Comparison of a capillary blood collection device and standard venepuncture for routine clinical biochemistry assays: developing reasonable adjustment phlebotomy for patients with learning disabilities

Attending a phlebotomy appointment can cause high levels of anxiety, especially in patients with learning disabilities (LD). This project explores the validation of blood tests using capillary blood versus routine venepuncture samples and looks at reducing healthcare inequalities in our local population by providing painless capillary blood testing. Aim: To validate reduced total serum volume required for 23 biochemistry tests, to investigate comparability of results from capillary blood using an upper arm device versus standard venous collection. A secondary aim was to determine the feasibility of capillary blood collection in a community-based population with LD and needle phobia. Materials & methods: Total serum sample volume was reduced until Beckman Coulter AU5800 and DXI800 automated analyzers flagged insufficient sample at a rate of <5% for 23 routine biochemistry tests. Venous and contemporary capillary collections were made from 74 primary care patient volunteers undergoing routine health checks, following informed consent. Comparative statistical analysis (Pearson/Spearman correlation, Bland–Altman) was used to determine interchangeability between the two sets of results. Supervised capillary sampling was then piloted in 20 patients with LD and needle phobia in a community setting. Questionnaires were provided for assessing user acceptability. Results: Total serum volume used for analysis was reduced by up to 30% for some assays. Interchangeability of results was seen with total bilirubin, ALT, ALP, total protein, phosphate, total, LDL and HDL cholesterol, triglycerides, vitamin B12, folate, TSH and prolactin. Further tests, while not completely interchangeable proved useful in longitudinal health monitoring. Conclusion: We have optimized testing capabilities within our laboratory by validating capillary blood for routine testing of commonly requested analytes. Microsamples obtained by capillary access provide a viable alternative to venous phlebotomy in patients with LD and needle phobia.