Using Registry Data to Construct a Comparison Group for Programmatic Effectiveness Evaluation: The New York City HIV Care Coordination Program

Abstract

Many nonrandomized interventions rely upon a pre-post design to evaluate effectiveness. Such designs cannot account for events external to the intervention that may produce the outcome. We describe a method to construct a surveillance registry-based comparison group, which allows for estimating the effectiveness of the intervention while controlling for secular trends in the outcome of interest. Using data from the population-based, human immunodeficiency virus Surveillance Registry in New York City, we created a contemporaneous comparison group for persons enrolled in the New York City human immunodeficiency virus Care Coordination Program (CCP) from December 2009 to March 2013. Inclusion in the Registry-based (non-CCP) comparison group required meeting CCP eligibility criteria. To control for secular trends in the outcome, we randomly assigned persons in the non-CCP, Registry-based comparison group a pseudoenrollment date such that the distribution of pseudoenrollment dates matched the distribution of enrollment dates among CCP enrollees. We then matched CCP to non-CCP persons on propensity for enrollment in the CCP, enrollment dates, and baseline viral load. Registry-based comparison group estimates were attenuated relative to pre-post estimates of program effectiveness. These methods have broad applicability for observational intervention effectiveness studies and programmatic evaluations for conditions with surveillance registries.

Figures

Figure 1.

Flow chart for inclusion in the study comparing members of the population-based, human immunodeficiency virus Surveillance Registry with participants in the human immunodeficiency virus Care Coordination Program (CCP) or for inclusion in the study comparing pre-post results for the CCP enrollees, New York City, 2009–2013. Surveillance Registry members who were not enrolled in CCP met CCP eligibility criteria. In both arms, medical care was defined as at least one CD4+ lymphocyte or viral load laboratory test in the 24-month follow-up period.