Biomedical subjects

J B Carlin

Publications and source records attributed to J B Carlin.

At least 91 records · Page 5Linked to original sources

PubMed1995

Sonographic measurement of renal enlargement in children with acute pyelonephritis and time needed for resolution: implications for renal growth assessment.

OBJECTIVE: Failure of a kidney to grow satisfactorily in childhood is evidence of renal disease. Because kidneys may enlarge during an episode of acute pyelonephritis, concomitant renal length measurements cannot be used as baselines for growth assessment. This study was designed to determine the degree of renal enlargement in children with acute pyelonephritis and the time the enlargement takes to resolve after treatment is started to find the optimum time for obtaining baseline measurements. SUBJECTS AND METHODS: In a cohort study, 180 children younger than 5 years old with their first proven acute urinary tract infection, with or without pyelonephritis, had renal scintigraphy and sonography within 15 days of starting treatment. The presence of cortical defects on scintigrams indicated pyelonephritis. The lengths of kidneys with and without scintigraphic defects (i.e., with and without pyelonephritis) were compared, adjusting for age and sex, and the length of kidneys with defects was related to time elapsed between the start of treatment and sonography. RESULTS: Ninety-nine kidneys (28%) in 77 children (43%) had scintigraphic defects. Kidneys with defects were an average of 3.2 mm longer than kidneys without defects. Length and time interval between treatment and sonography in kidneys with defects correlated negatively, with mean length approaching that of kidneys without defects by 10-11 days. CONCLUSION: Kidneys with acute pyelonephritis initially increase in length but return to normal on average by the 11th day of treatment. If poor renal growth is used as an indication of renal disease, sonography should be delayed or repeated at least 2 weeks after the start of treatment to determine the length of the uninflamed kidney.

Acute Disease↗

PubMed1994

Asthma, allergy and atopy in Asian immigrants in Melbourne.

OBJECTIVES: To compare the prevalence of asthma, hay fever and atopy in Asian immigrants in Melbourne with that in Australian-born non-Asians and Australian-born Asians, and to investigate the association of these conditions with atopic status, length of stay in Australia and IgE levels in Asian immigrants. DESIGN: We performed a cross-sectional study by telephone interviews, using standard questionnaire items on respiratory and allergic symptoms. A random sample of 636 recent Asian immigrants of ethnic Chinese origin, 109 Australian-born Asians and 424 Australian-born non-Asians were selected from the 1991 Melbourne Telephone Directory, using a presumptive surname list. Skin tests to determine atopic status were performed on 269 Asian immigrants and 167 of these also had serum levels of total and specific IgE estimated. RESULTS: In the under 20 years age group the prevalence of wheeze or asthma ever was higher in Australian-born non-Asians and Australian-born Asians than in Asian immigrants (P < 0.001), and the prevalence of hay fever was higher in Asian immigrants and Australian-born Asians than in Australian-born non-Asians. In those older than 20 years, hay fever was almost twice as common in Asian immigrants as in Australian-born non-Asians (P < 0.001 for 20-40 years age group; P < 0.01 for > 40 years). The prevalence of hay fever and, to a lesser degree, asthma in Asian immigrants increased significantly with length of stay in Australia, independent of age at arrival, sex and atopic status (trend test: P < 0.001 for hay fever; P = 0.05 for asthma). Atopy was more common in Asian immigrants and Australian-born Asians than in Australian-born non-Asians (P < 0.001) and was very strongly associated with both hay fever and asthma, irrespective of length of stay. Pollen and mite sensitivities were more common in Asian subjects (twice as common for Asian-born and 1.5 times for Australian-born) than non-Asian subjects (P < 0.01). Among Asian immigrants, elevated total IgE level (> 100 IU/mL) was strongly associated with a history of hay fever (P < 0.01) and wheeze or asthma ever (P < 0.05), atopy (P < 0.001) and the presence of specific IgE antibodies to grass pollen, dust mite, cockroach and Ascaris antigens (P < 0.05 for all). CONCLUSION: We found substantial differences in the prevalence of asthma, hay fever and atopy between Asian immigrants, Australian-born Asians and non-Asians. The prevalence of hay fever and asthma in Asian immigrants was strongly associated with length of stay in Australia, suggesting that environmental factors are important in the pathogenesis of these diseases.

Adolescent↗

PubMed1994

Factors in childhood as predictors of asthma in adult life.

