Heterogeneous effect of gestational weight gain on birth weight: quantile regression analysis from a population-based screening.

PURPOSE: Classical regression models might give an incomplete picture of the associations between predictors and outcomes. We investigated associations between gestational weight gain (GWG) and birth weight along the entire birth weight distribution with quantile regression and estimated effects of hypothetical prevention strategies. METHODS: The GWG-birth weight association was analyzed using quantile and classical regression models on data from a population-based gestational diabetes screening (n = 4760) at the Szent Imre Teaching Hospital in Budapest, Hungary (2002-2005). Birth weight distributions were modeled based on hypothetical GWG changes. RESULTS: At a body mass index of 20 kg/m(2), a 1-kg difference in GWG was associated with a 14.2 g (95% confidence interval, 10.0-20.9) higher birth weight at the fifth percentile of the birth weight distribution and a 29.0 g (21.3-35.6) higher birth weight at the 95th percentile. The coefficient from linear regression was 20.7 (17.5-24.0). Estimates differed modestly between the two regressions at a body mass index of 30 kg/m(2). A population-wide 2-kg decrease in GWG would rather affect the risk of macrosomia (-1.8%) than that of low birth weight (+0.4%). In contrast, a 3-kg decrease in GWG among overweight and obese women would lower macrosomia more modestly (-0.8%). CONCLUSIONS: A population-wide lowering of GWG would lead to greater improvements in the right tail of the birth weight distribution.

Investigating the relationship between mortality from respiratory diseases and childhood acute lymphoblastic leukaemia in Hungary.

Our aim was to investigate the ecological association between death from infectious disease of the respiratory system and the risk of acute lymphoid leukaemia (ALL) in children aged less than 7 years. Poisson regression analyses were carried out using overall data and gender-specific models. The study included 176 cases (92(52.3 %) boys and 84 (47.7 %) girls) of ALL in those aged 0-6 years in South Hungary. Eight cases were diagnosed before the age of 1 year. A significant risk of ALL disease was observed with higher levels of mortality from the chronic respiratory diseases (p = 0.035) and pneumonia (p = 0.010) among children aged 2-5 years (Odds Ratio for trend was 1.001 and 95%CI [1.000-1.002] and Odds ratio for trend was 1.013 and 95%CI [1.003-1.023], respectively). Significantly increased risk of childhood ALL was detected among children under 1 year of age residing in areas around birth with higher levels of mortality from influenza (Odds Ratio (OR) for trend was 1.05; 95%CI [1.01-1.09]; p = 0.012). This risk was also detected in girls (p < 0.001), but not in boys (p = 0.43). Our findings provide new evidence that will help to understand the different pattern of female and male childhood ALL occurrence , but further studies are needed using detailed individual medical history to clarify the role of influenza and other infectious diseases in the etiology of childhood ALL and to explain gender-specific effects.

The use of regression methods for the investigation of trends in suicide rates in Hungary between 1963 and 2011.

PURPOSE: Suicide rates in Hungary have been analyzed from different aspects in recent decades. However, only descriptive rates have been reported. The aim of our epidemiological study was to characterize the pattern of annual rates of suicide in Hungary during the period 1963-2011 by applying advanced statistical methods. METHODS: Annual suicide rates per 100,000 population (>6 years) for gender, age group and suicide method were determined from published frequency tables and reference population data obtained from the Hungarian Central Statistical Office. Trends and relative risks of suicide were investigated using negative binomial regression models overall and in stratified analyses (by gender, age group and suicide method). Joinpoint regression analyses were additionally applied to characterize trends and to find turning points during the period 1963-2011. RESULTS: Overall, 178,323 suicides (50,265 females and 128,058 males) were committed in Hungary during the investigated period. The risk of suicide was higher among males than females overall, in all age groups and for most suicide methods. The annual suicide rate exhibited a significant peak in 1982 and remained basically constant after 2006. Different segmented patterns were observed for the suicide rates in the various age groups. CONCLUSIONS: Suicide rates revealed segmented linear pattern. This is the first detailed trend analysis with risk estimates obtained via joinpoint and negative binomial regression methods simultaneously for age-specific suicide frequencies in Hungary.

Effect of secular trends on age-related trajectories of cardiovascular risk factors: the Whitehall II longitudinal study 1985-2009.

BACKGROUND: Secular trends in cardiovascular risk factors have been described, but few studies have examined simultaneously the effects of both ageing and secular trends within the same cohort. METHODS: Development of cardiovascular risk factors over the past three decades was analysed using serial measurements from 10 308 participants aged from 35 to 80 years over 25 years of follow-up from five clinical examination phases of the Whitehall II study. Changes of body mass index, waist circumference, blood pressure and total and high-density lipoprotein cholesterol distribution characteristics were analysed with quantile regression models in the 57-61 age group. Age-related trajectories of risk factors were assessed by fitting mixed-effects models with adjustment for year of birth to reveal secular trends. RESULTS: Average body mass index and waist circumference increased faster with age in women than in men, but the unfavourable secular trend was more marked in men. Distributions showed a fattening of the right tail in each consecutive phase, meaning a stronger increase in higher percentiles. Despite the higher obesity levels in younger birth cohorts, total cholesterol decreased markedly in the 57-61 age group along the entire distribution rather than in higher extremes only. CONCLUSION: The past three decades brought strong and heterogeneous changes in cardiovascular risk factor distributions. Secular trends appear to modify age-related trajectories of cardiovascular risk factors, which may be a source of bias in longitudinal analyses.

