Evaluation of a Screening Program for Heart Disease GENEVIEVE M. MATANOSKI, MD, DRPH, MAUREEN M. HENDERSON, MBBS, DRPH, OSCAR C. STINE, MD, DRPH, CORRINE COURPAS, MD, RAYMOND HEPNER, JR., MD, AND STUART WALKER, MD
Abstract: An evaluation of the effectiveness of a screening program using the Phono Cardio Scan to detect heart disease in 18,872 Baltimore (Maryland) elementary school children indicated that few cases were discovered and only one child had medical treatment instituted as a result of the program. Most of the chil-
dren referred to a cardiologist had known disease. There was considerable variability in performance both of the machine and of the three centers which were involved in the program. The sensitivity of the machine may have been low as reported in some other studies. (Am. J. Public Health 67:609-611, 1977)
Screening of children for heart disease through recording of heart sounds was simplified in the mid-1960s with the advent of a computerized machine, PhonoCardioScan (PCS).* Reports on the use of PCS in school-age children have indicated that about 5 to 12.5 per cent of the children will screen as positive.'-9 A high proportion (75 to 96 per cent) of these are false positives. The sensitivity of the device, or probability that it will detect children with heart disease, has varied from 64 to 98 per cent; the specificity, or probability that the screening test will correctly classify a child without a heart murmur, is consistently reported to be about 95 per
Methods
cent.1' 2, 4, 9
The Maryland Regional Medical Program decided to test this method of heart disease detection by implementing three pilot projects in Baltimore City. The program was to be evaluated by its acceptability to parents and children and by its effectiveness both in detecting and bringing to treatment children with heart disease and in de-labeling children erroneously diagnosed as having such disorders.
For a two-year period, three separate projects directed by three hospitals with different catchment populations agreed to follow similar screening procedures for heart disease detection in school children. Each center was to examine children from as many schools as possible in their area. The parents were to be asked by letter to sign a permission slip and complete a questionnaire which included questions about the past history of heart disease and any possible medication or limitation of activity related to such disease.* Standard forms for recording results were used by all three projects. According to the protocol, two types of children were to be referred to the cardiologist for examination: children who had positive histories* for heart disease, regardless of the results shown on PhonoCardioScan, and children who were outside normal limits on two screening tests or who had two technically unsatisfactory tests.
Results Address reprint requests to Dr. Genevieve M. Matanoski, Professor of Epidemiology, Johns Hopkins University, School of Hygiene and Public Health, 615 N. Wolfe Street, Baltimore, MD 21205. Drs. Henderson, Stine, and Hepner are with the University of Maryland; Dr. Courpas is with Baltimore City Hospitals; and Dr. Walker is with Mercy Hospital (Baltimore). This paper, submitted to the Journal April 1, 1976, was revised and accepted for publication January 31, 1977. The data in this paper were presented at the American Public Health Association Annual Meeting, November 1973, in San Francisco. *Trade name of Humetrics Division of Thiokol Chemical Corporation. AJPH July, 1977, Vol. 67, No. 7
There were differences in the size and demographic make-up of the target populations screened by the three cen*The two centers asked some of the questions in slightly different ways: "Has your child ever been known to have heart disease (trouble) or a heart murmur?" One center also asked specifically about a history ofrheumatic fever by simply listing these words (Center 2). Center 3 added a question on limitation of activities because of heart disease: "Is there anything your child is not allowed to do because of heart trouble?" 609
MATANOSKI, ET AL.
