1. *Centers for Disease Control and Prevention, Atlanta, GA
Identifying and Prioritizing High-Risk Patients for Influenza Vaccine During a Season of Vaccine Shortage
Mandy A Allison; Matthew F Daley; Jennifer Barrow; Norma Allred*; Lori A Crane; Brenda L Beaty; Stephen Berman; and Allison Kempe
*Centers for Disease Control and Prevention, Atlanta, GA

2. 2004-2005 Influenza Season Early October 2004 October-December
Chiron notifies CDC that it will be unable to supply inactivated vaccine
ACIP names priority groups
October-December
CDC and departments of health make efforts to redistribute vaccine
January 2005
ACIP expands priority group definitions
Many states broaden coverage
In response to Chiron corporation’s notification on October 5, 2004 that it would be unable to supply any inactivated vaccine to the United States for the season, the Advisory Committee on Immunization Practices or ACIP recommended that the available inactivated influenza vaccine be directed to certain priority groups including children with high risk conditions. The CDC recommended “aggressive efforts” to identify and vaccinate members of the priority groups. In the following months, the CDC and state and local departments of health as well as some private physician practices made efforts to redistribute the existing supply of influenza vaccine so that members of the high-risk priority groups could receive the vaccine. As vaccine supplies increased, the ACIP expanded its priority group definitions and many states began to broaden immunization efforts to include people who were not in priority groups.
NOTE: CHIRON VACCINE NOT LICENSED FOR CHILDREN < 4 YEARS

3. Influenza Season
This graph from the Colorado Department of Public Health and Environment shows influenza activity in Colorado during the season. Influenza activity remained at a low level until January 2005 when the number of influenza cases began to climb. Influenza activity peaked in mid-February.
So what were immunization rates in high risk groups during this shortage season?

4. Immunization Rates in 2004-2005
Among adults and children with High Risk Conditions (HRCs)—BRFSS data:
26% of 18 to 64 year olds immunized by 1/31/05
35% of 2 to 17 year olds immunized by 1/31/05
Despite the vaccine shortage, rates in adults with HRCs were similar to previous years
No national comparison data available for children
According to the Behavioral risk factor surveillance survey, 26% of 18 to 64 year olds with high risk conditions were immunized by January 31, 2005 and 35% of 2 to 17 year olds with high risk conditions were immunized.
Despite the shortage, the rates in adults with high risk conditions were similar to previous years. There is no national comparison data from previous years available for children.
Most notable is the finding that only about 1/3 of children and adults with high risk conditions for whom influenza vaccine is recommended actually received an immunization.

5. Role of Registries and Reminder/Recall
Registries with Reminder/Recall systems increase immunization rates in adults and children
Adults and Children—Cochrane Review
Adult influenza vaccination OR 1.66 ( )
Childhood influenza vaccination OR 2.87 ( )
Children with HRCs—Daley and colleagues
RCT in children aged 6 to 72 months with HRCs
42% of those identified and recalled received influenza vaccine
25% of controls received influenza vaccine
Immunization registries with reminder and recall systems have been used to increase immunization rates in adults and children. According to a recent Cochrane review by Jacobsen and Szilagyi, in adults who were recalled (by letter or telephone) the odds of receiving an influenza vaccine were about 1 and ½ times higher compared to adults who were not recalled; in children who were recalled the odds or receiving an influenza vaccine were about 3 times higher compared to children who were not recalled.
Daley and colleagues studied the utility of a registry and recall system specifically in children with high risk conditions. They conducted a randomized, controlled trial of a registry and recall system to identify and notify families of 6 to 72 month olds with high risk conditions in whom influenza vaccine was recommended. They found that 42% of young children with high risk conditions who were identified and recalled received an influenza vaccine compared to 25% of young children with high risk conditions who were not recalled.

