Growth and hematological changes in the Eskimo children of Wainwright, Alaska: 1968 to

Transcription

1 Growth and hematological changes in the Eskimo children of Wainwright, Alaska: 1968 to Kenneth M Petersen, MD and Larry J Brant, PhD Introduction ABSTRACT The growth and hematological status ofall 152 Eskimo children of Wainwright, AK observed in 1977 are reported and compared with the respective status ofthe children living there in Fifty-two children (34%) in the 1977 study were also in the 1968 study. Comparison of height data observed in 1977 with those observed in 1968 reveals that male children less than 1 1 yr of age and female children ages 3 to 9 yr showed a significant improvement in stature (p <.5). At the same time, an improvement in nutrition was observed among the children in 1977 as evidenced by the marked decrease in anemia for children under 6 yr (p <. 1). These changes in growth and hematological status have occurred during a time in which health services were improved, a supplemental nutrition program was instituted, and subsistence food gathering remained high. These changes underscore the contribution of environmental factors rather than of genetic variability to the growth potential of these children. Am J Clin Nuir 1984;39: KEY WORDS Anthropometry, child health services, diet, Eskimos, hemoglobin, nutrition, subsistence Many investigators have noted the smaller stature of the Alaskan Eskimo as compared to a reference North American white population (1-3). This difference might be due to genetic or environmental differences, nutritional deprivation, deficient primary health care, or a combination of these or other factors. Ifthere were only genetic differences to account for the smaller stature of the Eskimo, then one would not expect to find a difference in statures between two cohorts of Eskimo children from a stable, isolated, and homogeneous village collected at two time intervals roughly 1 yr apart. The purpose of this study is to test whether there are any differences in growth and nutritional status between two cohorts of Eskimo children observed in 1968 and Wainwright is a village of 375 Inupiat Eskimos located on the Arctic Ocean about 3 miles north of the Arctic Circle. The Wainwright Eskimos still maintain a lifestyle heavily dependent on subsistence hunting for a substantial portion of their diet. In 1968, as part of the United States participation in the International Biological Program s study of circumpolar peoples, the growth and nutrition of children in Wainwright, AK were assessed (4). An important finding was the anemia found in children less than 6 yr of age (5, 6). Also children in that same age group were of notably smaller stature than the North American reference population (6). A subsequent preliminary review of the village health records in 1977 (Petersen KM, unpublished observations) suggested that anemia and decreased stature in children under 6 yr old was not as preyalent as had been reported in the 1968 study. In 1968 the Community Health Aide Program (7) was established providing primary health care on a daily basis. Because most Alaskan Eskimos live in small, isolated yillages where there are few or no physicians, I From the Pediatric Service, Alaska Native Medical Center, Public Health Service, US Department of Health and Human Services, Anchorage, AK 9951, and Human Performance Section, Gerontology Research Center, National Institute on Aging, National Institutes of Health, Baltimore, MD Address reprint requests to: Larry J Brant, PhD, Longitudinal Program, Gerontology Research Center, Baltimore City Hospitals, Baltimore, MD Received April 2l, Accepted for publication October 4, The American Journal of Clinical Nutrition 39: MARCH 1984, pp Printed in U.S.A American Society for Clinical Nutrition

