BackgroundThe efficacy of neutrophil elastase inhibitor sivelestat in the treatment of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) remains controversial. A systematic review and meta-analysis were performed in accordance with the PRISMA guidelines assess the effect of sivelestat on ALI/ARDS patients, different studies were included.MethodsElectronic databases, National Knowledge Infrastructure (CNKI), Wan fang data, VIP, PubMed, Embase, Springer, Ovid and the Cochrane Library were searched using the following key words: (“Sivelestat” OR “Elaspol”) AND (“ARDS” OR “adult respiratory distress syndrome” OR “acute lung injury”). All databases published from January 2000 to August 2022. The treatment group was treated with sivelestat and the control group was given normal saline. The outcome measurements include the mortality of 28–30 days, mechanical ventilation time, ventilation free days, intensive care unit (ICU) stays, oxygenation index (PaO2/FiO2) on day 3, the incidence of adverse events. The literature search was conducted independently by 2 researchers using standardized methods. We used the Cochrane risk-of-bias tool to assess the quality of the included studies. Mean difference (MD), Standardized mean difference (SMD) and relative risk (RR) were calculated using random effects model or fixed effects model. All statistical analyses were performed using RevMan software 5.4.ResultsA total of 2050 patients were enrolled in 15 studies, including 1069 patients in treatment group and 981 patients in the control group. The results of the meta-analysis showed that: compared with the control group, sivelestat can reduce the mortality of 28–30 days (RR = 0.81, 95% CI = 0.66–0.98,p= 0.03) and the incidence of adverse events (RR = 0.91, 95% CI = 0.85–0.98,p= 0.01), shortened mechanical ventilation time (SMD = − 0.32, 95% CI = − 0.60 to − 0.04,p= 0.02) and ICU stays (SMD = − 0.72, 95% CI = − 0.92 to − 0.52,p< 0.00001), increased the ventilation free days (MD = 3.57, 95% CI = 3.42–3.73,p <0.00001) and improve oxygenation index (PaO2/FiO2) on day 3 (SMD = 0.88, 95% CI = 0.39–1.36,p= 0.0004).ConclusionsSivelestat can not only reduce the mortality of ALI/ARDS patients within 28–30 days and the incidence of adverse events, shorten the mechanical ventilation time and ICU stays, increase ventilation free days, but also improve the oxygenation index of patients on days 3, which has a good effect on the treatment of ALI/ARDS. These findings need to be verified in large-scale trials.