# Systematic Review on Individualized Versus Standardized Parental Nutrition in Preterm Infants
## 2 Materials and Methods
### Selection Criteria  
Inclusion criteria included all clinical trials published in any language, but providing an English language abstract. All retrieved records were imported into EndNote X9, and duplicates were removed automatically and by manual checking. The titles and abstracts of the outputs were screened independently by two reviewers ([PERSON] and [PERSON]) to select the potential trials. Then, the full text of each potential trial was further assessed for eligibility. The reviewers also screened the reference lists of eligible trials to identify further relevant eligible trials. All eligible trials were finally included after discussions between the reviewers. Two reviewers ([PERSON] and [PERSON]) extracted the following information: Author, year of publication or update, country or region, population, intervention, comparison, and outcomes. The GRADE approach was used to assess the quality of evidence and to interpret findings. Authors evaluated the level of evidence (LoE), the grade of recommendation (GOR), and the form of recommendation as described previously [11]. The SIGN classification was used to assign both the evidence level and the recommendation grade. The scales used to evaluate LoE, GOR, and form of recommendation are summarized in Tables 2-4 [11; 16]. \begin{table}
\begin{tabular}{l l} \hline \hline
**PICO Framework** & \\ \hline Population & Infants born preterm, up to 28 days after their due birth date \\ Intervention & Any standardized approach to providing parenteral nutrition \\ Comparison & Any individualized parenteral nutrition solutions (bespoke prescriptions) \\  & Protein intake \\  & Adverse events \\  & 1. & Sepsis \\ Outcomes & 2. & NEC, stage \(\geq\) 2 \\  & 3. & Mortality \\  & Duration of hospital stay \\  & Growth/anthropometric measures \\  & Neurodevelopmental outcomes \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Research questions defined following the PICO framework [14]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Judgement** & **Recommendation** \\ \hline Undesirable consequences clearly outweigh & Strong recommendation against \\ desirable consequences & Undesirable consequences probably outweigh & Conditional recommendation against \\ desirable consequences & Balance between desirable and undesirable consequences is & Recommendation for research and possibly conditional \\ closely balanced or uncertain & recommendation for use restricted to trials \\ \hline Desirable consequences probably outweigh & Conditional recommendation for \\ undesirable consequences & Conditional recommendation for \\ undesirable consequences & \\ \hline Desirable consequences clearly outweigh & Strong recommendation for \\ undesirable consequences & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Forms of recommendation [11; 16]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Level of Evidence** & **Type of Evidence** \\ \hline
**1++** & High quality meta-analyses, systematic reviews of randomized controlled trials (RCTs), or RCTs with a very low risk of bias \\ \hline
**1+** & Well conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias \\ \hline
**1\(-\)** & Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of bias \\ \hline
**2++** & High quality systematic reviews or case control or cohort studies. High quality case control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal \\ \hline
**2+** & Well conducted case control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal \\ \hline
**2\(-\)** & Case control or cohort studies with a high risk of confounding or bias and a significant risk \\ \hline
**3** & Non-analytic studies, e.g., case reports, case series \\ \hline
**4** & Expert opinion \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Rating scheme for the strength of the evidence [11; 16].