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JW Scientific American

JW Scientific American - AN ARTICLE FROM SCIENTIFIC...

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Unformatted text preview: AN ARTICLE FROM SCIENTIFIC AMERICAN APRIL 1982 VOL. 246 NO. Q REPRINTED NITH PERMISSION. COPYRIGHT (:) 1982 BY SCIENTIFIC AMERICAN, INC ALL RIGHTS RESERVED. I Variations in Medical Care among Small Areas The amount and cost ofhospfta/ trea (“ment 1'17 22 comm unity ha ve more to do With the number ofphysr'a’ans there, their medical speCI'altres and the procedures they prefer than With the health of the residents by John Wennberg and Alan Gittelsohn - There is a city in Maine where the surgical procedure of hysterecto~ my (removal of the uterus) was done so frequently in the past decade that if the rate persists, 70 percent of the women there will have had the opera- tion by the time they reach the age of 75. In a city less than 20 miles away the rate of hysterectomy is so much lower that if it persists, only 25 percent of the women will have lost their uterus by age 75. What could account for the disparity? It seems unlikely that there would be any large difference in the general health of the populations of the two neighboring cities, and after looking into the matter we have found none. The populations are similar in economic status. Differ‘ ences in the number of physicians, the supply of hospital beds and coverage by medical-insurance plans cannot explain the difference in the rate of surgery. In- stead the most important factor in deter- mining the rate of hysterectomy seems to be the style of medical practice of the physicians in the two cities. In one city surgeons appear to be enthusiastic about hysterectomy; in the other they appear to be skeptical of its value. We have examined the rate of surgery _ and other forms of medical treatment in 193 small areas in the six states of New England. The overall rate of sur- gery varies more than twofold among the areas. The total rate in a given area is correlated strongly with the number of surgeons there and with the number of hospital beds per capita; these are factors that themselves vary substantial- ly. The amount spent per capita on treat- ment in hospitals is also quite different from one area to the next. The rates of three of the most common surgical pro- cedures (hysterectomy, prostatectomy and tonsillectomy) vary even more dra~ matically: the highest rate is six times the lowest one. Even in communities with the same overall rate of surgery the rates of individual procedures can differ greatly. Hysterectomy, prostatec~ tomy and tonsillectomy cause much con~ 120 troversy among physicians. In the ab- sence of general agreement on their val— ue for individual patients the style of practice of the individual physician ap— pears to take precedence. The substantial variation from area to area in the consumption of medical care and in its per capita cost is sustained by the policies of hospital boards and ads ministrators, regulatory agencies and providers of medical insurance. The policies seldom take into account the ex- isting level of health care in a communiw ty; a common result is an increase in medical services in areas that already have high rates of consumption. When such inequities develop, the people re— ceiving the greater number of medical and surgical procedures do not neces- sarily benefit, particularly when the pro- cedures entail substantial risk. The 193 areas employed in our work cover the states of Connecticut, Maine, Massachusetts, New Hamp- shire, Rhode Island and Vermont. Our aim in constructing the areas was to specify the population that attends one local hospital. Except in cases of disor~ ders requiring elaborate treatment (such as cardiac surgery) people are generally treated at a nearby hospital. The atti- tude of the physicians at that hospital therefore has a strong influence on the rate of a given procedure in the sur~ rounding area. The analysis of medical care in small geographic areas has been made possi— ble by the establishment of computer- encoded records of hospital admissions in specific regions. In Maine, Rhode Is— land and Vermont there are registries that include information on each patient admitted to a hospital. The registry lists the patient’s age, sex, place of residence, diagnoses, surgical procedures, dates of admission and discharge and health on discharge. For Connecticut, Massachu- setts and New Hampshire our data on hospital admissions come from studies in which only the hospital and the pa- / tient‘s place of residence are record— ed. The expansion of health-insurance coverage, particularly the passage of the Federal Medicare Act in 1966, has yielded additional information about the medical care of specific populations. To construct the geographic areas we extracted from the records each pa- tient’s residence and the community in which treatment was received. In the records we utilized, the residence of the patient is recorded in the form of his Zip Code, minor