Table 1

PROMs of intentional (I) non-adherence—n=44 of 59 measures, 593 items5 6 14–55

No	Author, year, country	PROM/scale/rating/criteria/instrument	Outcome measure, number of intentional or unintentional items (I, UI, not reported)	Process measure, item domain: barriers (practical), behaviour (habit) or belief (perception)	Item construct	Classification of non-adherence	Method of scoring	Psychometric properties, (reliability and/or validity)	Setting, age* (years)±SD or IQR, correlates
1	Hogan et al, 1983, Canada14	Drug Attitude Inventory (DAI)	I=30	Belief (30-stop taking when feeling better or worse, etc)	30-item questionnaire E.g., feeling like a zombie after taking medication, take only when sick, unnatural to take medications, do not need medications once feel better, medication makes no difference and will do no harm if not taken	Habitual to occasional refusers of medications	Dichotomised scale high–low; yes=+2; no=+1	Good discriminant validity and reliability Test–retest reliability=0.82 Internal consistency, Cronbach’s alpha=0.93	Patients diagnosed with schizophrenia at a mental institution Mean age male: 40.0±12.8 Mean age female: 42.1±10.8 Juxtaposed against a 10-item (Van Putten & May) scale and clinical change over 3 weeks, as measured by the Brief Psychiatric Rating Scale
2	Morisky et al, 1986, USA5	Morisky, Green and Levine (MGL) Scale or MAQ	I=3, not reported=1	Barrier (1- forgetting), Behaviour (1-careless), Belief (2-stopping medications when feeling better/worse)	4-item questionnaire Forgetting, careless and stopping medications when feeling better or worse	High, medium, low adherence	Dichotomised scale high–low; yes=0; no=1	Good concurrent & predictive validity Internal consistency, Cronbach’s alpha=0.61	Patients with hypertension in 2 outpatient clinics of a large teaching hospital Median age (IQR): 54 (46-62) Juxtaposed against blood pressure measurements
3	Shea et al, 1992, USA15	Modified MGL Scale or MAQ	I=2, not reported=3	Barrier (1-forgetting), Behaviour (2-careless, self-management ‘Do you ever miss your medication for any reason?’), Belief (2-stopping medications when feeling better/worse)	5-item questionnaire derived from the 4 items developed by Morisky et al Minor modifications made to the wording of the original 4th question Added the 5th question: ‘Do you ever miss taking your high blood pressure medication for any reason?’	More adherent (n=87) or less adherent (n=115)	Dichotomised scale high–low; yes=0; no=1	Good concurrent & predictive validity Internal consistency, Cronbach’s alpha=0.71	Patients with incidence of hypertensive urgency and emergency Mean age: 54.7±11.5 in less adherent group; mean age: 59.8±11.8 in more adherent group Juxtaposed against blood pressure measurements and emergency admissions
4	Barber et al, 1997, USA16	The Comparison of Ophthalmic Medications for Tolerability (COMTOL) Questionnaire	I=3, not reported=1	4 questions on adherence: Barrier (1- forgetting), Behaviour (1- careless), Belief (2- stopped when feeling better, satisfaction)	4 of 12 items assessed adherence Measured side effects and limitations in ADL /HRQoL, medication compliance† and patient satisfaction with the medication	Higher scores (4 and 5)=higher adherence	5-point Likert scale (where 5=I did not miss any dose, 4=rarely, 3=a few times, 2=fairly often and 1=usually, almost always and always)	Good-to-excellent internal consistency Cronbach’s alpha=0.73–0.98	Patients with open-angle glaucoma or ocular hypertension Mean age: 53.4 (range 33–82) Juxtaposed against drugs’ known side effects and impact on ADL such as reading, driving or walking several blocks
5	Horne and Weinman, 1999, UK17	Beliefs about Medicine Questionnaire (BMQ)	I=18	Belief (18): specific items (10); general items (8)	18-item cognitive representation of medication 2 subscales: BMQ-Specific scale, i.e., specific-necessity, specific-concerns; BMQ-General scale, i.e, general overuse and general harm	Higher scores in BMQ-General scale meant an overall negative perception of medication; High scores in the Specific-Concerns scale represented the notion that adverse reactions were potentially harmful when taking medication on a regular basis; High scores in the Specific-Necessity scale represented patient’s need to adhere to medication to maintain health.	5-point Likert scale with scores ranging from 4 to 20	Good discriminant validity: the diabetic group had higher specific-necessity score; the asthmatic and psychiatric samples had higher specific-concerns score; patients attending the complementary clinic had higher scores for both general harm and overuse scales	Patients with asthma, diabetes and psychiatric conditions from hospital clinics and cardiac, general medical and renal (haemodialysis recipients) inpatients of hospitals A matched group of patients seeking care from allopathic (community pharmacy) and complimentary sources (homeopathy herbal clinic) Age range: 45.5–63.6 Juxtaposed against IPQ, RAM and the Sensitive Soma Scale
