Diary also provided instructions to the patient on how to perform their PFT correctly.

Once the PFT manoeuvre was completed the e-Diary provided feedback on the quality of the test.

Table 1: Individual test feedback messages provided back to the patient and associated quality criteria
Message Criteria
Blow out faster Time to PEFgreater than 120 milliseconds from start of test
Do not cough Cough detected in the 1st second
Blow longer Forced Expiratory Time less than 1 second
Good test If any of the above are not met

If the patient was able to achieve 3 good tests that met the ATS/ERS 2005 criteria1 for repeatability the e-Diary would indicate the session has been completed.

If the patient did not meet the ATS/ERS 2005 criteria1 for repeatability, the e-Diary would provide feedback that the
blows were not consistent and ask the patient to perform another test. The e-Diary allowed a maximum of 5 PFT tests
to be performed by the patient per session.

Home PFT sessions from 174 patients who participated in the clinical trial from 09-Nov-2011 to 18-Dec-2012 were
used in this analysis.

Results

A total of 35,615 Home PFT sessions were recorded using the In2itive e-Diary device. 17,886 AM and 17,729 PM
sessions were recorded. The repeatability for both PEF and FEV1 was calculated as the difference between the two
highest readings (Table 2).

95.2% of the sessions achieved the ATS/ERS 2005 repeatability criteria1 for PEF.

96.7% of the sessions achieved the ATS/ERS 2005 repeatability criteria1 for FEV1.

96% of the sessions had 3 or more PEF results, however this dropped to 94% for FEV1 (see table 3). There were
48 (0.13%) sessions that had no PEF data recorded, and 645 (1.81%) sessions where no FEV1 data was recorded.
597 of these sessions did have PEF measurements, so despite the feedback message to the patient to ‘blow longer’
this didn’t result in an expiration time of at least 1 second.

Table 2: % of accepted and rejected sessions as judged by repeatability
PEV FEV1
* PEF criteria for repeatability 2 highest results < 40L/min difference
* FEV1 criteria for repeatability 2 highest results < 150ml difference
n % n %
Acceptable sessions* 33,894 95.2 34,012 96.7
Rejected sessions* 1721 4.8 1603 3.3
Table 3: Number of manoeuvres recorded per session
Manoeuvres recorded per session PEV FEV1
n % n %
3 111264 98.4 62448 55.2
2 1143 1.01 25709 22.7
1 687 0.61 17666 15.6
0 4 0.004 7275 6.4

Conclusion

Using the new Vitalograph In2itive e-Diary, asthmatic patients in this clinical trial were able to produce more repeatable PEF and FEV1 results at home compared to previous trials that have used the older design of the e-Diary. Providing instant feedback to the patient the In2itive e-Diary has been shown to improve the quality of the spirometry that patients can achieve when performing PFTs at home, in both PEF and FEV1.

This instant feedback is important for patients when recording PEF and FEV1 at home in the absence of coaching and guidance from trained medical staff which is only present during clinic PFTs. In this clinical trial, the number of FEV1 manoeuvres recorded using the new In2itive e-Diary increased dramatically compared to the older design of the e-Diary which provided less feedback. When using the new Vitalograph In2itivie e-diary in clinical trials improved collection of home spirometry data can be expected with greater accuracy and repeatability.

Bibliography

1. Miller MR et al. ATS/ERS Standardisation of spirometry, Eur Resp J 2005; 26: 319 - 338 2. Harrison AJ, Sowman G. Repeatability of Home PEF and FEV1 in a pharmaceutical trial. Am J Resp Crit Care Med 2010; 181:A5799 3. Harrison Aleck, Watson Elizabeth. Huff and puff; repeatability of serial home PEF & FEV1 recordings in a pharmaceutical trial. Eur Respir J 2010; 36: S54: E3967

Acknowledgements

Vectura Limited for use of their data, contributing to the design and writing of this poster.