6. Study Objectives
To assess whether practices using an immunization registry and recall system were able to:
Target children with HRCs
Maintain immunization rates for children with HRCs during the vaccine shortage
Vaccinate children with HRCs earlier in the season compared to healthy children
Using the same study setting, we sought to assess whether practices using an immunization registry and recall system were able to selectively target children with high risk conditions, maintain immunization rates for children with these conditions during the vaccine shortage, and vaccinate children with these conditions earlier in the season compared to healthy children.

7. Methods: Study Setting
4 pediatric practices in metropolitan Denver, CO
Practices participated in a regional immunization registry and shared a common billing system
During BOTH the and seasons, the practices identified children with HRCs and sent recall letters but did not send recall letters to healthy children
Our study was conducted in 4 pediatric practices in metropolitan Denver, CO. These practices participated in a regional immunization registry and shared a common billing system. During both the and seasons, the practices identified children with high risk conditions and sent recall letters to these children, but they did not send recall letters to healthy children.

8. Data Sources Billing database Accuracy of billing data
Demographic data
Visit and diagnosis information
CPT codes of all immunizations given
Accuracy of billing data
Compared to medical record review, 90% of children with HRCs identified
At least 96% of immunizations captured
We used data from the practices’ billing database to conduct this study, including demographic data, visit and diagnosis information, and CPT codes of all immunizations given.
In the previously cited study by Daley and colleagues, the billing database correctly identified 90% of children with high risk conditions when compared to review of children’s medical records.
Immunization registry data was not available for , but review of the immunization data revealed that only 4% of immunizations recorded in registry were not recorded in the billing database indicating that the billing database captures at least 96% of all immunizations.

9. Population
Children 24 to 72 months old during and/or seasons
Any office visit in prior 18 months
Record in billing database and immunization registry
Children with high risk conditions (HRCs)
, N = 1,166
, N = 1,053
Healthy children
, N = 10, 117
, N = 10,387
Our study population included all children between 24 and 72 months of age during the and/or seasons who had an office visit in the prior 18 months and who had a record in the billing database and immunization registry.
1, to 72 month old children with high risk conditions were identified in the 4 practices in and 1,053 children with high risk conditions were identified in
The healthy study population included more than 10, to 72 month olds each season.

10. High Risk Condition Definition
Chronic pulmonary disease
Chronic heart disease
Chronic renal disease
Hematologic disease
Immune suppression
Metabolic
Kawasaki disease/Rheumatoid arthritis (aspirin therapy)
Others:
Down syndrome
Muscular dystrophy
Cerebral palsy
This slide lists the conditions for which children were classified as high risk.

11. ID and Recall of Children with HRCs
Search of billing database using ICD-9-CM codes
Identified all eligible 24 to 72 month old children with an encounter for a HRC in the previous 2 years as of 10/1/03 or 10/1/04
All identified children received 1-3 recall letters
Strongly encouraged influenza vaccination
Provided telephone number to schedule appointment
Each year the billing database was searched using ICD-9 codes for the conditions described in the previous slide in order to identify all eligible 24 to 72 month old children who had an encounter for a high risk condition in the previous 2 years as of october 1. All identified children received one to three recall letters that strongly encouraged influenza vaccination and provided a telephone number to schedule an appointment at that child’s practice.

12. target children with HRC’s?
Were practices able to
target children with HRC’s?
In order to determine whether practices were able to selectively target children with high risk conditions…,

13. Results: Immunization Rates
Population
Season
HRC
Healthy
p-value
03-04
62%
41%
<0.0001
04-05
60%
28%
we used chi-square analysis to compare the proportion of immunized children with high risk conditions to the proportion of immunized children without high risk conditions in each season.
More children with high risk conditions were immunized compared to healthy children in both and with 62% of children with high risk conditions versus 41% of healthy children being immunized in and 60% versus 28% in

14. Were practices able to maintain immunization rates for
children with HRCs
during a shortage?
In order to determine whether practices were able to maintain immunization rates for children with high risk conditions during a shortage…,

15. Results: Immunization Rates
Population
Season
HRC
Healthy
03-04
62%
41%
04-05
60%
28%
Difference 2%
13%
p-value
0.3
<0.0001
we used chi-square analysis to compare the proportion of immunized children with high risk condtions between and (the shortage year). We also compared the proportion of immunized healthy children between the two seasons.
For children with high risk conditions, immunization rates were unchanged between seasons while for healthy children the immunization rate decreased by 13%.