2 community health aides have been trained as substitute physicians using radio or satellite communication to confer with a hospital-based physician. In addition to managing serious medical problems, the community health aide delivers health education and other preventive services. In this study we report on the height, weight, and Hb measurements of the Wainwright children collected during 1977 and compare these results with corresponding measurements taken in Materials and methods In 1977 height, weight, and Hb determinations were obtained on all ofthe children ofwainwright, AK. The study includes single observations on 152 children (81 males and 7 1 females) ranging in age from 1 month to I 7 yr. The heights were obtained in stocking feet and the weights in underclothes. Hb concentrations were determined from fingerstick blood samples by the cyanmethemoglobin method using a portable instrument with a flow cell and a fixed-wavelength (54 nm) lightemitting diode (Royco Model 72-A Hemoglobinometer, Royco Instruments Inc. Menlo Park, CA). All Hb concentrations were determined by one investigator and the coefficient ofvariation for this determination under field conditions averaged 1.3%. This variation was within the guidelines set by the College of American Pathologists (8). Height and weight measurements were obtained in a similar fashion in 1968 and were made available for this study by Dr Paul Jamison. Hb values measured by a comparable method (9)during the earlier study were supplied by Dr HE Sauberlich. Hb values for children in each study were compared to a reference standard ( 1). The resulting percentiles for 1968 and 1977 were tested for significance using a comparison of two proportions ( 1 1). Comparisons of the height and weight data collected in the 2 study yr were made using a reference population as recommended by Waterlow et al (12). Heights and weights for both years were converted to percentiles using the 1976 National Center for Health Statistics (NCHS) growth data (13). Sex-specific height and weight comparisons for the 2 study yr were made using a linear regression with age as the independent variable. The regressions were performed using a probit transformation in order to linearize the percentiles by extending the ends of the scale of the percentiles more than the middle ( 1 1). Moreover, this probit transformation has the effect of regaining the homogeneity of variances which was lost when height and weight measurements were converted to NCHS percentiles. C. For each sex, height, and weight grouping, the difference between the predicted regression equations for 1977 and 1968 was calculated along with SE of the difference (11). Each difference and the SE of that difference were used to calculate the corresponding 95% lower confidence limit which is referred to as the 95% confidence line. All predicted values on the 1977 line which lie above the 95% confidence line were consid- GROWTH AND HEMATOLOGICAL CHANGE IN ESKIMOS 461 ered significantly greater than the corresponding predicted values on the 1968 line. Results Information on mean heights and weights along with SD are given for the 8 1 male and 7 1 female children ages 1 month through 17 yr in Table 1. Following the recommendations of Waterlow et al (12), each of the individual 1977 height and weight measurements summarized in Table 1 was converted to percentiles using the 1976 NCHS growth data. In order to make height and weight growth comparisons between the 1977 and 1968 Wainwright children, the 1968 Wainwright growth observations were also converted to percentiles of the 1976 NCHS growth data. Height Figures 1 and 2 show the linear regressions of height percentile on age for male and female children, respectively, measured in 1968 and In 1977 there was a significant negative correlation between height percentile and age for males (p <.1) and females (p <. 1). The younger the child, the greater the height percentile. No such correlation was found for either sex in Figure 1 also shows the 95% confidence line for measuring the male cross-sectional growth differences between 1968 and Percentiles on the 1977 regression line for all ages less than 1.8 yr lie above this confidence line and thus are significantly greater than the corresponding percentiles on the 1968 regression line. For example, comparison of the 1977 height percentiles with the confidence line reveals that the stature of 1- to 2-yr-old males in 1977 exceeded 1- to 2- yr-old males in 1968 by approximately 25% while only an increase of 15% was required for significance (p.5). Similarly, Figure 2 shows the corresponding 95% confidence line for measuring female growth improvement. Comparison ofthe 1977 female height percentiles with the confidence line reveals that a significant cross-sectional growth improvement occurred between the ages of 3.2 and 9.1 yr (p.5). The 1977 females at age 6 yr, for example, were 11.5% greater in stature than the stature for the corresponding 1968 females.

3 462 PETERSEN AND BRANT TABLE I Characteristics of Wainwright, AK children in 1977 by age and sex: number, body ht (cm), and wt (kg) Li. LU Age is Male children Female children n Hi (mean ± SD) Wi (mean ± SD) n Hi (mean ± SD) Wi (mean ± SD) < ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±.6 S ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± Y X r-.37 p.cl , O I LU (2 LU Y X I r--.9 p AGE (years) FIG 1. Regressions of percentile heights versus age for males in 1968 and All points on the 1977 line for ages less than 1.8 yr (arrow) lie above the 95% confidence line and thus are significantly greater than the corresponding points on the 1968 line. Weigh! An analysis similar to that done for the height data was also done for the weight data. Figures 3 and 4 show the linear regressions of weight percentile on age for male and female children, respectively, measured in 1968 and A significant negative correlation between weight percentile and age was found for males (p <.1) and females (p <.5) in 1977, and to a lesser degree (p <.5) for both sexes in LINE U) z Li. w LU Y X r-o.35 p< AGE (years) FIG 2. Regressions of percentile heights versus age for females in 1968 and All points on the 1977 line between the ages 3.2 and 9. 1 yr (arrows) lie above the 95% confidence line and thus are significantly greater than the corresponding points on the 1968 line. The younger the child the greater the weight percentile in both 1968 and The difference between 1977 and 1968 predicted growth equations for each sex indicated no significajfl growth change represented by weight si #{241}ce the 95% confidence lines for both males (Fig 3) and females (Fig 4) exceeds the percentiles on the 1977 regression lines at all ages. Hb Table 2 gives the mean and SD of the hemoglobin concentrations at each age for LINE