6	Svarstad et al, 1999, USA6	Brief Medication Questionnaire	I=7, UI=2	Behaviour (7), Belief (2)	9-item questionnaire to screen adherence and barriers to adherence 5-item Regimen Screen that asks patients how they took each medication in the past week (How many times did you miss taking a pill?) 2-item Belief Screen that asks about drug effects and bothersome features (How much it bothers you?) 2-item Recall Screen about potential difficulties remembering (I stop or interrupt therapy, decrease the prescribed amount, take extra doses than prescribed)	Positive score ≥1 indicated positive screen for potential non-adherence or recall barriers; Belief barriers—Type of non-adherence in past week according to MEMS electronic prescribing: repeat=took at least 20% over or under the prescribed amount; sporadic=took 1%–19% over or under the prescribed amount	4-point Likert scale (range=0–2)	Concurrent and predictive validity Discriminant validity: Regimen and Belief Screens had 80%–100% sensitivity for ‘repeat’ non-adherence Recall screen had 90% sensitivity for ‘sporadic’ non-adherence	Recruited in 3 pharmacies if non-institutionalised Mean age=52.6 Juxtaposed against pill count
7	Thompson et al, 2000, Australia18	Medication Adherence Rating Scale (MARS)	I=8, UI=2	Barrier (1- forgetting), Behaviour (1-careless), Belief (8-stopping medications when feeling better/worse)	10-item questionnaire E.g., thoughts are clearer, prevent getting sick, take when sick, and stop when feeling worse, feel unnatural/weird/ tired/sluggish	Adherent or non-adherent	Dichotomised scale: yes=0; no=1	Good concurrent and predictive validity, good discriminant and content validity Internal consistency, Cronbach’s alpha=0.75	Majority with schizophrenia, others with psychosis-like symptoms Mean: 32.9+11.1 Juxtaposed against lithium levels and carer ratings of compliance
8	Duong et al, 2001, France19	Patient Medication Adherence Questionnaire	I=42, UI=13, not reported=6	Barrier (13- ADL/routine affected, sociodemographic), Behaviour (12- self-confidence, support, motivation), Belief (36- adverse effect, comorbidities, knowledge, attitude, perception)	61-item questionnaire E.g., frequency of non-adherence, adverse effects, social support, psychological status, knowledge, attitudes, perception, alcohol and illicit drug use, socioeconomic status	Adherent or non-adherent	4-point or 6-point Likert scale (ranging from strongly agree to strongly disagree)	Moderate predictive validity for half of the items (author suggested for future, PMAQ to focus on the variables identified as strong predictors of non-adherence)	Patients enrolled in Dijon Hospital AIDS day-care Mean age: 40 (range: 21–79) Juxtaposed against viral RNA level and plasma PI concentration
9	Horne and Weinman, 2002, UK20	Medication Adherence Report Scale (MARS-9)	I=6, UI=1, not reported=2	Barrier (1- forgetting), Behaviour (2- self-management), Belief (6- avoid if can, keep reserve medication, use when needed, alter dose, decide to miss, decide to take less)	9-item questionnaire forgetting, alter dose, stop taking, use when breathless, decide to miss, take less, avoid, as reserve, use regularly	Higher scores=higher adherence	5-point Likert scale (where 5=never, 4=rarely, 3=sometimes, 2=often and 1=very often)	Good construct and predictive validity Internal consistency, Cronbach’s alpha=0.85	Community-based asthma clinics Mean age: 49.3±8.1; age range: 16–84 years Juxtaposed against IPQ and BMQ
10	Walsh et al, 2002, UK21	Medication Adherence Self-Report Inventory (MASRI)	Not reported=12	Behaviour (12-self-management, commitment, motivation)	12 items with 2 themes First part: 5 questions on missing doses and 1 question on VAS: Second part: 4 questions on timing of doses and 2 on VAS	Adherent or non-adherent	Dichotomised scale: (yes=0; no=1) Two response formats: 5-point Likert scale and a VAS (ratio scale) First part related to the doses actually taken; VASDOSE=VAS for the proportion of doses taken in the preceding month	Moderate predictive validity (1 item), good discriminant and content validity (VASDOSE)	HIV-infected adults from public specialist clinics Age range: 18–65 Juxtaposed against MEMS, pill count and viral RNA level
