Site specific osteoarthritis and the index to ring finger length ratio

OBJECTIVE

To quantify the relationship between the index to ring finger length ratio second digit:fourth digit(2D:4D) and radiographic osteoarthritis (OA) of the knee.

METHODS

Data from the Clearwater Osteoarthritis Study (COS) were analyzed. We selected a random sample of 236 subjects with knee OA (Kellgren-Lawrence scores >or=2) and compared their finger length ratio pattern with a random sample of 242 controls. Finger length measurements were recorded from digitized hand radiographs. Subjects were classified into three groups: type 1 (index finger longer than ring finger), type 2 (fingers of equal length) and type 3 (index finger shorter than ring finger). Using a case-control design, we calculated odds ratios (OR).

RESULTS

The type 3 finger pattern was significantly associated with knee OA (OR 2.59, 95% confidence interval (CI) 1.54-4.37). Women demonstrated a stronger association of visual type 3 finger pattern and knee OA (OR 4.40, 95% CI 2.62-7.38) compared to men (OR 2.59, 95% CI 1.34-5.00).

CONCLUSIONS

The type 3 finger length pattern is associated, to a statistically significant degree, with OA of the knee. The type 3 finger length pattern (ring finger longer than index finger) appears to be an indicator of OA predisposition. Consideration of this pattern in clinical assessments may be an added aid as clinicians screen patients for OA risk.

Body mass index growth in a sample of U.S. children: repeated measures data analysis of the Minneapolis Children's Blood Pressure Study

Longitudinal assessments of the body mass index (BMI) in children and adolescents are limited. The purpose of the study was to describe the growth patterns of the BMI in children and young adults. Black and White children of Minneapolis Children's Blood Pressure Study (MCBPS) were 6 to 9 years old at entry and were followed for 12 years at 19 separate visits. Those with at least five visits (n = 1,302) were included for analysis, using non-linear mixed effects models in conjunction with the Gompertz curve. The growth patterns of four sex-ethnic groups were different at three levels: starting level (SL) (kg/m(2)), asymptote level (AL) (kg/m(2)), and peak growth age (PGA) (in years). In this context, SL is the average BMI level at age 6, AL is the average BMI level when growth diminishes, and PGA is the average age at which the rate of growth in the BMI peaks. The SL (16.3 +/- 0.1) for White males was significantly greater than SL in the other three sex-ethnic groups, among which there were no significant differences. There was a significant ethnic difference in AL between Black females (25.5 +/- 0.3) and White females (24.4 +/- 0.2) and a marginally significant difference in AL between Black females and Black males (24.4 +/- 0.3). For PGA, only sex differences were significant: Black females reached the peak at the earliest age at (11.5 +/- 0.1) years, followed by White females (11.7 +/- 0.1), Black males (12.6 +/- 0.1), and White males (12.8 +/- 0.1).

Regional patterns in the incidence of aplastic anemia in Thailand. The Aplastic Anemia Study Group

The annual incidence of aplastic anemia has been determined in a rigorous and standardized epidemiologic study conducted in Thailand. A total of 374 cases were identified over a period of 3-6 years in three geographically defined and distinct regions of the country; Bangkok, Khonkaen in the northeast, and Songkla in the south. The incidence was 3.9 cases per million persons in Bangkok, 3.0 per million in Songkla, and 5.0 per million in Khonkaen. These rates are as high or higher than in any region of Europe or Israel as reported in the International Agranulocytosis and Aplastic Anemia Study, in which the methods and case definition were the same. Rates were stable over the course of the study. There were marked differences in incidence between northern and southern rural regions of Thailand, and among Bangkok suburbs. These differences, together with an unusual peak in the incidence among young people in Bangkok, suggest the possibility of occupational and environmental factors in the etiology of aplastic anemia.

