Childhood leukaemia and socioeconomic status: what is the evidence?

The objectives of this systematic review are to summarise the current literature on socioeconomic status (SES) and the risk of childhood leukaemia, to highlight methodological problems and formulate recommendations for future research. Starting from the systematic review of Poole et al. (Socioeconomic status and childhood leukaemia: a review. Int. J. Epidemiol. 2006;35(2):370-384.), an electronic literature search was performed covering August 2002-April 2008. It showed that (1) the results are heterogeneous, with no clear evidence to support a relation between SES and childhood leukaemia; (2) a number of factors, most importantly selection bias, might explain inconsistencies between studies; (3) there is some support for an association between SES at birth (rather than later in childhood) and childhood leukaemia and (4) if there are any associations, these are weak, limited to the most extreme SES groups (the 10-20% most or least deprived). This makes it unlikely that they would act as strong confounders in research addressing associations between other exposures and childhood leukaemia. Future research should minimise case and control selection bias, distinguish between different SES measures and leukaemia subtypes and consider timing of exposures and cancer outcome

Association between reported exposure to road traffic and respiratory symptoms in children: evidence of bias

Background Many studies showing effects of traffic-related air pollution on health rely on self-reported exposure, which may be inaccurate. We estimated the association between self-reported exposure to road traffic and respiratory symptoms in preschool children, and investigated whether the effect could have been caused by reporting bias. Methods In a random sample of 8700 preschool children in Leicestershire, UK, exposure to road traffic and respiratory symptoms were assessed by a postal questionnaire (response rate 80%). The association between traffic exposure and respiratory outcomes was assessed using unconditional logistic regression and conditional regression models (matching by postcode). Results Prevalence odds ratios (95% confidence intervals) for self-reported road traffic exposure, comparing the categories ‘moderate' and ‘dense', respectively, with ‘little or no' were for current wheezing: 1.26 (1.13-1.42) and 1.30 (1.09-1.55); chronic rhinitis: 1.18 (1.05-1.31) and 1.31 (1.11-1.56); night cough: 1.17 (1.04-1.32) and 1.36 (1.14-1.62); and bronchodilator use: 1.20 (1.04-1.38) and 1.18 (0.95-1.46). Matched analysis only comparing symptomatic and asymptomatic children living at the same postcode (thus exposed to similar road traffic) showed similar ORs, suggesting that parents of children with respiratory symptoms reported more road traffic than parents of asymptomatic children. Conclusions Our study suggests that reporting bias could explain some or even all the association between reported exposure to road traffic and disease. Over-reporting of exposure by only 10% of parents of symptomatic children would be sufficient to produce the effect sizes shown in this study. Future research should be based only on objective measurements of traffic exposur

Nuclear power plants and childhood leukaemia: lessons from the past and future directions

In the 1980s, leukaemia clusters were discovered around nuclear fuel reprocessing plants in Sellafield and Dounreay in the United Kingdom. This raised public concern about the risk of childhood leukaemia near nuclear power plants (NPPs). Since then, the topic has been well-studied, but methodological limitations make results difficult to interpret. Our review aims to: (1.) summarise current evidence on the relationship between NPPs and risk of childhood leukaemia, with a focus on the Swiss CANUPIS (Childhood cancer and nuclear power plants in Switzerland) study; (2.) discuss the limitations of previous research; and (3.) suggest directions for future research. There are various reasons that previous studies produced inconclusive results. These include: inadequate study designs and limited statistical power due to the low prevalence of exposure (living near a NPP) and outcome (leukaemia); lack of accurate exposure estimates; limited knowledge of the aetiology of childhood leukaemia, particularly of vulnerable time windows and latent periods; use of residential location at time of diagnosis only and lack of data on address histories; and inability to adjust for potential confounders. We conclude that risk of childhood leukaemia around NPPs should continue to be monitored and that study designs should be improved and standardised. Data should be pooled internationally to increase the statistical power. More research needs to be done on other putative risk factors for childhood cancer such as low-dose ionizing radiation, exposure to certain chemicals and exposure to infections. Studies should be designed to allow examining multiple exposures

Long-term social and professional outcomes in adults after pediatric kidney failure.

BACKGROUND Little is known about the long-term social and professional outcomes in adults after pediatric kidney replacement therapy (KRT). In this study, we described social and professional outcomes of adults after kidney failure during childhood and compared these outcomes with the general population. METHODS We sent a questionnaire to 143 individuals registered in the Swiss Pediatric Renal Registry (SPRR) with KRT starting before the age of 18 years. In the questionnaire, we assessed social (partner relationship, living situation, having children) and professional (education, employment) outcomes. Logistic regression models adjusted for age at study and sex were used to compare outcomes with a representative sample of the Swiss general population and to identify socio-demographic and clinical characteristics associated with adverse outcomes. RESULTS Our study included 80 patients (response rate 56%) with a mean age of 39 years (range 19-63). Compared to the general population, study participants were more likely to not have a partner (OR = 3.7, 95%CI 2.3-5.9), live alone (OR = 2.5, 95%CI 1.5-4.1), not have children (OR = 6.8, 95%CI 3.3-14.0), and be unemployed (OR = 3.9, 95%CI 1.8-8.6). No differences were found for educational achievement (p = 0.876). Participants on dialysis at time of study were more often unemployed compared to transplanted participants (OR = 5.0, 95%CI 1.2-21.4) and participants with > 1 kidney transplantation more often had a lower education (OR = 3.2, 95%CI 1.0-10.2). CONCLUSIONS Adults after pediatric kidney failure are at risk to experience adverse social and professional outcomes. Increased awareness among healthcare professionals and additional psycho-social support could contribute to mitigate those risks. A higher resolution version of the Graphical abstract is available as Supplementary information

Breastfeeding and Respiratory Tract Infections during the First 2 Years of Life.

