Knowledge Item:
CA-Medical Outcomes-28
More Complex Hierarchical Linear
Models Showing Differential Change for Groups Formed by Demographic
Categories and Drug Abuse Status
Hierarchical Linear Modeling (or
HLM)
methods are used to study change in Viral loads over time. For each
person, an individual trend is line fit to that patient's quality of
life scores 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 the average patients experience decreasing Viral load over the
course of their involvement with the programs represented here. This
Knowledge Item studies the rate of change as a function of different
service needs and vulnerabilities of the patient. A
number of service needs-vulnerabilities are related to both the
initial Viral load status of the patient at the time of enrollment
into the program and to the rate of change throughout the program.
The following general
tendencies were found in the trends in Viral loads.
-
Females
had slightly higher Viral loads than males when
services started (p < .06).
-
There
are no statistically significant project type differences in
patient Viral loads when
services started.
-
There were no Gender
by Project Type interactions in initial Viral loads.
On average,
-
Viral loads decreased.
-
There is
no statistically significant differential change in Viral loads over time by
Gender.
-
Patients
from University-based Comprehensive Care projects showed greater
change in Viral loads over time with Viral loads decreasing more rapidly.
-
There is
no statistically significant differential change due to the Gender by
Project Type interaction in
Viral Load over time.
-
The
degree of viral load decrease over time is largely unrelated to patient
demographic factors including status as a drug abuser.
This difference
is not statistically significant.
This difference
is not statistically significant.
This difference
is statistically significant but of little practical significance.
This difference
is not statistically significant.
Knowledge Item Citation: Huba, G. J., Melchior, L. A., Panter, A. T., and the HRSA/HAB SPNS Cooperative Agreement Steering Committee (1998-2001). Knowledge Item:
CA-Medical Outcomes-28 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.
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