Data_Sheet_1_Regression discontinuity design for the study of health effects of exposures acting early in life.pdf

Regression discontinuity design (RDD) is a quasi-experimental approach to study the causal effect of an exposure on later outcomes by exploiting the discontinuity in the exposure probability at an assignment variable cut-off. With the intent of facilitating the use of RDD in the Developmental Origins of Health and Disease (DOHaD) research, we describe the main aspects of the study design and review the studies, assignment variables and exposures that have been investigated to identify short- and long-term health effects of early life exposures. We also provide a brief overview of some of the methodological considerations for the RDD identification using an example of a DOHaD study. An increasing number of studies investigating the effects of early life environmental stressors on health outcomes use RDD, mostly in the context of education, social and welfare policies, healthcare organization and insurance, and clinical management. Age and calendar time are the mostly used assignment variables to study the effects of various early life policies and programs, shock events and guidelines. Maternal and newborn characteristics, such as age, birth weight and gestational age are frequently used assignment variables to study the effects of the type of neonatal care, health insurance, and newborn benefits, while socioeconomic measures have been used to study the effects of social and welfare programs. RDD has advantages, including intuitive interpretation, and transparent and simple graphical representation. It provides valid causal estimates if the assumptions, relatively weak compared to other non-experimental study designs, are met. Its use to study health effects of exposures acting early in life has been limited to studies based on registries and administrative databases, while birth cohort data has not been exploited so far using this design. Local causal effect around the cut-off, difficulty in reaching high statistical power compared to other study designs, and the rarity of settings outside of policy and program evaluations hamper the widespread use of RDD in the DOHaD research. Still, the assignment variables’ cut-offs for exposures applied in previous studies can be used, if appropriate, in other settings and with additional outcomes to address different research questions.</p

Cumulative mortality from prostate cancer by APC and GSTP1 methylation status in the non-neoplastic tissue adjacent to the tumour.

<p>Cumulative mortality from prostate cancer by APC and GSTP1 methylation status in the non-neoplastic tissue adjacent to the tumour.</p

Factors associated with gene methylation in non-neoplastic tissue adjacent to the tumour (NTAT).

a<p>POR, prevalence odds ratio adjusted for age (categorised as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0068162#pone-0068162-t001" target="_blank">Table 1</a>), source of tumour tissue (biopsy, prostatectomy, TURP), calendar year of diagnosis (1980s, 1990s); Gleason score was introduced in the model as alternative to tumour tissue methylation in APC and GSTP1; CI, confidence interval.</p

Selected characteristics of the 157 study subjects with prostate cancer.

a<p>TURP, transurethral resection of the prostate;</p><p>NTAT, non-neoplastic tissue adjacent to the tumour.</p

Primers and probes used for the real-time PCR.

a<p>GSTP1, glutathione S-transferase; APC, adenomatous polyposis coli.</p

Hazard ratios (HR) and 95% confidence intervals (CI) of prostate cancer mortality for methylation of APC and GSTP1 in the non-neoplastic tissue adjacent to the tumour (NTAT).

a<p>N, number of prostate cancer deaths.</p>b<p>HR, hazard ratio adjusted for age, calendar year at diagnosis, source of tumour tissue.</p>c<p>HR, hazard ratio adjusted for age, calendar year at diagnosis, source of tumour tissue, and methylation in tumour tissue.</p>d<p>HR, hazard ratio adjusted for age, calendar year at diagnosis, source of tumour tissue, methylation in tumour tissue and Gleason score.</p

LINE-1 methylation status in prostate cancer and non-neoplastic tissue adjacent to tumor in association with mortality

<p>Aberrant DNA methylation seems to be associated with prostate cancer behavior. We investigated LINE-1 methylation in prostate cancer and non-neoplastic tissue adjacent to tumor (NTAT) in association with mortality from prostate cancer. We selected 157 prostate cancer patients with available NTAT from 2 cohorts of patients diagnosed between 1982–1988 and 1993–1996, followed up until 2010. An association between LINE-1 hypomethylation and prostate cancer mortality in tumor was suggested [hazard ratio per 5% decrease in LINE-1 methylation levels: 1.40, 95% confidence interval (CI): 0.95–2.01]. After stratification of the patients for Gleason score, the association was present only for those with a Gleason score of at least 8. Among these, low (<75%) vs. high (>80%) LINE-1 methylation was associated with a hazard ratio of 4.68 (95% CI: 1.03–21.34). LINE-1 methylation in the NTAT was not associated with prostate cancer mortality. Our results are consistent with the hypothesis that tumor tissue global hypomethylation may be a late event in prostate cancerogenesis and is associated with tumor progression.</p

Association between indicators of fertility and risk of testicular cancer.

<p>Association between indicators of fertility and risk of testicular cancer.</p

Selected characteristics of cases and controls.

<p>Selected characteristics of cases and controls.</p

Assessment of effect modification of KITLG on number of children fathered.

<p>Assessment of effect modification of KITLG on number of children fathered.</p