Point-of-Care Test Reagents Could Aid Risk Assessment for In-Home Care of Older Adults

With more older adults residing at home, point-of-care (POC) test reagents for in-home settings could aid in risk assessment and home care, particularly for settings with limited resources, according to a new study published in Diagnostics.

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The older adult population is increasing globally, with the share of the global population aged 65 years or above anticipated to rise from 10% in 2022 to 16% in 2050. In particular, the aging population in Japan is growing quite rapidly, leading to the establishment of a community-based integrated care system by 2025 to ensure provision of health care, nursing care, preventive care, housing, and livelihood support in the older population. The ultimate goal of this system is to promote independent living for older adults as long as possible.

To achieve this, a visiting nurse needs to detect changes in the physical and cognitive condition of older adults and decide whether they should be taken to a physician or hospital, or given antibiotics and monitored at home. However, due to a lack of equipment that can be brought for in-home care, much of this evaluation must be done with limited physiological parameters, such as heart rate, blood pressure, oxygen saturation, level of consciousness, and temperature. This illustrates a significant need for better testing abilities in the home environment.

POC offer an important solution, enabling early detection of acute infections and diseases such as cancer, diabetes, and cardiovascular diseases. POC tests are widely used in a variety of settings, including intensive care units, emergency departments, physician offices, nursing homes, and inpatient care.

Importantly, POC tests, including CRP, could also help safely reduce antibiotic prescriptions amid growing concerns about antimicrobial resistance. As an adjunct to standard care, CRP POC tests likely reduce the number of participants given an antibiotic prescription among primary care patients presenting with acute respiratory infection symptoms, according to a study cited by the authors.

Investigators focused specifically on creating a C-reactive protein (CRP) POC test, which could be used to diagnose clinically significant judgment values in the home setting. They also evaluated the utility of the HemoCue [white blood cell] DIFF system and its ability to provide differential counts of white blood cells (WBCs), and compared these performances with a laboratory test using blood samples from patients with pneumonia.

CRP and WBC counts are often used as nonspecific markers of bacteremia and invasive local infections. CRP is an acute-phase protein synthesized by the liver in response to the secretion of several inflammatory cytokines. Importantly, the cause of inflammation cannot be identified using the CRP test, but it is still an essential test when infection is suspected.

The team developed a semiquantitative rapid test cassette for CRP level determination in whole blood samples, with a threshold value considered effective for risk assessment in older adults at home. The reagent is based on the principle of a colloidal gold immunochromatographic assay and the test results were read visually without any instrument. The device provided results after 5 minutes, using 10 mL of whole blood collected from a fingertip.

According to the study, the CRP POC test showed a comparable result to the laboratory method, with an average kappa index of 0.883. The leukocyte count also showed agreement with the reference method. However, although the correlation coefficients for both neutrophil and lymphocyte counts were acceptable, the researchers did observe that the measured values tended to be smaller in cases where the cell count was higher, indicating a weak correlation with the neutrophil-to-lymphocyte ratio.

Based on these findings, the investigators concluded that the CRP POC test and WBC counts provided reliable and accurate judgments. These and similar tools may help clinicians with risk management for older adults who still reside at home, patients with dementia who cannot communicate, and those living in depopulated areas.

Reference

Takenaka S, Moro H, Shimizu U, et al. Preparing of Point-of-Care Reagents for Risk Assessment in the Elderly at Home by a Home-Visit Nurse and Verification of Their Analytical Accuracy. Diagnostics (Basel). 2023;13(14):2407. doi:10.3390/diagnostics13142407