PREVENTIVE MEDICINE 11, 225-231 (1982)

The U.S. Air Force HEART Program: The Air Force Perspective1

CHARLES P. HATSELL AND DONNA L.GAUGHAN

U.S. Air Force School of Aerospace Medicine, Brooks Air Force Base, San Antonio. Texas 78235

The U.S. Air Force Health Evaluation and Risk Tabulation (HEART) Program was initi- ated to design and test a preventive cardiology program for active-duty Air Force members. Most cardiovascular incidents in active-duty personnel occur at a career point which signifi- cantly magnifies their operational and fiscal effect as the bulk of events disable or kill personnel during their years of peak productivity. A registered nurse managed the program at each of the four demonstration bases. The number of medical technicians and health coun- selors varied according to base population. The program includes risk factor screening, risk ranking, basewide education, and focal group intervention for those at high risk. Screening consisted of a health and habits questionnaire, blood pressure measurement, serum glucose, serum total and HDL cholesterol, as well as serum thiocyanate and exhaled carbon monoxide. The total population screened at first screen was 12,000 and 8,Otkl are expected at second screen. It is likely that due to the military capability for long-term foIIow-up, primary prevention begun at the time of entry to active duty could effectively reduce the number of cardiovascular events experienced yearly in the Air Force. The final product of HEART will be a detailed plan for an Air Force-wide preventive cardiology plan.

INTRODUCTION

In early 1977, the U.S. Air Force (USAF) made a significant commitment to preventive medicine by initiating the USAF Health Evaluation and Risk Tabula- tion (HEART) Program. The objective of HEART was to design and test an optimized preventive cardiology program for the active-duty Air Force. Need for such a program came from the recognition that cardiovascular disease (CVD) was the leading nonaccidental cause of death in active-duty Air Force members. Addi- tionally, the financial burden of Air Force CVD exceeds $60 million annually, making the effect of a modestly successful preventive cardiology program signifi- cant. In particular, it has been estimated that if such a program were in- stitutionalized Air Force-wide, its financial saving would exceed its cost of opera- tion (3).

The Air Force population presents special problems to the application of CVD prevention techniques. For example, the active-duty Air Force is young and man- ifestly free of CVD; benefits of CVD prevention lie far in the future for most Air Force members, so unusual motivational problems were anticipated. Another special characteristic of the Air Force is its mobility. The average length of as- signment to a particular base is 4 years, and most reassignments involve a reloca-

1 This article completes the Forum, “The U.S. Air Force HEART Program,” published in Preven- rive Medicine, Vol. 10, No. 3, May 1981.

225 0091-7435/82/020225-07$02.00/O Copyright 0 1982 by Academic Press, Inc. All rights of reproduction in any form reserved.

226 HATSELL AND GAUCHAN

tion to another base; therefore, continued participant follow-up would require careful and efftcient data management. A major portion of the design was devoted to the development of a specialized data base management system.

HEART was envisioned as a two-phase effort: program design and program test. The test phase would verify the integrability of the design into the active-duty Air Force. The exigency of rapid program implementation precluded a longitudinal study to confirm a reduction in CVD incidence; consequently, an inherent work- ing assumption was that the Air Force would be at least as responsive as civilian communities to CVD reduction efforts. Partial verification of this assumption will be sought by an analysis of pre- and post-intervention risk factor values.

THE USAF POPULATION

From the medical viewpoint, the USAF is primarily young and healthy. A preselection physical examination prior to entry eliminates most significant exist- ing disease or strong familial predisposition to specific diseases such as diabetes mellitus. Traditional medical problems confronting the military health systems have been those arising from peculiarities of the military mission and, for the most. part, have been extensively described. Military life does not confer any special resistance to cardiovascular disease or certain other long incubation period dis- eases. However, because of the centralized medical care and the potential for long-term follow-up there is an enhanced potential for mitigating diseases respon- sive to primary prevention.