11	De Klerk et al, 2003, Netherlands22	Compliance Questionnaire Rheumatology (CQR -19)	I=15, UI=4	Barrier (4-organiser used and stored strategically for ease of consumption, travelling/careless over weekends), Belief (15-trust in provider, stopping/alter medications when feeling better/worse/due to adverse effect/lack of efficacy)	19-item questionnaire E.g., trust (and fear) in healthcare provider, fewer problems after taking medications, no alternatives, access to medication (practicalities and when on vacation)	Unsatisfactory or good adherence	4-point Likert scale where 1=don’t agree at all; 2=don’t agree; 3=agree; 4=agree very much	Good discriminant and content validity, good reliabilitty Internal consistency, Cronbach’s alpha=0.71	Outpatients at the rheumatology wards of 3 hospitals Age range: 58–72 Juxtaposed against pill count using MEMS
12	Godin et al, 2003, Canada23	Self-Reported Questionnaire Assessing Adherence to Antiretroviral Medication	I=1, not reported=5	Barrier (6- stop taking temporarily one or more antiretroviral medication during the last month) Pills missed the preceding day Pills missed the penultimate day Pills missed during the preceding 7 days Taking the initiative to take fewer pills of one or more of antiretroviral medications during the last month Had missed taking one or more antiretroviral pills during the last month	6-item questionnaire Patients reported antiretroviral pills (n) missed on the preceding and penultimate days 3 questions used as aided-recall tools for situations that might have hampered the regular adherence to medication during the preceding 7 days 2 questions were used to assess non-adherence during the preceding 7 days Last question referred to the preceding 30 days as a time frame	Adherent or non-adherent (non-adherent if, for at least one measurement time, they reported having missed taking more than 5% of their pills on the preceding day)	5-point Likert scale (ranging from strongly disagree to strongly agree)	Adequate predictive validity with only one item Low sensitivity to detect increased viral load Internal consistency, Cronbach’s alpha=0.7686	HIV-infected patients from four clinics participated in a prospective longitudinal study Mean age: 43±8.39 Juxtaposed against change in viral load
13	Ogedegbe et al, 2003, USA24	Medication Adherence Self-Efficacy Scale (MASES)	I=26	Barrier (20- ADL/ routine/lifestyle access to medication), Behaviour (4- self-management refill, motivation, self-efficacy), Belief (2- adverse effect, take when feeling better)	26-item questionnaire measuring self-efficacy as a predictor of health behaviour E.g., how confident patients can take blood pressure medications on different occasions like when busy at home, when at work, when there is no one to remind, when worry about taking them for the rest of life, when they cause some side effects, when they cost a lot of money, when back home late from work, when do not have symptoms, when with family members, in public place, afraid of becoming dependent on them, afraid of affecting sexual performance, etc and how confident patients can carry out tasks such as filling prescription on time whatever the cost, etc	Adherent or non-adherent	3-point Likert scale (where 1=not at all sure, 2=somewhat sure, 3=very sure and 4=does not apply)	Good predictive and content validity Very good reliability Internal consistency, Cronbach’s alpha=0.95	Ambulatory African-American patients with hypertension in 2 sequential phases in urban primary care Mean age: 55.7±12.8; 58.9±12.6 Juxtaposed against mean clinic blood pressure measurements
14	Atkinson et al, 2004, USA25	Treatment Satisfaction Questionnaire for Medication (TSQM)	I=14	Barrier (3- ADL, convenience), Behaviour (4- confidence, motivation), Belief (7- adverse effect, knowledge)	14 items E.g., satisfaction regarding medication taking, experience with side effects, e.g., interfering with physical health and ability to function and mental function, convenience and confidence in medication taking	Adherent or non-adherent	5-point or 7-point Likert scale or a VAS (ratio scale)	Good reliability and construct validity Internal consistency, Cronbach’s alpha=0.85	8 patient groups (arthritis, asthma, major depression, type I diabetes, high cholesterol, hypertension, migraine and psoriasis) Mean age: 50.5±13 Age range: 18–88
15	Dolder et al, 2004, USA26	Brief Evaluation of Medication Influences and Beliefs (BEMIB)	I=7, UI=1	Barrier (1- forgetting), Behaviour (4-confidence, motivation), Belief (3- adverse effect, knowledge)	8 items E.g., feel better, prevent from hospitalisation, having a system that helps remember to take medications, forgetting, no problem getting medications from the hospital/pharmacy and having a psychotic disorder that antipsychotics can improve	Adherent or non-adherent	5-point Likert scale ranging from 1=completely disagree to 5=completely agree	Acceptable construct validity, acceptable reliability Internal consistency, Cronbach’s alpha=0.63	Middle-aged and older outpatients at psychiatry clinics Mean age: 57±12.1 Juxtaposed against DAI
