Medical Outcomes Knowledge Item 14: Results from HRSA/HAB's SPNS Innovative Models of Care

Knowledge Item: CA-Medical Outcomes-14
Hierarchical Linear Models Showing Change in CD4 Counts

Hierarchical Linear Modeling (or HLM) methods are used to study change in CD4 counts over time. For each person, an individual trend is line fit to that patient's CD4 counts over time. The method uses all observations for individual patients and takes into account the fact that patients received the assessments at different times in their treatment histories. After fitting "individual" curves for each patient, overall trends in the "average curves" or "trajectories" are studied and related to other factors. HLM modeling can be considered the "definitive" method for studying change in the kinds of naturally-occurring treatment assessment data from these projects.

The hierarchical models show that on average patients experience increasing CD4 counts over the course of their involvement with the programs represented here.

The following can be concluded from these models.

CD4 counts increase over time for all patients (p < .001).
There is no statistically significant differential change in CD4 counts over time by Gender.
There is no statistically significant differential change in CD4 counts over time by Project Type.
There is a Gender by Project Type interaction such that females from University-based Comprehensive Healthcare projects showed less increase in CD4 counts over time than other groups (p < .002). Note that these patients start with higher CD4 counts at enrollment.

A related set of results using an alternate definition of medical outcome is presented in Knowledge Item: CA-Medical Outcomes-52.

Knowledge Item Citation: Huba, G. J., Panter, A. T., Melchior, L. A., and the HRSA/HAB SPNS Cooperative Agreement Steering Committee (1998-2001). Knowledge Item: CA-Medical Outcomes-14 from HRSA/HAB's SPNS Cooperative Agreements on Innovative Models of Care, The Measurement Group Knowledge Base on HIV/AIDS Care, Online at www.TheMeasurementGroup.com.

Last Updated: March 25, 2005; data through June 15, 1999; analyses conducted March - May 2000.

Knowledge Base Citation: The Knowledge Base and this Knowledge Item were designed and authored by G. J. Huba, Ph.D.; in collaboration with Lisa A. Melchior, Ph.D.; A. T. Panter, Ph.D.; and the staff of The Measurement Group. Cite this work as "Huba, G. J., Melchior, L. A., and Panter, A. T. (1998 - 2001). The Measurement Group Knowledge Base on HIV/AIDS Care. On the World Wide Web: http://www.TheMeasurementGroup.com."

Questions or Comments: Contact The Measurement Group.

Use of Knowledge Base Information: Acceptable Uses and Limitations.

Collaborators from Participating Projects: Cooperative Agreement Steering Committee 1999.

Participating Projects: This Knowledge Base is based on the service delivery experiences of 27 Cooperative Agreement Projects on Innovative Models of HIV/AIDS Care. These projects and the Evaluation and Dissemination Center which produced this Knowledge Base were funded by the Health Resources and Services Administration (HRSA), HIV/AIDS Bureau (HAB) as Special Projects of National Significance (SPNS) between 1994 and 1999. Click the Model Programs button above for descriptions of the projects that contributed to this specific Knowledge Item, a list of key staff, and project grant numbers.

Why This Evaluation was Conducted: Editorial.

More Information: Design of this Knowledge Base.

Recommended Citation Format for Web Materials: American Psychological Association Publication Manual Section, Revised 2001.

Work on the Knowledge Base and the cross-cutting evaluation was supported in part by Grant Number 5 U90 HA 00030-05 from the Health Resources and Services Administration (HRSA), HIV/AIDS Bureau's (HAB) Special Projects of National Significance (SPNS). The contents of this Knowledge Base are solely the responsibility of The Measurement Group and do not necessarily represent the official views of HRSA or HRSA/HAB's Special Projects of National Significance nor may they represent the positions of the individual grantees whose projects are included in the cross-cutting evaluation.