Agranulocytosis in Bangkok, Thailand: a predominantly drug-induced disease with an unusually low incidence. Aplastic Anemia Study Group

Agranulocytosis, a syndrome characterized by a marked reduction in circulating granulocytes, is strongly associated with medical drug use in Europe and the United States. Unregulated use of common pharmaceutical agents in developing countries has been suspected of causing large numbers of cases of agranulocytosis and deaths, especially among children. To elucidate the incidence and etiology of agranulocytosis in Thailand, a population-based case-control study of symptomatic agranulocytosis that resulted in hospital admission was conducted in Bangkok from 1990 to 1994. An attempt was also made to study the disease in Khonkaen (in northeastern Thailand) and Songkla (in southern Thailand), but there were insufficient cases in the latter regions, and the analysis was confined to subjects from Bangkok. In that region, the overall incidence of agranulocytosis was 0.8 per million per year; there were no deaths. As expected, the incidence was higher in females (0.9 per million), and it increased with age (4.3 per million beyond age 60). Among 25 cases and 529 controls the relative risk estimate for a combined category of all suspect drugs was 9.2 (95% confidence interval = 3.9-21), and the proportion of cases that could be attributed to drug use was 68%. For individual drugs and drug classes the data were sparse; within these limitations, the strongest association appeared to be with antithyroid drugs. One case and three controls were exposed to dipyrone, a drug known to cause agranulocytosis; with such scanty data the risk could not be evaluated. Exposure to pesticides or solvents was not associated with an increased risk. This is the first formal epidemiologic study of agranulocytosis in a developing country. As in the West, most cases are attributable to medical drug use. However, the incidence of agranulocytosis in Bangkok, and apparently, in Thailand as a whole, is unusually low, and the disease does not pose a public health risk.

Evaluation of the accuracy of on-site multi-analyte drug testing devices in the determination of the prevalence of illicit drugs in drivers

A principal goal of this research was to conduct a field evaluation of "on-site" multi-analyte drug testing devices to determine the most accurate, efficient, and cost-effective device available for the purpose of rapidly detecting drivers under the influence of drugs. Four on-site kits were selected and evaluated for accuracy and efficiency for the detection of tetrahydrocannabinol (THC), the cocaine metabolites (COC), and opiates (OPI). From 16 December 1995 to 17 March 1996, 303 voluntary urine specimens were collected by law enforcement officers from persons arrested for driving-under-the-influence (DUI). These specimens were tested using the four selected kits and aliquots of the specimens were sent to a DHHS certified lab for "gold standard" comparison testing by immunoassay and Gas Chromatography/Mass Spectrometry. On-site kit sensitivity ranged from 82.9% to 100% for THC, 82.5% to 100% for COC, and all were at 100% for OPI. Specificity, and positive and negative predictive values were also determined. Accuracy ranged from 94.0% to 98.3% for THC, 97.4% to 98.0% for COC, and 99.7% to 100% for OPI. All four kits were in very close agreement on prevalence: 15.5% to 15.8% for THC, all were at 13.2% for COC, and all were at 0.7% for OPI. For law enforcement purposes, sensitivity may be the most important indicator in these kits.

Use of household pesticides and the risk of aplastic anaemia in Thailand. The Aplastic Anemia Study Group

BACKGROUND

Aplastic anaemia is a severe blood dyscrasia that is more common in Thailand than in Western countries. Its a etiology remains poorly understood.

METHODS

A case-control study was conducted in Bangkok and two rural regions of Thailand. The effect of household pesticides was evaluated among 253 incident cases of aplastic anaemia and 1174 hospital controls.

RESULTS

A total of 54% of the cases and 61% of the controls were exposed 1-6 months previously. For most individual household pesticides and for groups classified according to chemical type (organophosphates, pyrethrins, and organochlorines), the relative risk (RR) estimates approximated 1.0; upper 95% confidence limits were below 2.0 for many comparisons. A significant association was observed for exposure to combination products containing dichlorvos and propoxur, with an overall RR estimate of 1.7 (95% confidence interval [CI]: 1.1-2.6); the estimate for regular use was 1.6 (95% CI: 0.9-2.9).

CONCLUSIONS

The absence of a higher risk for the regular use of dichlorvos/propoxur reduces the credibility of the apparent association, which could well have been an artefact of multiple comparisons. We conclude that most household pesticides used in Thailand do not appear to increase the risk of aplastic anaemia.

