Maintaining Control of Chronic Obstructive Airway Disease: Adherence to Inhaled Therapy and Risks and Benefits of Switching Devices

Figures & data

Table 1. Description of the five potential domains related to non-adherence, as described by the World Health Organization (20)

Non-adherence domain	Examples
Patient	Lack of awareness of the consequences of poorly controlled disease (perceiver of asthma and COPD as innocuous diseases); poor perceivers and tolerance of symptoms (typical of elderly); concerns about drug side effects, or loss of efficacy, or development of addiction; dislike of the drug prescribed or the inhaler used to deliver the drug or treatment regimen; excessive (or low) expectations about treatment; forgetfulness; attitudes towards ill health (deny disease, refuse asthma as chronic disease, or regular treatment, perceive asthma only as allergic disease, typical of adolescents); stigmatizations (typical of cultural or religious issues)
Condition	Physical and cognitive impairments including depression, impaired vision of manual dexterity; comorbidities; asymptomatic disease
Health system	Poor medical-patient communication; poor medical-other health caregivers partnership in patients education; lack of continuity of care, no written plan; physician's underestimation of disease control; poor supervision, training, and follow-up of patients; poor education to inhaler training; poor knowledge of disease and treatment; incorrect choice of device; lack of discussion about patient's preference and side effects
Treatment	Complexity of regimen for frequency of doses and/or number of pills/inhalers; polypharmacy (complicating schedules or predisposing to trade-off among prescribed drugs); side effects; late onset of action; long-term treatment
Socioeconomic	Lack of access to health care; poor social support; high cost of medication (payment or co-payment); low literacy; distance to pharmacy

Figure 1. Adherence to prescribed therapy in generic chronic diseases (A) and in chronic respiratory diseases (B), both in studies in a real-world setting. Notably, in inhaled therapy, device misuse is a major additional cause of non-adherence in real life (14, 20, 21, 22, 28–31).

Figure 2. Three typical flow profile curves from patients inhaling through a DPI device. Using the classical DPIs, the only effective one is the A profile, which imposes an elevated acceleration at the start of inhalation. The B profile achieves the threshold flow too late, negatively conditioning the quality of particle size. The C profile is inadequate because it does not reach the threshold flow to accurately deliver the dose.

Table 2. Main characteristics differentiating classical and newer dry-powder inhalers (DPIs) (84, 99, 100)

	Classical DPIs	Newer DPIs
Risk of poor disaggregation of the released dose (99, 100)	Yes	No*
Dose release only at optimal flow for disaggregation (99)	No	Yes*
Low number of steps to prepare the inhalation (max 3) (99)	No	Yes
Triple feedback system^# for the dose inhalation (99)	No	Yes/No
Extrafine formulation (MMAD < 2 μm) (84)	No	Yes/No

In the last decade pharmaceutical research have developed new dry powder inhalers, with the objective to overcome lacks of previous devices. In this table are summarized some characteristics of newer devices that could allow a correct and effective use.

*Only for newer DPIs with Breath Actuated Mechanism (BAM).

# Feedback systems involving taste, sight and hearing.

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