The goal of this prospective single center feasibility study is to assess the feasibility of using BabyCheck and PO by GPs as an illness severity score for young infants > 6 months of age in order to aid the decision for referral to hospital.

The emergency GP posts in Leiderdorp will add the BabyCheck and PO to their standard evaluation of infants presenting with systemic illness < six months of age for a period of six months.

The feasibility will be determined by calculating the percentage of eligible infants in whom a complete BabyCheck score and PO data were retrieved. The investigators consider the protocol feasible if this is done in 80% of all eligible infants.

Young infants frequently visit general practitioners (GP) with acute pathology, such as infections. Assessing severity of illness in this group is often challenging, since the likelihood of serious illness in this group is low, deterioration of the clinical condition can occur more rapidly. Therefore, early recognition of pathology in young babies is pivotal.

The Netherlands Triage System (derived from the Manchester Triage System) is a reliable tool for both children and adults to decide if a patient should be seen by the GP. However, after presentation at the GP, a scoring system to assess illness severity in babies with a decision aid for referral to hospital, is currently lacking.

The BabyCheck is a scoring system developed and validated as a clinical checklist to assess young infants up to six months of age. The BabyCheck is validated in multiple low illness prevalent settings.

In addition, abnormal oxygen saturation and/or heart rate can be an early sign of infection, respiratory or circulatory pathology in infants. Since it is difficult to adequately judge oxygen saturation solely by skin colour, it is preferable to objectify this parameter via pulse oximetry (PO).

The aim of this study is to assess the feasibility of using BabyCheck and PO by GPs as an illness severity score for young infants < six months of age in order to aid the decision for referral to hospital.

Inclusion Criteria:

• Infants up to six months of age.
• Presenting with systemic illness (no injuries or traumata).
• Presenting at the emergency GP post of Leiderdorp.

Exclusion Criteria:

• Infants up to six months of age, presenting with traumata or that are in a resuscitation setting.
• Infants with referral to other hospitals than the Alrijne hospital. The location for referral is coded and available from the anonymized database of the emergency GP post.
• Infant < 1 month of age presenting with fever (body temperature > 38.0 ⁰C), with or without unknown origin, since these infants should always be referred according to the national guidelines for GPs.
• Infants < 3 months of age presenting with fever of unknown origin (temperature > 38.0 ⁰C), since these infants should always be referred according to the national guidelines for GPs.

Our study population consists of infants up to six months of age, presenting with systemic (non-traumatic/surgical) illness at the emergency GP post.