多种呼吸疾病致老年人死亡风险显著增加

圣安东尼奥——美国过敏、哮喘和免疫学会(AAAAI)2013年会上公布的第1次NHANES的随访结果显示，在基线时40~75岁的成人中观察到哮喘、过敏性疾病、阻塞性或限制性肺病导致远期全因死亡风险显著增加，但在基线时25~39岁的成人中未观察到这种情况。在这两个年龄组中均观察到哮喘导致远期呼吸原因死亡风险增加。研究者表示，这种关联不可能是由基础支气管炎或呼吸道感染死亡风险增加引起，而可能是由哮喘本身所致。

这项研究由波士顿布里格姆妇女医院的Jessica R. Savage博士及其同事进行，采用的数据来自1971~1975年全美健康和营养调查(NHANES)。该调查纳入31,937名成人，其中14,407人被纳入NHANESⅠ流行病学随访研究(NHEFS)，检查是否存在医生诊断的哮喘、过敏性鼻炎、食物过敏和荨麻疹。对一个包含6,913人的亚组进行了更详细的健康访谈和检查，包括支气管扩张剂前肺功能及用力呼气量与用力肺活量百分比预测值。2006年收集生命状况和死亡原因方面的数据。

在校正年龄、性别、收入、教育程度、种族和吸烟史后，对哮喘与死亡率之间的关联进行敏感性分析发现，基线时40~75岁的老年成人的远期死亡风险显著增加[危险比(HR)=1.22]，但在基线时25~29岁的年轻成人中未观察到这种情况(HR=1.20)。在排除诊断支气管炎的患者后，这两个年龄组的全因死亡HR均无统计学显著性(分别为1.16和1.52)。

老年组和年轻组哮喘与呼吸死亡之间关联的HR显著，分别为2.03和5.87。在排除支气管炎患者后，这两组的HR仍具有统计学显著性(分别为8.56和1.82)。

该研究还显示，诊断阻塞性肺病的老年患者的全因死亡和呼吸死亡风险均显著增加，并且诊断限制性肺病的老年患者的全因死亡和心血管死亡风险显著增加。

相反地，诊断荨麻疹的老年患者的心血管死亡风险降低。在诊断荨麻疹的年轻患者和诊断哮喘或中至重度肺阻塞的老年患者中观察到癌症相关死亡率出现轻微而非显著的增加。

研究者表示，过去30年来，美国的哮喘和过敏性疾病患者数量趋于增加。哮喘和过敏可直接损害肺功能，从而增加死亡风险，它们可能是导致全身炎症的免疫失调的标志物。该研究的主要结论是，诊断过敏的年轻成人的死亡风险未显著增加，虽然在年轻成人中观察到哮喘与呼吸死亡相关，但总体而言，年轻成人群体的风险较低。

NHEFS是由美国国立卫生统计中心和国立老化研究所联合美国公共卫生署的其他部门共同开展的一项计划。Savage博士声明无经济利益冲突。

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By: SHARON WORCESTER, Internal Medicine News Digital Network

SAN ANTONIO – A diagnosis of asthma, allergic disease, or obstructive or restrictive lung disease among participants in the first National Health and Nutrition Examination Survey conferred a significantly increased long-term risk of all-cause mortality for adults who were aged 40-75 years at baseline but not for those who were aged 25-39 years at baseline, according to findings from the study.

A diagnosis of asthma in the younger group conferred an increased long-term risk of death due to respiratory causes – as did a diagnosis of asthma in the older group, Dr. Jessica R. Savage reported in a poster at the annual meeting of the American Academy of Allergy, Asthma, and Immunology.

"This association was not likely explained by underlying bronchitis or an increased risk of death due to respiratory infection but was likely due to asthma itself," said Dr. Savage of Brigham and Women’s Hospital, Boston.

"I think the main conclusions are reassuring – no increase in mortality if you are young and have allergies. Some studies show an association between allergy and stroke/heart disease. We were worried that with the rising increase in allergy, there would be also an increase in these other diseases. But we did not see that, fortunately.

"We saw an association with asthma and respiratory death even in the young. Of course, one always needs to remember to be vigilant with asthmatics, but overall for young people the news is good," he said during an interview.

Data were obtained from the National Health and Nutrition Examination Survey (NHANES I), which was conducted from 1971 to 1975 and included 31,937 adults. Of these participants, 14,407 were included in the NHANES I Epidemiologic Follow-Up Study (NHEFS) and were assessed for doctor-diagnosed asthma, allergic rhinitis, food allergy, and urticaria. A subcohort of 6,913 subjects received a more detailed health interview and examination, including prebronchodilator spirometry and percent predicted forced expiratory volume and forced vital capacity. Vital status and cause of death were obtained in 2006.

After adjustment for age, gender, income, education, race, and smoking history, a sensitivity analysis for the association between asthma and mortality demonstrated a significantly increased long-term risk of death in those who were aged 40-75 years at baseline (hazard ratio, 1.22), but not for those aged 25-29 years at baseline (HR, 1.20). The hazard ratios for all-cause mortality in these groups, after exclusion of subjects with bronchitis were not statistically significant (1.16 and 1.52, respectively).

Hazard ratios for the association between asthma and respiratory mortality were significant at 2.03 and 5.87 for the older and younger groups, respectively. The hazard ratios for these groups remained statistically significant at 8.56 and 1.82, respectively, after exclusion of subjects with bronchitis.

This study also demonstrated that older subjects with obstructive lung disease were at significantly increased risk of both all-cause and respiratory mortality and that older subjects with restrictive lung disease were at significantly increased risk of both all-cause and cardiovascular mortality.

Conversely, older adults with urticaria had a reduced risk of cardiovascular mortality.

Cancer-related mortality was slightly, but not significantly, increased in the younger subjects diagnosed with urticaria, and in the older subjects diagnosed with asthma or moderate to severe lung obstruction.

"Asthma and allergic diseases, which typically manifest in childhood, have increased in the United States over the last 3 decades. Asthma and allergy may increase mortality by directly reducing lung function or may be markers of immune dysregulation that could lead to systemic inflammation," Dr. Savage noted, adding that although prior studies have demonstrated associations between allergic sensitization and stroke, hives and cancer, asthma and mortality, and obstructive lung disease and cardiovascular events, the effects of asthma and allergic disease on long-term mortality have been unclear.

"The findings (of this follow-up study) provide some insight regarding the effects of asthma and allergic disease on long-term mortality, Dr. Savage said.

The NHEFS is a joint project of the National Center for Health Statistics and the National Institute on Aging in collaboration with other agencies of the U.S. Public Health Service. Dr. Savage reported having no disclosures.