Feasibility and design of a novel smartphone app to deliver blood pressure-lowering inspiratory muscle strength training

PROJECT SUMMARYHigh blood pressure (BP), particularly high systolic BP (SBP), is the major modifiable risk factor for cardiovascular diseases (CVD) and related conditions. Indeed, over 50% of all adults have above-normal SBP (≥120 mmHg), placing them at increased disease risk. In addition, these adults face ~$2000/year in excess medical expenses compared to their peers with normal BP. Rates of BP control in the United States are worsening, predicting a new epidemic of disorders driven by above-normal SBP, and an increasing financial burden for those affected, unless innovative and affordable therapies with clinical efficacy can be adopted by, and translated to, this at-risk group.High-resistance inspiratory muscle strength training (IMST) is a novel lifestyle intervention involving repeated inhalations against resistance with a hand-held device. In a randomized, double-blind, sham- controlled, R21-funded study in adults with above-normal SBP (n=36), we found that IMST (30 breaths/day [~5 min/day] at 75% maximal inspiratory pressure [PIMAX], 6 days/week for 6 weeks) had excellent adherence (94% of prescribed training sessions completed), increased inspiratory muscle strength (~20% increase in PIMAX) and lowered SBP by 9 mmHg compared to low-resistance sham training – thus establishing the clinical efficacy of high-resistance IMST. Importantly, this 9-mmHg reduction in SBP compares favorably to time- intensive lifestyle strategies (e.g., aerobic exercise) and pharmacotherapy, without the side effects associated with medication. However, this trial was performed in the research clinic. Therefore, the next step in the overall translation of IMST for improving public health is to establish a vehicle to disseminate IMST instruction and promote intervention adherence by utilizing digital health technologies and creating a smartphone app.In this Phase I STTR application, we propose to begin the process of developing a smartphone app for commercialization that independently guides users through an IMST intervention for lowering SBP and reducing disease risk and the associated financial burden. This will be accomplished through 3 specific aims: Aim 1: Conduct iterative focus groups with adults who have above-normal SBP to collect potential user information for IMST smartphone app needs and preferences; Aim 2: Finalize the conceptual model and develop planned app components including printed wireframes, storyboards, and clickable wireframes; and Aim 3: Conduct beta testing on the clickable wireframes and finalize app design. Successful completion of the above aims will position us to develop the fully programmed high-resistance IMST smartphone app and apply for Phase II STTR funding to conduct a randomized clinical trial assessing the effectiveness of at-home IMST with the app for lowering SBP. Ultimately, our app will fill an unmet need in the marketplace by delivering an effective, adherable, cost-saving, BP-lowering intervention.