Research Involving Participants With Impaired Consent Capacity: An Examination of Methods to Determine Capacity to Consent

To examine methods of assessing consent capacity in research protocols involving participants with impaired consent capacity, and examine instruments used to evaluate research consent capacity. A retrospective review of 330 active research protocols involving participants lacking capacity to consent over a 10-year period (January 1, 2009, through March 1, 2019) was conducted to collect protocol characteristics (medical specialty, level of risk and type of study, consent and assent procedures, and type of vulnerable or protected population). Methods to assess consent capacity are described, and instruments to assess consent capacity are summarized. The specialties most frequently involving participants with impaired consent capacity in research were Neurology (27.3%), Critical Care (16.7%), and Surgery (10%). Type of studies are observational (43.9%), clinical trials (33%), chart review (11.5%), biobank (6.1%), and biomarker (5.5%). Minimal risk (53.3%) outnumbered greater than minimal risk (46.7%) studies. Most obtained written informed consent (77%) and assent (40.9%). The most common method to assess consent capacity was direct assessment by investigators (32.7%). Only 86 (26%) studies used instruments to assess consent capacity. Of the 13 instruments used, the most common was the Evaluation of Decision-Making Capacity for Consent to Act as a Research Subject, and is the only instrument that assesses all four components of decisional capacity: understanding, appreciation, reasoning, and choice. Generally, there was lack of uniformity in determining capacity to consent to research participation. Very few studies used instruments to assess consent capacity. Institutional review boards can provide greater guidance for research consent capacity determination.