Patient participation in urine specific gravity screening for arginine vasopressin deficiency in an inpatient neurosurgical clinic

Abstract

Objective: Detecting hypotonic urine (specific gravity < 1005 g/L) is crucial for the early identification of arginine vasopressin deficiency (AVP-deficiency), a common complication after pituitary surgery. This study aimed to evaluate the agreement between urine specific gravity measurements taken by patients using urine test strips and those taken by nurses using a refractometer, to assess the reliability of patient-conducted measurements for diagnosing this condition. Design: A prospective cohort study was conducted in a neurosurgical ward. Patients: The study included 110 participants who collectively provided 609 specific gravity measurements. Measurements: Specific gravity measurements were taken using Combur-10 urine test strips by patients and using an ATAGO MASTER-SUR/N alpha refractometer by nurses. Agreement was analysed using Weighted Kappa and intraclass correlation coefficient (ICC). Results: Moderate agreement was found between patient-conducted measurements and those from the refractometer (Kappa = 0.47, ICC = 0.69). Substantial to good agreement was observed between patient and nurse measurements using urine test strips (Kappa = 0.82, ICC = 0.89). A threshold of 1.015 g/L in test strip measurements ensured no cases of hypotonic urine were missed, reducing the need for nurse-led testing by 50%. Patient satisfaction was high (mean 7.8), while nurse satisfaction was lower (mean 6.4). Conclusions: Although patients are less accurate than nurses in measuring specific gravity, they can reliably screen for hypotonic urine in AVP-deficiency diagnostics using urine test strips. A higher cut-off point improves diagnostic accuracy, enhances patient participation and reduces the screening workload for nurses.