主要终点显著降低？啥意思？

Some meta-analyses have suggested that steroids may reduce mortality and increase ventilator-free days in ARDS, particularly in patients treated within 14 days of onset,23–25indicating that the role of steroids should be further evaluated in early ARDS. Very recently, an unblinded, randomized, controlled trial of 277 patients comparing a 10-day regimen of dexamethasone with placebo in early ARDS (within 30 hours of meeting the Berlin Criteria) was conducted, demonstrating a significant decrease in the primary end point of ventilator-free days at 28 days (12.3?9.9 vs 7.5?9.0 days;P<.0001), and a secondary end point of all-cause mortality at 60 days (21% vs 36%;P<.0047).26However, some criticisms of this trial included slow enrollment occurring over 5 years, an inability to complete the planned enrollment, and the exclusion of a large number of patients.

一些荟萃分析表明，类固醇可能会降低 ARDS 的死亡率并增加无机械通气天数，特别是在发病 14 天内接受治疗的患者，表明应进一步评估类固醇在ARDS 早期使用的作用。最近，一项研究对277名患者进行了非盲、随机、对照试验，比较了地塞米松组与安慰剂组（10天方案）在早期 ARDS （在满足柏林标准后的30小时内）中的应用，结果表明主要预后28天时无机械通气天数(12.3±9.9天：7.5±9.0天；P<0.0001)主要终点显著降低，以及次要预后 60天死亡率(21%：36%；P<.0047)显着降低。然而，该研究的批评包括研究持续了5年以上、未完成计划的招募以及大量患者被排除在研究外。

主要终点显著降低？啥意思？无机械通气天数显著降低？