16	Chisholm et al, 2005, USA27	Immunosuppressant Therapy Barrier Scale (ITBS)	I=13	Barrier (2- ADL, socioeconomic), Belief (11- adverse effect, frequency, and doses)	13-item questionnaire E.g., too many doses and frequency per day, cannot tell if immunosuppressants are helping, skipping doses when out of town/feel good/when think there maybe side effects, missing doses when depressed, confused/don’t understand about how/when to take medications, skip when short of money	Adherent or non-adherent	5-point Likert scale ranging from 1=strongly disagree to 5=strongly agree	Moderate construct and concurrent validity Internal consistency, Cronbach’s alpha=0.91	Patients who underwent transplant and on immunosuppressant therapy Mean age: 52.2±14.1; 54.79±14.3 Juxtaposed against graft rejection
17	Liu et al, 2006, USA28	Adherence to antiretroviral therapy	I=9, not reported=3	Barrier (3- forgetting), Behaviour (4- self-efficacy, support for taking antiretroviral), Belief (5- values placed on antiretroviral, healthcare providers, knowledge on resistance to antiretroviral)	12 items on adherence E.g., forgetting within 3 or 7 days, ‘over the past 3/7 days, how many times did you miss a dose of (this medication)?’ 3 domains: (1) medication regimen descriptions (e.g., ‘‘How many pills has your provider asked you to take each time?“), (2) medication regimen timing (e.g., ‘‘How long have you been on antiretroviral medication?”) and (3) attitudinal factors (e.g., ‘‘Taking HIV medication is too much trouble for what you get out of it.”)	Adherent or non-adherent —Fraction of the doses of medications taken divided by the doses of medication prescribed. Adherence was expressed as a percentage and capped at 100%	3-point Likert scale ranging from 1=none of the time, 2=sometimes, 3=all the time	Good criterion and construct validity	2 prospective longitudinal clinical investigations conducted at 5 HIV clinics Mean age: 38.76±8.1 Juxtaposed against pill count, self-report, serum antiretroviral levels, MEMS and medication diaries
18	George et al, 2006, Australia29	Beliefs and Behaviour Questionnaire (BBQ)	I=23, UI=2	Barrier (8- forgetting, confusion, lifestyle changes/storage/routine, refill prescriptions), Behaviour (1- follow strictly), Belief (16- satisfaction with healthcare provider, stop taking depending on mood)	25 items on adherence E.g., experience/ beliefs, physical barriers, confusion on medications, make changes to suit lifestyle and mood	Adherent or non-adherent	5-point Likert scale where 1=not at all and 5=extremely	Good validity and reliability Internal consistency, Cronbach’s alpha=0.5–0.9	Ambulatory patients with chronic lung diseases Mean age: 71.1±8.7 years Juxtaposed against MARS
19	Wetzels et al, 2006, Netherlands30	Maastricht Utrecht Adherence in Hypertension Questionnaire (MUAH)	I=17, UI=2	Barrier (3- forgetting, busy lifestyle), Behaviour (3- careless, lack of support, and discipline, unsure), Belief (13- stop taking when feeling better or worse, would take alternative, knowledge, aversion towards medication)	19 items on medication adherence E.g., positive attitude towards healthcare and medication, lack of discipline and aversion towards medication (MUAH)	Adherent or non-adherent	7-point Likert scale where 1=totally disagree to 7=totally agree	Good convergent validity Internal consistency, Cronbach’s alpha=0.63–0.8	Patients on medication for hypertension and part of a randomised clinical trial from 2 regions in the Netherlands Age range: 55–75 Juxtaposed against the BMQ, pharmacy refill records and MEMS
20	Glass et al, 2006, Switzerland46	Swiss HIV Cohort Study Adherence Questions (SHCS-AQ)	Not reported=2	Behaviour (2- self -management)	2 items on adherence Part 1: (1) How often did you miss a dose in the last 4 weeks? and (2) Did you have a period of no drug intake for >24 hours in the last 4 weeks? Yes/ No Part 2: VAS	Adherence defined in terms of missed doses (0, 1, 2 or >2) in the previous 28 days Taking <95% of doses in the past 4 weeks	Timing: daily, more than once a week, once a week, once every second week, once a month, never VAS: Yes/No	Good concurrent and predictive validity	Outpatients from clinics of participating HIV centres, associated hospitals or specialised private practices Mean age: 41.4±8.3 Juxtaposed against HIV viral load
21	Mannheimer et al, 2006, USA31	Center for Adherence Support Evaluation (CASE) Adherence Index	I=1, not reported=2	Barrier (1- difficult), Behaviour (2- self-management)	3-item questionnaire E.g., a composite (sum) of 3 measures of antiretroviral therapy, difficulty taking on time, average number of days per week at least 1 dose missed, last time missed at least one dose	Adherence level categorised as 100%, 80%–99% and <80%	Timing: all, most, about half, very few, none in the past 7 days	Good predictive validity	Participants in a longitudinal, prospective cross-site evaluation of 12 adherence programmes throughout the USA Mean age: 40.1±8.6 Juxtaposed against HIV RNA level
