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Emerging Infectious Diseases Journal


Volume 1: No. 4, October 2004

A Randomized Controlled Open Trial of Population-based Disease and Case Management in a Medicare Plus Choice Health Maintenance Organization

Figure. Flow chart illustrating participant eligibility, exclusion, enrollment, retention, survey participation, and attrition, including a comparison of the intervention and control groups, throughout the randomized controlled open trial.

This figure consists of a flowchart, which provides information on the numbers of individuals who participated in the study from beginning to end. It shows the number of individuals who were excluded from the study, how many disenrolled or died during the study, and how many took part in the three study surveys. In addition, the numbers are divided into two groups: the intervention group and the control group.

On September 30, 1999, there were 13,304 eligible Advantra members. Of these, a risk group of 1799 Advantra members was excluded from the study. Before the study start date, another 3001 members disenrolled.

The number of continuously enrolled members from January 1999 through December 1999 was 8504. The table below compares the intervention group and control group at three points in time: January 1, 2000, December 31, 2000, and June 30, 2001

  Intervention, n Control, n
Jan 1, 2000
Participating 4257 4247
1st survey respondents 3137 (74%) 3021 (71%)
Dec 31, 2000
Deceased 132 143
Disenrolled 383 311
Participating 3742 3793
2nd survey respondents 2778 (74%) 2699 (71%)
June 30, 2001
Deceased 191 211
Disenrolled 582 483
Participating 3484 3553
3rd Survey respondents 2733 (78%) 2650 (75%)
1st & 3rd Survey respondents 2271 (65%) 2176 (61%)

Table 1 presents results of the first survey, and Table 2 compares results from the first and third surveys.

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The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors’ affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.


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