Validation of the Identification of Medication Adherence Barriers Questionnaire (IMAB-Q); a Behavioural...

To validate the Identification of Medication Adherence Barriers Questionnaire (IMAB-Q) as a tool to guide practitioners to identify patients who require support to take their medicines as prescribed, their key barriers to adherence and select relevant behaviour change techniques.

Adults prescribed medication for cardiovascular disease prevention were recruited from nine community pharmacies in England. Participants completed the IMAB-Q comprising 30 items representing potential barriers to adherence developed from our previous mixed methods study (scoping review and focus groups) underpinned by the Theoretical Domains Framework. Participants also self-reported their adherence on a visual analogue scale (VAS) ranging from perfect adherence (100) to non-adherence (1). A subgroup of 30 participants completed the IMAB-Q twice to investigate test-retest reliability using weighted Kappa. Mokken scaling was used to investigate IMAB-Q structure. Spearman correlation was used to investigate IMAB-Q criterion validity compared to the VAS score.

From 1407 invitations, 608 valid responses were received. Respondents had a mean (SD) age of 70.12 (9.9) years and were prescribed a median (IQ) 4 (3, 6) medicines. Worry about unwanted effects (n = 212, 34.5%) and negative emotions evoked by medicine taking (n = 99, 16.1%) were most frequently reported. Mokken scaling did not organise related IMAB-Q items according to the TDF domains (scalability coefficient H = 0.3 to 0.6). Lower VAS self-reported adherence correlated with greater IMAB-Q reported barriers (rho = -0.14, p = 0.001). Test-retest reliability of IMAB-Q items ranged from kappa co-efficient 0.9 to 0.3 (p < 0.05).

The IMAB-Q is valid and reliable for identifying people not adhering and their barriers to adherence. Each IMAB-Q item is linked to a TDF domain which in turn is linked to relevant behaviour change techniques. The IMAB-Q can therefore guide patients and practitioners to select strategies tailored to a patient's identified barriers.