Study design and population

Inclusion criteria are age ≥18 years with a self-reported breathlessness intensity ≥3 on a 0–10 Numerical Rating Scale (NRS) during the prior 2 weeks not caused by an acute infection such as an upper respiratory tract infection or pneumonia. Participants should be clinically stable without expected need for hospital admission within 1 week, be able to walk without a personal aid (rollator allowed), be able to use a device (smartphone/pad) with internet access regularly and be able to read and complete baseline assessments. The default setting is 1 week of participation, but there is a possibility to continue for additional weeks at the discretion of the participant. Participants will be recruited into two different cohorts, one general cohort which include most participants and one smaller clinical subcohort study with fewer participants but with added data.

Recruitment

Potential participants will be identified by clinical and research staff at the centres of the participating investigators including primary care, pulmonary clinics and internal medicine/cardiology departments in Blekinge, Örebro and Skane University Hospitals (Lund/Malmö). Participants will also be recruited through advertisements in national and local newspapers and magazines including those of the Swedish Respiratory Society, the Swedish Heart-Lung Foundation and the Heart-Lung Association and on webportals/sites.

Mobile phone application-based data collection

The mobile phone application is available on the two major mobile platforms in the market today (iOS and Android) and can be downloaded for free through their respective distribution channels (ie, ‘App Store’ for Apple and ‘Google Play’ for Android) and installed directly on the participants’ personal mobile phones. It was developed by the company ‘Cybercom group’ in close collaboration with the authors of this article and tested repeatedly for functionality in pilot-testing by authors and a small group of healthy volunteers. To access and start the active survey a four-digit code is needed which is distributed to participants by research staff or through the advertising. Baseline data will be recorded when starting the application and individual daily start and stop times will be set. At regular intervals during each day, the application will cue the participant, using sound and homepage notifications, to self-rate the intensity of breathlessness during the last 10–15 min. Each cue can be ignored or filled in later. Recall of breathlessness during the preceding night or day and additional measurements are rated in the application each morning and, for the whole week at the end of each week in the study (figure 1). The participant can quit the application at any time and will be asked to complete the cessation/exit assessments for the completed part of that week. If any problems or questions arise during the study period, there is a help section within the application with an email address to the primary investigators. All application data, linked to the participant-specific study ID, is encrypted and transferred to a central database in real time via the internet connection. If no internet connection is available at the time of transfer or if for some reason the data transfer is interrupted, the data will be stored locally on the device and the application will try to resend when the connection is re-established and stabilised. The data will also be kept on the device until the end of the study as a safeguard to create a redundancy.

• Download figure
• Open in new tab
• Download powerpoint

Figure 1

Overview of the timing of planned assessments, starting with eligibility, consent and baseline assessments then continuing with several daily prompts asking on intensity of breathlessness as well as morning, evening and weekly assessments including daily recall and daily predictions as well as a weekly recall.

Clinical substudy

A subset of participants at the study centres will be asked to participate in a clinical substudy. In addition to the information regarding the main application-based study, these participants will receive specific information about the substudy on paper and be asked to give their written informed consent to participate. Data including demographics, diagnoses, measures of pulmonary and cardiac function, treatments and hospitalisations will be obtained from medical records and national registries with up to 5 years follow-up of diagnoses and hospitalisations (Patient Registry), dispensed medications (Prescribed Drug Registry) and survival (Causes of Death Registry). Participants in the clinical substudy will be assessed for cognitive impairment at the beginning of the study. Some participants will also be invited to take part in a semistructured qualitative interview focusing on their experience of breathlessness and specifically how they cognitively recall breathlessness over different time periods such as ‘now’, ‘last 24 hours’ or ‘last week’. This group of participants will also be interviewed shortly about their experiences on using the mobile application. A separate study protocol and analysis plan will be developed before starting the qualitative substudy.

Assessments

All planned assessments and scales within the application are presented in table 1. Some modifications and new questionnaires were adapted.

Breathlessness will be assessed using cued questions several times each day asking, ‘How intensive has your breathlessness been in the past 10–15 min?’, rated between 0 (no breathlessness) and 10 (worst imaginable breathlessness). The same type of assessment will be cued each morning (‘How intensive has your breathlessness been during the past night?’) and evening (‘How intensive has your breathlessness been during this day?’), as well as for the whole week (‘How intensive has your breathlessness been during the past week?’). The user will also be asked to predict, using a similar 0–10 NRS scale, how the intensity of breathlessness will be during the coming day, night or week using the question ‘How intensive do you expect your breathlessness to be in the coming day/night/week?’.

