Adderley Nicola, Humphreys Christopher J, Barnes Hayley, Ley Brett, Premji Zahra A, Johannson Kerri A
Faculty of Medicine, University of Calgary, Calgary, AB, Canada.
Dept of Medicine, University of Calgary, Calgary, AB, Canada.
Eur Respir J. 2020 Aug 6;56(2). doi: 10.1183/13993003.00206-2020. Print 2020 Aug.
The role of bronchoalveolar lavage fluid (BALF) lymphocyte percentage in diagnosing chronic hypersensitivity pneumonitis (CHP) is unclear. We conducted a systematic review and meta-analysis of bronchoalveolar lavage (BAL) lymphocyte percentage in the diagnosis of CHP.
We searched Medline, Embase and the Cochrane Library from inception to August 2019. Individual patient data were obtained to test performance characteristics of BAL lymphocyte percentage at different thresholds. Random-effects models were used for pooled estimates, with comparisons made between CHP and non-CHP interstitial lung diseases (ILDs).
Fifty-three studies were included in the systematic review and 42 in the meta-analysis. The pooled estimate for BAL lymphocyte percentage was 42.8% (95% CI 37.7-47.8, I=95.3%) in CHP, 10.0% (95% CI 6.9-13.1, I=91.2%) in idiopathic pulmonary fibrosis (IPF), 23.1% (95% CI 3.0-43.2, I=85.2%) in non-IPF idiopathic interstitial pneumonia (IIP), 23.4% (95% CI 11.0-35.9, I=45.7%) in connective-tissue disease associated ILD (CTD-ILD) and 31.2% (95% CI 17.6-44.8, I=95.2%) in sarcoidosis. Results differed between CHP and IPF (p<0.0001), non-IPF IIP (p=0.0309) or CTD-ILD (p=0.0824), but not between CHP and sarcoidosis (p=0.0966). Using individual patient data from eight studies, a lymphocyte percentage threshold of >20% provided a sensitivity of 68.1% and a specificity of 64.8% for CHP. Higher thresholds provided lower sensitivity with higher specificity. Older age and ever having smoked were associated with lower lymphocyte percentage in CHP.
BAL lymphocyte percentage is higher in CHP compared to IPF and other IIPs, with higher thresholds providing improved specificity at the cost of sensitivity. However, the parent studies are at risk of incorporation bias and prospective studies should evaluate the additive discriminate value of BAL lymphocyte percentage to accurately diagnose CHP.
支气管肺泡灌洗术（BAL）中淋巴细胞百分比在诊断慢性过敏性肺炎（CHP）中的作用尚不清楚。我们对支气管肺泡灌洗（BAL）淋巴细胞百分比在CHP诊断中的应用进行了系统评价和荟萃分析。
检索了自建库起至2019年8月的Medline、Embase和Cochrane图书馆。获取个体患者数据以检测不同阈值下BAL淋巴细胞百分比的诊断性能特征。采用随机效应模型进行合并估计，比较CHP与非CHP间质性肺疾病（ILD）。
系统评价纳入53项研究，荟萃分析纳入42项研究。CHP中BAL淋巴细胞百分比的合并估计值为42.8%（95%CI 37.7 - 47.8，I² = 95.3%），特发性肺纤维化（IPF）中为10.0%（95%CI 6.9 - 13.1，I² = 91.2%），非IPF特发性间质性肺炎（IIP）中为23.1%（95%CI 3.0 - 43.2，I² = 85.2%），结缔组织病相关ILD（CTD - ILD）中为23.4%（95%CI 11.0 - 35.9，I² = 45.7%），结节病中为31.2%（95%CI 17.6 - 44.8，I² = 95.2%）。CHP与IPF（p < 0.0001）、非IPF IIP（p = 0.0309）或CTD - ILD（p = 0.0824）之间结果存在差异，但CHP与结节病之间无差异（p = 0.0966）。利用8项研究的个体患者数据，淋巴细胞百分比阈值>20%时，CHP的敏感性为68.1%，特异性为64.8%。较高的阈值敏感性较低，但特异性较高。年龄较大和曾经吸烟与CHP中较低的淋巴细胞百分比相关。
与IPF和其他IIP相比，CHP中BAL淋巴细胞百分比更高，较高的阈值以敏感性为代价提高了特异性。然而，原始研究存在纳入偏倚风险，前瞻性研究应评估BAL淋巴细胞百分比的附加鉴别价值以准确诊断CHP。
