INhaler Compliance Assessmentâ„¢ (INCAâ„¢), (Dublin, Ireland)
The Inhaler Compliance Assessment (INCA) EMD is one of the most extensively evaluated devices to date(18, 20-27). However, it is limited for use with the Diskus inhaler only and has memory for 60 doses meaning it needs to be replaced every 30 days. The device consists of a microphone and a microprocessor that records the audio produced, initiated when the Diskus inhaler is first opened, with the recording completed when the inhaler is closed(18, 28). The audio recording includes sliding of the Diskus lever until it clicks, the patient exhalation and subsequent inhalation of the medication. Additionally, the amplitude of inhalation is recorded and correlates with peak inspiratory flow. A median amplitude of <0.016AU corresponds to an inspiratory flow rate of <30L/Min which is deemed insufficient for dry power inhalation(18). As such the device identifies critical inhaler technique errors as well as temporal use of the inhaler. This is important as errors can reoccur following an assessment of competence. For example, in one study despite all patients being judged as initially competent in the use of their inhaler, 17% had >20% errors during the first month of assessment. The majority of patients who made errors did so intermittently (24). Over the course of the study, the feedback provided by the INCA device led to a reduction in errors to <5%, resulting in observed improvements in quality of life. Furthermore, in a randomised control trial, the impact of personalised biofeedback resulted in a significant improvement in adherence compared to a group receiving intensive education in which a fall in the rate of adherence was observed(22).
The usefulness of the INCA monitoring device has also facilitated the interpretation of FeNO suppression testing as it allows the identification of intentional versus unintentional non-adherence in patients with apparent ICS-resistant high FeNO(18, 26). Despite being able to use the inhaler proficiently when initially shown, inadequate inhaler use over a 7-day period was evident in 67% of patients monitored with the INCA device(18). Similarly, another study of patients with suspected severe uncontrolled asthma found only 27% to have refractory symptoms despite good ICS adherence, whilst 35% were uncontrolled in the context of suboptimal adherence and therefore could be considered difficult-to-control(22).
The device has a reported failure rate of <2%(18). The algorithm has demonstrated a sensitivity of 95%, specificity of 94% and an accuracy of 89% in detecting inhalations. Analysis can be performed rapidly, presenting information in real time(18). Importantly, the use of the INCA has been shown to be acceptable to >90% of asthma patients attending a difficult asthma clinic(26).