The LUV study

The lung function variability (LUV) study is a multicenter observational study supervised by the Pediatric Respiratory Unit of the University Hospital of Patras, Greece.

It is based on the analysis of short- and long-term variability of various spirometric parameters, such as the Peak Expiratory Flow (PEF) and the Forced Expiratory Volume at 1 s (FEV1).

It is known that PEF and FEV1 values present significant daily fluctuations in both healthy and asthmatic individuals. However, although in healthy individuals the variability of PEF and FEV1 remains relatively constant over time, in patients with asthma it presents significantly different patterns, especially during periods of low disease control or prior to exacerbations. Thus, it has been shown that specific characteristics of the short- and long-term variability of PEF and FEV1 can be used to assess the level of asthma control and the effectiveness of controller medication, or to identify high-risk patients and predict the exacerbations of the disease. To date, however, all relevant studies have been performed in adults and were based on the retrospective analysis of spirometric parameters, usually obtained in the context of other studies.

The LUV study is the first to use exclusively real-time measurements for analyzing  the lung function variability in children and adolescents. The measurements are performed twice a day, morning and afternoon, over a period of 3 months, using ultra-portable spirometers capable of smartphone connection and real-time transmission of data to a central database. The final goal is to develop a telematic system for monitoring the level of asthma control in children and adolescents.

The study has been registered in the under number NCT04163146.

My child does not have asthma. Why should we participate?

To identify any aberrant pattern of PEF and FEV1 fluctuation over time, the physiological patterns must be determined.

Childhood is a period with important peculiarities: children (and their lungs) present different rates of development, they have different types of physical activity, they are more often exposed to respiratory infections and react to them differently compared to adults. These parameters are expected to influence the short- and long-term variability of lung function, even in children without special respiratory complains.

As mentioned above, the patterns of PEF and FEV1 variability in healthy children and adolescents are unknown. Therefore, the first and most important phase of the LUV study is to determine what is “normal” so that we can subsequently recognize what is “abnormal”.

How difficult is the measurement process?

The LUV study has been designed to require the minimum possible effort from you and your child. The whole process (device activation, measurements, etc) requires less than a couple of minutes.

The spirometers are small (smaller than your mobile phone), portable and completely independent. The technique is also simple. Your pediatrician will offer an initial demonstration when you receive the device; you can also find detailed instructions on this site (see “Materials”).

Measurements must be performed twice a day: in the morning (7:00 – 9:00 am, ideally when your child wakes up and before receiving any treatment) and in the afternoon (7:00 – 9:00 pm), again before the child receives any medication.

A dedicated app will guide you through the whole process.

How do I send the results?

The results are automatically transmitted to a central database every time you complete a measurement. No special actions are required from your part.

Do I need an internet connection?

An internet connection is not necessary to perform the measurements; only to send the results to the central database. However, even if you do not have internet access, the measurements are stored on your mobile and transmitted automatically next time you are online (see detailed instructions in “Material”).

I forgot a measurement. Is that a problem?

Unfortunately, to accurately determine the pattern of lung function variability, consecutive measurements at predetermined time points and for a long time period are required. This is the main challenge of this study and its success depends on it.

By omitting a single measurement, the results of the study are not significantly affected. However, the omission of two consecutive measurements or more than 5 individual measurements, can affect the calculation of variability indices and lead us to wrong conclusions.

Therefore, please be aware of the following:

  • If for any reason you missed a measurement, try to perform it at the first opportunity within the same day.
  • If a measurement is not possible to be performed, be sure that the next in the raw will not be missed.
  • If for any reason you know that some measurements will not be performed (e.g. you are away and forgot to take the spirometer with you), please inform your pediatrician or the study team (

My child is already receiving medication for asthma. Will the treatment change?

The LUV study is a non-interventional study. If your child is already receiving a specific medication, he/she will continue the treatment suggested by your pediatrician.

In case of abnormal measurements, we will immediately inform your pediatrician who will contact you and will probably adjust/change the treatment. However, this process can only have positive results for your child, because during the study period he/she will be under constant monitoring.

I do not wish to continue. Are there any consequences?

Certainly not! The participation in the LUV study is voluntary and you can withdraw from it at any time, without consequences. However, please inform your pediatrician in due time, so that we can dispatch your spirometer to another child.

Who has access to the study files? Is my child's personal data secured?

The LUV study is conducted in accordance with the Declaration of Helsinki for Good Clinical Practice. I was also approved by the Ethics Research Committee and the Scientific Council of the University Hospital of Patras (decision 329/02.04.19, ΑΔΑ 618Θ46906Γ-Γ0Χ).

Participants’ personal data (name, surname, email, disease, medication) will remain strictly confidential and will not be disclosed to third parties. Only the Principal Investigator of the study (S. Fouzas) has access to these data. Database entries and data processing will be anonymous (codified). The results of the study will be solely used for scientific purposes (presentations at conferences, publications in scientific journals, etc).

Who funds the study?

The study is exclusively funded by the “C. Caratheodory” funding Programme of the University of Patras, Greece ( The financial support concerns the purchase of the spirometers and the scholarship of the PhD candidate. None of the other study team members has any financial benefit related to the study.