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).