OBJECTIVE: To determine which factors measured in childhood predict asthma in adult life. DESIGN: Prospective study over 25 years of a birth cohort initially studied at the age of 7. SETTING: Tasmania, Australia. SUBJECTS: 1494 men and women surveyed in 1991-3 when aged 29 to 32 (75% of a random stratified sample from the 1968 Tasmanian asthma survey of children born in 1961 and at school in Tasmania). MAIN OUTCOME MEASURES: Self reported asthma or wheezy breathing in the previous 12 months (current asthma). RESULTS: Of the subjects with asthma or wheezy breathing by the age of 7, as reported by their parents 25.6% (190/741) reported current asthma as an adult compared with 10.8% (81/753) of subjects without parent reported childhood asthma (P < 0.001). Factors measured at the age of 7 that independently predicted current asthma as an adult were being female (odds ratio 1.57; 95% confidence interval 1.19 to 2.08); having a history of eczema (1.45; 1.04 to 2.03); having a low mild forced expiratory flow rate (interquartile odds ratio 1.40; 1.15 to 1.71); having a mother or father with a history of asthma (1.74 (1.23 to 2.47) and 1.68 (1.18 to 2.38) respectively); and having childhood asthma (1.59; 1.10 to 2.29) and, if so, having the first attack after the age of 2 (1.66; 1.17 to 2.36) or having had more than 10 attacks (1.70; 1.17 to 2.48). CONCLUSION: Children with asthma reported by their parents in 1968 were more likely than not to be free of symptoms as adults. The subjects who had more severe asthma (especially if it developed after the age of 2 and was associated with reduced expiratory flow), were female, or had parents who had asthma were at an increased risk of having asthma as an adult. These findings have implications for the treatment and prognosis of childhood asthma, targeting preventive and educational strategies and understanding the onset of asthma in adult life.

Adolescent↗

PubMed1994

Critical evaluation of three chest radiograph scores in cystic fibrosis.

BACKGROUND: A number of chest radiographic scores have been developed to assess the severity of respiratory disease in cystic fibrosis but critical statistical evaluation has been limited. In particular, the chest radiograph component of the National Institutes of Health (NIH) clinical score has not previously been validated. Three different chest radiograph scores have been compared and the association between them and lung function tests investigated. METHODS: The interobserver and intraobserver variation of the Brasfield, NIH chest radiograph, and the Royal Children's Hospital (RCH) chest radiograph score was assessed by three observers--a paediatric radiologist, a junior and a senior respiratory physician--who independently scored, on separate occasions, 62 chest radiographs randomly selected from three age strata of patients ranging from 7 to 18 years. Lung function tests were available for 61 patients obtained within three months of the chest radiograph. Two way analysis of variance was used to estimate components of variation in scores. RESULTS: Results were similar for the Brasfield and NIH scores, both of which demonstrated greater precision than the RCH score, but the estimated repeatability of the Brasfield and NIH scores can be expected to differ by up to 20% of the maximum score. The reliabilities (intraclass correlation) are all reasonably high at 0.74, 0.73, and 0.61 for the Brasfield, NIH, and RCH scores, respectively. The estimated correlation between radiographic scores and lung function tests, adjusted for attenuation caused by measurement error, showed a similar correlation for all three scoring methods ranging from 0.55 to 0.78. Correlations were slightly greater with FEV1% than FVC%. These correlations are substantial but not high, indicating that a large proportion of the variability in radiographic scores cannot be explained by lung function measurements. CONCLUSIONS: The Brasfield and NIH chest radiograph scores have very similar statistical profiles and can be equally recommended if a chest radiograph score is to be used. The RCH radiographic score appears to be less reliable. The limitations of these scores need to be understood.

Adolescent↗

PubMed1994

Measurement of functional severity of asthma in children.

The usefulness of surveys for measuring the severity of asthma in school-age children depends on the availability of reliable and valid questionnaires. The aim of this study was to develop a measure of functional severity of asthma over the previous 12 mo, for use in population studies and in investigating treatment regimens. Of 10,198 children surveyed, 9,192 (90%) in school Years 2, 7, and 10 (mean ages 8, 13, and 16 yr) in Melbourne were screened for wheeze. The parents of the 1,267 children with wheeze were interviewed. Symptoms and restriction of activity due to asthma were analyzed using factor analysis and the partial credit version of the item response theory measurement model. The result was a continuous severity scale that was highly consistent with the data, and with goodness of fit statistics indicating the severity of 97% of children was well described by the scale. The scale correlated significantly with school absence due to wheeze (r = 0.35), functional impairment during the 2 wk before interview (Functional Status II-R [FSII-R], r = 0.30), visits to medical care for wheeze (r = 0.22), and amount of medication (r = 0.36). For descriptive purposes, a simple index with four bands of severity was developed from the continuous severity scale: low severity (47% of children with wheeze), moderate (30%), mild (18%), and high (5%). The scale and index facilitate standardized description of the impact of asthma on daily life on the basis of responses to six survey questions.