ters.t However, a more serious problem was the lack of central supervision, quality control, and consistency checks of technician and cardiologist. In Centers 1 and 2 less than 3 per cent of the children screened were positive on the initial test, as compared to more than 10 per cent of those screened in Center 3. According to protocol all children with positive initial tests were to be rescreened and all children with histories of heart disease were to be examined by the cardiologist regardless of test results. Only Centers 2 and 3 rescreened initial positives and only Center 3 referred all children with a positive history to the cardiologist. The ratio of children with positive histories who also screened positive on two tests was 15 times higher in Center 3 than in Center 2. In Center 1 the cardiac screening was part of a multiphasic screening program, and only about one-half the target population was reached as compared to over 90 per cent in Centers 1 and 2. Although these anomalies pose problems in interpretation of many of the findings, 18,872 elementary school children were screened at least once by the PhonoCardioScan and 712 (3.8 per cent) were examined by a cardiologist because of one or more positive screening tests and/or a positive cardiac history. The outcome of the cardiologists' examinations are shown in Table 1 for each of the three Centers. Of those examined, about one per cent had clearly "organic" murmurs and 75 per cent had clearly functional murmurs on initial examination. All the cases with clearly organic murmurs had histories of heart disease. Over one-half the children in Center 2 and over three-quarters of the children in Center 3 with suspicious or questionable murmurs reported positive histories for heart disease. TABLE 1-0utcome of Cardiologist Examination of Children Referred After Screening
Total Referred Total Examined Classification of Murmur
Center 1
Center 2
Center3
32 26
105 104
625 580
on Iniial Examination
Organic (% of examinees) Functional (% of examinees) Questionable or Suspicious No murmur heard Quality of murmur not recorded Final Diagnoses RHD (known/unknown) CHD (Known/unknown)
0 9(35) 3 8 6 0 0
1(1) 74(70) 7 22 0 0
1(1/0)
5 (1) 472(81) 41 49 13 3 (2/1) 12(11/1)
Few of the cases detected required any active care by the cardiologist. Most received only an electrocardiogram and chest x-ray as additional diagnostic procedures; none had catheterization recommended. In Center 2, the one child with a clearly organic murmur had a known ventricular septal de-
tCenter 1, target population 763 (65 per cent Black) served the inner city; Center 2, target population 11,330 (85 per cent Black) also served the inner city; Center 3, target population 8,467 (3 per cent Black) served a lower middle class area. 610
fect, coarctation of the aorta, and pulmonic stenosis. The other seven children with questionable murmurs never had a more definitive diagnosis recorded subsequently. In Center 3, there were five children with clearly organic murmurs: one with rheumatic heart disease and four with congenital heart disease. All were known prior to the screening test. There were an additional 41 children in Center 3 who were initially classified as having suspicious or questionable heart murmurs. In 11 of these children, no final diagnosis was suggested. Among the remaining 30 children, 20 of the murmurs were finally classified as functional, and one other child, who had had an operation for patent ductus, had heart sounds which were eventually classified as normal. Among the nine cases which were diagnosed as having heart disease, five were classified as probable aortic or pulmonic stenosis and had positive histories; two had probable ventricular septal defect, one of which had been known previously; and two had rheumatic heart disease with mitral insufficiency, one ofwhich had been diagnosed previously. The one previously unknown case of rheumatic heart disease is the only child who was recorded as having been treated as a result of this screening program. The children with congenital heart disease who were discovered were simply followed for further evidence of disease. Protocol for the "de-labeling" objective of the study was followed only by Center 3. In Center 2, children were delabeled on the basis of a single negative PCS test or a positive test followed by a negative. Through this procedure, 92.1 per cent of the children with positive histories were de-labeled. Had Center 3 followed a similar procedure, 40.4 per cent of children with positive histories would have been de-labeled; however, a cardiologist's examinations of 136 Center 3 children who would have been de-labeled by Center 2 indicated that eight had murmurs suspicious of organic heart disease and should not be considered to have a normal cardiac status. De-labeling by the use of PCS alone would have erroneously classified these eight children.
