Table 3.

Advantages and disadvantages of various control recruitment strategies

	Advantages	Disadvantages
Traditional Recruitment Strategies
Spouses, relatives, and friends of enrolled stroke participants	• Already invested in research • If all spouses enrolled study well matched for sex • Exposed to same diet / environmental risks as stroke patient	• Tend to have fewer cardiovascular comorbidities
Stroke Mimics	• Undergo same stressor as stroke patient with acute hospitalization • May be critical in acute stroke diagnostic biomarker studies	• Predominantly female • Different vascular risk factors • Seizure physiology may confound stroke biomarker studies focused on treatment or prognosis
Clinics	• Patients and their spouses / relatives have established relationship with provider, therefore more likely to enroll as controls	• Need to be careful that other comorbidities (dementia, Parkinson’s, etc.) will not confound results • Can be challenging when recruiting from clinic other than home department
Community outreach events	• Great for targeting a particular demographic that is challenging to enroll otherwise	• May require added effort on the part of the investigator (travel, putting together stroke educational materials, etc.)
Retirement communities	• Good way to screen a large number of potential controls	• Requires gaining the trust of the facility manager • Many investigators may wish to exclude controls who are not able to live independently
Purchase samples from 3rd party vendor	• Samples can be gained quickly	• Cost prohibitive • May introduce significant bias since sample processing and handling likely different than stroke cohort
Modern Recruitment Strategies
Screening electronic health record	• Allows for good one-to-one matching of multiple demographic and comorbidity features simultaneously • More targeted strategy that mitigates some of the effort required for more traditional recruitment strategies described above	• Sometimes difficult to find large number of matches for minority populations • Requires programming investment • Still a fair bit of effort for research staff, ~10–20% of contacted matches end up enrolling
Online screening questionnaire	• Can be coupled with most of the traditional recruitment approaches described above • Allows researcher to gauge the fidelity of the match before proceeding to full enrollment • Hyperlink can be email blasted to hospital employees and to EHR health portal accounts to reach large numbers of potential controls	• May add additional layer of unnecessary work if one plans to use propensity score matching • Requires small programming investment