American journal of epidemiology
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Second malignancies in women diagnosed with thyroid cancer are of concern given the young average age at diagnosis and excellent survival. Data from the California Cancer Registry were used to evaluate the risk of second primary cancers among a retrospective population-based cohort of 10,932 women diagnosed with papillary thyroid cancer between 1988 and 1999. Follow-up was calculated from 2 months until the diagnosis of a second primary cancer, death, loss to follow-up, or December 31, 1999, whichever occurred first. ⋯ The incidence of invasive breast cancer was not elevated compared with California women overall (standardized incidence ratio (SIR) = 0.9, 95% confidence interval (CI): 0.7, 1.1) or when stratified by age, race/ethnicity, follow-up, or radiation treatment. An excess of in situ breast cancer (SIR = 1.6, 95% CI: 1.0, 2.4), kidney cancer (SIR = 3.9, 95% CI: 2.2, 6.3), and melanoma (SIR = 2.1, 95% CI: 1.3, 3.2) limited to the first 5 years after diagnosis was observed. Women with papillary thyroid cancer are at increased risk of in situ, but not invasive, breast cancer, kidney cancer, and melanoma.
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Comparative Study
Results of multivariable logistic regression, propensity matching, propensity adjustment, and propensity-based weighting under conditions of nonuniform effect.
Observational studies often provide the only available information about treatment effects. Control of confounding, however, remains challenging. The authors compared five methods for evaluating the effect of tissue plasminogen activator on death among 6,269 ischemic stroke patients registered in a German stroke registry: multivariable logistic regression, propensity score-matched analysis, regression adjustment with the propensity score, and two propensity score-based weighted methods-one estimating the treatment effect in the entire study population (inverse-probability-of-treatment weights), another in the treated population (standardized-mortality-ratio weights). ⋯ Exclusion of patients with a propensity score of <5% yielded comparable odds ratios of approximately 1 for all methods. High levels of nonuniform treatment effect render summary estimates very sensitive to the weighting system explicit or implicit in an adjustment technique. Researchers need to be clear about the population for which an overall treatment estimate is most suitable.
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Randomized Controlled Trial
Folate, vitamin B6, multivitamin supplements, and colorectal cancer risk in women.
The authors evaluated associations between intakes of folate and vitamin B(6) and colorectal cancer risk among women enrolled in a randomized trial on aspirin and vitamin E in disease prevention. At baseline (1992-1995), 37,916 US women aged >or=45 years who were free of cancer and cardiovascular disease provided dietary information. During an average of 10.1 years of follow-up (through February 20, 2004), 220 colorectal adenocarcinoma cases were documented. ⋯ The use of multivitamin supplements was not related to colorectal cancer risk. These findings suggest that higher dietary intakes of folate and vitamin B(6) may reduce the risk of colorectal cancer in women. An alternative explanation is that other factors related to dietary intakes of folate and vitamin B(6) account for the inverse associations.
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Using data from the current National Health and Nutrition Examination Survey (1999-2000), the authors assessed whether Helicobacter pylori infection is associated with iron deficiency and iron-deficiency anemia (IDA) in the United States. Iron deficiency was defined as at least two abnormal results out of three biomarkers of iron stores. IDA was defined as a low hemoglobin level in the presence of iron deficiency. ⋯ Multinomial logistic regression analyses indicated that H. pylori infection was associated with the prevalence of IDA (prevalence odds ratio (POR) = 2.6, 95% CI: 1.5, 4.6) and, to a lesser degree, other types of anemia (POR = 1.3, 95% CI: 1.0, 1.7). H. pylori infection was associated with a 40% increase in the prevalence of iron deficiency (POR = 1.4, 95% CI: 0.9, 2.0) after controlling for relevant covariates. In the United States, H. pylori infection was associated with iron deficiency/IDA regardless of the presence or absence of peptic ulcer disease.
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Transport noise is an increasingly prominent feature of the urban environment, making noise pollution an important environmental public health issue. This paper reports on the 2001-2003 RANCH project, the first cross-national epidemiologic study known to examine exposure-effect relations between aircraft and road traffic noise exposure and reading comprehension. Participants were 2,010 children aged 9-10 years from 89 schools around Amsterdam Schiphol, Madrid Barajas, and London Heathrow airports. ⋯ Aircraft noise exposure at home was highly correlated with aircraft noise exposure at school and demonstrated a similar linear association with impaired reading comprehension. Road traffic noise exposure at school was not associated with reading comprehension in either the absence or the presence of aircraft noise (beta = 0.003, p = 0.509; beta = 0.002, p = 0.540, respectively). Findings were consistent across the three countries, which varied with respect to a range of socioeconomic and environmental variables, thus offering robust evidence of a direct exposure-effect relation between aircraft noise and reading comprehension.