Low drug attributability of aplastic anemia in Thailand. The Aplastic Anemia Study Group

From 1989 to 1994, a population-based, case-control study of aplastic anemia was conducted in Thailand, including the regions of Bangkok, Khonkaen in the northeast, and Songkla in the south. An annual incidence in Bangkok of 3.7 cases per million population, about twice as high as in Western countries, has been reported. To evaluate the etiologic role of drugs, 253 subjects were compared with 1,174 hospital controls. With multivariate adjustment for confounding, a significant association was identified for exposure 2 to 6 months before admission to thiazide diuretics (relative risk estimate 7.7; 1.5 to 40). There were crude associations with sulfonamides (relative risk estimate, 7.9; P = 0.004) and mebendazole (6.3; P = 0.03) (there were insufficient data for multivariate adjustment). Excess risks for the three drugs were in the range of 9 to 12 cases per million users. There was no significant association with chloramphenicol, although the multivariate relative-risk estimate was elevated (2.7; 0.7 to 10). Other drugs that have been reported to increase the risk of aplastic anemia, such as nonsteroidal anti-inflammatory drugs and anticonvulsants, were not commonly used. There were no associations with commonly used drugs, including benzodiazepines, antihistamines, oral contraceptives, and herbal preparations. For all associated drugs, the overall etiologic fraction (the proportion of cases attributable to an exposure) was 5%, compared with 25% in Europe and Israel. Drugs are uncommon causes of aplastic anemia in Thailand, and their use does not explain the relatively high incidence of the disease in that country.

An association of aplastic anaemia in Thailand with low socioeconomic status. Aplastic Anemia Study Group

The relationship of socioeconomic status to the risk of aplastic anaemia was evaluated in a case-control study conducted in Bangkok and two rural regions of Thailand (Khonkaen and Songkla). Among 152 cases and 921 controls there were significant trends of increasing risk with decreasing years of education (P = 0.01) and total household income (P = 0.0001), after control for confounding. The relative risk estimate for those with monthly incomes of < 1500 baht (about $60 U.S.) was 3.9 (95% confidence interval 2.1-7.3) compared to those with monthly incomes of at least 5000 baht (about $200). The pattern of increasing risk with decreasing income was observed in all three regions, with significant trends in Bangkok (P = 0.004) and Khonkaen (P = 0.003). This finding may partly explain the high incidence of aplastic anaemia in Thailand. Low socioeconomic status may be a surrogate for one or more environmental factors that could cause aplastic anaemia, such as infectious pathogens or toxic exposures.

Physical activity as a risk factor for osteoarthritis of the knee

A case-control study was conducted to evaluate the association between knee osteoarthritis (OA) and physical activity (PA) among a community group aged 40 years and older. Case patients (85 males, 154 females) had radiologically confirmed knee OA with grade 2+ changes, according to Kellgren and Lawrence criteria. Control subjects (85 males, 154 females) had no radiologic evidence of knee OA. A statistically significant positive association between high PA level and knee OA was observed for women, with an age-adjusted odds ratio (OR) of 1.66 and 95% confidence interval (CI) of 1.01 to 2.72. In men no association was observed (OR = 0.95; 95% CI, 0.49 to 1.83). These associations persisted when controlling simultaneously for potential confounders including age, obesity, history of knee injury, and socioeconomic status, indicating that the OA-PA association is limited to women. One possible explanation is that risk factors for knee OA are influenced by hormones.

Short course training in epidemiology and biostatistics for graduate and undergraduate public health professionals

The University of South Florida has developed short courses of 2 to 3 days in epidemiology and biostatistics geared to public health workers. A key focus is providing skills which will assist local and State public health units to assess their status and measure progress with respect to achieving their explicitly stated health objectives for the year 2000. The courses were developed after the identification of the training needs in health departments and other public health settings. The training objectives were (a) to enhance the biostatistics skills of professionals involved in the analysis of health data; (b) to reinforce basic knowledge of epidemiologic methods and its practical applications in public health settings, including measures of disease frequency and association, epidemic outbreak investigations, and the identification and use of surveillance data; and (c) to demonstrate the application of the risk factor approach to select the interventions needed to reach health objectives for year 2000 and how to evaluate such interventions. A total of 43 students have taken this course series. Professional staff in health departments cannot always enroll in formal training in epidemiology and biostatistics because of time limitations or a lack of a bachelor's degree. However, the need exists. An alternative to such training could be the short course program described in this paper.

