Development and validation of a biological frailty score based on CRP, haemoglobin, albumin and vitamin D within an electronic health record database in France: a cross-sectional study.

Objectives: To easily detect frailty in a timely fashion, enabling targeted interventions and appropriate monitoring, will be a major worldwide public health and economic challenge as the proportion of older people increases in the population. Based on a review and meta-analysis showing that C-reactive protein (CRP), haemoglobin, albumin and vitamin D are associated with frailty, we aimed to develop and validate a biological score using these biomarkers for the detection of frailty. Design: We conducted a retrospective, cross-sectional, monocentric study using the electronic healthcare database of Lille University Hospital, France. Participants: Inclusion criteria were patients aged 50 and over, being hospitalised at Lille University Hospital between 1 January 2008 and 31 December 2021. We identified patients whose CRP, haemoglobin, albumin and vitamin D levels were measured. We selected patients whose assays fell within normal thresholds, outside acute clinical situations. Main outcome measures: To assess frailty, we used a scale adapted to electronic healthcare database, called the Hospital Frailty Risk Score. To develop and validate the predictive frailty score, the whole population was divided into a development and a validation cohort. Results: 26 554 patients were included, of which 17 702 were in the development cohort and 8852 in the validation cohort. Based on the results of the multivariate analysis, we developed an equation combining CRP, haemoglobin, albumin and vitamin D with age and sex to obtain a score referred to as the bFRAil (biological FRAilty) score. Within the validation cohort, the area under the curve for this score is 0.78 (0.77-0.80) and the negative predictive value is 83.7%. Conclusions: This study has made it possible, for the first time, to develop and validate in a hospital setting a biological score called bFRAil score based on simple, easily measurable biomarkers for identifying frail patients in daily medical practice. Further studies are needed to validate its use.