LETTERS TO THE EDITOR

1-

U

Letters Ito the Editor

Letters are welcomed and will be published, if found suitable, as space permits. The editors reserve the right to edit and abridge letters, to publish replies, and to solicit responses from authors and others. Letters should be submitted in duplicate, double-spaced (including references), and generally should not exceed 400 words.

Addendum to Article on 'Visit-Based Sampling' Subsequent to publication in the August 1977 Journal of our article on visit-based sampling,' Ralph Uliman (now at Columbia University School of Public Health) informed us of some prior work on the subject. The following should be added to our bibliography: two previous papers that describe a weighting methodology equivalent to ours,2' 3 its application to studies of hospital outpatients,4 5 and an earlier article that considers a similar objective.6 After discussing the weighting procedure with Mr. Ullman, we believe that two clarifications to our article should be made. First, the suggested computations are appropriate only when the weights are derived from the number of visits made within afixed interval, say, a given year. If, instead, each weight is derived from the number of visits made in the 12 months prior to the sampled visit, biased results are generally obtained. Second, our previous interpretation of the weight as an average interval between visits is appropriate only under special circumstances. Under more general conditions, in which utilization is clustered and non-random, the average interval and the weight may be quite different. Donald S. Shepard, PhD Lecturer Harvard School of Public Health Boston, MA 02115 and 954

Raymond Neutra, DPH Associate Prof. ofEpidemiology UCLA School ofPublic Health Los Angeles, CA 90024

REFERENCES 1. Shepard DS, Neutra R: A pitfall in sam pling medical visits. Am J Public Health 67:743-750, 1977. 2. Ullman R, Stratmann WC: Developing E profile of ambulatory utilization. Present ed at the 101st Annual Meeting of the American Public Health Association San Francisco, November 4-8, 1973. 3. Ullman R: Developing a profile of am. bulatory utilization-a sampling tech. nique. Proceedings of the Public Healti Conference on Records and Statistics 15th National Meeting. DHEW Pub, lication No. (HRA) 75-1214, U.S. De. partment of Health, Education, and Wel. fare, 1975, pp 207-210. 4. Ullman R, Block JA, Rozzi MV, Stratmann WC: Study provides data for planning hospital-based primary care. Hospitals 49(22):75, 1975. 5. Ullman R, Block JA, Stratmann WC: Ar emergency room's patients: their characteristics and utilization of hospital services. Med Care 13:1011-1020, 1975. 6. Lerner RC, Kirchner C: Social and eco. nomic characteristics of municipal hospital outpatients. Am J Public Health 57:401 -408, 1967.

Outreach and Use of Preventive Services I congratulate the authors of "The Effect of Outreach Workers . . ." ' for their interest in outreach services for disadvantaged children and the effect of outreach on utilization of preventive services for preschool children. Much as I would like to agree with their conclusions, particularly their final paragraph, I cannot, for their experimental design has three serious faults. The first fault is violation of the assumption basic to the use of person years methodology-equal risk of the variable under study except as influ-

enced by a given event.2 In a normal child health supervision plan, the preventive services listed, primarily immunizations, are heavily represented in the first year of life (six events), lightly represented in the second year (three events) and have no representation in the next two years.3 When the population is underimmunized, or immunized late, the standards for immunization are different.3 Therefore, both the age distributions within 0-4 years, and the two different sets of standards confound the statistics as published. The second fault is pooling of immunization events from "special injection clinics" with immunization events in regular outpatient clinics. Caregiver behavior in these two different clinic populations is different, as is their children's health.4'5 Pooling of these multiple confounding variables-different clinics, different caregivers' behaviors, and different child health status-hopelessly entangles the conclusions in uncertainties. The third fault has to do with "volunteerism"6 7 or self-selection of 25 percent of the families as requesting outreach services, and the pooling of their data with outreach families who received these services whether requested or not. The requesting families, simply by requesting, have demonstrated without question that they are different from non-requesting families. Pooling all receiving outreach introduces sufficient bias to explain most of the differences between the two groups in the authors' Table 1. Resolution of these three faults can be made; first, separate the two different clinic populations; second, use age at receiving selected immunizations; and third, consider those families requesting outreach services separately when comparing "outreach" with "no outreach". For example, compare age distributions at administration of #3 AJPH September 1979, Vol. 69, No. 9

LETTERS TO THE EDITOR

DPT (due at age six months) in the two different styles of clinics in those requesting and receiving outreach. The same comparisons might be made for MMR (due at age 15 months), or #4 DPT (due at age 18 months). Since the main value of outreach services is to promote engagement of disadvantaged families in a complete and continuing system care,4'5 and not for immunization alone, the concept offered by the authors is of sufficient importance to justify the effort that will be required to put the effect of outreach services for disadvantage families on sound ground. Ray Hepner, MD, MPH Department ofPediatrics University of Maryland Baltimore, MD 21201

