本帖最後由 lsc0019 於 2009-4-18 10:57 編輯
作者：Deborah Brauser
出處：WebMD醫學新聞
April 3, 2009 — 根據4月版Environmental Health期刊的前溯世代研究結果，年長婦女若有較高的血鉛濃度，死亡風險會增加，特別是有冠心病(CHD)的人。
賓州匹茲堡大學流行病學系的Naila Khalil博士寫道，鉛是一種「多重標的毒素」，會影響心血管、腎臟、神經系統，甚至會造成這些系統發病而死亡。儘管在過去30年間，血鉛濃度下降，環境鉛曝露仍然是個公共衛生問題。
作者指出，在職業基礎與環境基礎世代中，均發現鉛與死亡率之間的關聯。作者寫道，在本研究中，我們的目標在確認血鉛與年長社區婦女各種原因死亡、血鉛特定死亡之間的關係。
Khalil博士及其團隊評估533名年紀在65至87歲的婦女(平均年紀72.5 ± 4.4歲；範圍68至89歲)，從1986到1988年納入Study of Osteoporotic Fractures這個研究，追蹤超過12年。
以原子吸收分光光譜儀測量血鉛濃度，分類為小於8 μg/dL或者大於8 μg/dL(相當於0.384 μmol/L)。使用Cox比例涉險迴歸分析各種原因死亡與特定原因死亡的相對風險。
此外，每個研究對象於開始時完成有關教育、抽菸和/或飲酒、散步運動、糖尿病、高血壓以及目前使用雌激素狀況等的問卷。根據死亡證明、醫院出院摘要確認死亡的共有41名病患 (33%)。
研究結果顯示，血鉛濃度大於8 μg/dL者，因CHD而死亡的風險，是血鉛濃度小於8 μg/dL者的將近3倍。
研究婦女之平均血鉛濃度是5.3 ± 2.3 μg/dL (範圍：1 – 21 μg/dL)。在95%以上完成12.0 ± 3年的追蹤之後，總共有123人(23%)死亡。這些婦女的血鉛濃度為5.56 ± 3 μg/dL (0.27 ± 0.14 μmol/L)，比存活者的5.17 ± 2.0 μg/dL (0.25 ± 0.1 μmol/L; P = .09)高出7%。
此外，相較於血鉛濃度小於8 μg/dL者，血鉛濃度高於8 μg/dL者，多變項校正各種原因死亡率風險增加59%(風險比[HR]為1.59；95%信心區間[CI]為1.02 – 2.49；P = .041)，CHD死亡率風險高3倍(HR，3.08；95% CI，1.23 – 7.70；P = .016)。
與存活者相較，死亡的婦女較年長、比較可能抽菸、有高血壓。死亡婦女則較少有散步運動。血鉛濃度大於8 μg/dL者，飲酒量和抽菸比率也較高，且髖骨骨質密度較低了8%。
血鉛濃度和中風、癌症或者非心血管死亡之間沒有關聯。
研究限制包括，研究對象只有白人婦女，所以研究發現無法運用到非白人的女性或男性。其他限制包括，也和心血管疾病有關的污染物，如鎘，並未被測量是否有同時出現；未測量因為鉛濃度不同而不同的因素，導致結果可能有誤；只有33%的死亡案例具有死亡證明與出院摘要，這可能對死因的分類結果造成錯誤。
研究作者結論表示，我們的研究將[National Health and Nutritional Examination Survey]第三次研究之結果延伸到社區年長女性。就我們所知，這是首次探究此關聯的研究。我們的結果指出，現有有關鉛對年長者健康之不良影響的證據，比較屬於歷史性的環境鉛曝露。
多位研究作者宣告財務關係。這些宣告的完整列表可見於原始文獻中。
Environ Health. 線上發表於2009年4月3日。
Elevated Blood Lead Concentrations Associated With Higher Mortality From Coronary Heart Disease for Older Women
By Deborah Brauser
Medscape Medical News
April 3, 2009 — Older women with higher concentrations of blood lead have an increased risk for death, especially from coronary heart disease (CHD), according to the results of a prospective cohort study reported in the April issue of Environmental Health.
