POS1398 RHEUMATOLOGICAL PATIENTS PERFORMING BLOOD SELF-SAMPLING FOR DMARD THERAPY SAFETY: A PROOF OF CONCEPT STUDY COMPARING WITH VENOUS BLOOD SAMPLES
Authors: S. A. Just, P. Toftegaard, U. Jakobsen, T. R. Larsen
Journal: Annals of the Rheumatic Diseases (2021)

Background: Regular blood sampling is a requirement for rheumatological patients receiving csDMARD, bDMARD or tsDMARD therapies (1). The frequent blood sampling affects the patient’s life as they use a substantial amount of time at hospitals or by the general practitioner. Often visits are time-consuming with transport, waiting time, and for some patient’s costly long travels. Giving patients the option of taking the blood samples themself in their own home, as part of a patient-centred monitoring approach, could provide the patient much higher degree of independence. Further, it may increase the quality of life, cause higher compliance with taking the control samples and possibly reduce health care costs. Objectives: 1. To investigate if rheumatological patients can take capillary blood samples and describe patient-reported outcomes (PRO) about the procedure. 2. Compare the venous and capillary samples’ results. 3. Test if the laboratory automated analysis equipment can handle the small capillary samples. Methods: 21 rheumatological patients, underwent capillary and venous blood sampling at up to 4 occasions (1-2 months between). Instructions were available on a pictogram. PRO data were assessed by questionnaires. The patient performed blood extraction to the capillary samples from a finger after using a device making a small incision (2 mm depth and 3 mm width). Two capillary tubes (one Microtainer K2-EDTA and one Microtainer lithium heparin with gel) were filled with a total volume of approximately 1.0 mL blood. A phlebotomist took the venous sample. Blood samples were analyzed for alanine aminotransferase (ALAT), albumin, alkaline phosphatase (ALP), calcium, C-reactive protein (CRP), creatinine, potassium, lactate dehydrogenase (LDH), urate, hemolysis index, erythrocyte corpuscular volume (MCV), haemoglobin, leukocytes, differential count and platelets. Results: A total of 53 paired capillary (C) and venous (V) samples were taken. The average perceived pain of the procedure of C sampling was VAS: 10.3 (SD:14.4) (0-100) versus V sampling VAS: 8.5 (SD:11.7). 90% of patients would accept it as a future form of blood sampling. Differences in blood samples (C versus V) were: CRP (-3.4%); Hemoglobin (-1.4%); Creatinine (-4.4%), ALAT (-2.9%), neutrophils (1.43%), platelets (-16.9%). The index of hemolysis was on average 128.9 mg/dL (SD: 203) in C versus 6.7 mg/dL (SD: 4.6) in V. Results was evaluated by a rheumatologist, and 92.5% of capillary samples could be used to evaluate the safety of DMARD treatment based on the most critical samples for this: ALAT, creatinine, neutrophils and platelets (1). The 7.5 % not accepted were all due to aggregated platelets leading to low platelet count. There was hemolysis in 18% of the samples, but the analysis results could be used despite this. Conclusion: In the majority of rheumatological patients, capillary self-sampling is well tolerated. We show that it is possible to extract the needed results from the capillary samples to evaluate DMARD treatment safety, despite higher hemolysis index. Using capillary samples taken at home could be a central instrument in future rheumatological patient-centred monitoring. References: [1]Rigby WFC et al. Review of Routine Laboratory Monitoring for Patients with Rheumatoid Arthritis Receiving Biologic or Nonbiologic DMARDs. Int J Rheumatol . 2017 Disclosure of Interests: None declared