22	Risser et al, 2007, USA32	The Self-Efficacy for Appropriate Medication Use Scale (SEAMS)	I=13	Barrier (4- fill Rx, keep to appointment, inconvenience, routine), Behaviour (2- no social support, discipline), Belief (7- stop taking when feeling better or worse, alternative, knowledge, adverse effect towards medication)	13 items from 21 on adherence, e.g., self-efficacy in adhering to prescribed medications	Adherent or non-adherent	3-point Likert scale (where 1=not confident, 2=somewhat confident, and 3=very confident)	Good construct validity Internal consistency, Cronbach’s alpha=0.89	Patients with coronary heart disease (CHD) and other comorbid conditions Mean age: 63.8±10.4 Juxtaposed against Morisky scale
23	Gehi et al, 2007, USA33	Single-item measure of self-reported adherence	I=1	Behaviour (1- discipline)	Single item Strictly following the prescribed frequency	Adherent or non-adherent, Non-adherence=taking medications as prescribed 75% of the time or less	5-point Likert scale (where 1=all of the time and 5=less than half the time)	Good predictive validity	Outpatients with stable CHD Mean age: 64±11 Juxtaposed against cardiovascular events (CHD death, MI or stroke)
24	Prado et al, 2007, Brazil34	Self-report on adherence	I=1	Behaviour (1- discipline)	Single item Strictly following the prescribed frequency, if not, justify with reason	Adherent or non-adherent	Dichotomised scale: yes=0; no=1	Moderate predictive validity	Primary care hypertensives 54% aged >60 Juxtaposed against pill count
25	Byerly et al, 2008, USA35	Brief Adherence Rating Scale (BARS)	Not reported=4	Behaviour (4- self-management, commitment, motivation)	4 items 3 items (number of doses missed in a day, in a month, and reduced dose, if any) 1-item VAS to assess the proportion of doses taken in the past month (0%–100%)	Adherent or non-adherent	Nominal scale: number of days patient did not take or took less over past 1 month and the proportion of doses taken by the patient in the past month (0%–100%)	Good concurrent and predictive validity; excellent reliability Internal consistency, Cronbach’s alpha=0.92	Outpatients with schizophrenia and schizoaffective disorder from public mental health clinics Mean age: 44.3±9.1; age range: 21–59 Juxtaposed against MEMS
26	Kerr et al, 2008, Canada36	Self-reported HAART adherence	Not reported=1	Behaviour (1- self-management)	Single item Frequency of taking medication in the last 6 months	Adherent or non-adherent	5-point Likert scale (where 1=occasionally (<25%) and 5=always (100%))	Moderate predictive validity	HIV-infected patients enrolled in the Vancouver Injection Drug Users Study Mean age: 40±6.8 Juxtaposed against pharmacy refill data
27	Deschamps et al, 2008, Belgium37	European HIV Treatment Questionnaire (EHTQ)	Not reported=2	Behaviour (2- self-management)	2-item questionnaire on frequency and doses	Non-adherence was defined as (1) adherence: the percentage of doses taken compared with the total doses prescribed and (2) drug holidays: no medication intake for 24 hours+50% of the dosing interval of the medication	Nominal scale: either less than 100% or 1 or more days per 30 days	Poor concurrent validity	HIV-positive adults on antiretroviral therapy followed up at a university hospital Mean age: not presented Juxtaposed against SHCS-AQ and MEMS
28	Lu et al, 2008, USA38	Self-reported antiretroviral adherence questionnaire	I=1, not reported=4	Behaviour (5- self management, commitment)	5-item questionnaire 2 items (past 3 days and 7 days: number of doses missed) 3 items (past 1 month: frequency: ‘Did you take all your medications all the time?’; percentage: ‘What percentage of the time were you able to take your medications exactly as your doctor prescribed them?’; and ability: ‘‘Rate your ability to take all your medications as prescribed’	Adherent or non- adherent	Both nominal scale and rated on 6-point Likert scale where for (1) frequency: 1=none of the time to 6=all the time; (2) percentage of the time were able to take medications exactly as prescribed (0%–100%); (3) ability to take all medications as prescribed (very poor–excellent)	Good convergent and predictive validity	Patients on antiretrovirals from academic medical centres, a community health centre, a general practice based in an academic medical centre and a private infectious diseases practice Mean age: 42 (SD not available) Juxtaposed against MEMS
