American journal of epidemiology
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Data indicate an inverse association between dietary calcium and magnesium intakes and blood pressure (BP); however, much less is known about associations between urinary calcium and magnesium excretion and BP in general populations. The authors assessed the relation of BP to 24-hour excretion of calcium and magnesium in 2 cross-sectional studies. The International Study of Macro- and Micro-Nutrients and Blood Pressure (INTERMAP) comprised 4,679 persons aged 40-59 years from 17 population samples in China, Japan, the United Kingdom, and the United States, and the International Cooperative Study on Salt, Other Factors, and Blood Pressure (INTERSALT) comprised 10,067 persons aged 20-59 years from 52 samples around the world. ⋯ Qualitatively similar associations were observed in INTERSALT analyses. Associations between magnesium excretion and BP were small and nonsignificant for most of the models examined. The present data suggest that altered calcium homoeostasis, as exhibited by increased calcium excretion, is associated with higher BP levels.
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Preliminary evidence suggests that daytime sleepiness may predate clinical diagnosis of Parkinson disease. The authors examined daytime napping and nighttime sleeping durations, reported in 1996-1997 by 220,934 US NIH-AARP Diet and Health Study participants, in relation to Parkinson disease diagnoses at 3 clinical stages: established (cases diagnosed before 1995, n = 267), recent (1995-1999, n = 396), and prediagnostic (2000 and after, n = 770). Odds ratios and 95% confidence intervals were derived from multivariate logistic regression models. ⋯ Further control for health status or nighttime sleeping duration attenuated the association for established cases but made little difference for recent or prediagnostic cases. In the nighttime sleeping analysis, a clear U-shaped association with Parkinson disease was observed for established cases; however, this association was attenuated markedly for recent cases and disappeared for prediagnostic cases. This study supports the notion that daytime sleepiness, but not nighttime sleeping duration, is one of the early nonmotor symptoms of Parkinson disease.
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Lifestyle factors such as smoking, obesity, and level of physical activity predict low back pain (LBP) and sciatica. The authors investigated whether participating in sports, smoking, and being overweight or obese at 14 years of age predicted hospitalizations due to LBP or sciatica in adulthood. In 1980, at the age of 14 years, a total of 11,399 members of the 1966 Northern Finland Birth Cohort returned the postal questionnaire. ⋯ Among females, overweight was associated with an increased risk of second-time hospitalization for surgical treatment for sciatica (hazard ratio = 7.1, 95% confidence interval: 1.5, 34.4). Among males, smoking was associated with an increased risk of first-time nonsurgical hospitalization (hazard ratio = 1.8, 95% confidence interval: 1.2, 2.7) and second-time surgical hospitalization (hazard ratio = 3.2, 95% confidence interval: 1.2, 8.2). The authors found potentially modifiable risk factors in adolescence that predicted hospital treatments for low back disorders during adolescence and young adulthood.
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In randomized trials with follow-up, outcomes such as quality of life may be undefined for individuals who die before the follow-up is complete. In such settings, restricting analysis to those who survive can give rise to biased outcome comparisons. ⋯ They give both a sensitivity analysis technique and conditions under which a crude comparison provides a conservative estimate of the SACE. The method is illustrated using data from the ARDSnet (Acute Respiratory Distress Syndrome Network) clinical trial comparing low-volume ventilation and traditional ventilation methods for individuals with acute respiratory distress syndrome.