Dual-system use: are there implications for risk adjustment and quality assessment?

The authors examined the implications of dual-system use for risk adjustment and quality assessment. The sample (n = 34 151) included all veterans dually enrolled in the Veterans Health Administration (VA) and the private sector in 1998 with (1) an inpatient discharge from either a VA or Medicare setting for 1 of 6 conditions/procedures and (2) inpatient and/or outpatient use in both the VA and private sector. The authors used the Diagnostic Cost Groups risk-adjustment system to obtain concurrent and prospective health status (relative risk scores) using veterans' Medicare diagnoses only, VA diagnoses only, and diagnoses from both systems. Both concurrent and prospective relative risk scores increased when diagnoses from both systems were used; the population's disease profile also was affected. The authors conclude that it is important to capture the true disease burden of the population by obtaining diagnoses from all health care systems providing care to facilitate meaningful comparisons of performance.