Most cardiovascular events in the active-duty military population occur at a career point which significantly magnifies their operational and fiscal effects. There are approximately 500 first cardiovascular events per year in the active duty Air Force and most of these events result in either death or an early retirement, frequently permanent disability. To understand the age-specific cardiovascular event rate in the USAF, it is necessary to be aware of the age distribution of the active duty population. Figure 1 shows a comparison between the USAF and U.S. general population, and Fig. 2 shows the Air Force age-specific first-event rate for cardiovascular disease. The peak in the event rate at the relatively young age of 40 years results from the youth of the population. The bulk of cardiovascular events disable or kill personnel during their years of peak productivity; furthermore,

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Population density comparison between U.S. Air Force and U.S. general FIG. 1. population.

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THE U.S. AIR FORCE HEART PROGRAM 227

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replacement must be from within the Air Force. These are salient factors con- tributing to the high cost of this particular disease.

Like the U.S. secular population, in recent years the Air Force has enjoyed a decline in overall first cardiovascular event incidence; however, the bulk of this decline has been in the 35 years and older age group with the incidence in the younger personnel remaining relatively constant. Figure 3 shows this age group incidence comparison. While some of these younger victims may have had a strong inherited predisposition to cardiovascular disease, it is likely that many of these events could have been avoided by primary prevention begun at the time of entry to active duty.

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FIG. 3. Air Force adjusted frequencies of heart aback and stroke. Adjusted to the 1977 USAF population.

228 HATSELL AND GAUGHAN

KEY DECISIONS

In addition to the design constraints imposed by the Air Force environment and the lifestyle of its members, certain fact-of-life constraints gave additional a priori structure to HEART. The Air Force physician shortage was acute in 1977, ren- dering a program entirely operated by paramedical personnel highly desirable; hence a structure utilizing a registered nurse as manager of each base-level HEART activity was chosen. Health counselors and medical technicians would be utilized in numbers dictated by the base population.

As extensive experience with institutional preventive cardiology resided in the civilian medical community, the Air Force sought to contract the design and test phases through competitive procurement. The normal procurement cycle coupled with efforts directed toward cost containment, and the imperative of a timely program implementation limited the design and test phases to a total span of 3 years. Fifteen months were allocated to program design and the remaining 21 months to program test.

Several contractors submitted proposals which were extensively reviewed by a selection committee of preventive medicine specialists, laboratory officers, health educators, data processing specialists, and Air Force program managers. Final selection was of the team of the American Health Foundation, New York, and Booz Allen and Hamilton, Bethesda, Maryland. The design phase began in August 1978, and was completed in December 1979. Program testing began in January 1980, and will be completed by the end of the fiscal year 1981. A schedule of the entire HEART program is shown in Fig. 4.

The final product of HEART will be an implementation package which will contain the final program design, base, implementation sequence, and fiscal and manpower requirements. Although the basic design centers around cardiovascular disease, the HEART structure should be generalizable to other long incubation period diseases as well.

OEFINITION A PROCUREMENT

CONTRACT AWARII

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DEMONSTRATION

IMPLEMENTATION PACAA6E

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FIG. 4. HEART program schedule.

THE U.S. AIR FORCE HEART PROGRAM 229

THE PROGRAM DESIGN

The HEART Program includes risk factor screening, risk-ranking with defini- tion of a high-risk fraction, basewide (communitywide) education, and focused intervention for the high-risk fraction. The overall program concept is shown in Fig. 5.

Screening consists of a health and habits questionnaire, systolic and diastolic blood pressure, serum glucose, serum total and HDL cholesterol, serum thiocyanate, and exhaled carbon monoxide. The latter two measurements were included for correlation with questionnaire data on smoking. A goal in designing the screening operation was to minimize time away from the job, so question- naires are sent to participants in advance of screening to avoid delays at the screening station. All data are entered into a minicomputer located at the screen- ing station; additionally, the clinical data are used to risk-rank each screenee.