16. Were practices able to immunize
children with HRCs
earlier in the season?
Finally, in order to examine whether practices were able to immunize children with high risk conditions earlier in the season…,

17. Results: Timing of Immunizations
Time to immunization from September 1
Population
HRC
Healthy
Season
Mean
25 to75%ile Range
p-value
03-04
65 days
48 to 81 days
72 days
53 to 89 days
<0.0001
04-05
50 days
37 to 60 days
63 days
34 to 98 days
we used survival analysis and log rank tests to compare time to immunization between children with high risk conditions and healthy children in each season.
In both seasons, children with high risk conditions were immunized slightly earlier in the season compared to healthy children. In the mean time to immunization from September 1, was 65 days for children with high risk conditions and 72 days for healthy children. In the mean times were 50 days and 63 days, respectively.

18. Results: Immunization Rates and Timing
This graph shows both immunization rates and timing of immunizations for healthy children and children with high risk conditions in both seasons. The slope of the lines indicates the number of immunizations being given during each time period. In more high risk children (represented by the solid blue line) were immunized and were immunized earlier (as shown by the steeper slope in October and November) compared to healthy children (represented by the dotted blue line). In 04-05, more high risk children (represented by the solid peach line) were immunized and were immunized earlier (as shown by the steeper slope in mid-September through October) compared to healthy children (represented by the dotted peach line). Note that after the first ½ of October, 2004 (when the ACIP made its priority group announcement) the dotted peach line flattens out indicating that few immunizations were given to healthy children after the announcement was made.

19. Strengths and Limitations
Other factors may have affected immunization behavior and immunization rates:
Media coverage
Parents’ attitudes regarding vaccine
Timing and severity of influenza season
Strengths
Objectively assessed immunization rates
Used same pediatric practices using same methods to identify and recall high risk children to compare between seasons
Our study is somewhat limited by its observational design. Factors such as media coverage of illness and deaths due to influenza, parents’ attitudes regarding the influenza vaccine, and the timing or severity of the influenza season are likely to influence parents’ and providers’ immunization behavior.
Therefore, besides the practices’ ability to identify and recall children with high risk conditions, other factors may have influenced the immunization rates that we observed.
The strengths of our study are the objective assessment of immunization rates based on billing data and the use of the same pediatric practices using the same methods to identify and recall high risk children to compare between seasons.

20. Conclusions Target children with HRCs for influenza vaccine
Pediatric practices with a system to identify and recall children with HRCs were able to:
Target children with HRCs for influenza vaccine
Maintain high immunization rates in children with HRCs despite vaccine shortage
Vaccinate children with HRCs earlier in the year than healthy children
In conclusion, pediatric practices with a system to identify and recall children with high risk conditions were able to: target children with high risk conditions for the influenza vaccine, maintain high immunization rates in children with high risk conditions despite a vaccine shortage in and vaccinate children with high risk conditions earlier in the season compared to healthy children.

21. Implications
A registry and recall system aided pediatric practices in following ACIP recommendations during a vaccine shortage.
Practices should be encouraged to use electronic databases to identify children with HRCs and link this information to immunization registries in order to help prioritize those most in need of vaccine when there is a shortage.
Thus an immunization registry and recall system aided the practices in following the ACIP recommendations during the vaccine shortage.
As electronic medical records and billing systems become more common, practices should be encouraged to use these databases to identify children with high risk conditions and link this information to immunization registries in order to help prioritize children who are most in need of vaccine when there is a shortage.

22. Acknowledgements This investigation was supported by:
Centers for Disease Control and Prevention
Association of American Medical Colleges
Technical support also provided by the Colorado Immunization Information System
Finally, I would like to acknowledge the support of the CDC and AAMC and my colleagues, many of whom are in the audience.