civil division (township, for example) or census tract. For each of these small units of residence we deter— mined the community in which resi- dents are most likely to be hospitalized. All townships, census tracts and so on whose residents were most likely to go to a particular community to be treated were combined to form a hospital area. The 193 hospital areas defined in “ this way generally have populations of between 10,000 and 200,000, which is large enough for them to have stable rates of medical procedures. In almost all the areas the majority of hospital treatment is provided by facilities within the area. By counting the surgical procedures . done on the population of a hospital area in a given period, the per capita rate of surgery can be calculated. Simi- lar methods give the rate of other kinds of medical treatment. Insurance—reim' bursement rates can be calculated by totaling the reimbursements received by residents and dividing by the num— ber of residents who are members of an insurance program. The number of hospital beds per capita is also readily determined. Although the hospital areas can be em— ployed in a variety of analyses, much of our work has concerned rates of sur- gery because the information on surgi- cal procedures in regional record-keep— ing systems has been shown to be more reliable than that for other forms of treatment or for diagnosis. After adjusting for differences in age 4. among populations we have calculated the rates of hospital admission for surgi— cal procedures in the 11 most populous hospital areas in each of three states: Maine, Rhode Island and Vermont. Pro- cedures done on residents of a hospital area are counted toward the area’s total whether the operation took place within the area or outside it. Among the hospi- tal areas in each state the overall rate of surgery varies by a factor of about two. The variation in the rates of certain common procedures are more dramatic than the variation in the total. The high- est hysterectomy rate in the 33 areas (some 90 procedures per 10,000 women per year in 1975) is about four times the lowest rate. The highest rate of prosta- tectomy is also about four times the lowest rate. For tonsillectomy the high— est rate (about 60 procedures per 10,000 people per year) is six times the lowest rate. In many cases the diflerence be- tween the extreme rates for a procedure and the average rate for all the areas is statistically significant, indicating that the difference is unlikely to be a result of chance variation. Because of the wide range of rates residents of different areas face very different probabilities of having surgery. In one area of Vermont the ton- sillectomy rate from 1969 through 1971 was such that if it had persisted, 60 per- cent of all children would have had their tonsils removed by age 20. In a second Vermont area the rate was such that only 8 percent would have had their tonsils removed by age 20. In the area with fewer tonsillectomies, however, the prostatectorny rate was such that 59 percent of all men would have had their prostate gland removed by age 80. In a neighboring area only 35 percent would have had a prostatectomy by age 80. It is important to note that such large disparities in the rate of surgery are not observed for all common surgical pro— ~ cedures. The rates of cholecystectomy (surgical removal of the gallbladder) and appendectomy, for example, vary by a ratio of less than three to one. In few cases is the difference between the rate for an individual area and the aver- age rate statistically significant. The rate of herniorrhaphy (surgical repair of her- nia) varies even less, and most of the variation seems attributable to chance. The ratio of hospital beds to popula- tion and the average cost of being hospi- talized also vary greatly among New England communities. In the 11 most populous hospital areas in Vermont the highest ratio of hospital beds to popula tion is 6.8 beds per 1,000 people; the 7 lowest is 3.7. In Connecticut the highest ratio is more than four per 1,000; the lowest is less than two. (The ratios have been adjusted to compensate for resi~ dents treated outside their hespital ar- eas.) The Federal Health Planning Pro~ gram has specified four beds per 1,000 people as its standard for health-care planning; the ratios in New England thus range from well below the standard to well above it. Furthermore, the difier- ence between small areas is so great that the number of beds per capita in a state or a county (a measure often used in health planning) is not a reliable indica- tor of conditions in each community. The average reimbursement per area resident by agencies that provide medi- cal insurance is another highly variable quantity. In Bostonrthe area of Massa- chusetts with the highest rate of Medi- HOSPITAL AREAS of Vermont are small areas in which most residents go to a single hospi- tal. The hospital areas are indicated by heavy lines; boundaries between townships within an area are indicated by light lines; hospitals are