Discussion This study was initiated in the inner city on the presumption that the population in this area would have the highest levels of undetected disease. Using the PCS as a screening tool, 18,872 children were screened, but only one child with rheumatic heart disease was eventually placed under prophylactic therapy as a result of the program. Suspected cases of congenital heart disease were simply recommended for follow-up without further diagnostic tests. If the major purpose of a screening program for heart disease is the detection and treatment of children with undiagnosed lesions, it would be difficult to justify such a program based on the results of this study. Many children are erroneously diagnosed as having heart disease by physicians and parents and are frequently forced into a state of limited physical activity by such diagnoses. 15 It would be helpful if simple screening through a device such as PCS would allow us to de-label these children. As indicated in this study, such a procedure would be impossible using PCS AJPH July, 1977, Vol. 67, No. 7
HEART DISEASE SCREENING
because the machine erroneously labels as "normal" children who have "suspicious" cardiac murmurs. It is also unlikely that parents or physicians would accept the machine's diagnosis without confirmation by a cardiologist. If a physical examination by a cardiologist is required anyway, the initial machine screening of the small number of children with positive histories for heart disease is an unnecessary addition to the de-labeling process. In this study the overall prevalence of heart disease by cardiologist's diagnosis in Center 3 (with the highest yield) is only 19 per 10,000 children screened. This ratio is one-half to one-fifth that reported in other surveys. A possible explanation for this low prevalence as well as for the machine's erroneous de-labeling of children who have heart murmurs might be the low sensitivity of this screening device. Such a conclusion would be compatible with the sensitivity of 57 per cent as reported by Blackman et al.16 Henikoff, Stevens and Perry4 reported a similar value of 64 per cent for a single screening and an increase of 12 per cent when a repeat test was given. Other studies which suggest a high sensitivity for this machine are not supported by the current data. There is no apparent explanation as to why the performance of the machine varies in the hands of different investigators screening different populations. Serious questions must be raised about the appropriateness of using this machine to screen for heart disease in school children under conditions similar to those of this study.
REFERENCES 1. Durnin, R. E., et al. Heart sound screening in children by analogdigital circuitry. Public Health Reports No. 9, 80:761-770, 1965. 2. Levy, M. E., et al. Screening children's heart sounds with a portable computer. Bio-Medical Engineering 446-456, 1966.
3. Durnin, R. E., et al. Heart-sound screening in children: Use of a portable analog-digital computer (Field Study-Los Angeles 1966). JAMA 203:111-116, 1968. 4. Henikoff, L. M., et al. Detection of heart disease in children 1919-1967. Circulation 38:375-385, 1968. 5. King, E. L. and Woolley, P. 0. Heart sound screening in Gallatin County, Montana. Rocky Mountain Medical Journal 65:3740, 1968. 6. Auerback, M. L. Heart sound screening in high, low and middle income communities. California Medicine 110: 120-124, 1969. 7. Cayler, G. G., et al. Mass screening of school children for heart disease. Public Health Reports No. 6, 84:479-482, 1969. 8. Dennison, D. and Fenimore, J. A. A heart sound screening program for elementary children. J. School Health 41:349-351, 1971. 9. Halfon, S. T., et al. Primary prevention of rheumatic fever in Jerusalem school children: lII. Screening for heart disease by means of the PhonoCardioScan. Israel J. Med. Sci. 6:584-588, 1970. 10. Miller, R. A., et al. The detection of heart disease in children: Results of a mass field trial with use of tape-recorded heart sounds. Circulation 25:85-95, 1962. 11. Miller, R. A., et al. The detection of heart disease in children: Results of mass field trials with use of tape recorded heart sounds. II. The Michigan City study. Circulation 32:956-965, 1965. 12. Smith, J. M., et al. The detection of heart disease in children: Results of mass field trials with use of tape recorded heart sounds. III. The Chicago area high school study. Circulation 32:966-976, 1965. 13. Reynolds, J. L. Heart disease screening of preschool children: Comparison of computer and physical examination methods. Amer J. Dis Child 119:488-493, 1970. 14. Morton, W. Heart disease prevalence in school children in two Colorado communities. Am. J. Public Health 52:991-1001, 1962. 15. Bergman, A. B. and Stamm, S. J. The morbidity of cardiac nondisease in school children. N. Eng. J. Medicine 276:1008-1013, 1967. 16. Blackman, N. S., et al. Cardiac screening by computerized auscultation. Am. J. Public Health 59:1177-1187, 1969.
Columbia University Schools of Social Work and Public Health Announce Joint Program Ajoint program leading to the degrees of master of science in social work and master of public health has been announced by the Columbia University schools of Social Work and Public Health. The program is designed to equip students with the specialized social work skills and public health knowledge needed to develop and operate integrated services in a broad range of settings offering career opportunities. All requirements for the two degrees may be completed in two calendar years (six consecutive terms). For further information and admission forms contact: Admissions Office, Columbia University School of Social Work, 622 West 113 Street, New York, NY 10025. (212) 280-5319.