Absenteeism↗

PubMed1993

Australian Rules football injuries in children and adolescents.

OBJECTIVE: To ascertain the incidence, severity, risk factors, and outcomes of injuries in children and adolescents playing Australian Rules football. DESIGN SETTING AND SUBJECTS: A prospective cohort study of football injuries in children and adolescents playing community football. We studied a stratified random sample of 54 teams and clinics (18 under-15 teams, 18 under-10 teams and 18 Vickick clinics for children under 10 years) from the Melbourne metropolitan area. Football exposure, injuries and associated risk factors were recorded for 1253 players during the 1992 football season. RESULTS: Vickick, a modified form of the game, had the lowest rates of injury for all levels of injury severity, with an overall rate of 3.49 injuries per 1000 player-hours. The rate in the under-10 age group was 2.4 times higher (95% confidence interval [CI], 1.5-3.8) than that in Vickick, and the under-15 rate was 1.2 times (95% CI, 0.9-1.6) that of the under-10s. The under-15 age group had significantly more injuries that led to use of health services than the under-10 and Vickick groups, with rates of 3.93 (95% CI, 2.9-4.9), 0.64 (95% CI, 0.2-1.4), and 0.33 (95% CI, 0.1-0.8) injuries per 1000 players-hours respectively. Injuries were largely to soft tissues (sprains 26%, haematomas 25%) and to the lower limb (43%). Very few serious injuries occurred (19 fractures and three injuries with loss of consciousness); nearly all of these were in the under-15s. Rule modifications in under-10 teams and clinics were associated with an injury rate of 5.8 injuries per 1000 player-hours (95% CI, 4.4-7.3) compared with 7.5 injuries per 1000 player-hours (95% CI, 5.2-9.8) when no modification was used. Alterations to the ruck contest, decreased contact, field size and player numbers were significantly associated with lower injury rates, while body size was not. Of the 30% of injuries resulting in a health service consultation, the most common health provider was a medical practitioner. Very few required expensive investigation or treatment. CONCLUSION: Injury rates were low in children under age 10, but higher in adolescents. Most injuries were minor, and did not result in a health professional consultation. Rule modifications were associated with substantially lower injury rates at the under-10 level, and should be promoted as a safe way to learn football skills.

Adolescent↗

PubMed1993

Serum insulin distributions and reproducibility of the relationship between 2-hour insulin and plasma glucose levels in Asian Indian, Creole, and Chinese Mauritians. Mauritius NCD Study Group.

The relationship of 2-hour (post-75 g oral glucose) serum insulin levels with plasma glucose levels was studied in a population-based random sample comprising 2,627 Hindu Indians, 685 Muslim Indians, 1,351 Creoles (African, European, and Indian admixture), and 415 Chinese from the Indian Ocean island of Mauritius. Known diabetic subjects taking oral hypoglycemic drugs or insulin were excluded from these analyses; 64% of all diabetic subjects had usable glucose and insulin data. Both fasting and 2-hour postload insulin levels were significantly higher in women than in men, and levels in both sexes were significantly greater in Hindu and Muslim Indian subjects than in Creoles or Chinese even after controlling for differences in age, body mass index (BMI), waist to hip ratio (WHR), and plasma glucose level. Levels in Muslims were higher than those in Hindus; it was unclear whether these ethnic differences represented hereditary or unmeasured environmental factors closely associated with ethnicity. All four ethnic groups demonstrated similar inverted U- or V-shaped curves when 2-hour insulin was plotted against either basal or 2-hour glucose. Both quadratic (U) and two-piece (V) regression models improved over linear models for 2-hour insulin versus either fasting or 2-hour glucose in all ethnic groups, although in statistical terms they were good models only for the 2-hour glucose comparison. The two-piece models were associated with modest increases in R2 compared with the quadratic models, but it was not possible to precisely determine optimal turning points with either model. However, in all ethnic groups, 2-hour insulin levels decreased above glucose levels of 7.1 to 7.8 (fasting) and 11.3 to 13.5 mmol/L (2-hour) in quadratic models, and 7.5 to 9.5 (fasting) and 8.5 to 10.5 mmol/L (2-hour) in two-piece models. The shape and point of inflection of the quadratic and two-piece curves were influenced little by gender, obesity, fat distribution, and physical activity. These results are in accord with those observed in cross-sectional and longitudinal studies in other ethnic groups, and support the generality of the plasma glucose levels currently used to define diabetes mellitus, which physiologically correspond with a decrease in beta-cell responsiveness to glucose. Asian Indians appear to have an ethnic propensity to hyperinsulinemia that is not explained by obesity or adverse fat distribution.