4 GROWTH AND HEMATOLOGICAL CHANGE IN ESKIMOS 463 ir Y-M X TABLE 2 Hb concentrations (g/dl) of Wainwright children, 1977 Li ) L)z 8 Age Hb concentration Male (mean ± SD) Female (mean ± SD) I- C..) Y X r-24 p(oa AGE (years) FIG 3. Regressions of percentile weights versus age for males in 1968 and No points on the 1977 line lie above the 95% confidence line and thus none is significantly greater than the corresponding points on the 1968 line. C,) C.) z I- z C..) ns-i nx -.-isii l s <I 11.6± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±.9 12.* ± ± ± ± ±.6 13.± ± ± ± ± ± ± ± * * * Single observation. age group had a Hb below the lower limit (p <.1). Discussion Growth and nutritional changes in an in- Y-74O-1 digenous population of Eskimo children r--th p<o were examined by comparing height, weight, and Hb measurements taken in 1968 and again in Reference populations rep- resenting other North American children I I I ;, I I I I I I I were used in making these comparisons. For AG the height and weight data, measurements E years) were expressed as percentiles ofthe reference FIG 4. Regressions of percentile weights versus age population before doing a regression of the for females in 1968 and No points on the 1977 line lie above the 95% confidence line and thus none is percentiles versus age. Because of the small significantly greater than the corresponding points on number of children at some of the ages in the 1968 line. one or both study years, comparisons of the means at every age were not meaningful the male and female children in Wainwright, and/or impossible. Use of linear regression Hb concentrations determined in each was advantageous because it made possible of the study years were compared to the the comparison of the height and weight distribution of the Hb concentrations of the measurements between 1977 and Dallman and Siimes (1) reference popula- Height is one of the most important intion. Dallman and Siimes (1) reported a dices of nutritional status (12), as is Hb median Hb of 12.5 g/dl and a lower limit concentration, particularly in populations (3rd percentile) of 1 1. g/dl for children ages such as the Eskimos which do not have 6 months to 5 yr. In 1968, 2 of 33 Wain- reported hereditary anemias such as thalaswright children in this age group had a Hb semia minor. When the height percentiles of concentration below 11. g/dl, while in Wainwright Eskimo children in 1977 were 1977, only seven of 39 children in the same compared with those in 1968 (Fig 1 and 2),

5 464 PETERSEN AND BRANT a significant improvement was found in the stature of male children less than 1.8 yr of age and in the stature of female children between 3.2 and 9. 1 yr of age. Anemia was also found to be much less prevalent in 1977 than in 1968 for children under 6 yr. Fifty-two ofthe 152 children in the 1977 study were also in the 1968 study. Comparison of height and weight percentiles for these children revealed that they had approximately the same NCHS percentile in both years. This also can be seen in the case of height on close examination of Figures 1 and 2. The greater height percentiles of younger children and the smaller height percentiles of older children in the most recent survey results in the significant negative correlation between height and age found for both males and females in This negative correlation and the relative similarity of the height percentiles regardless of age for 1968 helps explain the convergence of the two lines at the oldest ages. Measurements collected on children in both study years represent information potentially useful in future longitudinal studies. What has occurred over the past decade in this north coast village that might account for the apparent improvement in the growth and nutritional status of these children? Some might argue that the increase in stature of the younger children in 1977 over their counterparts in 1968 may be due to non-eskimo genetic admixture (2). However, there has been no appreciable change in the genealogy of Wainwright people since approximately 19 when some hybridization occurred through marriage with white whalers ( 14). Between the 1968 and 1977 studies, the population of Wainwright increased from 38 to 375 Eskimos. During the same period the number of households increased from 52 to 81 with a net effect of decreasing the average number of persons per household by one. During the years between the two studies, health care and preventive health activities became more available. In 1968 the Community Health Aide Program became established, enabling placement of salaried, trained health care providers in each village. One emphasis of this program is the early recognition and treatment ofanemia. In addition, the community health aide provides family planning, prenatal care and well child care. Beginning in 1974, the community health aide in Wainwright provided education in nutrition and assisted in the operation of a supplemental food program for pregnant and lactating women, infants, and children. Certainly an important factor in evaluating nutritional changes is the food supply. The general diet of the Wainwright villagers is comprised chiefly of the food obtained by subsistance activities or purchased from the village cooperative store. Most of the food stocked by the store is delivered once a year by barge when ice conditions allow. No important changes in the type or amount of nutrients contained in the foods received by the store were discovered upon study of the store s inventory in 1968 and With regards to carbohydrates, for example, the apparent decrease in the consumption of flour and sugar is offset by the increased supplies of prepared foods and the marked increase in consumption of sweetened beverages. Subsistence meat supplies were very important in both study years with 85% of the households obtaining more than half of their food from subsistence activities of hunting, fishing, and gathering and only 2% primarily dependent on the store for meat ( 15). In 1968 approximately 225, lb of caribou, the primary source of meat, were used by the village (1 5). There are not similar comparison figures for 1977, but we do know that 87% of households identified caribou as the primary (6%) or secondary (27%) source of meat (1 5). In both study years two bowhead whales were taken representing about 5, lb of meat for the community. The importance ofthis population s subsistence lifestyle to their general diet thus appears to have remained comparable between 1968 and The subsistence food supply may, however, have changed since In 1977 there were significant threats to subsistence hunting. The International Whaling Commission temporarily banned all bowhead hunting. When hunting resumed it was restricted. The Arctic caribou herd which numbered