AJPH July, 1977, Vol. 67, No. 7
611
Abstract: An evaluation of the effectiveness of a screening program using the Phono Cardio Scan to detect heart disease in 18,872 Baltimore (Maryland) elementary school children indicated that few cases were discovered and only one child had medical treatment instituted as a result of the program. Most of the chil-
dren referred to a cardiologist had known disease. There was considerable variability in performance both of the machine and of the three centers which were involved in the program. The sensitivity of the machine may have been low as reported in some other studies. (Am. J. Public Health 67:609-611, 1977)
Screening of children for heart disease through recording of heart sounds was simplified in the mid-1960s with the advent of a computerized machine, PhonoCardioScan (PCS).* Reports on the use of PCS in school-age children have indicated that about 5 to 12.5 per cent of the children will screen as positive.'-9 A high proportion (75 to 96 per cent) of these are false positives. The sensitivity of the device, or probability that it will detect children with heart disease, has varied from 64 to 98 per cent; the specificity, or probability that the screening test will correctly classify a child without a heart murmur, is consistently reported to be about 95 per
Methods
cent.1' 2, 4, 9
The Maryland Regional Medical Program decided to test this method of heart disease detection by implementing three pilot projects in Baltimore City. The program was to be evaluated by its acceptability to parents and children and by its effectiveness both in detecting and bringing to treatment children with heart disease and in de-labeling children erroneously diagnosed as having such disorders.
For a two-year period, three separate projects directed by three hospitals with different catchment populations agreed to follow similar screening procedures for heart disease detection in school children. Each center was to examine children from as many schools as possible in their area. The parents were to be asked by letter to sign a permission slip and complete a questionnaire which included questions about the past history of heart disease and any possible medication or limitation of activity related to such disease.* Standard forms for recording results were used by all three projects. According to the protocol, two types of children were to be referred to the cardiologist for examination: children who had positive histories* for heart disease, regardless of the results shown on PhonoCardioScan, and children who were outside normal limits on two screening tests or who had two technically unsatisfactory tests.
Results Address reprint requests to Dr. Genevieve M. Matanoski, Professor of Epidemiology, Johns Hopkins University, School of Hygiene and Public Health, 615 N. Wolfe Street, Baltimore, MD 21205. Drs. Henderson, Stine, and Hepner are with the University of Maryland; Dr. Courpas is with Baltimore City Hospitals; and Dr. Walker is with Mercy Hospital (Baltimore). This paper, submitted to the Journal April 1, 1976, was revised and accepted for publication January 31, 1977. The data in this paper were presented at the American Public Health Association Annual Meeting, November 1973, in San Francisco. *Trade name of Humetrics Division of Thiokol Chemical Corporation. AJPH July, 1977, Vol. 67, No. 7
There were differences in the size and demographic make-up of the target populations screened by the three cen*The two centers asked some of the questions in slightly different ways: "Has your child ever been known to have heart disease (trouble) or a heart murmur?" One center also asked specifically about a history ofrheumatic fever by simply listing these words (Center 2). Center 3 added a question on limitation of activities because of heart disease: "Is there anything your child is not allowed to do because of heart trouble?" 609
MATANOSKI, ET AL.
