2011. Geographic Variation in
the Treatment of Early-Stage Prostate Cancer across VA Medical Centers
C Fung, Greater Los Angeles VA Healthcare System, B Spencer, Greater Los Angeles Healthcare System, LV Rubenstein, Greater Los Angeles Healthcare System
Objectives: The proposed
study asks the question, "Is there geographic variation across VA Medical
Centers in the use of radiation, surgery, and "watchful waiting" in
patients with early stage prostate cancer?"
Methods: We selected
demographic and clinical variables including age, race, ethnicity, class of
case, grade of disease, marital status at time of diagnosis, insurance, type of
treatment, stage of disease, and VISN. We
generated a variable, "geographical region," from the VISN variable.
We used a nested logit model to determine the relationship between geographic
region and treatment use, after adjusting for demographic and clinical
variables. For the lower level, we performed logistic regression, modeling the
relationship between geographic region and the potentially curative treatment
options, surgery and radiation. For the upper level, we performed logistic
regression, modeling the relationship between geographic regions and the
treatment options, surgery/radiation and non-curative treatment ("watchful
waiting”). We calculated the probability of surgery, radiation, and
non-curative treatment for each geographic region.
Results: The west region
appears to have higher predicted probability of surgery compared to other
geographic regions and lower predicted probability of radiation compared to
other geographic region. Patients in the west region have slightly lower
probability of undergoing non-curative treatments such as "watchful
waiting" compared to patients in other geographic regions.
In all regions except the south, patients have a higher predicted
probability of receiving either surgery or radiation than non-curative
surgery, radiation, and "watchful waiting" are all acceptable forms of
treatment for early-stage prostate cancer, prior studies suggest that geographic
variation exists in the use of modalities of treatment. Our results suggest that
geographic variation in the care of early-stage prostate cancer also exists in
the VA system.
Impact: This study prompts us to explore the mechanisms that cause variations in practice patterns and implementation of new practices.