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Screening for renal diseases
February 1976
The Journal of P E D I A T R I C S
369
Screening for renal diseases DISEASES O F T H E K I D N E Y and their complications represent a significant cause of disability and death in the adult population. Recently, major national resources have been committed to the very costly management of chronic renal failure. A search for evidence that a significant proportion of renal disease in adult life is a by-product of known renal disease in childhood has been unrewarding. The observation that it is unusual for the patient with early asymptomatic evidence of renal disease to contact a physician logically leads us to examine the health of asymptomatic, presumably well populations. This activity fits well the image of the physician as a promotor of health through prevention of disability due to disease. The studies reported elsewhere in this issue 1 and previous!y2by Dodge and co-workers describe the results of a five-year program of screening for renal disease initiated on the premise that early detection of asymptomatic disease might permit a desirable alternative to the conventional system of attempting to treat established disease. In the field of tuberculosis control, the widespread screening of children and adults for tuberculin skin sensitivity has amply supported this thesis and in part contributed to the good control of tuberculosis we enjoy today. Such success was possible, however, because case findings could be followed by specific, effective, antimicrobial therapy. Dodge and associates 1, ~ raise a number of relevant questions concerning the wisdom and propriety of screening for renal disease. They imply that such efforts, at least when carried out on a mass screening basis, may be unrewarding. Screening programs often identify a number of asymptomatic suspects who then pose the question of what to do next. Hematuria and proteinuria suggest disturbed renal glomerular function, but when do these isolated findings indicate the need for more extensive investigation? For example, the number of schoolaged girls with asymptomatic abnormalities of blood pressure, growth, urinalysis, or urine culture in any one year (about 1%) is far in excess of the anticipated annual adult mortality from chronic renal disease (less than 0.03%), suggesting that most of the abnormalities detected in schoolchildren are transient or nonprogressive. In addition, the cumulative frequency in girls of abnormali-
ties suggestive of renal disease from the prevalence and incidence data of Dodge and associates 1 projected for the 16 years of childhood may exceed 10%. Since part of the mortality in adult life relates to later onset renal disease, such as the renal complications of diabetes and arterial hypertension, only a portion of the eventual overall mortality can be assigned to abnormalities detected in childhood. See related article, p. 327.
Not only does this study fail to support a definite link between asymptomatic abnormalities in the urinalysis of school-aged children and later progressive renal disease, it also introduces a series of more general questions as to the value and justification of screening for the detection of renal disease generally. First, and perhaps particularly important for the medical profession, is the observation of the individual physician's response to an abnormality reported to him from the screening study. This varied from no concern to equally inappropriate complex and invasive studies. This varied response pattern appeared to be due, at least in part, to the physician's uncertainty as to the meaning of the abnormality found and the nature of an appropriate response. Dodge and associates provide some guidance in this matter by suggesting the number of examinations to be made and the level of proteinuria, hematuria, bacteriuria, or blood pressure, which should be judged as grounds for further observation. At the same time, this report encourages the physician to consider longitudinal observations rather than the early introduction of more definitive studies unless other objective evidence of disease is found from the total medical examination of the patient. It also implies the need and obligation for coupling of screening programs with appropriate opportunities for professional education. At the time these studies were initiated, it was the authors hope that they might be able to identify certain patients whose findings suggested a high risk for future renal disease, perhaps because they exhibited more than one of the abnormalities being sought. In the study cohort, the incidence of two or more abnormalities in the
Vol. 88, No. 2, pp. 369-370
370
Editor's' column
same patient was no greater than the incidence for the second abnormality in the population generally. Thus, the patients with proteinuria had only a slightly greater frequency of hematuria than did their nonproteinuric peers. The presence of modest elevations of blood pressure did not occur more frequently in children with proteinuria or hematuria than in the population at large. A third question centers about the fact that, at the present time, there is limited evidence that the progressive course of many chronic, renal diseases can be arrested by available therapeutic methods. Is it, therefore, reasonable for the physician to seek to identify conditions he knows he cannot influence? Further, the identification of a large number of children with benign or transient abnormalities may create serious economic and psychosocial problems for the children and their families. What responsibility does the physician have in the prevention of unnecessary health-related anxieties and how often do these lead to secondary problems? Finally, the very significant direct and indirect cost of screening in dollars and utilization of scarce medical facilities raises the serious question of priorities. The meaning of this question is magnified when we consider the cost in relation to the questions raised in the previous