The criterion-related validity of the Northwick Park Dependency Score as a generic nursing dependency instrument for different rehabilitation patient groups

OBJECTIVE: To investigate the criterion or concurrent validity of the Northwick Park Dependency Score (NPDS) for determining nursing dependence in different rehabilitation groups, with the Barthel Index (BI) and the Care Dependency Scale (CDS).

DESIGN: Cross-sectional study.

SETTING: Centre for Rehabilitation of the University Medical Center Groningen, The Netherlands.

SUBJECTS: Patients after stroke, spinal cord injury, multitrauma, head injury, amputation, rheumatoid arthritis, diabetes mellitus, lung diseases, tuberculosis and coronary artery disease. One hundred and fifty-four patients were included.

MEASURES: The Northwick Park Dependency Score (NPDS), the Barthel Index (BI) and the Care Dependency Scale (CDS).

RESULTS: The correlation (rho) between the NPDS and the BI for all groups was -0.87; R2=0.76 (n=154). Per patient group rho varied from -0.70 (R2=0.49) to -0.93 (R2=0.86). The overall correlation between the NPDS and CDS was larger than the criterion of rho=0.60 (r=-0.74; R2=0.55) but was <0.60 in the rheumatoid arthritis and tuberculosis group. The overall correlation between BI and CDS exceeded the criterion (r=0.75; R2=0.56).

CONCLUSIONS: The NPDS is a generic nursing dependency instrument that can be used as a valid measure across various patient groups in rehabilitation.