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Growth-faltering rates in California, Guatemala, and Tamil Nadu: Implications for growth-monitoring programmes
Reynaldo Martorell and Meera Shekar
Our objective was to compare rates of growth faltering in developed and developing countries. To this end, data from the Berkeley guidance study were compared with data for Guatemala and Tamil Nadu. An objection might be raised because the subjects from Berkeley were born in 1928 and 1929. Any infections that may have occurred in these children would have been treated symptomatically, because no effective antibacterial drugs existed at the time. Vaccines (e.g., for measles) were also not available. Whereas this suggests that growth faltering might be less common in Berkeley today than it was in 1928, there are other considerations to the contrary. These children were taller than the WHO/NCHS median, and as adults they were taller than today's average for the United States and as tall as northern Europeans. This is not surprising since the subjects were from an affluent university community. Clearly, the Berkeley population cannot be considered to have been constrained in physical growth in an important way. They grew faster than the Fels Research Institute sample (1928-1978), which is the basis for the WHO/NCHS reference curves for young children. Another important observation is that increments in the Fels data set did not change over the 50 years of data collection [18]. Perhaps growth is nearly the same in well-to-do children in Berkeley today as it was in 1928. Another potential objection is that both the Guatemalan and Tamil Nadu populations were benefiting from nutrition and health interventions. Undoubtedly, other populations lacking these services might show even greater rates of growth faltering. These potential objections do not undermine the present study. Choosing well-to-do samples with somewhat less growth faltering and malnourished samples with more growth faltering would not alter the general nature of our observations and conclusions.
One interesting aspect of the results is that, when the growth-faltering criteria that are used in Tamil Nadu to select children for supplementary feeding are applied to the subjects from Berkeley, we find that a significant percentage of them would have been selected. From 12 to 24 months of age, 17% of the children in Berkeley had at least one episode of faltering, using the criterion of a gain of 0 g or less over three months. All of these children would have been admitted to feeding in Tamil Nadu. Some 36.8% of them would have been placed at risk because they had at least one period when they gained less than 300 g, and would have been admitted to feeding if the next monthly weighing also indicated a similarly limited gain. However, the data are not available to check how many ultimately would have been chosen for supplementary feeding.
These findings do not invalidate the use of growth monitoring to select children for intervention in developing countries. The rates of faltering were considerably higher in Guatemala and Tamil Nadu. For example, the percentage of children with at least one period with failure to gain weight (<= 0 g) was 45.4% in Guatemala and 42.0% in Tamil Nadu, compared with 17.6% in Berkeley. When the criterion of a gain of less than 300 g is used, the majority of the subjects in Guatemala (82.4%) and Tamil Nadu (73.3%) were found to falter at least once, compared with 36.8% in Berkeley.
Some of the children in well-to-do populations who falter according to the criteria given are probably constrained in their growth by infections and dietary problems, among other factors. Paediatricians in industrialized societies should continue to monitor growth for the same reasons as in developing countries—to identify such children, to assess the possible reasons for their faltering growth, and to recommend appropriate actions. On the other hand, some children may have been classified as faltering because of measurement factors: actual measurement error or day-to-day variation (e.g., differences in weight caused by hydration levels, micturition, and defecation). Still another possibility is that growth may not be linear; healthy children may grow in spurts rather than continuously [19]. In other words, some sporadic growth faltering may have no functional implications, suggesting that, like any diagnostic tool, growth monitoring, as applied in Tamil Nadu, probably picks up a number of false positives.
Ultimately, programme planners must take the availability of resources into account in deciding what percentage of the population can be targeted for special attention or intervention. The application of either of the criteria discussed—weight gain of less than 300 g or of 0 g or less over three months during the second year of life—to Tamil Nadu and Guatemala identifies very large percentages of the population; for many settings, tending to the needs of so many would overwhelm resources. On the other hand, the TINP, an exceptionally well-planned and well-staffed programme, has applied these criteria successfully for many years [14].
Even if one is interested in growth monitoring only as an educational tool for promoting better child care, one should be concerned about a criterion that identifies too many in the population. If the instrument is too all-inclusive, there is little justification for its use, particularly if it requires considerable time and resources to apply.
Age should be considered as a targeting criterion. There is a consensus that growth retardation in developing countries is limited to the first two years of life in most populations and up to three years in others [20]. Monitoring the weight of children older than three years would appear to be of less priority in societies where this pattern of growth retardation applies. Therefore, focusing on children under the age of three years may be one way of decreasing the burden of growth monitoring. In addition, a means of identifying the most needy young children may be required, growth monitoring being one possibility.
In summary, the results indicate that commonly used criteria to define growth faltering in developing countries also identify a significant portion of children in developed societies; however, the proportion is two to three times greater in developing countries. Programmes in developing countries should consider selecting criteria that identify only that portion of the population that can be effectively handled. This necessarily implies departing from the simplest guidelines about the trajectory of the growth curve (i.e., whether it is going up, flat, or going down) and using instead guidelines that specify rates of weight gain at different ages, and this may make growth monitoring impractical in many settings.
This study was funded by grant HD22440 from the US National Institutes of Health and grant 9202716-000 from the Pew Charitable Trusts.
Useful comments and suggestions were given by E. Frongillo, M. Latham, D. Pelletier, and M. Ruel.