“…Unplanned readmission refers to readmission to hospital due to postoperative complications, wound infection, and so on after discharge during the follow‐up period of the study. Nine studies (Acevedo & Leon, 2010; Arance Garcia et al, 2015; Bowling et al, 2017; Gabriel et al, 2020; Gregori et al, 2018; Hofer et al, 2008; Livermore et al, 2011; Rosero & Joshi, 2014; Tandon et al, 2016) examined the association between BMI and unplanned readmission for day surgery patients, and they could be grouped in three ways: seven articles (Acevedo & Leon, 2010; Arance Garcia et al, 2015; Bowling et al, 2017; Gabriel et al, 2020; Gregori et al, 2018; Livermore et al, 2011; Tandon et al, 2016) were grouped by BMI >30 kg/m 2 versus BMI <30 kg/m 2 ; two articles were grouped by BMI ≤25 kg/m 2 versus BMI ≥40 kg/m 2 (Hofer et al, 2008; Rosero & Joshi, 2014). Whether we compared the impacts of higher versus lower BMI on unplanned readmission (nine articles) (Acevedo & Leon, 2010; Arance Garcia et al, 2015; Bowling et al, 2017; Gabriel et al, 2020; Gregori et al, 2018; Hofer et al, 2008; Livermore et al, 2011; Rosero & Joshi, 2014; Tandon et al, 2016) or compared the impact of BMI >30 kg/m 2 versus BMI <30 kg/m 2 on unplanned readmission (seven articles) (Acevedo & Leon, 2010; Arance Garcia et al, 2015; Bowling et al, 2017; Gabriel et al, 2020; Gregori et al, 2018; Livermore et al, 2011; Tandon et al, 2016), the pooled results indicated that higher BMI was not associated with increased risk of unplanned readmission for day surgery patients (odds ratio [OR], 0.93; 95% CI, 0.70–1.20; and OR, 0.90; 95% CI, 0.67–1.21, respectively).…”