Breastfeeding protects against respiratory tract infections (RTIs) in infants [1–3], but whether its effects persist beyond that age is not well understood. Some studies have reported that protection diminishes soon after weaning [2], while others have found that it extends until the age of 2 years [4] or more [5, 6]. It is noteworthy that many previous studies grouped RTIs broadly into upper or lower tract infections, rather than studying specific diseases [3, 7], and few adjusted adequately for confounding factors [5] or investigated a possible effect modification by sex, which had been suggested by several studies showing a stronger protection in girls [8, 9]. This study aimed to quantify the protective effect of breastfeeding against RTIs during the first 2 years of life, while adjusting for potential confounding factors and testing whether the effect varied by sex. We analysed data from the Leicester Respiratory Cohorts, a population-based random sample of children from Leicestershire, UK, which has been described in detail elsewhere [10]. For this analysis we included only children born between 1996 and 1997 who were aged 1–1.99 years at the date of the first survey in 1998. Parents completed a standardised questionnaire that requested detailed information on breastfeeding and respiratory symptoms. We assessed the duration of breastfeeding (no breastfeeding, ⩽6 months or >6 months), the prevalence of frequent colds (>6 episodes), ear infections and croup within the last 12 months, and any episodes of bronchiolitis or pneumonia. We extracted perinatal data and demographic information from maternity records. The Leicestershire Health Authority Research Ethics Committee approved the study. The survey requested information on a number of RTIs for each child, so we first performed an omnibus logistic regression to determine whether breastfeeding was associated with the occurrence of any RTI. By reforming the data into long format, this omnibus logistic regression also adjusted for the clustering of observations within each child [11]. Following a significant omnibus test, we performed unadjusted and adjusted logistic regressions to determine which RTIs were affected by breastfeeding practice. Adjusted models controlled for sex, ethnicity, socioeconomic status (Townsend deprivation score [12]), perinatal factors (gestational age, birthweight, birth season), environmental factors ( pre- and post-natal maternal smoking, number of older siblings, day care attendance) and parental history of asthma, hay fever and bronchitis. We tested for effect modification by sex by adding interaction terms into adjusted models. Finally, we performed a sensitivity analysis including a subgroup of children with information on exact breastfeeding duration, by using breastfeeding as a continuous exposure, rather than categorical. All analyses were performed in Stata (version 14.2, Stata Corporation, Austin, TX, USA). The survey in 1998 was sent to 5400 families with children aged between 1 and 1.99 years. Questionnaires were returned by 4100 parents (response rate of 76%). After excluding 47 children who had no breastfeeding information and 13 children born extremely prematurely (gestational age of <28 weeks [13]), 4040 children remained in the analysis. Of these, 52% were boys, 81% were white and 19% were of South Asian ethnic origin, 1659 (41%) had never been breastfed, 1639 (41%) had been breastfed for ⩽6 months and 742 (18%) for >6 months. Of the 4040 included children, 769 (19%) were reported by their parents to have had frequent colds, 1685 (42%) ear infections and 293 (7%) croup within the last 12 months. Any episodes of bronchiolitis were reported for 453 children (11%) and pneumonia for 53 (1%)Peer-reviewedPublisher Versio

Health-related quality of life in adults after pediatric kidney failure in Switzerland.

BACKGROUND Little is known about health-related quality of life (HRQoL) in adults after kidney failure during childhood. In this study, we analyzed HRQoL of adults after pediatric kidney failure in Switzerland and investigated socio-demographic and clinical factors associated with HRQoL. METHODS In this cohort study, we sent questionnaires to 143 eligible patients registered in the Swiss Pediatric Renal Registry with continuous kidney replacement therapy starting before the age of 18 years. We assessed HRQoL using the Short-Form 36 version 1, compared HRQoL scores between our sample and the Swiss general population, and used linear regression models to examine socio-demographic and clinical factors associated with HRQoL. RESULTS We included 79 patients (response rate 55%) with a mean age of 38.6 years (range 19.4-63.1). Compared to the general population, HRQoL scores were lower for physical functioning (- 12.43, p < 0.001), role physical (- 13.85, p = 0.001), general health (- 14.42, p < 0.001), vitality (- 4.98, p = 0.035), and physical HRQoL (- 6.11, p < 0.001), but we found no difference in mental HRQoL (- 0.13, p = 0.932). The socio-demographic factors-lower education, unemployment, and not being in a relationship-were associated with lower HRQoL. The only clinical factor associated with HRQoL was the type of kidney disease. Patients with acquired kidney diseases had lower mental HRQoL than patients with congenital anomalies of the kidney and urinary tract (- 11.4, p = 0.007) or monogenetic hereditary diseases (- 9.5, p = 0.018). CONCLUSIONS Adults after pediatric kidney failure in Switzerland have lower physical, but similar mental HRQoL compared to the general population. Subgroups may require special attention with regard to their HRQoL. A higher resolution version of the Graphical abstract is available as Supplementary information