A major problem facing the designers of HEART was that of risk-ranking the Air Force population. It was felt that as much data as possible should be applied to estimating risk. Several estimators for cardiovascular risk were available; most were based on the log-odds ratio for a cardiovascular event. A severe shortcoming of extant estimators was that they were derived from longitudinal studies on populations much older than Air Force population. To test the effectiveness of such an estimator applied to the Air Force, the Framingham age-specific estimator (2) was applied retrospectively to the 1974- 1977 Air Force population. Figure 6 shows that risk was overestimated for the younger ages, but was reasonably well estimated for the older age groups (>35 years). Since this estimator is monotonic in risk factor values it was felt that the ranks would be approximately correct even if the estimates would not directly represent risk; therefore, the approach taken was to apply the Framingham age- and sex-specific estimator to risk-rank the population, but to avoid a probabilistic interpretation of the numerical estimates.

Screening results consisting of risk factor values, a guide to their interpretation, and a notice as to low-, average-, or high-risk status are provided to each screenee within 2 weeks of screening. Those at high risk are offered an intervention pro- gram focused on the specific abnormal risk factors. Details of this intervention were the subject of a previous paper (1).

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FIG. 5. HEART program design.

230 HATSELL AND GAUGHAN

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A6E FIG. 6. Comparison between predicted and observed age-specific CVD event rate.

The HEART design phase was completed in December 1979, and preparation for the test phase was begun in January 1980.

THE PROGRAM TEST

Functional integrability of the HEART Program into Air Force life is the major topic to be addressed by the program test. Thorough testing of computer software, participant scheduling, patient flow, forms handling, and central data handling are central goals of the test phase. Due to the short period available, a longitudinal determination of the effectiveness will not be possible; however, pre- and postin- tervention risk factor screening will allow identification of risk decrements due to HEART.

As the USAF is divided into commands, each with a specific mission, testing at several AF bases representing some of the major commands was desirable. Addi- tionally, the total population which could be effectively managed within resource constraints was felt to be between 10,000 and 15,000. After reviewing many bases and matching for population distributions, four Air Force bases were chosen for test: Pease AFB, New Hampshire, Charleston AFB, South Carolina, Reese AFB, Texas, and Carswell AFB, Texas. The program was configured differently at each base to allow for differentiating the effectiveness of focal intervention and base-wide education. Pease AFB has a base-wide cardiovascular disease educa- tion program and focused intervention for those at high risk; Charleston AFB has only the focused intervention; and Reese AFB has only the base-wide education component. Carswell AFB was chosen as the control base, where intervention will not take place and participant’s screening results will not be reported to them until after the second screen unless immediate medical attention would be prudent as a result of a discovery at the initial screening.

The total population initially screened is approximately 12,000, with about 8,000 expected at the rescreen due to normal efflux from the bases during the test period.

THE U.S. AIR FORCE HEART PROGRAM 231

SOME FINAL REMARKS

The product of the HEART Program will be a detailed plan for Air Force-wide institutionalization of a preventive cardiology program. A projected effectiveness analysis will be included in the plan to allow the Air Force to decide the level of effort that can be applied to preventive cardiology in years to come.

A spin-off of HEART which may prove to be of immense value will be a robust cardiovascular data base on a young population. At the time of this paper’s prepa- ration, the first screen had been completed and preliminary data analysis was beginning. Results of this analysis should be reported in the near future.

REFERENCES

1. Arnold, C. B., and Jacobson, L. Risk reduction in the U.S. Air Force primary prevention HEART Program. Prev. Med. 10, 270-276 (1980).

2. Kannel, W. B., McGee, D., and Gordon, T. A general cardiovascular disease risk profile: The Framingham Study. Amer. J. Cardiol. 38, 46-51 (1976).

3. Petersen, C C., Ravindran, A., Sweet, A. L., and Cote, L. J. “1980 Purdue University Report,” Project Report 0219-53-1287. Purdue University School of Industrial Engineering, Lafayette, Ind., October 1980.