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1 Department of Radiology, Hospital of the University of Pennsylvania, 3400
Spruce St., Philadelphia, PA 19104.
2 Present address: Park Avenue Radiologists, 525 Park Ave., New York, NY
10021.
3 Department of Radiology, Lenox Hill Hospital, 100 E. 77th St., New York, NY
10021.
Received March 7, 2002;
accepted after revision May 30, 2002.
Address correspondence to M. E. Liebeskind.
Abstract
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MATERIALS AND METHODS. Use of sonography was compared with use of CT and MR imaging of the abdomen, pelvis, and retroperitoneum in adult patients in 1993 and 1998 at an academic medical center. Clinicians who requested the greatest number of examinations in both years were surveyed to assess their perception of changes in their practice patterns during the interim.
RESULTS. Between 1993 and 1998, the use of sonography relative to
the other cross-sectional imaging modalities decreased from 56% to 43%
(p
0.001). During the same time, CT use increased from 30% to
41% (p
0.001), and MR imaging use increased from 14% to 16%
(p
0.001). Survey responses indicated that potential cost saving
was not a major factor in physicians' decisions to use sonography rather than
other cross-sectional imaging modalities.
CONCLUSION. Sonographic utilization decreased during a 5-year period in which managed care provided an increasingly large proportion of overall reimbursement. Cost did not appear to be a major factor in selection of diagnostic tests. Differences over time in refering clinicians' perception of the relative usefulness of sonography, CT, and MR imaging may have contributed to the change in usage patterns.
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A relatively greater increase in outpatient visits compared with inpatient admissions is a further manifestation of the growth of managed care; from 1993 to 1998, inpatient admissions at this hospital increased by 15.2%, from 30,073 to 34,655, whereas outpatient visits increased by 40.4%, from 513,593 to 721,107. Furthermore, the decreasing length of inpatient admissions reflects the shift toward managed care and capitation reimbursement. At this hospital, the average inpatient stay decreased by 21%, from 7.7 to 6.1 days, between 1993 and 1998.
The use of diagnostic imaging overall at this hospital changed between 1993 and 1998. Although the total number of all imaging studies increased by 12%from 213,322 in 1993 to 238,730 in 1998the number of radiologic examinations per patient visit (inpatient and outpatient combined) decreased from 0.39 to 0.32 over the same period. The reason for this decrease is not clear, but an emphasis on cost containment may be a contributing factor.
The purpose of this study was to investigate the effect of a cost-conscious environment on radiology practice patterns and to evaluate physician perceptions of how the pressures of a managed care environment may have contributed to changes in their use of sonography as opposed to CT or MR imaging. Sonographic examinations remain less expensive than other cross-sectional modalities such as CT or MR imaging [4]; our study evaluates whether an increasing focus on cost containment may have influenced patterns of sonographic use.
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Chi-square analysis was used to compare the proportionate use of sonography, CT, and MR imaging in 1993 and 1998 for imaging the abdomen, pelvis, and retroperitoneum, as well as the proportionate usage of each modality for inpatient and outpatient studies of the abdomen, pelvis, and retroperitoneum in both years. In addition, chi-square analysis was used to compare the relative frequency with which the abdomen, pelvis, and retroperitoneum were imaged using sonography in 1993 and 1998.
A multiple-choice questionnaire was then created for the top 70 referring physicians to the sonography section (the complete survey and tabulated responses are included in Appendix 1). The survey asked eight questions designed to assess the responders' impressions of their personal practice patterns and any interval change in technology among sonography, CT, and MR imaging. All questions were in multiple-choice format to maximize response rates and to facilitate evaluation of responses. The goal was to determine the perceived use of sonography and the perceived relative usefulness of CT and MR imaging.
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0.001;
Table 1). CT and MR imaging
usage both increased significantly during the same period (p
0.001; Table 1).
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From 1993 to 1998, the use of sonography decreased for both inpatient (from
42% to 38%, p
0.001; Table
2) and outpatient studies (from 63% to 45%, p
0.001;
Table 2). Both inpatient and
outpatient CT increased significantly during this time (p
0.001;
Table 2), whereas inpatient MR
imaging decreased significantly and outpatient MR imaging increased
significantly (p
0.001; Table
2).
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Sonography of the abdomen as a proportion of all cross-sectional imaging of
the abdomen remained constant (55%) from 1993 to 1998, whereas the percentage
of CT decreased and the percentage of MR imaging increased significantly
(Table 3). For imaging of the
pelvis, sonography was the most frequently used modality in both 1993 (81%)
and 1998 (74%), but the decrease in use over that time period was
statistically significant (p
0.001). For retroperitoneal
imaging, definitive conclusions are difficult to draw because MR imaging of
the retroperitoneum was not coded as a separate entity in 1998; however, it is
expected that the actual use of MR imaging for evaluating the retroperitoneum
was minimal compared with the other modalities. On the basis of the data
available, sonography of the retroperitoneum as a proportion of all
cross-sectional imaging of the retroperitoneum decreased significantly, from
1993 (26%) to 1998 (19%) (p
0.001), whereas CT use increased
significantly, from 72% to 81% (p
0.001).
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Of all sonographic examinations performed of the abdomen, pelvis, and
retroperitoneum, in 1993 21% were abdominal, 63% were pelvic, and 17% were
retroperitoneal. In 1998, 32% were abdominal (p
0.001), 46% were
pelvic (p
0.001), and 21% were retroperitoneal (p
0.001).
Survey Results
We received 37 completed responses to the survey, 22 to the initial survey
and 15 when a second letter and survey were mailed to initial nonresponders.
Of the top 70 referring physicians, two were not practicing at the study
hospital in the past year, resulting in a response rate of 53% (37/70).