Bronchodilator testing "confidence intervals" based on the level of bronchial responsiveness

"Confidence intervals" based upon inhalation of placebo have been proposed as criteria for defining a significant response to an inhaled bronchodilator. The published intervals were derived from a clinically heterogeneous population. We calculated the difference (delta) between spirometric data before and after placebo in 109 consecutive patients referred for methacholine bronchoprovocation challenge testing. The mean delta, expressed both as a percent change and as actual volume change for both the FVC and FEV1, was not significantly different in patients with bronchial hyperresponsiveness, as compared to subjects with a negative methacholine challenge test; however, the variance of measurements in hyperresponsive subjects was significantly greater than that of the normal population. In addition, as the category of responsiveness increased from mild to moderate to severe hyperresponsiveness, so did the variance within these groups. A negative correlation between the measured PC20FEV1 and the volume and percent change was noted. We conclude that patients with hyperresponsive airways may display increased spirometric variation before and after placebo. This general approach for establishing normal limits for defining a significant response appears to be valid, but the actual values used may vary, depending on the composition of the population tested and the goals of the study. Also, the use of the term, "confidence intervals," in this context is inappropriate; and we propose, instead, the use of percentiles and the simpler terms, upper 90th or 95th percentiles.

Prevalence and mortality rate of congestive heart failure in the United States

OBJECTIVES

The study was designed to determine the prevalence and mortality rate of congestive heart failure in noninstitutionalized men and women in the U.S.

BACKGROUND

Congestive heart failure is a serious condition with significant morbidity and mortality. Earlier epidemiologic descriptions of congestive heart failure were constructed from small surveys, limited data, hospital records or death certificates. No nationally representative data from noninstitutionalized persons have been examined.

METHODS

Data collected from the National Health and Nutrition Examination Survey (NHANES-I, 1971 to 1975) were used to determine the prevalence of heart failure on the basis of both self-reporting and a clinical definition. Mortality data were derived from the NHANES-I Epidemiologic Follow-up Study (1982 to 1986).

RESULTS

The prevalence of self-reported congestive heart failure approximates 1.1% of the noninstitutionalized U.S. adult population; the prevalence of congestive heart failure based on clinical criteria is 2%. These estimates suggest that between 1 and 2 million adults are affected. Mortality at 10 and 15 years for those persons with congestive heart failure increases in graded fashion with advancing age, with men more likely to die than women. In the group greater than or equal to 55 years old, the 15-year total mortality rate was 39.1% for women and 71.8% for men.

CONCLUSIONS

Congestive heart failure is a common problem in the U.S., with significant prevalence and mortality, both of which increase with advancing age. As the population of the U.S. becomes older, the health care impact of congestive heart failure will probably grow.

Identification of sentinel health events as indicators of environmental contamination

The consensus process was applied to addressing a public health topic; this was a novel endeavor. The following question was addressed: What role, if any, should sentinel health events play in the decision-making process for identifying the effects of environmental exposure? The panel developed three levels of sentinel health events lists: those that are clearly identifiable, those that are potential signs, and those that are indicators of body burdens. Additionally, the panel developed several salient statements regarding the principles of environmental health surveillance and, especially, recommendations for future research.

Incidence of aplastic anemia in Bangkok. The Aplastic Anemia Study Group

The annual incidence of aplastic anemia in metropolitan Bangkok, Thailand, and its five suburban provinces was prospectively determined. All patients first diagnosed during the period from January through December 1989 who met specific clinical and pathologic criteria were included. Thirty-two cases were identified, yielding an overall incidence of 3.7 per million. The incidence rates for the age groups 0 through 24, 25 through 59, and over 60 years were 4.3, 3.2, and 2.1 per million, respectively; the highest rate, 7.2 per million, was found for individuals aged 15 to 24 years. The male-to-female ratio was 1.9. The incidence of aplastic anemia in Bangkok is higher than that reported in recent European studies. The peak rate in young persons is almost fourfold higher than in comparable recent western studies and suggests an environmental etiology peculiar to Thailand.