29	Kripalani et al, 2009, USA39	Adherence to Refills and Medications Scale (ARMS)	I=11, UI=1	Barrier (7- fill Rx, keep to appointment, inconvenience, cost), Behaviour (3- careless, discipline, ability to follow instruction), Belief (2- stop taking when feeling better or worse)	12-item scale 2 subscales: (a) adherence to the filling or refilling of prescriptions on schedule; (b) adherence to taking medications	Adherent or non- adherent	4-point Likert scale where 1=none to 4=all	Good criterion and predictive validity Internal consistency, Cronbach’s alpha=0.81	Patients with CHD attending a primary care clinic Mean age: 63.7±10.3 Juxtaposed against Morisky scale, medication refill adherence and blood pressure measurements
30	Duggan et al, 2009, USA40	Adherence to antiretroviral therapy	I=30	Barrier (7- storage, physical difficulty, routine), Behaviour (7- support, motivation, self-management), Belief (16- values placed on antiretrovirals, healthcare providers, knowledge on antiretrovirals, stigma)	30 items 3 categories of questions: (a) acceptance/avoidance; (b) completely tethered and (c) motivation Have you ever thought having HIV was a ‘punishment’? Do you feel that your medicines are hard to take? Do you believe the medicines for HIV that you take are working for you?	Adherent or non- adherent	Positive/negative–add 1 mark for positive and minus 1 for negative	Good criterion and predictive validity	Patients seeking treatment for HIV infection Age range: 18–51 Juxtaposed against change in viral load
31	Gabriel and Violato, 2010, Canada41	Antidepressant Adherence Scale (AAS)	I=3, not reported=1	Barrier (1- forgetting), Behaviour (1- careless), Belief (2- stopping medications when feeling better/worse)	4-item questionnaire Forgetting, careless and stopping medications when feeling better or worse Measure the frequency of any or all these omissions during the 4 weeks	High, medium, low adherence	Nominal scale: high–low	Moderate concurrent & predictive validity (adherence level correlated with knowledge and attitude scores); acceptable reliability Internal consistency, Cronbach’s alpha=0.66	Patients treated as outpatients at university hospital following referrals by their family physicians Mean age 52±11.6 Juxtaposed against depression literacy (knowledge and attitudes towards depression and its treatments); 2 instruments completed: MCQ knowledge test of depression and its treatment, and a Likert self-report questionnaire to measure attitudes toward depression and its treatments
32	Unni et al, 2014, USA42	Medication Adherence Reasons Scale (MARS)	I=15	Barrier (8- access, challenges in physical dexterity, routine), Behaviour (2- self-management, support), Belief (5- attitude, side effects, number of concurrent medications, healthcare provider trust, treatment efficacy)	15 items related to medication adherence E.g., management, belief, multiple medications, availability, forgetfulness	Adherent or non- adherent	5-point Likert scale where 1=none of the time to 5=all of the time	Moderate concurrent & predictive validity; acceptable reliability Internal consistency, Cronbach’s alpha=0.8–0.9	Internet users taking cholesterol-lowering medications or asthma maintenance medications or both Mean age: asthma: 48.7; hypercholesterolaemia: 59.4 Juxtaposed against Morisky scale
33	Muller et al, 2015, Germany43	Adherence Barrier Questionnaire (ABQ)	I=14	Barrier (3- forgetting, challenges, cost), Behaviour (4- careless), Belief (7- stopping medications when feeling better/worse, knowledge)	14 items Intentional adherence barriers (3) Medication-related barriers (4) Unintentional adherence barriers (4) Healthcare system-related barriers (3)	Adherent or non- adherent	4-point Likert scale where 1=strongly disagree and 4=strongly agree	Good construct validity and reliability Internal consistency, Cronbach’s alpha=0.82	Patients with atrial fibrillation from several general practices - mean age: 72.7±9.3 Juxtaposed against anticoagulation quality achieved by patients treated with oral anticoagulants
34	Kleppe et al, 2015, Netherlands44	The Probabilistic Medication Adherence Scale (ProMAS)	I=7, UI=4, not reported=7	Barrier (2- away from home, Rx refill), Behaviour (11- self-management), Belief (5- trust in doctor)	18 items E.g., forgetting, take at a later moment, stopped, did not take, have taken all that should, take exactly the same time every day, never changed frequency of use	Adherent or non- adherent	Dichotomised scale high–low; yes=0; no=1	Good discriminant validity and reliability	Elderly receiving medications for chronic conditions recruited by a Dutch agency Mean age: 68±7.1 Juxtaposed against MARS
35	Sidorkiewicz et al, 2016, France45	Sidorkiewicz adherence tool	I=2, not reported=3	Barrier (2- holiday/weekends, forgetting), Behaviour (3- self-management, timing careless)	5 items (a) Early discontinuation of the drug; (b) systematic omission of a daily dose (e.g., at noon); (c) drug holidays; (d) skipping doses and (e) schedule errors	High, good, moderate, poor, very poor adherence	Nominal scale assisted by pictogram; Never to sometimes (6–7 days or more)	Good construct validity and test–retest reliability	Consecutive patients in 6 general practices and 6 care units of university hospitals Median age (IQR): 59.1 (42.5–70.6) Juxtaposed against (1) Liu instrument28); (2) the Adherence Estimator; (3) Physician’s rating of patient’s adherence; (4) Morisky scale and (5) Treatment Burden Questionnaire
