The reviewed studies have a number of methodological limitations. Heterogeneity is the most important one. Consensus on all aspects of follow-up research is essential for well-founded conclusions. For example, structured and standardised evaluation of: (1) organ system function with a validated tool such as the Paediatric Logistic Organ Dysfunction (PELOD) score [13, 42, 60, 71] ; (2) neurocognitive function; (3) complications of PICU treatment; and (4) (HR)QoL are warranted. Multi-centre studies as proposed by the Collaborative Pediatric Critical Care Research Network (CPCCRN) with a uniform approach will provide answers either in general PICU cohorts or in disease-oriented study groups [76] .