"Lead is a multitargeted toxicant, affecting cardiovascular, renal, and nervous systems, and may contribute to morbidity and mortality through its adverse impacts on these systems," write Naila Khalil, PhD, from the Department of Epidemiology at the University of Pittsburgh, Pennsylvania, and colleagues. "Despite declines in blood lead concentrations during the past 30 years, environmental lead exposure continues to be a public health concern."
The authors note that associations between lead and mortality have been observed previously in both occupational and community-based cohorts. In this study, "We aimed to determine the association between blood lead, and all cause and cause specific mortality in elderly, community residing women," write the authors.
Dr. Khalil and her team evaluated a cohort of 533 women aged 65 to 87 years (mean age, 72.5 ± 4.4 years; range, 68 – 89 years) who were enrolled in the Study of Osteoporotic Fractures at research centers in Baltimore, Maryland, and Monongahela Valley, Pennsylvania, from 1986 to 1988 and were followed up for more than 12 years.
Blood lead concentrations were determined by atomic absorption spectrometry and categorized as either less than 8 μg/dL or 8 μg/dL or higher (0.384 μmol/L for both). Relative risk for all-cause and cause-specific mortality were determined through Cox proportional hazards regression analysis.
Also, each participant completed a baseline questionnaire about education, smoking and/or alcohol use, walking for disease, diabetes, hypertension, and current estrogen use. Deaths were confirmed by death certificates, and hospital discharge summaries were obtained for 41 patients who died (33%).
Study results showed that those with blood lead concentrations higher than 8 μg/dL had an increased risk for mortality and were 3 times more likely to die from CHD compared with participants who had blood lead concentrations lower than 8 μg/dL.
The mean blood lead concentration of the women studied was 5.3 ± 2.3 μg/dL (range, 1 – 21 μg/dL). After 12.0 ± 3 years of greater than 95% complete follow-up, a total of 123 participants (23%) died. These women had a 7% higher mean (± standard deviation) blood lead concentration at 5.56 ± 3 μg/dL (0.27 ± 0.14 μmol/L) than survivors at 5.17 ± 2.0 μg/dL (0.25 ± 0.1 μmol/L; P = .09).
In addition, those with blood lead concentrations of 8 μg/dL or higher had a 59% increased risk for multivariate adjusted all-cause mortality (hazard ratio [HR], 1.59; 95% confidence interval [CI], 1.02 – 2.49; P = .041) and a 3-fold higher risk for CHD mortality (HR, 3.08; 95% CI, 1.23 – 7.70; P = .016) compared with women with blood lead concentrations lower than 8 μg/dL.
Compared with the survivors, women who died were older, more likely to smoke, and had hypertension. A lower proportion of women who died had reported walking for exercise.
Participants with lead concentration of 8 μg/dL or higher had higher alcohol intake, were likely to smoke, and had 8% lower hip bone mineral density.
There was no association between blood lead level and stroke, cancer, or noncardiovascular death.
Study limitations include participation being limited to white women, so the findings may not apply to nonwhite women or men. Other limitations include that the presence of co-contaminants such as cadmium, which might be associated with cardiovascular disease, were not determined; factors that differ by lead concentrations were not measured, leading to a possible confounding of the results; and that a reliance on death certificates and discharge summaries available for only 33% of the participants may have resulted in some misclassification of cause of death.
"Our study extends the findings of higher mortality associated with blood lead concentrations from [National Health and Nutritional Examination Survey] III surveys to community dwelling older women," conclude the study authors. "To our knowledge, this is the first study to look at [this association]. Our results add to the existing evidence of adverse affects of lead on health as seen in an older cohort who experienced greater historic environment lead exposure."
Several of the study authors have disclosed financial relationships. A complete list of these disclosures is available in the original article.
Environ Health. Published online April 3 2009. |
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