Feasibility, reliability and satisfaction of (automated) capillary carcinoembryonic antigen measurements for future home-based blood sampling: the prospective CASA-I study.

Aim: Follow-up for colorectal cancer (CRC) necessitates regular monitoring of carcinoembryonic antigen (CEA) at the hospital. Capillary home-based blood collection, including minimally invasive techniques such as lancet sampling or an automated upper arm device (TAP-II), has the potential to replace a significant portion of hospital-based blood sampling, thereby enhancing self-reliance and quality of life. The objectives of this study were to assess the feasibility, reliability and preference for CEA blood collection.

Methods: Baseline venous and capillary (by lancet and TAP-II) blood samples were collected from 102 participants, including 20 CRC patients with elevated CEA levels, 60 CRC patients undergoing postoperative outpatient monitoring and 20 healthy volunteers. The second group performed capillary blood collections at home on two consecutive follow-up appointments and subsequently sent them to the hospital. Satisfaction was assessed via patient reported outcome measures on pain, burden, ease of use and preference.

Results: The Pearson's correlation test of all usable samples resulted in a linear coefficient of 0.998 (95% CI 0.997-0.998) for the TAP-II method and 0.997 (95% CI 0.996-0.998) for the lancet method, both compared to venipuncture. Following the initial blood collection, 86% of the participants (n = 102) favoured the TAP-II, rating it as the least painful and burdensome option. After two home-based blood samples, the preference for the TAP-II method persisted, with 64% of the patients endorsing its use.

Conclusion: This study demonstrated the feasibility of home-based capillary sampling of CEA. The TAP-II blood collection is the most reliable method and is preferred by patients over venipuncture and lancet sampling.