Histopathology of lung cancers among smokers and nonsmokers in Florida

A study was undertaken of the relationship between lung cancer cell type and age, race, sex and smoking characteristics. The study population consisted of 35 183 cases of microscopically confirmed carcinoma of the lung, first diagnosed between 1981 and 1985, among residents of the state of Florida. The data suggested that the histological types of lung cancer observed varied by age, sex and the use of cigarettes. The number of cigarettes smoked per day did not appear to influence the cell types observed. The study indicated that adenocarcinomas occurred more frequently in lung cancer cases diagnosed at earlier ages, among both men and women. Among women who smoked, there was an increased proportion of small cell carcinomas compared to nonsmoking women, while in male smokers, the increase appeared primarily in squamous cell carcinomas.

Progress in the battle against hypertension. Changes in blood pressure levels in the United States from 1960 to 1980

Intensive efforts by practicing physicians and public health workers to identify and treat persons with hypertension have been underway for many years. In this report, changes in blood pressure levels in the United States are assessed based on nationally representative health (and nutrition) examination surveys conducted by the National Center for Health Statistics in 1960 to 1962, 1971 to 1974, and 1976 to 1980. Analysis of age-adjusted data for adults aged 18 to 74 years (including those on antihypertensive medication) indicates that between the first and third surveys for whites and blacks, respectively, mean systolic blood pressure declined 5 and 10 mm Hg; the proportion of persons with systolic blood pressure of 140 mm Hg or higher fell 18 and 31%; the proportion with undiagnosed hypertension decreased 17 and 59%; and the proportion taking antihypertensive medications rose 71 and 31%. These differences between the first and third surveys were all statistically significant (p less than 0.05 or better). Changes in diastolic blood pressure levels were generally not significant among race-sex groups. The proportion of persons with definite hypertension (i.e., systolic blood pressure greater than or equal to 160 mm Hg, and/or diastolic blood pressure greater than or equal to 95 mm Hg, and/or taking antihypertensive medication) declined among blacks but rose slightly among whites. Study results are consistent with the recent decline in cardiovascular disease mortality.

Predictors of good function: the Framingham Study

This paper asks the question: among 1474 Framingham Study participants aged 35-68 years who were healthy at their fourth examination (1954-1958), what are the physiologic, behavioral, and demographic characteristics that distinguish those who survive and report good function from those who do not after 21 years of biennial observations? Although a larger proportion of women than men survived, their functional status was not as good. Multiple logistic regression analysis revealed that age, alcohol intake, cigarette smoking, ventricular rate, and education were all significantly related to functional status for men, with all but the last of these factors inversely related to good function. For women, the only significant predictor other than age was education, which, as with men, was directly associated with good function. The effect of education is probably mediated by numerous factors such as availability and use of health care services, quality of health care, occupation, and lifestyle.

Representativeness of the Framingham risk model for coronary heart disease mortality: a comparison with a national cohort study

The Framingham Heart Study has been the foundation upon which several national policies regarding risk factors for coronary heart disease mortality are based. The NHANES I Epidemiologic Followup Study is the first national cohort study based upon a comprehensive medical examination of a probability sample of United States adults. The average follow-up time was 10 years. This study afforded an opportunity to evaluate the generalizability of the Framingham risk model, using systolic blood pressure, total cholesterol, and cigarette smoking, to the U.S. population with respect to predicting death from coronary heart disease. The Framingham model predicts remarkably well for this national sample. The major risk factors for coronary heart disease mortality described in previous Framingham analyses are applicable to the United States white adult population.

Trends in total mortality and mortality from heart disease in 26 countries from 1950 to 1978

Death rates for total mortality and for non-rheumatic heart disease and hypertension ('heart disease') are described for men and women ages 45-64 in six time periods during 1950-78 for 26 countries. Rates for men in high-rate countries are three times those in low-rate countries. This variation is more striking for men than women. There were marked increases for heart disease in men in most countries, but in 13 countries there was a slowing or reversal of that trend in the 1960's or 1970's or acceleration of an already downward trend. In 22 countries long-term declines for heart disease occurred in women. There was a widening of the north/south gradient in Europe and of the male/female ratio of heart disease mortality. Countries with high heart disease death rates in men had high ratios of heart disease to total death. Other countries experienced a rise in proportionate mortality. In women, proportionate mortality for heart disease remained flat or declined in most countries. In spite of these changes in rates, each country seems to have a range for heart disease mortality that is characteristic of its population and environmental setting so that profound changes in rates do not substantially alter their relative ranking. Our intent is to stimulate the search for reasons why heart disease mortality recently declined in some countries but not in others (already begun in the WHO-sponsored MONICA programme). Our forthcoming monograph on international mortality trends for the major causes of death will be a next step in this process.