ters.t However, a more serious problem was the lack of central supervision, quality control, and consistency checks of technician and cardiologist. In Centers 1 and 2 less than 3 per cent of the children screened were positive on the initial test, as compared to more than 10 per cent of those screened in Center 3. According to protocol all children with positive initial tests were to be rescreened and all children with histories of heart disease were to be examined by the cardiologist regardless of test results. Only Centers 2 and 3 rescreened initial positives and only Center 3 referred all children with a positive history to the cardiologist. The ratio of children with positive histories who also screened positive on two tests was 15 times higher in Center 3 than in Center 2. In Center 1 the cardiac screening was part of a multiphasic screening program, and only about one-half the target population was reached as compared to over 90 per cent in Centers 1 and 2. Although these anomalies pose problems in interpretation of many of the findings, 18,872 elementary school children were screened at least once by the PhonoCardioScan and 712 (3.8 per cent) were examined by a cardiologist because of one or more positive screening tests and/or a positive cardiac history. The outcome of the cardiologists' examinations are shown in Table 1 for each of the three Centers. Of those examined, about one per cent had clearly "organic" murmurs and 75 per cent had clearly functional murmurs on initial examination. All the cases with clearly organic murmurs had histories of heart disease. Over one-half the children in Center 2 and over three-quarters of the children in Center 3 with suspicious or questionable murmurs reported positive histories for heart disease. TABLE 1-0utcome of Cardiologist Examination of Children Referred After Screening
Total Referred Total Examined Classification of Murmur
Center 1
Center 2
Center3
32 26
105 104
625 580
on Iniial Examination
Organic (% of examinees) Functional (% of examinees) Questionable or Suspicious No murmur heard Quality of murmur not recorded Final Diagnoses RHD (known/unknown) CHD (Known/unknown)
0 9(35) 3 8 6 0 0
1(1) 74(70) 7 22 0 0
1(1/0)
5 (1) 472(81) 41 49 13 3 (2/1) 12(11/1)
Few of the cases detected required any active care by the cardiologist. Most received only an electrocardiogram and chest x-ray as additional diagnostic procedures; none had catheterization recommended. In Center 2, the one child with a clearly organic murmur had a known ventricular septal de-
tCenter 1, target population 763 (65 per cent Black) served the inner city; Center 2, target population 11,330 (85 per cent Black) also served the inner city; Center 3, target population 8,467 (3 per cent Black) served a lower middle class area. 610
fect, coarctation of the aorta, and pulmonic stenosis. The other seven children with questionable murmurs never had a more definitive diagnosis recorded subsequently. In Center 3, there were five children with clearly organic murmurs: one with rheumatic heart disease and four with congenital heart disease. All were known prior to the screening test. There were an additional 41 children in Center 3 who were initially classified as having suspicious or questionable heart murmurs. In 11 of these children, no final diagnosis was suggested. Among the remaining 30 children, 20 of the murmurs were finally classified as functional, and one other child, who had had an operation for patent ductus, had heart sounds which were eventually classified as normal. Among the nine cases which were diagnosed as having heart disease, five were classified as probable aortic or pulmonic stenosis and had positive histories; two had probable ventricular septal defect, one of which had been known previously; and two had rheumatic heart disease with mitral insufficiency, one ofwhich had been diagnosed previously. The one previously unknown case of rheumatic heart disease is the only child who was recorded as having been treated as a result of this screening program. The children with congenital heart disease who were discovered were simply followed for further evidence of disease. Protocol for the "de-labeling" objective of the study was followed only by Center 3. In Center 2, children were delabeled on the basis of a single negative PCS test or a positive test followed by a negative. Through this procedure, 92.1 per cent of the children with positive histories were de-labeled. Had Center 3 followed a similar procedure, 40.4 per cent of children with positive histories would have been de-labeled; however, a cardiologist's examinations of 136 Center 3 children who would have been de-labeled by Center 2 indicated that eight had murmurs suspicious of organic heart disease and should not be considered to have a normal cardiac status. De-labeling by the use of PCS alone would have erroneously classified these eight children.