Adult↗

PubMed1993

Bias, prevalence and kappa.

Since the introduction of Cohen's kappa as a chance-adjusted measure of agreement between two observers, several "paradoxes" in its interpretation have been pointed out. The difficulties occur because kappa not only measures agreement but is also affected in complex ways by the presence of bias between observers and by the distributions of data across the categories that are used ("prevalence"). In this paper, new indices that provide independent measures of bias and prevalence, as well as of observed agreement, are defined and a simple formula is derived that expresses kappa in terms of these three indices. When comparisons are made between agreement studies it can be misleading to report kappa values alone, and it is recommended that researchers also include quantitative indicators of bias and prevalence.

Data Interpretation, Statistical↗

PubMed1993

The associations between childhood asthma and atopy, and parental asthma, hay fever and smoking.

The aim of this analysis was to examine the degree to which a life time prevalence of asthma in a 7-year-old child is statistically associated with atopic conditions of the child, and with parental asthma, hay fever and smoking. In 1968, 8585 children who were born in 1961 and who were attending school in Tasmania were surveyed. This comprised 99% of the eligible population. The prevalence of a history of asthma in the 7-year-olds was 16.2% (males 19.0%, females 13.2%). Multiple logistic regression analysis showed that a history of asthma in a 7-year-old was associated with the child being male (odds ratio [OR] 1.56; 99% confidence interval 1.30-1.86), having a history of hay fever (3.86; 3.12-4.78), eczema (2.04; 1.63-2.55), hives (1.34; 1.09-1.65) or allergy to foods or medicines (1.70; 1.26-2.30), the child's mother or father having a history of asthma (2.63; 2.08-3.31 or 2.52; 1.99-3.19, respectively), and the mother being a smoker (1.26; 1.05-1.51). Parental hay fever and paternal smoking were not independently associated with childhood asthma. The strength of association between childhood asthma and parental asthma was independent of the sex of either the parent or the child, and of atopic conditions in the child. In the 133 children for whom both parents were asthmatic, 65 (49%) had a history of asthma.(ABSTRACT TRUNCATED AT 250 WORDS)

Asthma↗

PubMed1993

Assessing the extent of the Australian HIV epidemic from AIDS surveillance data.

Current knowledge about human immunodeficiency virus (HIV) disease is used to assess past and future trends in Australian HIV/AIDS (acquired immune deficiency syndrome) incidence, focusing on the precision with which such assessments can be made. The statistical method of back-projection is applied to reconstruct the past pattern of HIV incidence from surveillance data on AIDS incidence to June 1992. The results indicate that HIV incidence rose rapidly in the early 1980s to peak in 1983-1984, followed by a sharp decline. This finding is insensitive to plausible variations from the assumptions made, and is consistent with both success in preventive strategies and high levels of infection in a subgroup having a high probability of exposure. Cumulative HIV incidence to the end of 1987 is estimated with a 90 per cent confidence interval from 9,350 to 10,350. Estimation of the cumulative HIV incidence to June 1992 is less precise, with a 90 per cent confidence interval of 12,900 to 17,800. After adjustment for underreporting the incidence could be as high as 22,000, but only if recent infection rates, which cannot be quantified accurately, were very high. Based on data to June 1992, the estimated trend in AIDS incidence indicates 680 new cases in 1993, rising gradually to 695 in 1995. The estimated rate of increase in AIDS incidence over the recent past and near future is significantly less than that observed earlier in the epidemic. This is a consequence of both the earlier peak in HIV incidence and the effect of therapy.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Reference ranges for respiratory rate measured by thermistry (12-84 months).

Previous studies of respiratory rate in children have had a number of methodological problems. The aim of this study was to construct age specific reference ranges for respiratory rate. Respiratory rate in children attending childcare centres, kindergartens, and schools was measured using a nasal thermocouple to obtain respiratory waveforms. Reference ranges were constructed using data from 293 awake children between 12 and 84 months, and from 123 sleeping children between 12 and 60 months. The mean respiratory rate declined with increasing age and was significantly lower, with lower variability, during sleep than wakefulness. Neither the awake nor sleeping reference ranges were significantly affected by sex, nor by the presence of past respiratory nor current respiratory symptoms.

