Health care utilization and receipt of cholesterol testing by veterans with and those without mental illness

OBJECTIVE: We examined the relationship between mental illness, health care utilization and rates of cholesterol testing. METHODS: We conducted a retrospective cohort study using Veterans Affairs (VA) administrative data on 64,490 United States veterans who used VA New England Health Care System outpatient services between January 1998 and June 2001. A total of 10,100 veterans (15.7%) had a mental illness treated with medication. We examined the interaction between mental illness and outpatient service utilization with respect to the likelihood of receiving a cholesterol test, adjusting for major demographic and clinical covariates. RESULTS: Among veterans using VA outpatient services infrequently, those with mental illness were less likely than non-mentally ill control subjects to receive a cholesterol test during the study period (first quartile adjusted OR=0.45, 95% CI=0.37-0.54; second quartile adjusted OR=0.50, 95% CI=0.45-0.57). Mentally ill subjects with more frequent utilization of VA services were as likely as (third quartile adjusted OR=1.01, 95% CI=0.91-1.13) or more likely than (fourth quartile adjusted OR=2.73, 95% CI=2.46-3.03) non-mentally ill subjects to receive cholesterol testing. CONCLUSIONS: Mental illness was associated with a lower likelihood of cholesterol testing in subjects who used fewer VA outpatient services. The observed disparity attenuated at higher levels of service utilization.