36	Weinman et al, 2018, UK47	Intentional Non-Adherence Scale (INAS)	I=22	Barrier (3- inconvenience, schedule, cost) Behaviour (1- self-management) Belief (18- knowledge, treatment efficacy, perception, trust in healthcare provider, attitude)	22 items on adherence E.g., ‘To see if I really need it’, ‘Because I don't like chemicals in my body’, ‘Because my body is sensitive to the effects of the medicine’, ‘Because I think the drug might become less effective over time’ and ‘Because it reminds me that I have an illness’.	Adherent or non-adherent	5-point Likert scale where 1=strongly disagree, 2=disagree, 3=neutral, 4=agree, 5=strongly agree	Good construct and moderate predictive validity Internal consistency, Cronbach’s alpha=0.93	Patients from 3 different outpatient clinics (hypertension, oncology and gout) Mean age: hypertension, 56.2; oncology, 62.2; gout, 61.6 Juxtaposed against a biomarker measure and with self-reported adherence (BMQ, PAM, BIPQ)
37	Tan et al, 2019, China48	A Chinese and Western medication adherence scale	I=29, UI=2	Barrier (1-forgotten) Behaviour (4- self-management, careless) Belief (26- knowledge, side effects, dose, stopped taking when feeling better/worse)	31 items Measures knowledge, belief and behaviour	Higher scores, better the patients’ medication adherence.	Nominal scale: MCQ options A–E	Good content and construct validity; excellent internal consistency and test–retest reliability Internal consistency, Cronbach’s alpha=0.92	Patients with CKD who kept long-term follow-up visits to the chronic disease department of a hospital Age range age: 18–80 Juxtaposed against MGL Scale
38	Sustersic et al, 2019, France49	The Global Adherence Scale for Acute Conditions (GASAC) Questionnaire	I=21, not reported=3	Barrier (2- forgetting, Rx refill), Behaviour (3- self-management), Belief (19- felt better/worse, confidence in healthcare providers, system)	24 items about adherence 3 index questions 21 additional questions on reasons for non-adherence (self, healthcare provider and healthcare system reasons) E.g., forgetting, did not refill Rx, issues with treatment regimen, did more harm than good, felt better or worse, confidence in healthcare providers and system	Low, highly adherent	Ordinal scale where 1=no; 2=rather not; 3=rather yes; 4=yes —final score was expressed as the ratio between 0 and 1	Good content and construct validity Internal consistency, Cronbach’s alpha=0.78	Patients consulting a hospital emergency department Age range: 21–71 Juxtaposed against Girerd questionnaire
39	Hatah et al, 2020, Malaysia50	Malaysia Medication Adherence Assessment Tool (MyMAAT)	I=9, not reported=3	Barrier (2- Rx refill), Behaviour (6- self-management, social support), Belief (4- did not take when felt better, did not see the significance, fear of side effects, lack of dosing knowledge)	12 items 5 constructs: Medication-taking behaviour Perceived utility of medications i.e., benefits, costs and efficacy Perceived barriers Perceived self-efficacy and social support Perceived severity and susceptibility of diabetes	Higher scores indicated better adherence	5-point Likert scale where 5=strongly disagree to 1=strongly agree	Good content and construct validity, good–excellent reliability Internal consistency, Cronbach’s alpha=0.91	Patients with diabetes who presented to primary and secondary care (public hospitals and clinics) Mean age: 57.2±10.8 Juxtaposed against SEAMS and MPR
40	Khatib et al, 2020, UK51	My experience of taking medicine (Mymeds) questionnaire	I=13, UI=1	Barrier (7- refill Rx, forgetting, physical dexterity), Belief (7- did not take when felt better, lack knowledge on dosing and side effects)	14 items 6 sections: current medicines, understanding and satisfaction with medicines, concerns about medicines, practical barriers, fitting medicines into daily routine and adherence to secondary prevention medicine over the past month	Adherent or non-adherent	5-point Likert scale for how often each medicine was taken as prescribed in the past month (all of the time; nearly all of the time; most of the time; about half the time; less than half the time) 4-point Likert scale from 1=strongly agree to 4=strongly disagree for other items	Good face validity	Patients prescribed with medicine for secondary prevention of CHD events at clinics Mean age 70.5±10.9 Juxtaposed against MMAS-8