Age Factors↗

PubMed1993

Gas enema for the reduction of intussusception: relationship between clinical signs and symptoms and outcome.

OBJECTIVE: The aim of this study was to establish the extent to which the clinical features of intussusception can be used to predict successful outcome of gas enema and to determine whether the nonsurgical management of intussusception in children can be improved by refining the criteria used to select patients for gas enema. SUBJECTS AND METHODS: Clinical data on 282 consecutive episodes of intussusception (255 patients) were collected prospectively from January 1987 to July 1991. Gas enema was performed in 273 episodes, in which the clinical signs and symptoms were studied by using logistic regression. Nine patients had primary surgery. RESULTS: Gas enema was successful in 216 (79%) of 273 enemas attempted. Fifty-seven patients had surgery after unsuccessful enema. Univariate analysis showed significant associations between successful enema and duration of signs and symptoms less than 12 hr, no rectal bleeding, absence of small-bowel obstruction, presence of a palpable mass, and normal hydration. Multivariate analysis showed that dehydration, small-bowel obstruction, and duration of signs and symptoms longer than 12 hr were significant predictors of unsuccessful enema; yet, in these groups the rate of success still justified attempted enema. Even in severe dehydration, the successful enema reduction rate was 31%. CONCLUSION: Our data suggest that although the factors identified had some predictive value in determining the outcome of attempted enema reduction, they could not be used to indicate patients in whom enema reduction should not be attempted. All patients with intussusception should have a gas enema if the absolute contraindications to enema (i.e., peritonitis or perforation) are absent.

Child↗

PubMed1992

Familial aggregation of a disease consequent upon correlation between relatives in a risk factor measured on a continuous scale.

Correlation between relatives in one or more risk factors for a disease will contribute to the risk in relatives of an affected individual, irrespective of the cause(s) of the correlation. In this paper, a model is proposed to quantify the relation between 1) the correlation (rho) between a random pair of relatives in a quantitative risk factor, 2) the dependence of the probability of being affected on a risk factor, assumed to be a logistic function and summarized by a risk ratio (RR) between upper and lower quartiles, and 3) the resultant disease association between relatives, represented as an odds ratio. For one risk factor, the odds ratio is almost independent of disease frequency across the range 0.001-0.1, and is approximately linearly related to rho on a logarithmic scale. An odds ratio between relatives of about 2 occurs if rho = 1 and RR = 9, if rho = 0.6 and RR = 20, or if rho = 0.3 and RR = 100. For two independent risk factors with the same risk ratio and rho, the resultant odds ratio exceeds unity by about twice as much as when there is one risk factor. That is, even moderate familial aggregation of a disease is consistent with there being one or more strong familial (genetic and/or environmental) risk factors. Illustrations of the model are discussed.

Breast Neoplasms↗

PubMed1992

Importance of complete follow-up of spontaneous fetal loss after amniocentesis and chorion villus sampling.

Women who are the most difficult to trace after amniocentesis or chorion villus sampling are often those who have had an adverse pregnancy outcome. To calculate total fetal loss figures for use in prenatal counselling we have followed in a multicentre study 100% of women who had undergone these procedures. Early spontaneous loss (within three weeks of the procedure) and total spontaneous loss were much lower after amniocentesis (0.2% and 1.3%, respectively) than after chorion villus sampling (1.2% and 2.9%). Four spontaneous fetal losses among the 20 pregnancies that were the most difficult to follow-up increased the loss rate by 0.5% for chorion villus sampling. Risk of early fetal loss after chorion villus sampling was related to experience of the operator (relative risk [RR] 4.3, p = 0.003), and total fetal loss was lower in pregnancies tested at 10 weeks' or more gestational age compared with those tested before 10 weeks' (RR 0.4, p = 0.01). A table showing the frequency of each of the seven possible outcomes after amniocentesis and chorion villus sampling is useful in counselling those considering one or other test.

Abortion, Spontaneous↗

PubMed1992

Meta-analysis for 2 x 2 tables: a Bayesian approach.