paragraphs. Studies of the prevalence and incidence of bacteriuria reported earlier2 indicate that similar arguments can be developed for (or against) screening of girls by urine culture. Two interesting sidelights of these studies emerge when compliance is considered. First, with careful planning and thorough education of the target population, a high rate of compliance for participation in the urine screening procedures can be achieved. By contrast, with the usual means of referral for medical care, the compliance rate (in patients with detected abnormality) for seeking care is surprisingly low. These findings are similar to the reports of others 3 5 and emphasize that in planning any mass screening program, education for compliance with followup recommendations is as important as education for initial inclusion in the study group. These studies by Dodge and associates provide a fiveyear longitudinal view of blood pressure, growth, and urine examinations of some 10,000 schoolchildren, 5,000
The Journal of Pediatrics February 1976 of whom were examined consecutively. They suggest that screening for detection of renal disease will be best accomplished by the primary care physician in his office so that interpretation, counseling, and follow-up may be coordinated. The physician is urged to remember that an abnormality detected in a single urine examination has low reliability and that a minimum of one, and preferably two, additional examinations should be undertaken for confirmation. The benign or transient nature of the findings encourages the physician to select long-term observations as his initial management plan unless other evidence of disease is found on complete medical examination. Finally, where screening for renal disease is deemed appropriate, care must be taken to include plans for professional education programs and programs to motivate the public for both initial participation and complicance with recommended medical follow-up. The most important general conclusion from these studies is the recognition of the need for critical examination of the priority of screening in the delivery of medical care. All of the factors involved in screening should be defined, evaluated, and planned so that the benefits and debits of each procedure can be weighed carefully and a positive overall effect projected before decision is made for implementation or continuation. C. W. Daeschner, M.D. Department of Pediatrics University of Texas Medical Branch Galveston, Texas 77550 REFERENCES
1. Dodge WF, West EF, Smith EH, and Bunce H I I l : Proteinuria and hematuria in school children; Epidemiology and early natural history, J PEDIATR88:327, 1976. 2. Dodge WF, West EF, and Travis LB: Bacteriuria in school children. Observations on outcome following detection in 110 girls, Am J Dis Child 127:364, 1974. 3. Cauffman JG, Peterson EL, and Emrich JA: Medical care of school children: Factors influencing outcome of referral from a school health program, Am J Public Health 57:60, 1967. 4. Gabrielson IW, Levin LS, and Ellison MD: Factors affecting school health fotlow~up, Am J Public Health 57:48, 1967. 5. Fletcher SW, et al: Management of hypertension, JAMA 233:242, 1975.
The Journal of P E D I A T R I C S
369
Screening for renal diseases DISEASES O F T H E K I D N E Y and their complications represent a significant cause of disability and death in the adult population. Recently, major national resources have been committed to the very costly management of chronic renal failure. A search for evidence that a significant proportion of renal disease in adult life is a by-product of known renal disease in childhood has been unrewarding. The observation that it is unusual for the patient with early asymptomatic evidence of renal disease to contact a physician logically leads us to examine the health of asymptomatic, presumably well populations. This activity fits well the image of the physician as a promotor of health through prevention of disability due to disease. The studies reported elsewhere in this issue 1 and previous!y2by Dodge and co-workers describe the results of a five-year program of screening for renal disease initiated on the premise that early detection of asymptomatic disease might permit a desirable alternative to the conventional system of attempting to treat established disease. In the field of tuberculosis control, the widespread screening of children and adults for tuberculin skin sensitivity has amply supported this thesis and in part contributed to the good control of tuberculosis we enjoy today. Such success was possible, however, because case findings could be followed by specific, effective, antimicrobial therapy. Dodge and associates 1, ~ raise a number of relevant questions concerning the wisdom and propriety of screening for renal disease. They imply that such efforts, at least when carried out on a mass screening basis, may be unrewarding. Screening programs often identify a number of asymptomatic suspects who then pose the question of what to do next. Hematuria and proteinuria suggest disturbed renal glomerular function, but when do these isolated findings indicate the need for more extensive investigation? For example, the number of schoolaged girls with asymptomatic abnormalities of blood pressure, growth, urinalysis, or urine culture in any one year (about 1%) is far in excess of the anticipated annual adult mortality from chronic renal disease (less than 0.03%), suggesting that most of the abnormalities detected in schoolchildren are transient or nonprogressive. In addition, the cumulative frequency in girls of abnormali-
ties suggestive of renal disease from the prevalence and incidence data of Dodge and associates 1 projected for the 16 years of childhood may exceed 10%. Since part of the mortality in adult life relates to later onset renal disease, such as the renal complications of diabetes and arterial hypertension, only a portion of the eventual overall mortality can be assigned to abnormalities detected in childhood. See related article, p. 327.