Responses were evaluated overall by question as well as by grouping
respondents into three broad clinical practice categories (medicine, 21
responses; surgery, nine responses; and obstetrics and gynecology, seven
responses). Results of the survey are included in Appendix 1, which summarizes
the distribution of responses.
Responses to the first question were fairly uniform among the various clinical specialties, with 38% of respondents reporting that cost was "not at all" a factor in choosing sonography, and only 11% answering that cost was "very important" in choosing sonography
In terms of the potential ability to obtain results of a sonographic examination more quickly than results of a CT or MR imaging examination, more than half the respondents indicated that scheduling was "very important" or "important" to the choice of sonography over CT or MR imaging.
The third question asked whether the respondent uses sonography more as a diagnostic tool or as follow-up than previously. Sixty-five percent responded that they have not changed their use of sonography during the 5-year period. However, a distinction was seen among the specialties, with 57% of the obstetriciangynecologists responding that they were more likely to use sonography as a primary diagnostic tool than previously.
Overall, 65% of respondents said that sonographic technology has not changed, but that CT and MR imaging technology have improved over the interval. Again, responses from obstetriciangynecologists differed from those of other specialists: 43% of obstetriciangynecologists responded that sonography has become a better diagnostic tool, compared with 29% of all respondents.
Overall, 76% of respondents reported that no new indications for abdominal sonography had changed their use of sonography during the period in question. Twenty-six percent of internal medicine specialists responded that abdominal sonography was now less useful than CT or MR imaging, in part because of the increasing usefulness of MR imaging of the liver.
Both retroperitoneal and pelvic sonography were reported to have no new indication by 83% of referring physicians surveyed.
Finally, when asked whether the respondent ordered tests differently than before 1994, 46% of respondents reported that their practice had not changed. Twenty-four percent of respondents reported that they ordered fewer sonographic examinations, 14% stated that they ordered more sonographic examinations, and 16% reported that they ordered fewer tests overall.
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The decrease in outpatient sonography use (from 63% to 45%) was relatively greater than the decrease in inpatient sonography use (from 42% to 38%). In part, the ease of scheduling inpatient sonographic examinations may account for the smaller decrease relative to outpatient studies, as evidenced by survey responses in which almost 60% of physicians thought that scheduling was "important" or "very important" in their choice of sonography as opposed to CT or MR imaging.
Changes in usage patterns differed for abdominal, pelvic, and retroperitoneal studies. Sonography as a proportion of all cross-sectional imaging of the abdomen remained constant, whereas CT decreased and MR imaging increased. For pelvic imaging, use of sonography decreased and use of CT remained relatively constant (the percentages were statistically significantly different but numerically very similar), and MR imaging use increased. Retroperitoneal imaging was more difficult to determine because of a coding anomaly for MR imaging in 1998, but apparently the use of sonography decreased and the use of CT increased. Reasons for these changes in usage patterns are not clear; most surveyed physicians reported no new indication that changed their use of sonography, CT, or MR imaging during the time in question.
The results of the referring physician survey support the notion that cost was not the major factor in selecting an imaging test; only one third of surveyed physicians described cost concerns as "important" or "very important" in their choice of sonography as opposed to CT or MR imaging.
Multiple factors may have influenced clinicians' ordering of imaging tests. No major changes occurred in the practice groups of referring clinicians over the interim, nor were new services in place at the institution that might account for the changes in cross-sectional imaging use. The proportion of imaging requests from referring departments such as obstetricsgynecology and oncology remained relatively constant during the time in question. No significant changes occurred in the institution as a whole or in the radiology department. Increases in purchases of sonography, CT, and MR imaging equipment occurred during the time in question, but no disproportionate increase occurred for any of these modalities. The mean scheduling backlog was approximately 1 month for each of the modalities in question and did not change substantially between 1993 and 1998. No major changes occurred in departmental or section leadership. The radiology department did not lose sonographic studies to other departments. In addition, no substantial or disproportionate changes occurred in charges for sonography, CT, or MR imaging between 1993 and 1998, and no new studies were introduced or promoted in an attempt to increase utilization during that time. Finally, no change occurred in the hours during which sonography, CT, or MR imaging was available. The survey results suggest that a change in the perceived relative usefulness of the three imaging modalities may account for the relative increase in the use of CT and MR imaging: when queried about evolution of diagnostic imaging technology, 65% of respondents indicated that CT and MR imaging had improved and that sonography had not changed.
The findings of the survey suggest that almost half of the top referring clinicians to the sonography section do not perceive a change in their practice patterns despite the increasing percentage of managed care payers. This response may be because referral to the radiology department overall has not decreased; one quarter of respondents believed that they ordered fewer sonographic studies than CT or MR imaging examinations.
Our study is limited to a single academic medical center with active transplantation, trauma, and other specialty programs. The referral patterns to the radiology department and the sonography section necessarily reflect the clinical practice patterns of the institution and the strengths and weaknesses of particular departments within the institution. Therefore, these findings may not generalize to other institutions or other clinical settings. Nonetheless, the decrease in utilization of sonography relative to CT and MR imaging was not an expected result. Ideally, our study would be replicated at a range of both tertiary care and community hospitals in many geographic areas to determine whether changes in radiology practice patterns exist and the direction of these potential changes.
In summary, the use of sonography (for abdominal, pelvic, and retroperitoneal examinations) decreased in both the inpatient and outpatient populations during a 5-year period in which managed care health insurance represented an increasing proportion of the population at a large academic medical center. Cost did not appear to be the major factor in the decision to select a particular cross-sectional imaging study. Differences over time in referring clinicians' perceptions of the relative usefulness of sonography, CT, and MR imaging may have contributed to the change in usage patterns.
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