Coronary heart disease mortality rates in United States blacks, 1968-1978: interstate variation

It has been shown that, among white males and females, recent declines in mortality from coronary heart disease (CHD) have not been uniform by region or state. Some clustering has emerged. To describe trends for the black population by states, we compared CHD death rates for persons aged 35 to 74 years for the years 1968-1972 in combination with rates for 1978. Reported mortality from 34 states with reasonably large black populations was described. Not all of the recent geographic shifts for white CHD mortality rates were apparent for blacks. Yet there were similarities, chief of which were the slower decline, and therefore worsening, of relative CHD mortality in certain states in Appalachia.

Blood pressure in adolescence. The United States Health Examination survey

A nationally representative sample of adolescents 12-17 years of age were examined in the U.S. Health Examination Survey and relationships between blood pressure and other variables were explored. During adolescence, blood pressure increases more rapidly in males than in females and only small racial differences are present. Weight has the strongest relationship to both systolic and diastolic pressure. Physiological maturation assessed by skeletal age and adiposity (skinfold thickness) are components of weight and each is also related to blood pressure. Although systolic murmurs are related to blood pressure at the time of examination, the murmurs are transitory and not predictive of future pressures. All factors were equally influential in each race-sex group. No significant relationships were found between geographic or demographic variables and blood pressure. These observations indicate the important relationships of physiological maturation and adiposity to adolescent blood pressure.

Blood pressure in childhood. The National Health Examination Survey

Data were analyzed from the U.S. Health Examination Survey (Cycle II) to determine relationships between blood pressure and other characteristics. This survey examined a national probability sample of children aged 6-11 years. Significant relationships were found for blood pressure and the following variables: chronological and skeletal age, skinfold thickness (adiposity) and other anthropometric measurements, pulse rate, and systolic murmurs. These relationships may be interpreted as indicating important relationships between blood pressure and growth, adiposity, and hemodynamic manifestations of cardiac output. Data from this representative population portray blood pressure relationships in childhood.

Secondary sex characteristics of boys 12 to 17 years of age: the U.S. Health Examination Survey

Data from the United States Health Examination Survey, Cycle III, were used to describe secondary sexual characteristics and their relationship to skeletal age in a representative sample of adolescent males aged 12 to 17 years. This survey utilized a national probability sample of youths selected to represent the U.S. population with respect to age, race, sex, geographic region, and socioeconomic status. Good concordance was found between Tanner stages for pubic hair and for genitalia. Sexual characteristics developed similarly for white and black boys, and socioeconomic status did not influence this development. Skeletal age and serum urate levels were closely related to development of pubic hair and genitalia. These data permit the physician to compare the development of individual patients with a representative sample of contemporaneous U.S. boys.

A longitudinal study of body fatness in childhood and adolescence

Data from the United States Health Examination Surveys were analyzed to determine changes in body fatness between childhood and adolescence. A national probability sample (2,177 children) was examined in both Cycle II (6 to 11 years) and Cycle III (12 to 17 years) of these surveys and comprised the study cohort. The interval between examinations was three or four years. Adiposity was measured as skinfold thickness and correlations between childhood and adolescent adiposity were explored. High rank-order correlations were found between the two examinations for each race-sex group (P less than 0.001). The relationship between childhood and adolescent fatness was independent of stature, skeletal and sexual maturation, and economic status. Childhood fatness was the most predictive factor for adolescent fatness. This strong relationship indicates that the potentially obese adolescent can be identified during childhood.

