Inflammatory biomarkers are reportedly increased in depressed patients. Several studies have been conducted using neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), and monocyte/lymphocyte ratio (MLR). The objective of this systematic review was to study the relationship between these peripheral biomarkers and suicidality in depressed patients with/without suicidal behavior, including suicide attempts and ideation, and healthy controls.

We searched the following relevant terms in the PubMed, Web of Science, and Scopus databases published in the last 5 years. We assessed the methodological quality of included studies using the Oxford criteria and reviewed the evidence following PRISMA guidelines.

Eleven studies were retained for the data synthesis, with a total sample of 1,701 participants, of which the majority (819) were patients with depression and suicidal behavior, 494 were depressed patients without suicidal behavior, and only 388 were healthy participants. Our results reinforce the idea that NLR could be an attractive, convenient, and cost-effective trait marker of suicidal vulnerability in patients with major depressive disorder (MDD).

Future large-scale replication studies are needed to examine the apparently understudied role of PLR and MLR in depressed patients in greater depth.

Congenital heart diseases (CHD) are the most common causes of birth defects that have increased the risk of infections. Neonatal sepsis is a life-threatening condition and early diagnosis can be life-saving. We aimed to evaluate the potential role of the systemic immune-inflammatory index in the early diagnosis of neonatal sepsis.

A retrospective cohort study was conducted on 166 newborns with a diagnosis of neonatal sepsis who were admitted to our hospital with CHD between January 2017 and June 2021. Haematological indices including neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, and systemic immune-inflammatory index were calculated for all patients at the time of diagnosis of neonatal sepsis (sepsis). The sepsis values of these indices were compared with the admission values (pre-sepsis) of the patients.

The mean gestational age and birth weight of the patients were 38.36 ± 1.42 weeks and 3057.75 ± 484.68 g. It was found that absolute neutrophil count, systemic immune-inflammatory index, neutrophil/lymphocyte ratio, but not platelet/lymphocyte ratio were significantly increased at the time of sepsis. The receiver operating characteristic curve showed that systemic immune-inflammatory index, neutrophil/lymphocyte ratio, and absolute neutrophil count have predictive ability to define neonatal sepsis among newborns with CHD. The systemic immune-inflammatory index produced an area under the curve receiver operating characteristic curve of 0.76 (70% sensitivity, 70.5% specificity). To discriminate neonatal sepsis, the cut-off values of systemic immune-inflammatory index, neutrophil/lymphocyte ratio, and absolute neutrophil count were 517.19, 2.62, and 9210/mm3, respectively.

As an easily accessible and reliable indicator, systemic immune-inflammatory index may be used in combination with the other parameters in the early diagnosis of neonatal sepsis.