indicated by circles. The six New England states have been divided into 193 hospital areas for an analysis of geographic variations in medical care. Because most care in each hospital area is provided by physicians at the local hospital the attitudes of those physicians have a large effect on rates of treatment. Although the residents of most hospital areas appear to have similar health, rates of common surgical procedures vary W, as much as sixfold from one area to another. The number of hospital beds per capita and the amount spent per capita on hospital care also vary greatly. In two areas there are two hospi- tals. In the areas without hospitals the residents receive most of their care in New Hampshire. / 121 care reimbursement, an average of $640 was paid to each person enrolled in the program in 1975. Across the Charles River in Cambridge the amount was $540. In Manchester, N.H., less than 50 miles away, it was $176. . The amount spent per capita on al treatment in hospitals is also quite in- consistent. In 1975, $324 was spent per capita in Boston; in Providence, $225 was spent. In New Haven, on the other hand, per capita expenditure was $153; in Hanover, N.H., it was $120. In all these areas the majority of admissions are to major teaching hospitals. The services provided in the hospitals are probably similar; one would not expect such a disparity in the amount spent on treatment. ' i’ Our work has shown that residents of L some areas receive much more medical treatment than others and spend more on that care. Why? One might assume that such differences are caused by bet- ter health in some communities, but this does not appear to be the case.>Surveys we made in selected hospital areas show that differences in the health of residents and in the other factors that affect the demand for medical care account for , TOWNSHIP HOSPITAL" 1 2‘ 3 4 5 , 6 7 "8 9 A 55 1,236 200 19 76 ‘4 ' s V' 1a 49 B o 82 o 16 85 826 '10 7 '13 c AND a 3 37 4 18 o 82 1,421 831 2,332 OTHER HOSPITALS 6 104 129 10 32 92 386 ' 72 ,230 GEOGRAPHIC DIVISIONS from which the 193 hospital areas were assembled included townships, census tracts and Zip Code units. Patients’ addresses and the hospitalsywhere they ‘ were treated were, taken from regional registries of hospital treatment. (Whether the town, the Zip Code or the census tract was recorded depended on the state.) For each small geographic di- vision it was determined which community the residents were most likely to go to for hospital treatment. The illustration shows nine townships whose boundaries are indicated by light lines. There are four hospitals in the townships, indicated by circles: one hospital each in townships 2 and 5 and two hospitals in township 8. The table indicates where the residents of each town- ship wcnt for hospital treatment in a single year. On the basis of this information the townships V 'were combined to form the three hospital areas whose boundaries are indicated by heavy lines. In each hospital area most of the residents are treated at hospitals in a single community. 122_ / only a small amount of the difference in the consumption of services. Ronald M. Andersen and Lu Ann Aday of the University of Chicago have listed certain characteristics that influence whether or not an individual will seek medical treatment. The most important factors are those that affect the person’s health or the perception of health. A variety of studies, however, have found that “enabling factors” such as income, health-insurance coverage and education can also have a strong effect. In addition “predisposing fac- tors" such as skepticism or faith in medi- Vcine appear to play a role. In the course of our work we have tried to determine how much of the observed difference in medical care could be explained bysuch characteristics. With Floyd J. Fowler, lid, of the University of Massachusetts at Boston we interviewed residents of six Vermont hospital areas. The residents were chosen to provide a representative sample of the local populations. The total surgery rate and the amount spent per capita on hospital treat- ment differed as much as twofold in the six areas; rates of some surgical proce— dures varied even more. The interviews, hoiivever, showed that the residents dif- fered little in the factors affecting the consumption of medical services. The average numbers of episodes of acute and chronic illness in each area were similar, as were the proportion of peo- ple with an income below the poverty level, the proportion with various kinds of health insurance and the proportion with access to a physician. Indeed, ap- proximately equal proportions Of the people in the areas visit a physician each year, as would be expected in popula- ‘ tions of similar wealth and health. The large differences in surgical rates and the amount spent on hospital care must ’therefore be’traced to factors that come into play after patients have contact with physicians. ' What is it that takes effect after the patient sees a physician to increase the patient’s chance