Seasonal variation of childhood acute lymphoblastic leukaemia is different between girls and boys.

The aim of this study was to investigate seasonal trends in the incidence of acute lymphoblastic leukaemia (ALL) around the times of birth and diagnosis in children aged 0-4 years and also to examine gender specific effects. Children born in South Hungary during 1981-1997 were analysed. Registrations of first malignancies for children, diagnosed under age 5 years before the end of 2002 were obtained from the Hungarian Paediatric Oncology Group providing a representative sample of Hungarian children over a 17 year period of time. Data were available on the corresponding numbers of births for each month of the study period were obtained. Statistical analyses were performed using logistic regression with harmonic components. The study analysed 121 cases of children, aged under 5 years, who were diagnosed with ALL. We found no seasonal effect related to date of diagnosis. However, there was seasonal variability for ALL related to date of birth. Maximal rates were seen in children born in February and August in the simple harmonic regression model for all children diagnosed with ALL. Analysis by gender found evidence of seasonality related to month of birth with peaks in February and August in boys, but different seasonal effects were seen for girls (peak in November, nadir in May). Our study provides some evidence that male specific immune responses to infections around the time of birth could explain the male predominance in the incidence of ALL.

Neuroblastoma in hungary.

In a cohort study we investigated the incidence and distribution of the age and stage of neuroblastoma at diagnosis, and the outcome, in children aged 0-14 years during 1988-1998 in Hungary. The proportion of neuroblastoma in age groups of 0 year old, 1-4 year old, 5-9 year old and 10-14 year old children was 30%, 53%, 12% and 5%, respectively. The proportion of stage 1-2, stage 3-4 and stage 4s cases was 30%, 65% and 3%, respectively. Hungarian data were compared with data reported for other Western European countries. The distribution of age at diagnosis of Hungarian cases was significantly different from France and Germany (p < 0.05), but not different from that of the United Kingdom (UK). However, the proportion of stage 1-2 neuroblastoma was higher in Hungarian children (30%) than that reported in French, German and UK children. The incidence and survival of neuroblastoma in Hungary is broadly comparable to that reported elsewhere in Europe.

Childhood acute lymphoblastic leukaemia in relation to population mixing around the time of birth in South Hungary.

In a retrospective epidemiological study of 481,984 live births in South Hungary, we investigated whether higher levels of population mixing around the time of birth is a risk factor for acute lymphoblastic leukemia (ALL) under age 5 years. Poisson regression was used to investigate the relationship between risk of ALL and the population-mixing index based on the number of incomers in each county district for each year, standardized to have a range of 0-1. Among all children, the risk of ALL increased significantly with increasing population mixing around the time of birth (trend across the range of 0-1 RR = 2.1 95% CI: 1.02-4.44). This effect was more marked for boys (RR = 3.1 95% CI: 1.13-8.51), which supports a sex-specific effect of exposures on risk of ALL.

Addictive behaviour of adolescents in secondary schools in Hungary.

OBJECTIVE: To investigate drug use among secondary schoolchildren aged 14-18 years in the city of Szeged in Hungary in order to observe and describe drug use, smoking and alcohol intake and to find risk factors for these behaviours. METHODS: The questionnaire was concerned with recreational drug use, smoking and drinking habits as well as family structure and life-style based upon the European School Project on Alcohol and Other Drugs questionnaire. Statistical methods used were the chi2 test and multiple logistic regression analysis. The standard errors were estimated using the Huber-White procedure. RESULTS: Overall 20% of schoolchildren reported experience of drug usage. Boys were significantly more likely to report drug use than girls (chi2=4.65; p=0.031). Cannabis was the most commonly reported drug used (96%). The proportion of drug users was significantly higher among those who had smoked (13%) or were current smokers (65%) compared to those who never smoked (1%; chi2=164.7; p<0.001). Moreover, the risk of drug use was significantly higher in those children who reported a drug user in the family (OR 9.3; 95% CI 4.3-19.9; p<0.001). CONCLUSIONS: Our findings support the hypothesis that strategies for the prevention of drug use should consider the association between drug and tobacco use.

Prevalence and risk factors of human papilloma virus infection in asymptomatic women in southeastern Hungary.

A survey was carried out to determine the prevalence of genital human papilloma virus (HPV) infection in asymptomatic women. The overall prevalence of HPV infection was 23%. Age (under 24 years), pathological cytology were significantly associated with exposure to HPV infection. HPV screening is important for young women, especially, where there is a pathological cytological diagnosis.

Childhood cancer in relation to infections in the community during pregnancy and around the time of birth.

In a retrospective cohort study of 404,106 live births in the northern region of England, 1975-1986, we investigated whether higher levels of community infections during the mother's pregnancy and in early life were risk factors for cancer, by diagnostic group (leukaemia and non-Hodgkin's lymphoma, Hodgkin's disease, brain/spinal tumours, neuroblastoma, other tumours), diagnosed 1975-2001 under age 15 years. Logistic regression was used to relate risk to measures of community infections (measles, respiratory and other infections) in 3 prenatal and 2 postnatal quarters. There was an increased risk of Hodgkin's disease among children exposed around birth to higher levels of measles (odds ratio for trend = 2.3, 95% confidence interval 1.3-4.2, p = 0.01). For other diagnostic groups, there was no consistent evidence of an association between risk and exposure to infections. Although the significant association observed for Hodgkin's disease may be a chance finding, consequent to multiple hypothesis testing or the ecologic nature of the study, it is consistent with other recent epidemiologic results suggesting that the risk of Hodgkin's disease may be associated with exposure to infections.