Comparison of inpatients with major mental illness who do and do not consent to low-risk research.

The generalizability of research data depends on the degree to which the studied sample represents the larger population of interest. By influencing the likelihood of research participation, socio-demographic and clinical factors could bias a sample. To evaluate this, we retrospectively identified 155 consecutive admissions over an 18-month period to a general acute male psychiatry inpatient unit in a Veterans Affairs Hospital on which all competent patients were offered the opportunity to participate in low-risk clinical research. Male inpatients who did (N=70) and did not consent (N=85) were compared on 17 variables. Patients who consented to research were somewhat younger (M(difference)=4.6 year) and were significantly more likely to carry a diagnosis of schizophrenia. The groups did not differ in financial resources, living situation or alcohol/drug abuse. We conclude that at least in this setting, general socio-demographic and clinical variables were not major influences on sample selection.