of being hospitalized or of having surgery or a diagnostic pro- cedure? The crucial factor appears to be the system of medical care in the community. Although health and other demographic factors do not differ much among the six areas, the number of hos- pital beds and the number of physicians in proportion to the population vary widely. Moreover, the supply of hospi- tal facilities and the types of physicians who practice in the area are closely cor— related with overall consumption rates. Where there are many hospital beds per capita and many physicians whose spe- cialty or style of practice requires fre- quent hospitalization, there is more treatment in hospitals and greater ex- penditure per capita for hospital care. In hospital areas where there'are many general surgeons the surgery rate is high. The surgery rate and the rate of hospi- talization are also high in communities where a large proportion of the general practitioners do surgery. In areas where there are many internists many diagnosi- tic tests are given. ‘ That the overall rate of surgery is in— fluenced by the ratio of surgeons to pop- ulation has been known for some time. In 1970 John P. Bunker of the Stanford University School of Medicine found that the total surgery rate in the U.S. was about twice that in Britain, where there are fewer surgeons per capita. In TONSILLECTOMY RHODE ISLAND MAlNE VERMONT HYSTEFIECTOMY RHODE ISLAND MAINE VERMONT PROSTATECTOMY RHODE ISLAND MAINE VERMONT CHOLECYSTECTOMY ,RHODEISLAND MAINE VERMONT APPENDECTOMY RHODE ISLAND MAINE VEFIMONT HEFINIORRHAPHY RHODE ISLAND MAINE VERMONT 00" O 1973 a study supported by the Ameri— can College of Surgeons showed an anal- ogous relation in'regions of the U.S. The total rate of surgery and the like lihood of being admitted to a hos- , pital for treatment thus depend on the supply of physicians and hospital beds in the area. The wide variations in the rates of individual procedures, howev- er, are not caused by differences in the supply of resources alone. Our work suggests that such variations are due to differences in the style of medical prac- tice of local physicians. We examined the total surgery rate and the rate of in- dividual procedures in the five most populous hospital areas in Maine. In three of the areas the total rate is close to the average for the state, in one area the rate is above average and in one it is below average. In each area, however, a different surgical procedure is the com— monest one; all the commonest proce- dures are among those whose rates vary widely. For example, hysterectomy is the commonest procedure in one of the areas but the least common in another, o. 00:. O .0 . U... 20 30 40 50 60 7O 80 90 PROCEDURES PER 10,000 PEOPLE PER YEAR RATES OF SURGICAL PROCEDURES vary greatly among hos- pital areas. The rates shown are for the six commonest surgical pro- cedures for the repair or removal of an organ in the 11 most popu- lous hospital areas of Maine, Rhode Island and Vermont. The rate of tonsillectomy varies about sixfold among the 33 areas; the rates of hysterectomy and prostatectomy vary about fourfold. Moreover, many of the extreme rates for these procedures differ from the aver- age rate for the state by an amount that is statistically significant (col— or). There is much disagreement among physicians on the value of these procedures and the conditions for which they should be done. The rates of cholecystectomy (gallbladder removal) and appendecto- my vary less, and few of the extreme rates for these procedures differ from the state average by an amount that is statistically significant. The rate of herniorrhaphy (surgical repair of hernia) varies least. /’ . 1 ') Q TONSILLECTOMY PROBABILITY l J l l L J 30 4o 50 so 70 so AGE (YEARS) HYSTERECTOMY PROBABILITY (J I __J_ l l l O _L r | .L 50 60 70 80 O 10 20 30 40 AGE (YEARS) PROSTATECTOMY PROBABILITY Li) I o 10 20 so 40 50 ‘ AGE (YEARS) PROBABILITY OF HAVING SURGERY in 11 Vermont hospital areas has a wide range of variation as a result or the differences in surgical rates. In each graph the lines indicate the frac- tion of the population that would have had the procedure if the rates of surgery prevailing in about 1970 had persisted. The top line is for the area with the highest rate of the 11. The mid- dle line is based on the average rate for the state. The bottom line is for the area with the lowest rate. In one hospital area 60 percent of all children will have had their tonsils removed by age 20, whereas in another area fewer than 10 percent will have a tonsillectomy by that age. The fractions that will haV‘e had hysterectomy and prostatectomy also Show substantial differences. / 124. although the two areas have the same overall rate of surgery. In each of the five areas of Maine the rates of common surgical procedures constitute a “surgical signature” that tends to be consistent over many years, unless physicians leave the area or enter it. In each signature the rates of some procedures ex...
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