Clinical significance of microscopic polyangiitis with interstitial lung disease and bronchiectasis: probability of preexisting comorbidities

The association between pulmonary involvement and microscopic polyangiitis (MPA) has been increasingly recognized in recent years. Whether interstitial lung disease (ILD) and bronchiectasis (BE) are disease manifestations of MPA, preexisting comorbidities or important complications remains unclear. The purpose of this study was to determine the clinical characteristics and prognosis of MPA with pulmonary involvement to further guide clinical management. The data for 97 patients with a definitive diagnosis of MPA were retrospectively reviewed. The MPA diagnosis was based on the 2012 revised Chapel Hill Consensus Conference (CHCC) criteria. The baseline clinical information and laboratory parameters were collected and analysed at each patient’s initial diagnosis. Forty-seven out of the 97 (48.5%) patients who were diagnosed with MPA presented with pulmonary involvement, including 37 patients with ILD, 12 patients with BE and two patients with diffuse alveolar haemorrhage (DAH). ILD and BE antedated MPA in 56.76% and 75.00% of the patients, respectively. Compared with that in the MPA-BE group, the serum LDH level (222.86 ± 68.19 vs. 171.58 ± 31.43, <i>p</i> = .016) in the MPA-ILD group was significantly higher. In the multivariate Cox analysis, elevated serum creatinine (HR 4.08, confidence interval (CI) 1.38–12.05, <i>p</i> = .011) was an independent risk factor for shorter survival in MPA patients with pulmonary involvement, and treatment with glucocorticoid pulse cyclophosphamide therapy (HR 0.095, 95% CI 0.019–0.47, <i>p</i> = .004) was independently associated with prolonged survival. Among the patients in the MPA-ILD group, acute exacerbations of ILD (HR 4.55 CI 1.16–17.86, <i>p</i> = .029) and elevated serum creatinine (HR 4.95, CI 1.39–17.54, <i>p</i> = .014) were independently associated with a poor prognosis, and treatment with glucocorticoids (HR 0.057, 95% CI 0.012–0.28, <i>p</i> &lt; .001) was independently associated with significant prolongation of survival. Patients with MPA have a high prevalence of pulmonary involvement, and ILD is the most common subtype of MPA. ILD and BE can be considered preexisting comorbidities of MPA. Elevated serum creatinine was associated with shorter survival. However, remission induction regimens with glucocorticoids and/or immunosuppressants may improve this outcome.

近年来，肺受累与显微镜下多血管炎（microscopic polyangiitis, MPA）之间的关联已愈发得到学界认可。目前尚不明确间质性肺疾病（interstitial lung disease, ILD）与支气管扩张（bronchiectasis, BE）究竟属于MPA的疾病表型、既往合并症还是重要并发症。本研究旨在明确伴肺受累MPA患者的临床特征与预后，以进一步指导临床诊疗实践。本研究回顾性分析了97例经明确诊断的MPA患者的临床资料。MPA的诊断依据2012年修订版查珀尔希尔共识会议（Chapel Hill Consensus Conference, CHCC）标准。收集并分析所有患者初诊时的基线临床信息与实验室检测指标。97例确诊MPA患者中，47例（48.5%）存在肺受累，其中37例合并间质性肺疾病（ILD）、12例合并支气管扩张（BE），另有2例合并弥漫性肺泡出血（diffuse alveolar haemorrhage, DAH）。间质性肺疾病与支气管扩张分别在56.76%与75.00%的患者中先于MPA发生。与支气管扩张合并MPA组相比，间质性肺疾病合并MPA组患者的血清乳酸脱氢酶（lactate dehydrogenase, LDH）水平显著更高（222.86±68.19 vs. 171.58±31.43，P=0.016）。多变量Cox分析显示，血清肌酐升高（风险比hazard ratio, HR 4.08，95%置信区间confidence interval, CI 1.38~12.05，P=0.011）是伴肺受累MPA患者生存期缩短的独立危险因素；而糖皮质激素冲击联合环磷酰胺治疗（HR 0.095，95%CI 0.019~0.47，P=0.004）与患者生存期延长独立相关。在间质性肺疾病合并MPA组患者中，间质性肺疾病急性加重（HR 4.55，95%CI 1.16~17.86，P=0.029）与血清肌酐升高（HR 4.95，95%CI 1.39~17.54，P=0.014）均为预后不良的独立危险因素；而糖皮质激素治疗（HR 0.057，95%CI 0.012~0.28，P<0.001）与生存期显著延长独立相关。MPA患者肺受累的患病率较高，其中间质性肺疾病是最常见的肺受累亚型。间质性肺疾病与支气管扩张可被视为MPA的既往合并症。血清肌酐升高与生存期缩短相关，而采用糖皮质激素联合或不联合免疫抑制剂的诱导缓解方案可改善此类患者的预后。