This paper develops and implements a fully Bayesian approach to meta-analysis, in which uncertainty about effects in distinct but comparable studies is represented by an exchangeable prior distribution. Specifically, hierarchical normal models are used, along with a parametrization that allows a unified approach to deal easily with both clinical trial and case-control study data. Monte Carlo methods are used to obtain posterior distributions for parameters of interest, integrating out the unknown parameters of the exchangeable prior or 'random effects' distribution. The approach is illustrated with two examples, the first involving a data set on the effect of beta-blockers after myocardial infarction, and the second based on a classic data set comprising 14 case-control studies on the effects of smoking on lung cancer. In both examples, rather different conclusions from those previously published are obtained. In particular, it is claimed that widely used methods for meta-analysis, which involve complete pooling of 'O-E' values, lead to understatement of uncertainty in the estimation of overall or typical effect size.

Adrenergic beta-Antagonists↗

PubMed1992

Smoking in aborigines and persons of European descent in southeastern Australia: prevalence and associations with food habits, body fat distribution and other cardiovascular risk factors.

As part of a population-base study of risk factors for heart disease, we aimed to establish the prevalence of smoking and to identify associations between smoking and other risk factors in Australian Aborigines (n = 306) and persons of European descent (n = 553) in two country towns. Smoking prevalence was first analysed as a dichotomy (current smokers compared with nonsmokers), and according to three levels of exposure (< 10, 10-20 and > 20 cigarettes per day), and two levels of nonexposure (never and former smoker). Other behavioural, biochemical and physical variables were included in multivariable analyses. Of the Aborigines, 64.4 per cent (95 per cent confidence interval (CI) 59.0 per cent to 69.8 per cent) were current cigarette smokers, compared with 22.8 per cent of non-Aborigines (CI 19.3 per cent to 26.3 per cent). For persons aged 13 to 54 years, using the five categories of exposure, smoking in Aborigines again far exceeded that in non-Aborigines in all age groups (for males chi 2 = 72.8, for females chi 2 = 94.6, 4 df, P = < 0.0001 for both sexes). In non-Aboriginal females, the highest prevalence was in the youngest group (56 per cent of those aged 13 to 17 years). Food habit was associated with smoking. Subjects who ate meat without trimming the fat were more likely to smoke. In Australian country towns, Aborigines and all young women need smoking cessation programs. The nutritional status of smokers requires further study.

Adolescent↗

PubMed1992

Body mass index and duration of breast feeding: a survival analysis during the first six months of life.

STUDY OBJECTIVE: The aim was to determine whether excess weight in lactating women is associated with earlier cessation of breastfeeding. DESIGN: The study was to prospective cohort analysis using a community sample of women. SETTING: Geelong the regional centre of the Barwon Region of Victoria, Australia, in 1984-85. SUBJECTS: All women who were breast feeding and whose first infant was born between 1 May 1984 and 30 April 1985 were asked to participate. Of these, 739 women participated, a response rate of 81%. MAIN RESULTS: Smoking, mother's age and occupation, the time the infant was first put to the breast, and mother's body mass index at one month postpartum all exerted statistically significant independent effects on the duration of breast feeding, assessed using Cox's proportional hazards regression modelling. The strongest effects were for smoking, with an adjusted relative risk for cessation of breast feeding of 2.5 (95% CI 1.9 to 3.1) for 10 cigarettes per day v no smoking, and maternal age, with relative risk of 2.2 (95% CI 1.5 to 3.1) for a 20 year old mother relative to a 30 year old. The relative risk for women with a body mass index above 26 was 1.5 (95% CI 1.1 to 2.0). CONCLUSIONS: Excess weight at one month postpartum, as determined by a body mass index above the normal range, was found to be an independent risk factor for early cessation of breast feeding and together with smoking, maternal age, occupation, and the time the infant is first put to the breast can be used to identify, early in the postpartum period, those women most likely to benefit from counselling in order to breast feed their infants successfully.

Adolescent↗

PubMed1991

A method of non-parametric back-projection and its application to AIDS data.

The method of back-projection has been used to estimate the unobserved past incidence of infection with the human immunodeficiency virus (HIV) and to obtain projections of future AIDS incidence. Here a new approach to back-projection, which avoids parametric assumptions about the form of the HIV infection intensity, is described. This approach gives the data greater opportunity to determine the shape of the estimated intensity function. The method is based on a modification of an EM algorithm for maximum likelihood estimation that incorporates smoothing of the estimated parameters. It is easy to implement on a computer because the computations are based on explicit formulae. The method is illustrated with applications to AIDS data from Australia, U.S.A. and Japanese haemophiliacs.

Acquired Immunodeficiency Syndrome↗