Discussion This study was initiated in the inner city on the presumption that the population in this area would have the highest levels of undetected disease. Using the PCS as a screening tool, 18,872 children were screened, but only one child with rheumatic heart disease was eventually placed under prophylactic therapy as a result of the program. Suspected cases of congenital heart disease were simply recommended for follow-up without further diagnostic tests. If the major purpose of a screening program for heart disease is the detection and treatment of children with undiagnosed lesions, it would be difficult to justify such a program based on the results of this study. Many children are erroneously diagnosed as having heart disease by physicians and parents and are frequently forced into a state of limited physical activity by such diagnoses. 15 It would be helpful if simple screening through a device such as PCS would allow us to de-label these children. As indicated in this study, such a procedure would be impossible using PCS AJPH July, 1977, Vol. 67, No. 7
HEART DISEASE SCREENING
because the machine erroneously labels as "normal" children who have "suspicious" cardiac murmurs. It is also unlikely that parents or physicians would accept the machine's diagnosis without confirmation by a cardiologist. If a physical examination by a cardiologist is required anyway, the initial machine screening of the small number of children with positive histories for heart disease is an unnecessary addition to the de-labeling process. In this study the overall prevalence of heart disease by cardiologist's diagnosis in Center 3 (with the highest yield) is only 19 per 10,000 children screened. This ratio is one-half to one-fifth that reported in other surveys. A possible explanation for this low prevalence as well as for the machine's erroneous de-labeling of children who have heart murmurs might be the low sensitivity of this screening device. Such a conclusion would be compatible with the sensitivity of 57 per cent as reported by Blackman et al.16 Henikoff, Stevens and Perry4 reported a similar value of 64 per cent for a single screening and an increase of 12 per cent when a repeat test was given. Other studies which suggest a high sensitivity for this machine are not supported by the current data. There is no apparent explanation as to why the performance of the machine varies in the hands of different investigators screening different populations. Serious questions must be raised about the appropriateness of using this machine to screen for heart disease in school children under conditions similar to those of this study.
REFERENCES 1. Durnin, R. E., et al. Heart sound screening in children by analogdigital circuitry. Public Health Reports No. 9, 80:761-770, 1965. 2. Levy, M. E., et al. Screening children's heart sounds with a portable computer. Bio-Medical Engineering 446-456, 1966.
3. Durnin, R. E., et al. Heart-sound screening in children: Use of a portable analog-digital computer (Field Study-Los Angeles 1966). JAMA 203:111-116, 1968. 4. Henikoff, L. M., et al. Detection of heart disease in children 1919-1967. Circulation 38:375-385, 1968. 5. King, E. L. and Woolley, P. 0. Heart sound screening in Gallatin County, Montana. Rocky Mountain Medical Journal 65:3740, 1968. 6. Auerback, M. L. Heart sound screening in high, low and middle income communities. California Medicine 110: 120-124, 1969. 7. Cayler, G. G., et al. Mass screening of school children for heart disease. Public Health Reports No. 6, 84:479-482, 1969. 8. Dennison, D. and Fenimore, J. A. A heart sound screening program for elementary children. J. School Health 41:349-351, 1971. 9. Halfon, S. T., et al. Primary prevention of rheumatic fever in Jerusalem school children: lII. Screening for heart disease by means of the PhonoCardioScan. Israel J. Med. Sci. 6:584-588, 1970. 10. Miller, R. A., et al. The detection of heart disease in children: Results of a mass field trial with use of tape-recorded heart sounds. Circulation 25:85-95, 1962. 11. Miller, R. A., et al. The detection of heart disease in children: Results of mass field trials with use of tape recorded heart sounds. II. The Michigan City study. Circulation 32:956-965, 1965. 12. Smith, J. M., et al. The detection of heart disease in children: Results of mass field trials with use of tape recorded heart sounds. III. The Chicago area high school study. Circulation 32:966-976, 1965. 13. Reynolds, J. L. Heart disease screening of preschool children: Comparison of computer and physical examination methods. Amer J. Dis Child 119:488-493, 1970. 14. Morton, W. Heart disease prevalence in school children in two Colorado communities. Am. J. Public Health 52:991-1001, 1962. 15. Bergman, A. B. and Stamm, S. J. The morbidity of cardiac nondisease in school children. N. Eng. J. Medicine 276:1008-1013, 1967. 16. Blackman, N. S., et al. Cardiac screening by computerized auscultation. Am. J. Public Health 59:1177-1187, 1969.
Columbia University Schools of Social Work and Public Health Announce Joint Program Ajoint program leading to the degrees of master of science in social work and master of public health has been announced by the Columbia University schools of Social Work and Public Health. The program is designed to equip students with the specialized social work skills and public health knowledge needed to develop and operate integrated services in a broad range of settings offering career opportunities. All requirements for the two degrees may be completed in two calendar years (six consecutive terms). For further information and admission forms contact: Admissions Office, Columbia University School of Social Work, 622 West 113 Street, New York, NY 10025. (212) 280-5319.
AJPH July, 1977, Vol. 67, No. 7
611