6 GROWTH AND HEMATOLOGICAL CHANGE IN ESKIMOS , in 197 diminished to 6, by 1976 ( 16). These food supply changes could have a deleterious effect on the nutrition of the children, since shifts in subsistence patterns are frequently accompanied by a deterioration in health. Environmental changes such as these, and potential decreases in future supplemental nutrition programs, make the ongoing comparison of growth and nutritional changes presented here important. Conclusions A change has occurred in the growth pattern of Eskimo children in the arctic village ofwainwright, AK between 1968 and The stature of young children has increased. There has been a concomitant reduction of anemia in the same group. Since there has been no new genetic admixture, these changes likely reflect the improved availability of primary and preventive health care and the improved living conditions. These changes may also be due to the addition of a supplemental food program in a community that continues to have a relatively undisturbed subsistence food supply. El The authors thank Robert Burgess, MD, Thomas Bender, MD, and Thomas Bellinger for their assistance in clinical evaluations and data analysis. We also thank Alan Sorkin, PhD and Jordan Tobin, MD for assistance in preparing this manuscript. References 1. Heller CA, Scott EM, Hammes LM. Height, weight, and growth of Alaskan Eskimos. Am J Dis Child l967;l 13: Jamison PL. Growth of Wainwright Eskimos: stature and weight. Arctic Anthropol 197;7: Maynard JE, Hammes LM. A study of growth, morbidity and mortality among Eskimo infants of western Alaska. Bull WHO l97;42: International study of circumpolar peoples, US participation in the international biological program. In: Report no 6 of the US National Committee for the International Biological Program. Washington, DC: National Academy of Sciences, 1974: Sauberlich HE, Goad W, Herman YF, Milan F, Jamison P. Preliminary report on the nutrition survey conducted among the Eskimos of Wainwright, Alaska, January 21-27, Arctic Anthropol l97;7: Sauberlich HE, Goad W, Herman YF, Milan F, Jamison P. Biochemical assessment of the nutritional status ofthe Eskimos ofwainwright, Alaska, Am J Clin Nutr 1972;25: Johnson W. The Alaska community health aide program. In: Proceedings 3th Alaska science conference. Fairbanks, AK: American Association for the Advancement of Science, Alaska Division and American Chemical Society, 1979:12(abstr). 8. Koepke JA. Interlaboratory trials: the quality control survey programme ofthe College of American Pathologists. In: Lewis SM, Coster JF, eds. Quality control in haematology. London: Academic Press, 1975: Interdepartmental committee on nutrition for national defense. Manual for nutrition surveys. 2nd ed. Washington, DC: US Government Printing Office, Dallman PR, Siimes MA. Percentile curves for hemoglobin and red cell volume in infancy and childhood. J Pediatr l979;94: Armitage P. Statistical methods in medical research. Oxford: Blackwell Scientific Publications, Waterlow JC, Buzino R, Keller W, Lane JM, Nichaman MZ, Tanner JM. The presentation and use of height and weight data for comparing the nutritional status ofgroups ofchildren under the age of 1 years. Bull WHO l977;55: National Center for Health Statistics: NCHS growth charts, Monthly vital statistics report. Health examination survey data. Washington, DC: United States Department of Health, Education and Welfare, Public Health Service (Health Resources Administration) ;25:(suppl 1-22). 14. Milan FA. The demography of an Alaskan Eskimo village. Arctic Anthropol l97;7: Peterson WJ. A study of the effect of the limit on bowhead whale taken by Eskimos of Arctic Alaska. Washington, DC: US Department of the Interior, Bureau of Indian Affairs, May Wood G. Where have all the caribou gone. Alaska Conserv Rev l977;l7:6-7.