Not only does this study fail to support a definite link between asymptomatic abnormalities in the urinalysis of school-aged children and later progressive renal disease, it also introduces a series of more general questions as to the value and justification of screening for the detection of renal disease generally. First, and perhaps particularly important for the medical profession, is the observation of the individual physician's response to an abnormality reported to him from the screening study. This varied from no concern to equally inappropriate complex and invasive studies. This varied response pattern appeared to be due, at least in part, to the physician's uncertainty as to the meaning of the abnormality found and the nature of an appropriate response. Dodge and associates provide some guidance in this matter by suggesting the number of examinations to be made and the level of proteinuria, hematuria, bacteriuria, or blood pressure, which should be judged as grounds for further observation. At the same time, this report encourages the physician to consider longitudinal observations rather than the early introduction of more definitive studies unless other objective evidence of disease is found from the total medical examination of the patient. It also implies the need and obligation for coupling of screening programs with appropriate opportunities for professional education. At the time these studies were initiated, it was the authors hope that they might be able to identify certain patients whose findings suggested a high risk for future renal disease, perhaps because they exhibited more than one of the abnormalities being sought. In the study cohort, the incidence of two or more abnormalities in the
Vol. 88, No. 2, pp. 369-370
370
Editor's' column
same patient was no greater than the incidence for the second abnormality in the population generally. Thus, the patients with proteinuria had only a slightly greater frequency of hematuria than did their nonproteinuric peers. The presence of modest elevations of blood pressure did not occur more frequently in children with proteinuria or hematuria than in the population at large. A third question centers about the fact that, at the present time, there is limited evidence that the progressive course of many chronic, renal diseases can be arrested by available therapeutic methods. Is it, therefore, reasonable for the physician to seek to identify conditions he knows he cannot influence? Further, the identification of a large number of children with benign or transient abnormalities may create serious economic and psychosocial problems for the children and their families. What responsibility does the physician have in the prevention of unnecessary health-related anxieties and how often do these lead to secondary problems? Finally, the very significant direct and indirect cost of screening in dollars and utilization of scarce medical facilities raises the serious question of priorities. The meaning of this question is magnified when we consider the cost in relation to the questions raised in the previous paragraphs. Studies of the prevalence and incidence of bacteriuria reported earlier2 indicate that similar arguments can be developed for (or against) screening of girls by urine culture. Two interesting sidelights of these studies emerge when compliance is considered. First, with careful planning and thorough education of the target population, a high rate of compliance for participation in the urine screening procedures can be achieved. By contrast, with the usual means of referral for medical care, the compliance rate (in patients with detected abnormality) for seeking care is surprisingly low. These findings are similar to the reports of others 3 5 and emphasize that in planning any mass screening program, education for compliance with followup recommendations is as important as education for initial inclusion in the study group. These studies by Dodge and associates provide a fiveyear longitudinal view of blood pressure, growth, and urine examinations of some 10,000 schoolchildren, 5,000
The Journal of Pediatrics February 1976 of whom were examined consecutively. They suggest that screening for detection of renal disease will be best accomplished by the primary care physician in his office so that interpretation, counseling, and follow-up may be coordinated. The physician is urged to remember that an abnormality detected in a single urine examination has low reliability and that a minimum of one, and preferably two, additional examinations should be undertaken for confirmation. The benign or transient nature of the findings encourages the physician to select long-term observations as his initial management plan unless other evidence of disease is found on complete medical examination. Finally, where screening for renal disease is deemed appropriate, care must be taken to include plans for professional education programs and programs to motivate the public for both initial participation and complicance with recommended medical follow-up. The most important general conclusion from these studies is the recognition of the need for critical examination of the priority of screening in the delivery of medical care. All of the factors involved in screening should be defined, evaluated, and planned so that the benefits and debits of each procedure can be weighed carefully and a positive overall effect projected before decision is made for implementation or continuation. C. W. Daeschner, M.D. Department of Pediatrics University of Texas Medical Branch Galveston, Texas 77550 REFERENCES
1. Dodge WF, West EF, Smith EH, and Bunce H I I l : Proteinuria and hematuria in school children; Epidemiology and early natural history, J PEDIATR88:327, 1976. 2. Dodge WF, West EF, and Travis LB: Bacteriuria in school children. Observations on outcome following detection in 110 girls, Am J Dis Child 127:364, 1974. 3. Cauffman JG, Peterson EL, and Emrich JA: Medical care of school children: Factors influencing outcome of referral from a school health program, Am J Public Health 57:60, 1967. 4. Gabrielson IW, Levin LS, and Ellison MD: Factors affecting school health fotlow~up, Am J Public Health 57:48, 1967. 5. Fletcher SW, et al: Management of hypertension, JAMA 233:242, 1975.