Background It is unclear if bronchopulmonary dysplasia (BPD) is independently associated with reduced expiratory airflow at school age. Objective To determine the independent associations of moderate–severe BPD, mild BPD, gestational age and birth weight z-score with expiratory airflow in children born extremely preterm (EP; <28 weeks’ gestation). Methods All EP survivors born in Victoria, Australia, in three eras (1991–1992, n=225; 1997, n=151; and 2005, n=170) were recruited at birth and 418/546 (77%) had valid spirometry data at 8 years. BPD was classified as moderate–severe (oxygen requirement at 36 weeks’ postmenstrual age), or mild (oxygen >28 days but not at 36 weeks’ postmenstrual age). Expiratory airflow variables, including the forced expired volume in 1 s (FEV1), were measured and values converted to z-scores. Results Compared with no BPD (n=94), moderate–severe BPD (n=193) was associated with a substantial reduction in expiratory airflow (eg, zFEV1 mean difference −0.69, 95% CI −0.97 to –0.41; p<0.001), but mild BPD (n=131) was not (zFEV1 mean difference 0.01, 95% CI −0.28 to 0.31; p=0.93). On multivariable analysis, moderate–severe BPD remained strongly associated with reduced airflow (zFEV1 mean difference −0.63, 95% CI −0.92 to –0.33; p<0.001), but mild BPD (zFEV1 mean difference 0.04, 95% CI −0.26 to 0.34; p=0.27), gestational age (zFEV1 0.06 mean increase per week, 95% CI −0.05 to 0.17; p=0.29) and birth weight z-score (zFEV1 0.07 mean increase per SD, 95% CI −0.06 to 0.20; p=0.28) were not. Conclusions In children born EP, moderate–severe BPD, but not mild BPD was independently associated with reduced expiratory airflow at 8 years. All data relevant to the study are included in the article or uploaded as supplemental information.

中文翻译：

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后表面活性剂时代极早产儿 8 岁时的支气管肺发育不良和呼气气流

背景 目前尚不清楚支气管肺发育不良 (BPD) 是否与学龄期呼气气流减少独立相关。目的 确定中重度 BPD、轻度 BPD、胎龄和出生体重 z 评分与极早产儿（EP；<28 孕周）呼气气流的独立关联。方法 在三个时代（1991-1992，n=225；1997，n=151；和 2005，n=170）出生于澳大利亚维多利亚的所有 EP 幸存者在出生时被招募，418/546 (77%) 进行了有效的肺活量测定8 年的数据。BPD 分为中度至重度（停经后 36 周时的氧气需求）或轻度（停经后 36 周时需氧 >28 天，但不需要）。测量呼气气流变量，包括 1 秒内的用力呼气量 (FEV1)，并将值转换为 z 分数。结果 与无 BPD (n=94) 相比，中重度 BPD (n=193) 与呼气气流显着减少相关（例如，zFEV1 平均差 -0.69，95% CI -0.97 至 –0.41；p<0.001 )，但轻度 BPD (n=131) 并非如此（zFEV1 平均差 0.01，95% CI -0.28 至 0.31；p=0.93）。在多变量分析中，中重度 BPD 仍然与气流减少密切相关（zFEV1 平均差 -0.63，95% CI -0.92 至 –0.33；p<0.001），但轻度 BPD（zFEV1 平均差 0.04，95% CI -0.26 至0.34；p=0.27）、胎龄（zFEV1 每周平均增加 0.06，95% CI -0.05 至 0.17；p=0.29）和出生体重 z 评分（zFEV1 平均增加 0.07 每标准差，95% CI -0.06 至 0.20 ; p=0.28) 不是。结论 在 EP 出生的儿童中，中度至重度 BPD，而非轻度 BPD 与 8 岁时呼气气流减少独立相关。