# Systematic Review on Individualized Versus Standardized Parental Nutrition in Preterm Infants
## 4 Discussion
### Conclusion 1: The LoE of the Available Studies Comparing SPN vs. IPN Is Very Low (LoE1- and LoE 2-)
#### 4.2.2 Ready to Use SPN Bags  
Several more recent observational trials suggest that ready to use SPN solutions may facilitate early (first week) achievement of protein needs (Figure 2). Similar results regarding higher amino acid intake with SPN vs. IPN were reported by [PERSON] 2006 and [PERSON] 2003. In a prospective cohort study, [PERSON] studied 58 neonates, with a gestational age <33 weeks, and found that neonates with SPN received more AA each day and more Ca and P on the third day of life [25]. [PERSON] et al. studied 40 neonates with a gestational age <32 weeks and found that SPN was superior in terms of early glucose provision and AA on day 3 of life (less variation in PN protocol and earlier onset compared with personalized PN) and a better Ca/P ratio in the first week of life [22]. In 2010, [PERSON] et al. studied 107 newborns with a gestational age <33 weeks and found that those receiving standard PN had significantly higher glucose, AA, lipids, sodium, and magnesium [21].  
The study by [PERSON] et al. was designed as a retrospective cohort study comparing IPN (2005-2007) to two-in-one SPN (2008-2009), a second two-in-one SPN (2010-2011), and finally a triple-chamber-SPN (2012-2013) consequently [19]. With regard to the present review, for analysis of first week protein intake, Group 1 (IPN) vs. Group 4 (SPN), the licensed triple-chamber manufactured by the industry, were used. SPN manufactured by the industry under regulated quality standards, was associated with improved protein intake, and the protein target was more likely to be achieved [19].  
Finally, Morgan 2019 compares the data of two RCTs performed in the same department 2004-2006 and 2009-2012 [18]. The first study was a RCT of normal vs. high nutrient IPN, the second a RCT of SPN vs. high nutrient SPN. The forest plots provide two comparisons based on this data. Standard SPN vs. standard IPN ([PERSON] 2019 part A) and high nutrients SPN vs. high nutrients IPN ([PERSON] 2019 part B). SPN was introduced within 6 h of birth with an amino acid starting dose of 1.8 g/kg/day, while IPN was introduced within 24 h (where possible) with a starting dose of 1 g/kg/day. SPN can improve PN efficiency and compliance with guidelines. The earlier and faster introduction of SPN compared with IPN resulted in much higher target protein intakes for the SPN groups in the first 5 days of life. The first factor that may improve the protein intake is the lower level of deviation from the protocol. Mean gestational ages were lower in the IPN groups.  
Altogether, expert individualization by a pharmacy may improve PN nutrient intake in preterm infants [20; 24]. However, all the observed effects on nutrient intake of SPN vs. historical IPN controls entirely depend on historical changes in SPN and IPN composition and nutritional targets. Of note, the SPN arm of the [PERSON] et al., 2020 study (Figure 2) was the only subgroup which, on average, approached current preterm infants target protein needs.  
Conclusion 3: Reflecting the Above-Mentioned Data on Protein Intake, IPN with Pharmaceutical Individualization Was Associated with Better in-Hospital Growth [20; 24] Whereas Most Recent Observational Studies Using Ready to Use SPN Solutions Observed Better Growth Than Historic Controls without Pharmaceutical IPN Individualization (Figure 5)