Method of assessment Examples Parameter Measure Advantages Disadvantages
Physician assessment
Questions asked during clinic visit
Indication of non-adherence
Easy to gather information Quick Inexpensive Subjective Not standardised Risk of recall bias
Self-reported questionnaire
Medication Adherence Report Scale for asthma (MARS-A)10, Morisky Medical Adherence Scale (MMAS) 11,Test of Adherence to inhalers (TAI)12
Pre-established cut-off point determines whether patient is adherent or non-adherent
Easy to use Inexpensive Subjective Risk of recall and reporting bias leading to overestimation of adherence Usually only available in English
Prescription Database
Medication Possession Ratio (MPR), Proportion of Days Covered (PDC)
Percentage calculated
Objective Easy to use Inexpensive Adherence can be measured over a long time interval Non-adherent patients can be easily identified
Evidence of dispensed medication does not equate to medication administered
Dose Counter
Dose counter on inhaler
Comparison of expected to actual dose counter reading
Quick Easy to use Inexpensive Not on all devices have a dose counter ‘Dose dumping’ will conceal non-adherence
T2 Biomarker
FeNO Suppression Test
Change in FeNO
Objective Identifies non-adherence when used with DOT Identifies patients with ICS-resistant T2 inflammation who may benefit from biologic therapy Cost Time and resource dependent for patient and HCP Not widely used
Serum drug level
Serum ICS concentration
Serum concentration
Objective
Invasive Cost
Electronic Monitoring Devices
INCA, Propeller, Hailie, Turbu+ Respiro, Herotracker, CapMedic, Digihaler
Frequency of inhaler use
Objective Some can distinguish between intentional and non-intentional (e.g. error in inhaler technique) non-adherence Patterns of non-adherence can be identified Usually requires the patient to own a smartphone device and be technologically literate Cost