REFERENCES 1. Colombo TJ, Freeborn DK, Mullooly JP, Burnham VR: The effect of outreach workers' educational efforts on disadvantaged preschool children's use of preventive services, Am J Public Health

69:465-468, 1979. 2. Sheps MC: On the person years concept in epidemiology and demography", Milbank Mem Fund Q 44:69-91, 1966. 3. Report of the Committee on Infectious Diseases, 18th Ed. 1977, American Academy of Pediatrics, P.O. Box 1034, Evanston, IL 60204. 4. Wallace HM: Health Care of Mothers and Children in National Health Services: Implications for the United States, Ballinger, Cambridge, MA, 1975, p 54 and pp 302-308. 5. Harper PA: Preventive Pediatrics, Appleton, NY, 1962 pp 614-17 and 660. 6. The National Diet-Heart Study: Final Report, Amer Heart Assoc Monograph No. 18, New York: The American Heart Association, Inc., 1968. 7. Crocetti AF: An interview study of volunteers and nonvolunteers in a medical research project. Thesis, Dr PH School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD.

Authors' Response We appreciate Dr. Hepner's response to our outreach paper and would like to comment on his remarks. The Neighborhood Health Center families were integrated into the Kaiser-Permanente Medical Care Program and were treated as other Health Plan members. They were another benefit AJPH September 1979, Vol. 69, No. 9

group and received care in the same medical care system and in the same manner as other subscribers. To test the effect of outreach services, Neighborhood Health Center families were randomly assigned to different coordinator categories. There is no reason to assume that coordinator groups had different standards for immunizations. Although coordinators and their families were randomized, differences in age distributions could have occurred by chance. Single year age specific rates will be compared in a subsequent analysis which addresses the use of preventive services by the Neighborhood Health Center participants and the general Kaiser-Permanente Health Plan population. Use of person years as the denominator was an appropriate method of comparing average rates in the study since most of the children had full 12 months' Health Plan eligibility, and any chance imbalance in the period of eligibility would have had a small effect on the overall rates. The second point by Dr. Hepner relates to the pooling of immunization events from "special injection clinics" versus regular outpatient clinics. The use of the term "injection clinic" is misleading perhaps. Each Kaiser-Permanente outpatient facility contained an injection room. All children (including Neighborhood Health Center children) must have been seen by a KaiserPermanente pediatrician and have had a physician's order to recieve a shot or procedure from the injection room. There were no different clinics or different care givers and all coordinator categories were chosen from the Neighborhood Health Center population. The purpose of randomization was to prevent systematic bias. The final point concerns volunteering or self selection. The "on request" coordinator category contained families who were randomly assigned, as did the other groups. They had a coordinator who could be contacted or not contacted. The services we analyzed (the dependent variable) were not coordinator services but medical care contacts with Kaiser-Permanente providers. Families did not volunteer to be in a coordinator category-they were assigned randomly. The outreach program's main ob-

jectives were to help the Neighborhood Health Center families gain access to and appropriately use the medical care system. As Dr. Hepner suggests, these are valuable ends. We described the program and its general impact in an earlier article. ' Donald K. Freeborn, PhD, et al. Associate Director Health Services Research Center Kaiser-Permanente Medical Care Program, Oregon

REFERENCE 1. Freebom DK, et al: The effect of outreach workers' services on the medical care utilization of a disadvantaged population. J Community Health 3:306-320, 1978. Editor's Note: In the article by Colombo, Freeborn, Mullooly and Burnham, published in the May issue of this Joumal, there was a typographical error in their Table 2. Readers are referred to p 957, this issue, where the corrected table appears.

Is Amniocentesis a Disease Prevention Measure? In "The Growing Demand for Midtrimester Amniocentesis: A Systems Approach to Forecasting the Need for Facilities,"' Selle, et al, endorsed abortion as a method to reduce public expenditures for defective children. Without delving into the controversial moral aspects of this endorsement, I nevertheless wish to respectfully challenge the use of the phrase "disease prevention" to describe such a program. The philosophical reason why the presence of a governmental support program can be logically used by some people to justify fetal euthanasia is because the pre-birth human being is considered by them to be a "non-person." Whenever a human being is assumed to be a non-person, the utilitarian arguments used by Selle, et al, become logical incentives for making the public policy changes they discuss in their article. Even under this assumption, however, the fetus is not considered to be a non-organism, but is recognized biologically to be an individual human being. 955

Outreach and use of preventive services.

LETTERS TO THE EDITOR 1- U Letters Ito the Editor Letters are welcomed and will be published, if found suitable, as space permits. The editors res...
397KB Sizes 0 Downloads 0 Views