Table 1 Characteristics of interventions included (n = 23)

Publication year

2005 (n = 2)

2007 (n = 1)

2010 (n = 2)

2011 (n = 3)

2012 (n = 5)

2013 (n = 3)

2015 (n = 2)

2016 (n = 3)

2017 (n = 2)

Country

Austria (n = 3)^a

Denmark (n = 3)^a

Germany (n = 6)^a

Ireland (n = 2)^a

Netherlands (n = 4)

United Kingdom (n = 8)^a

Taiwan (n = 1)^a

Study design

Cohort analytic group design (n = 2)

Cohort (one group pre/post) (n = 9)

Controlled trial (n = 5)

Interrupted time series (n = 1)

Randomized controlled trial (RCT) (n = 5)

Observational study (n = 1)

Study Setting

Community (n = 6)

Health Professionals (n = 2)

Outpatients (n = 5)

Telephone and/or mail intervention (n = 10)

Duration of intervention and follow-up

No follow-up (n = 13)

Follow up ≤3 months (n = 4)

Follow-up> 3 months (n = 4)

Unknown (n = 2)

Age of participants

Children (8–12) (n = 1)

Adults (> 16) (n = 22)

Health Literacy Measure

Critical Health Competence List (n = 1)

Brief questions to identify patient with inadequate health literacy (n = 1)

Critical HL assessed by interview (n = 1)

Level of Knowledge (n = 3)

REALM-R (n = 2)

Newest Vital Sign Test (n = 1)

Level of reading ability (n = 2)

Level of mild intellectual disabilities (n = 1)

Numeracy competence (n = 4)

Skills towards decision making in a health context (n = 1)

Not specified (n = 1)

Danish version of TOFHLA (n = 3)

Dutch version of SAHL (n = 2)

Focus of included studies

Disease specific: (n = 9) of which Diabetes (n = 5), Cancer (n = 1), COPD (n = 3), Osteoarthritis (n = 1), Rheumatoid arthritis (n = 1), Multiple Sclerosis (n = 1), Renal patients (n = 1);

People working or using health care (n = 2)

Hard to reach groups (n = 3)

Outpatients not specified (n = 1)

People with mild intellectual disabilities (n = 1)

Smokers (n = 1)

General population (n = 4)

Health issues

Diabetes, Cancer, OA, MS, RA, participation in treatment, knowledge, understanding of medication, adherence to medication, interpretation of information about treatment, appraisal skills in judging medical information, self-management, active participation in treatment, empowerment, self-management skills and confidence, motivation to self-manage, risk-communication, decision-making in medical treatment, symptom monitoring and recognition, reaching disadvantaged groups, health promotion, health status, social participation and integration, access to health care, health care use, communication of medical information.