Physiologic determinants of serum urate levels in adolescence

During adolescence, serum urate increases and adult levels are achieved. Physiologic factors related to serum urate were investigated in a nationally representative population of 6,768 youths aged 12 to 17 years (the US Health Examination Survey). Serum urate concentration increases markedly from ages 12 to 14 years in males, and levels were related to sexual and skeletal maturation. Although similar relationships were observed in females, the association is less striking, probably because of earlier pubescence, which was not captured in this study, and a pronounced androgenic response. In the later stages of adolescence (ages 15 to 17 years for males and 13 to 17 years for females), body composition (body mass index and skinfold thickness), blood pressure, and hematocrit have stronger relationships than sexual and somatic maturation. These latter relationships are similar to those in adults. This survey affords a portrayal of physiologic interrelationships with serum uric acid during adolescence.

Tracking of blood lipids and blood pressures in school age children: the Muscatine study

In four cross sectional school screens, the Muscatine Study has sampled 8,909 school children; 820 have been studied repeatedly over a six-year period. Tracking of measurements described by the relationship between repeated observations and the relationship between peer rank orderings over the six-year period has been studied. For height and weight, correlations between observations six years apart were approximately 0.74 and about 60% of children initially in the upper quintile were there again six years later. Six-year correlations were 0.65 for skinfold and 0.61 for cholesterol. Four-year correlation for fasting triglyceride was 0.40. Six-year correlations were 0.30 for casual systolic blood pressure and 0.18 for diastolic blood pressure. Peer rank orderings for both blood pressures were highly variable. Height and weight track well, and thus routine measurement of these variables are useful in identifying children with growth perturbing disorders. Cholesterol and, to a lesser degree, triglycerides also track, and a significant proportion of children with initially high values demonstrated consistently high values throughout the study period. Blood pressures do not track as well; consistently high blood pressures are unusual, thus indicating the need for repeated blood pressure measurements to identify children with persistent elevated levels. The future significance of transient blood pressure elevations has yet to be established.

Coronary heart disease risk factors in school children: the Muscatine study

The frequency of coronary risk factors was documented in 4,829 school children in Muscatine, Iowa, over a 14-month period of time. Serum cholesterol levels were similar for children at all ages; the mean serum cholesterol level was 182 mg/dl (SD lus or minus 29). Twenty four percent had levels larger than or equal to 200 mg/dl, 9% were larger than or equal to 220 mg/dl, 3 % were larger than or equal to 240 mg/dl, and 1% were larger than or equal to 260 mg/dl. Casual levels of serum triglyceride increased with age: the mean level was 71 mg/dl (SD plus or minus 36) at age 6 years and 108 mg/dl (SD plus or minus 45) at age 18 years. Only 15% of the children had serum triglyceride levels of 140 mg/dl or more. Blood pressure increased strikingly with age. No child between 6 and 9 years of age had blood pressures larger than or equal to 140 mm Hg systolic or larger than or equal to 90 mm Hg diastolic. In the age group 14 to 18 years, 8.9% had systolic blood pressures larger than or equal to 140 mm Hg, 12.2% had diastolic blood pressures larger than or equal to 90 mm Hg, and in 4.4% both pressures were at or above these levels. Obesity also increased through the school years. At ages 6 to 9 years, 20% had weights relative to those of the group as a whole of larger than or equal to 110%, and 5% were larger than or equal to 130%; in the 14 to 18 years age group, 25% had relative weights of larger than or equal to 110%, and 8% were larger than or equal to 130%. These data indicate that a considerable number of school-age children have risk factors which in adults are predictive of coronary heart disease.

The first derivative thoracic impedance cardiogram

When an alternating current of high frequency is applied to the thorax, the first derivative of the impedance to this current is affected by the cardiac cycle resulting in a characteristic wave form.

Phonocardiograms, electrocardiograms, and first derivative thoracic impedance cardiograms were recorded simultaneously in 91 subjects. The first derivative thoracic impedance cardiograms were found to have sharply demarcated points which occur synchronously with the first heart sound, aortic second sound, pulmonic second sound, mitral opening snap, third heart sound, and fourth heart sound. The first derivative thoracic impedance cardiogram may thus be used not only as a reference tracing to help identify heart sounds on the phonocardiogram, but also for directly timing the intervals within the cardiac cycle.

Study of some factors contributing to aerosol production by the air-turbine handpiece

Assay of the dental aerosol cloud generated during tooth-cutting procedures revealed that 95% of the colloidal cloud particles are capable of reaching the alveoli of the lung and may represent a serious health hazard.