41	Goh et al, 2020, Malaysia52	Patient-Medication Adherence Instrument (P-MAI) and a Healthcare Professional-Medication Adherence Instrument (H-MAI)	I=24, not reported=2	Barrier (13- routine, forgetting, Rx refill, cost, other coexisting conditions, missed appointments, lack of privacy, confused about instructions), Behaviour (3- take less/more as directed), Belief (10- knowledge, relationship with healthcare provider, dosing, stopped taking when feeling better/worse, efficacy)	26 items on patient-reported adherence (P-MAI-9) Adherence=2 items; knowledge/ belief=7 items and reason(s) for not taking medications as directed for the past 2 weeks=17 items	Higher score indicates better adherence	5-point Likert scale where 1=strongly disagree to 5=strongly agree	Good content and construct validity Internal consistency, Cronbach’s alpha=0.72	Patients diagnosed with DM, taking at least one oral hypoglycaemic agent and enrolled in tertiary-based primary care clinics Median age (IQR): 63 (57–69) P-MAI juxtaposed against H-MAI
42	Haag et al, 2021, Switzerland53	Barriers to Oral short-Term antibiotic Adherence (BIOTICA)	I=15	Barrier (4- difficulty to swallow, forgetting, difficult to incorporate in daily life, no support from caregiver), Behaviour (3- no intention to take/intend to miss a dose), Belief (8- side effect/ interactions, knowledge, unnecessary, unfamiliar with consequence, no trust in prescriber, information could not be understood / insufficient)	15 items Barrier-items were in 10 of 11 theoretical domain framework and included environmental context and resources, knowledge, social influence, emotions, beliefs about capabilities Intentions, memory, skills, beliefs about consequences and social, professional role and identity	Higher scores indicated higher degree of non-adherence	5-point Likert scale where 1=strongly disagree to 5=strongly agree	Good content and construct validity Internal consistency, Cronbach’s alpha=0.72 Item correlation >0.2 (acceptable)	Patients assessed before antibiotic initiation in the outpatient setting (pharmacies and surgeries) Mean age 51.53±16.7 (range: 19–85 years) Juxtaposed against pill count by MEMS REDCap
43	De Las Cuevas et al, 2021, Spain54	Patient Health Beliefs Questionnaire on Psychiatric Treatment	I=8	Belief (8- side effect/ interactions, knowledge, unnecessary, unfamiliar with consequence, no trust in prescriber, information could not be understood / insufficient)	17-item self-reported health beliefs scale. 2 subscales (8 items) were related to medications: Negative aspects of medication (pharmacophobia) Positive aspects of medication (pharmacophilia)	Higher scores on each subscale indicate a stronger belief towards psychotropic treatment	6-point Likert scale where 1=totally disagree, 6=totally agree	Good construct validity and reliability	Outpatients with schizophrenia and other psychiatric conditions Mean age 41.2±12 (n=212 for schizophrenia) and 44.5±14 (n=1160 for other mental disorders) Juxtaposed against Sidorkiewicz Adherence Tool
44	Seyma and Baysal, 2022, Turkey55	Scale for Compliance to the Treatment in Type II Diabetes Mellitus	I=7	Behaviour (3– anxious when time for insulin, schedules, medication intake, take regularly), Belief (4– knowledge on DM, consequence of condition, trust in healthcare, diet over medication)	30-item self-reported adherence to type 2 DM treatment	Good, moderate, poor adherence	5-point Likert scale where 1=strongly agree, 5=strongly disagree	Good content and construct validity Internal consistency, Cronbach’s alpha=0.7	Patients with DM presenting to the Internal Diseases and Endocrinology clinics of a hospital Mean age 54.6±9.5 Juxtaposed against Diabetes Health Literacy Scale

Number of measures, n=44 of 59; Intentional, I items=491, Unintentional, UI items=35, Not reported=67 items.
For a measure to be classified as Intentional, >30% of its items are to be Intentional and the remainder Unintentional and/or Not reported (if any).
*Some values were reported as median, range or not reported.
†All terms related to adherence, e.g., compliance is standardised and reported as adherence; Belief=326, Barrier=135, Behaviour=132 items.
ADL, activities of daily living; BIPQ, Brief Illness Perception Questionnaire; CKD, chronic kidney disease; DM, diabetes mellitus; HAART, Highly Active Antiretroviral Therapy; HRQoL, health-related quality of life; IPQ, Illness Perception Questionnaire; MAQ, Medication Adherence Questionnaire; MCQ, multiple choice questions; MEMS, medication events monitoring system; MI, myocardial infarction; MMAS, Morisky Medication Adherence Scale; MPR, medication possession ratio; PAM, Patient Activation Measure; PI, protease inhibitor; PMAQ, Patient Medication Adherence Questionnaire; PROMs, patient-reported outcome measures; RAM, Reported Adherence to Medication Scale; VAS, Visual Analogue Scale.