THE USE OF ARM CIRCUMFERENCE FOR SIMPLIFIED SCREENING FOR MALNUTRITION BY MINIMALLY TRAINED HEALTH WORKERS

Because of its simplicity and low cost, arm circumference (AC) is being used increasingly in screening for protein energy malnutrition among pre-school children in many parts of the developing world, especially where minimally trained health workers are employed. The objectives of this study were as follows: (1) To determine the relationship of the AC measure with weight for age and weight for height in the detection of malnutrition among pre-school children in a Guatemalan Indian village. (2) To determine the performance of minimally trained promoters under field conditions in measuring AC, weight and height. (3) To describe the practical aspects of taking AC measures versus weight, age and height.^ The study was conducted in San Pablo La Laguna, one of four villages situated on the shores of Lake Atitlan, Guatemala, in which a program of simplified medical care was implemented by the Institute for Nutrition for Central America and Panama (INCAP). Weight, height, AC and age data were collected for 144 chronically malnourished children. The measurements obtained by the trained investigator under the controlled conditions of the health post were correlated against one another and AC was found to have a correlation with weight for age of 0.7127 and with weight for height of 0.7911, both well within the 0.65 to 0.80 range reported in the literature. False positive and false negative analysis showed that AC was more sensitive when compared with weight for height than with weight for age. This was fortunate since, especially in areas with widespread chronic malnutrition, weight for height detects those acute cases in immediate danger of complicating illness or death. Moreover, most of the cases identified as malnourished by AC, but not by weight for height (false positives), were either young or very stunted which made their selection by AC better than weight for height. The large number of cases detected by weight for age, but not by AC (false negative rate--40%) were, however, mostly beyond the critical age period and had normal weight for heights.^ The performance of AC, weight for height and weight for age under field conditions in the hands of minimally trained health workers was also analyzed by correlating these measurements against the same criterion measurements taken under ideally controlled conditions of the health post. AC had the highest correlation with itself indicating that it deteriorated the least in the move to the field. Moreover, there was a high correlation between AC in the field and criterion weight for height (0.7509); this correlation was almost as high as that for field weight for height versus the same measure in the health post (0.7588). The implication is that field errors are so great for the compounded weight for height variable that, in the field, AC is about as good a predictor of the ideal weight for height measure.^ Minimally trained health workers made more errors than the investigator as exemplified by their lower intra-observer correlation coefficients. They consistently measured larger than the investigator for all measures. Also there was a great deal of variability between these minimally trained workers indicating that careful training and followup is necessary for the success of the AC measure.^ AC has many practical advantages compared to the other anthropometric tools. It does not require age data, which are often unreliable in these settings, and does not require sophisticated subtraction and two dimensional table-handling skills that weight for age and weight for height require. The measure is also more easily applied with less disturbance to the child and the community. The AC tape is cheap and not easily damaged or jarred out of calibration while being transported in rugged settings, as is often the case with weight scales. Moreover, it can be kept in a health worker's pocket at all times for continual use in a widespread range of settings. ^

False -positives and false-negatives in tests for trend

False-positive and false-negative values were calculated for five different designs of the trend test and it was demonstrated that a design suggested by Portier and Hoel in 1984 for a different problem produced the lowest false-positive and false-negative rates when applied to historical spontaneous tumor rate data for Fischer Rats. ^

Humoral immunity in tuberculin skin test anergy and its role in high-risk persons exposed to active tuberculosis.

The most common test to identify latent tuberculosis is the tuberculin skin test that detects T cell responses of delayed type hypersensitivity type IV. Since it produces false negative reactions in active tuberculosis or in high-risk persons exposed to tuberculosis patients as shown in this report, we studied antibody profiles to explain the anergy of such responses in high-risk individuals without active infection. Our results showed that humoral immunity against tuberculin, regardless of the result of the tuberculin skin test is important for protection from active tuberculosis and that the presence of high antibody titers is a more reliable indicator of infection latency suggesting that latency can be based on the levels of antibodies together with in vitro proliferation of peripheral blood mononuclear cells in the presence of the purified protein derivative. Importantly, anti-tuberculin IgG antibody levels mediate the anergy described herein, which could also prevent reactivation of disease in high-risk individuals with high antibody titers. Such anti-tuberculin IgG antibodies were also found associated with blocking and/or stimulation of in vitro cultures of PBMC with tuberculin. In this regard, future studies need to establish if immune responses to Mycobacterium tuberculosis can generate a broad spectrum of reactions either toward Th1 responses favoring stimulation by cytokines or by antibodies and those toward diminished responses by Th2 cytokines or blocking by antibodies; possibly involving mechanisms of antibody dependent protection from Mtb by different subclasses of IgG.

A STUDY TO INVESTIGATE DIET DIVERSITY AS A NUTRITION ASSESSMENT INSTRUMENT

Nutrient intake and specific food item data from 24-hour dietary recalls were utilized to study the relationship between measures of diet diversity and dietary adequacy in a population of white females of child-bearing age and socioeconomic subgroups of that population. As the basis of the diet diversity measures, twelve food groups were constructed from the 24-hour recall data and the number of unique foods per food group counted and weighted according to specified weighting schemes. Utilizing these food groups, nine diet diversity indices were developed.^ Sensitivity/specificity analysis was used to determine the ability of varying levels of selected diet diversity indices to identify individuals above and below preselected intakes of different nutrients. The true prevalence proportions, sensitivity and specificity, false positive and false negative rates, and positive predictive values observed at the selected levels of diet diversity indices were investigated in relation to the objectives and resources of a variety of nutrition improvement programs. Diet diversity indices constructed from the total population data were evaluated as screening tools for respondent nutrient intakes in each of the socioeconomic subgroups as well.^ The results of the sensitivity/specificity analysis demonstrated that the false positive rate, the false negative rate, or both were too high at each diversity cut-off level to validate the widespread use of any of the diversity indices in the dietary assessment of the study population. Although diet diversity has been shown to be highly correlated with the intakes of a number of nutrients, the diet diversity indices constructed in this study did not adequately represent nutrient intakes in the diet as reported, in this study, intakes as reported in the 24-hour dietary recall. Specific cut-off levels of selected diversity indices might have limited application in some nutrition programs. The results were applicable to the sensitivity/specificity analyses in the socioeconomic subgroups as well as in the total population. ^