支气管扩张或可预测COPD患者死亡

一项西班牙研究显示，仅凭支气管扩张即可预测中至重度慢性阻塞性肺病(COPD)患者的死亡率，且独立于肺功能和其他危险因素。这一结果意味着“支气管扩张可被视为新的COPD预后因素”。这项研究发表在《美国呼吸与危重症医学杂志》2月7日在线版上(Am. J. Respir. Crit. Care Med. 2013 Feb. 7 [doi:10.1164/rccm.201208-1518OC])

主要研究者、西班牙瓦伦西亚大学医院的Miguel Angel Martínez-García博士表示，确认支气管扩张“具有重要的临床意义”，原因是高分辨率CT易于诊断这种情况，而且我们已掌握了针对其慢性支气管炎症和感染的有效治疗手段。这些患者应接受不同的诊断和治疗，因此可以被视为一种新的表型：COPD伴支气管扩张。

我们已知道支气管扩张与COPD患者更严重的急性加重、更频繁的细菌定植以及更严重的损伤相关。但对于支气管扩张与死亡率的关联——或者前者作为预后因素的可行性，我们之前并不清楚。

研究者对115例中至重度COPD伴支气管扩张患者和86例COPD不伴支气管扩张患者进行了随访。多数患者为男性，平均年龄为70岁左右，平均体重属于超重范围。平均吸烟史为60.7包-年，COPD病程超过10年。少数患者有结核或活动性肺炎病史。

结果显示，支气管扩张组有43例患者(37%)死亡，而无支气管扩张组仅死亡8例(9%)。COPD急性加重是最常见的死亡原因。

在校正呼吸困难、体重指数、潜在致病性呼吸道微生物及其他潜在混淆因素之后，研究者发现，COPD伴支气管扩张患者的死亡几率是COPD不伴支气管扩张患者的2.5倍[危险比(HR)，2.54；95置信区间(CI)，1.16~5.56；P=0.02]。

伴支气管扩张的患者还表现为“临床和功能方面的COPD病情更重，全身炎症指标浓度更高，以及气道中潜在致病性微生物(PPM)更多见”。支气管扩张组有59%(68例)患者分离出呼吸道PPM，而这一比例在无支气管扩张组中仅为20%(17例)。最常见的是流感嗜血杆菌，其次为铜绿假单胞菌。

研究者认为，细菌性呼吸道定植和随后发生的炎症，很可能在支气管扩张过程中起到了重要作用，而后者又反过来加剧细菌定植，从而形成恶性循环。但早期识别这一亚组患者并使用口服莫西沙星或吸入性抗生素，有可能打破这一恶性循环。

作者声称无相关利益冲突。Praxis制药资助了这项研究。

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By: M. ALEXANDER OTTO, Internal Medicine News Digital Network

Bronchiectasis alone predicted mortality in patients with moderate to severe chronic obstructive pulmonary disease, independent of pulmonary function and other risk factors, a study by Spanish investigators has shown.

That finding means that "bronchiectasis could be a new prognostic factor" for COPD, the study’s authors predicted.

Confirmation of bronchiectasis "would have a major clinical impact," because high-resolution CT can readily diagnose the condition, and effective therapy is available to treat the chronic bronchial inflammation and infection that plague patients, said lead investigator Dr. Miguel Angel Martínez-García of the Polytechnic and University La Fe Hospital in Valencia, Spain, and his colleagues (Am. J. Respir. Crit. Care Med. 2013 Feb. 7 [doi:10.1164/rccm.201208-1518OC]).

Conceivably, those patients could be "subject to different diagnostic and therapeutic approaches and, therefore, define a new phenotype": COPD with bronchiectasis, Dr. Martínez-García said.

Bronchiectasis is already known to be associated with worse exacerbations, more frequent bacterial colonizations, and greater degrees of impairment in COPD patients. But its relationship to mortality – or its utility as a prognostic factor – hasn’t been demonstrated until now, the researchers noted.

The investigators followed 115 patients with moderate to severe COPD and with bronchiectasis and 86 COPD patients without bronchiectasis for a median of 48 months. A total of 43 patients (37%) died in the bronchiectasis group, but only 8 patients (9%) in the nonbronchiectasis group died. COPD exacerbations were the most common cause of death.

COPD patients with bronchiectasis were 2.5 times more likely to die than those without bronchiectasis, after adjustment for factors such as dyspnea, body mass index, the presence of potentially pathogenic respiratory microorganisms, and other potential confounders (hazard ratio, 2.54; 95%CI: 1.16-5.56; P = .02).

Patients with bronchiectasis also presented with "a more severe form of COPD in clinical and functional terms, as well as a greater concentration of parameters of systemic inflammation and a greater presence of" potentially pathogenic microorganisms (PPMs) in their airways, the investigators said.

Bacterial respiratory colonization and subsequent inflammation probably play an important role in dilating the bronchioles and causing bronchiectasis – which leads to more colonization and a vicious cycle. But that cycle might "be broken by the early identification of this subgroup of patients" and the use of oral moxifloxacin or inhaled antibiotics, they said.

A total of 59% (68) of patients with bronchiectasis, but only 20% (17) of those without it, had PPM respiratory isolates, most commonly Haemophilus influenzae, followed by Pseudomonas aeruginosa.

Most of the patients were men and, on average, around 70 years old and overweight. Overall, they had an average smoking history of 60.7 pack-years and had COPD for more than decade. A minority of patients had tuberculosis histories or active pneumonia.

The authors said they had no relevant financial disclosures. Praxis Pharmaceutical funded the study.