Table 4.

Results from trials of verbal discussion with test/feedback or teach-back interventions to improve patient comprehension in informed consent

Source	Study country	N	Mean patient age (and range if specified)	Patients’ education	Procedure	Intervention	Elements of patient comprehension assessed	Comprehension assessment tool	Timing of patient comprehension assessment relative to informed consent consultation*	Risk of bias for patient comprehension outcome†	Results	Group favored‡
Kesänen et al. (2016)	Finland	100	62.5 y	76% did not complete high school, 24% completed high school	Spinal stenosis surgery	Routine, preoperative education ( face-to-face discussion with a surgeon and nurse plus written material) followed by a “Knowledge Test Feedback Intervention” (patients took a test, received results with corrections, then completed an "empowering telephone discourse based on the patients' existing knowledge" with a nurse) versus routine preoperative education along (control)	Risks, benefits, alternatives, general knowledge about procedure	27-item true/ false/ do not know test	Delayed	Some concerns for bias	At admission: 21.6 out of 27 (SD 3.4) intervention vs. 15.4 out of 27 (SD 4.1), P < 0.0001 At discharge: 21.4 out of 27 (SD 3.4) intervention vs. 15.2 out of 27 (SD 4.2) control, P < 0.0001 At 6 months: 20.3 out of 27 (SD 4.5) intervention vs. 14.6 out of 27 (SD 3.9) control, P < 0.0001	Intervention
Fink et al. (2010)	USA	575	61.9 y	12.1% did not complete high school, 34.2% completed high school, 35.8% some college or trade school, 17.8% college graduate	Carotid endarterectomy, laparoscopic cholecystectomy, radical prostatectomy, and total hip arthroplasty	Standard informed consent using iMedConsent web-based tool but when the participants were ready to sign the consent a repeat back dialog was initiated that prompted the provider to test the participant on key information (the provider could then provide additional information and education depending on the participants’ responses) versus standard informed consent using iMedConsent along (control)	Risks, benefits, alternatives, general knowledge about procedure	23 to 26-item questionnaire depending on the procedure	Immediately	Some concerns for bias	Total mean comprehension scores for all operations 71.4% intervention vs. 68.2% control, P = 0.03	Intervention

^*Immediately: within 1 hour of informed consent consultation; delayed: more than 24 hours after informed consent consultation

^†Assessed using the Cochrane Risk of Bias 2.0 tool, see Table 7 for details

^‡If a study reported an improvement in patient comprehension on a single item or multiple items of the comprehension assessment but if overall score did not improve, we considered neither or no group to be favored