The Patient Health Questionnaire (PHQ) is a self-administered version of the Primary Care Evaluation of Mental Disorders diagnostic instrument for common mental disorders which are in the public domain and free to use in research. The PHQ-15 comprises 15 somatic symptoms from the PHQ, each symptom scored from 0 (‘not bothered at all’) to 2 (‘bothered a lot’).16 A minor modification was made in this study by removing one question (pain or problems during sexual intercourse) as the question, during pilot testing, was not deemed to be fully appropriate to ask in this format. The total score of PHQ-15 will be recalculated due to having one question missing in accordance to the instructions from the American Psychiatric Association.17

To assess the self-efficacy of breathlessness, an NRS will be used with the question ‘How confident are you that you can manage breathing difficulty or avoid breathing difficulty during the day’ anchored at 0 (Not at all confident) and 10 (Very confident).

Before and after the main study, the user will be asked some general questions concerning technical knowledge and previous experience on using a smartphone (online supplementary appendix 1a). After the study, some questions will be asked to evaluate the user’s experiences on using the application (online supplementary appendix 1b).

For the participants in the clinical substudy, Montreal Cognitive Assessment Tool (MoCA) will be used to assess for cognitive impairment.18 19 MoCA is a brief and sensitive test for cognitive impairment, assessing visuospatial and executive functions, verbal ability, episodic memory, orientation and attention.19 It has been validated in numerous diseases, including cognitive impairment related to dyspnoea, COPD and heart failure.20–22

Power and sample size

To obtain a power of 80% to detect a clinically and statistically significant difference of 1 point on a 0–10 NRS between the mean experienced and the recalled daily breathlessness score, assuming a pooled SD of 1.81 points, a minimum of 30 participants need to be included into the main study. This is consistent with the sample size of Meek et al .15 To account for loss of data and ensure adequate power, at least 45 participants with data for at least 2 days will be included prior to analysis of the primary research question. The data collection will continue even after this sample size is reached in order to answer also secondary research questions. Specific statistical analysis plans will be developed for each objective.

Statistical analyses

Baseline characteristics will be tabulated using standard descriptive statistics. Mean, peak and end values of experienced, recalled and predicted breathlessness will be graphed and cross-tabulated. Associations between experienced, recalled and predicted breathlessness will be analysed using a mixed model repeated measures approach. Predictors of the difference score between recalled and experienced breathlessness, and between predicted and subsequently experienced breathlessness, respectively, will be analysed using multilevel mixed effects linear regression. Models will then be adjusted for potential confounders including age, sex, body mass index, level of anxiety, depression and functional status. The choice of an appropriate covariance structure will be evaluated.

The minimal clinically important difference score is defined as a 0.5 (small) and 1.0 (moderate/large) change in NRS score.23 The percentage of difference scores ≥0.5 and ≥1.0 points will be calculated.

Statistical significance will be defined as a two-sided p value of <0.05.

Confidentiality

In the application, data are de-identified using a study ID number. For patients who do not participate in the clinical substudy, the Swedish social security number is not recorded. For patients in the clinical substudy, clinical data will be cross-linked with data collected through the application using a key between the study ID (used in the application) and the participant’s Swedish social security number stored securely at the clinical centre.

The database used for the unidentified clinical data is located physically at Blekinge Institute of Technology and is used for several other clinical studies including the Swedish National Study of Ageing and Care (http://ltblekinge.se/snac) following all relevant protocols for data security and integrity. The code key containing the identifier are kept in a locked cupboard on a computer/USB memory not connected to the Internet.

Dissemination

Data will be presented on the group level only, ensuring that individual participants cannot be identified. The findings will be published in national and international peer-reviewed scientific journals and presented on relevant scientific conferences. The de-identified data will be posted in an open access data repository in accordance with the requirements of the scientific journal. Planned future papers will be concerning main and secondary endpoints as well as qualitative analyses on breathlessness measurements.

Authorship will be determined in accordance with the International Committee of Medical Journal Editors guidelines.