Prospective cohort study

Improved detection of PTH imbalance may benefit dialysis patients.

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New data demonstrate an association between lower levels of non-oxidized biologically active parathyroid hormone and increased mortality in hemodialysis patients, suggesting the need for improved assays.

“The current tests for parathyroid hormone levels overlook a key factor. When parathyroid hormone interacts with oxygen under conditions of stress such as end-stage kidney disease, it becomes biologically inactive,” researcherBerthold Hocher, MD, PhD, of the University of Potsdam in Germany, said in a press release.

Researchers conducted a prospective cohort study of 340 hemodialysis patients (224 men, 116 women; median age, 66 years) with end-stage CKD. They measured parathyroid hormone (PTH) levels using a third-generation intact parathyroid hormone electrochemiluminescence immunoassay system (ECLIA; Roche iPTH, Roche Diagnostics) directly and after prior removal of oxidized biologically inactive PTH using an antihuman oxidized parathyroid monoclonal antibody (Immundiagnostik AG).

During 5-year follow-up, 50% of the patients died. Cardiovascular diseaseaccounted for 60% of the deaths, according to the researchers, followed by infections (23%), cancer (11%) and unknown causes (6%).

Results revealed higher median non-oxidized biologically active PTH levels in those who survived (7.2 ng/L) vs. those who did not (5 ng/L; P=.002).

Survival was increased among patients in the highest tertile of non-oxidized biologically active PTH compared with the lowest (P=.0008). Additionally, in the highest tertile, median survival was 1,702 days compared with 453 days in the lowest tertile.

Data also showed that, after multivariable adjustment, older age appeared to increase risk for death, but higher levels of non-oxidized biologically active PTH decreased risk for death.

In an analysis of a subgroup of patients with intact PTH levels above the upper normal range of 70 ng/L at baseline, mortality appeared to be associated with oxidized biologically inactive PTH levels but not non-oxidized biologically active PTH levels.

“With more precise parathyroid hormone testing, health care professionals will have the information they need to improve clinical outcomes,” Hocher said. “The nephrology community has long recognized there is an issue with current testing approaches, and now we can solve this problem and improve patient care.”

Perceived job insecurity as a risk factor for incident coronary heart disease: systematic review and meta-analysis.

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Abstract

Objective To determine the association between self reported job insecurity and incident coronary heart disease.

Design A meta-analysis combining individual level data from a collaborative consortium and published studies identified by a systematic review.

Data sources We obtained individual level data from 13 cohort studies participating in the Individual-Participant-Data Meta-analysis in Working Populations Consortium. Four published prospective cohort studies were identified by searches of Medline (to August 2012) and Embase databases (to October 2012), supplemented by manual searches.

Review methods Prospective cohort studies that reported risk estimates for clinically verified incident coronary heart disease by the level of self reported job insecurity. Two independent reviewers extracted published data. Summary estimates of association were obtained using random effects models.

Results The literature search yielded four cohort studies. Together with 13 cohort studies with individual participant data, the meta-analysis comprised up to 174 438 participants with a mean follow-up of 9.7 years and 1892 incident cases of coronary heart disease. Age adjusted relative risk of high versus low job insecurity was 1.32 (95% confidence interval 1.09 to 1.59). The relative risk of job insecurity adjusted for sociodemographic and risk factors was 1.19 (1.00 to 1.42). There was no evidence of significant differences in this association by sex, age (<50 v ≥50 years), national unemployment rate, welfare regime, or job insecurity measure.

Conclusions The modest association between perceived job insecurity and incident coronary heart disease is partly attributable to poorer socioeconomic circumstances and less favourable risk factor profiles among people with job insecurity.

Source: BMJ

Elevated Glucose Levels Associated with Dementia.

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Higher glucose levels are associated with increased dementia risk, according to a prospective cohort study in the New England Journal of Medicine.

Researchers followed roughly 2100 people aged 65 and older who were free of dementia at baseline. Over a median follow-up of 6.8 years, patients had at least five measurements of glucose or glycated hemoglobin taken. About a quarter of patients developed dementia.

For all participants, the risk for dementia increased with increasing glucose readings. For patients without diabetes, an average glucose level of 115 mg/dL was associated with an 18% higher risk for dementia, compared with a level of 100 mg/dL. For those with diabetes, 190 mg/dL was associated with a 40% increased risk, relative to 160 mg/dL.

The authors speculate that microvascular disease of the central nervous system could contribute to the association.

Source: NEJM

Dietary cadmium exposure and prostate cancer incidence: a population-based prospective cohort study.

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Experimental data convincingly propose the toxic metal cadmium as a prostate carcinogen. Cadmium is widely dispersed into the environment and, consequently, food is contaminated.

Methods:

A population-based cohort of 41 089 Swedish men aged 45–79 years was followed prospectively from 1998 through 2009 to assess the association between food frequency questionnaire-based estimates of dietary cadmium exposure (at baseline, 1998) and incidence of prostate cancer (3085 cases, of which 894 were localised and 794 advanced) and through 2008 for prostate cancer mortality (326 fatal cases).

Results:

Mean dietary cadmium exposure was 19 μg per day±s.d. 3.7. Multivariable-adjusted dietary cadmium exposure was positively associated with overall prostate cancer, comparing extreme tertiles; rate ratio (RR) 1.13 (95% confidence interval (CI): 1.03–1.24). For subtypes of prostate cancer, the RR was 1.29 (95% CI: 1.08–1.53) for localised, 1.05 (95% CI: 0.87–1.25) for advanced, and 1.14 (95% CI: 0.86–1.51) for fatal cases. No statistically significant difference was observed in the multivariable-adjusted risk estimates between tumour subtypes (Pheterogeneity=0.27). For localised prostate cancer, RR was 1.55 (1.16–2.08) among men with a small waist circumference and RR 1.45 (1.15, 1.83) among ever smokers.

Conclusion:

Our findings provide support that dietary cadmium exposure may have a role in prostate cancer development.

Source: British journal of oncology

 

Keywords:

dietary cadmium; epidemiology; prospective cohort; prostate cancer; subtypes