Vormfelde 2014.

Methods	Cluster randomised controlled trial of 22 GP practices
Participants	N randomised: intervention = 185 patients versus comparator = 134 patients Diagnosis of patients: AF, thrombosis, pulmonary embolism, heart valve replacement, unknown Demographics for total cohort: Age: 73±10 intervention versus 72±10 usual care % female: 56% intervention versus 58% usual care % white: not stated % education above primary level: not stated Demographics of the AF patients: N = 14 Treatment group n = 141 versus usual care n = 81 Age: intervention mean 74.5 (SD 8.0) versus usual care mean 72.9 (SD 9.4) Female: intervention = 72 (45.6%) versus usual care = 38 (46.9%) ≥ 10 years education: intervention 32 (20.3%) versus usual care 28 (34.6%) Inclusion/exclusion criteria: All patients taking OAT (with a range of indications) with ability to consent to participation and adequate German language skills were included. Exclusion criteria included residence in a nursing home and patients in cross coverage.
Interventions	Type: parallell randomised controlled trial Content: Practice nurses delivered the educational intervention session consisting of a 20‐minute video presentation, an eight‐page brochure, and a corresponding questionnaire. The information was on 13 topics pertaining to oral anticoagulation with phenprocoumon according to the internationally recognised model and recommendations. Usual care included patients who were only given a brochure. Duration: one hour Facilitator: practice nurse Setting: general practice
Outcomes	Primary outcome: number of correctly answered questions from the 13‐item OAT questionnaire Secondary outcomes: time spent in therapeutic range, subjective feelings of safety and complications related to OAT
Country	Germany
Comparison	patients who were only given the brochure
Length follow‐up	six months
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The first 22 GPs that agreed to participate were included. The Institute for Medical Statistics randomised these 22 practices into two equal‐sized trial groups (intervention versus control) by random permutation.
Allocation concealment (selection bias)	High risk	Of the 85 general medical practices contacted, 22 general medical practices agreed to participate (26%). There is risk of bias from participation of more highly motivated and better educated individuals than average, who knew they were being tested.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The authors do not state whether the researchers or personnel were blinded regarding to which arm the participants were randomised. However, we can assume that participants and practice nurses were not blinded to treatment allocation due to the nature of the intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	The authors do not state whether their data analysis was blinded regarding to which group the patients were randomised.
Incomplete outcome data (attrition bias) All outcomes	High risk	Of the 979 anticoagulated patients who were identified in the 22 practices, 319 completed the trial (33%). During follow‐up, for the intervention arm (n = 194), nine (5%) did not complete the trial as eight moved away and one died. For the control arm (n = 151), 17 (11%) patients did not complete the trial as six moved away, three died, and eight chose to drop out. INR analysis was possible in 157/194 (81%) patients in the intervention group and 91/151 (60%) in the control arm; overall attrition was greater than 20% and more patients in the control group did not have INR data at follow‐up available for the analyses.
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes were reported.
Other bias	High risk	Improvement in knowledge was dependent on the practice where the patient education was delivered which was probably due to differences in the discussion with the nurse after the video presentation.