Cystatin-C estimated GFR in palliative care patientts

Background

Accurate assessment of kidney function is crucial for safe drug prescribing in palliative care. Creatinine-based estimated glomerular filtration rate (eGFR(cr)) may overestimate kidney function in patients with reduced muscle mass, a common condition in advanced disease and palliative care populations. Cystatin C–based eGFR (eGFR(cys)) has been proposed as a potentially more accurate alternative, as it is less influenced by muscle mass. However, limited data exist regarding the extent of discordance between eGFR(cr) and eGFR(cys) in specialised palliative care and the possible implications for medication safety.

Methods

This retrospective single-centre observational study includes adult patients treated on a specialised inpatient palliative care ward in whom kidney function assessment was clinically indicated and routinely performed using simultaneous serum creatinine and cystatin C measurements. The primary objective is to evaluate the extent to which eGFR(cr) may overestimate kidney function compared with eGFR(cys). In addition, the study investigates how frequently eGFR(cr) classifies patients as having an eGFR ≥30 ml/min while eGFR(cys) indicates severe renal impairment (<30 ml/min). Medication prescriptions in patients with discordant classification are reviewed for drugs with renal dosing considerations. Exploratory analyses assess factors associated with discordance between eGFR estimates.

Discussion

This study aims to improve understanding of kidney function assessment in palliative care populations characterised by frailty, sarcopenia, and advanced disease. By examining discrepancies between creatinine- and cystatin C–based eGFR estimates and their implications for prescribing practices, the project seeks to generate evidence relevant to medication safety in palliative care. The findings may help identify patient groups in whom cystatin C measurement could provide clinically relevant additional information and inform future prospective validation studies using measured glomerular filtration rate methods.