Design: Methodological research.

 Methods: The construction of the instrument was based on literature review related to child development, human resource, and patient classification systems. The content validity of the instrument was done by the Delphi technique, with the consensus of 70% of agreement between experts and the reliability was evaluated by its equivalence using the Kappa coefficient.

 Results: The final version of the instrument was possible after four stages of the Delphi technique and the instrument was composed by 11 indicators of care and each indicator is rated from one to four points representing the increasing of nursing care intensity. In order to measure the pediatric patient level of complexity of care, the nurse needs to evaluate the child in each indicator and the total score will determine the child complexity of care.  The inter-rater reliability resulted in high level of agreement between the two raters for the indicators: oxygenation, medication therapy, eliminations, family participation and support (Kappa coefficient from 0.81 to 0.86), and good level of agreement for the indicators: body hygiene, mobility and deambulation, cutaneous mucosa integrity and feeding, interval of controls of vital sign (Kappa coefficient from 0.41 to 0.67). Only the indicator activity had a weak level of agreement between raters (Kappa coefficient equal to 0.38).

 Conclusions: Initial results showed a satisfactory level of reliability for the PCS. The PCS is a useful instrument for measuring the level of complexity of nursing care required by pediatric patients, and an important tool for manages in the allocation of nursing resources. Overall, the psychometric properties of the instrument were satisfactory but there is a need for continuous evaluation and verification of others studies.