“…There were 11 studies which were part of larger longitudinal or interventional studies [ [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] ], and 13 multicentre studies [ 7 , 21 , 23 , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] ]. The majority of studies included general ICU patients, however some studies investigated specific ICU patient populations including: Acute Respiratory Distress Syndrome (ARDS) [ 7 , 23 , 28 , 34 , 35 ], sepsis [ 21 , 36 ], blunt chest trauma [ 37 ] and severe acute respiratory syndrome (SARS) [ 25 ]. Almost all studies were published after 2010 ( n = 29), and there was wide variation in both the duration of follow-up (Median 12 months, IQR 6–30) and the sample size (Median 87, IQR 50–167).…”