Comparing Vitamin D Results and Acceptability of Sampling Obtained From Dried Blood Spot, Tasso+ Capillary Sampling, and Venous Blood. (VitD TASSO)

Evaluation of a Capillary Self-sampling Device for Vitamin D Testing

This study will evaluate the performance and acceptability of different sampling methods for measuring vitamin D, specifically 25-hydroxyvitamin D₂ and 25-hydroxyvitamin D₃.

Study Overview

• Status: Not yet recruiting
• Conditions: Vitamin D
• Intervention / Treatment: Device: Vit D Tasso+

Detailed Description

This study will evaluate the performance and acceptability of different sampling methods for measuring vitamin D, specifically 25-hydroxyvitamin D₂ and 25-hydroxyvitamin D₃. It will compare results obtained from the routine self-collected dried blood spot (DBS) cards currently in use in our laboratory, with paired capillary and venous serum samples. This compares the collection using three approaches: finger-prick DBS, venepuncture, and the CE-marked Tasso+ upper-arm self-sampling device. The study aims to assess both quantitative agreement between sample types and user acceptability of each collection method.

• Study Type: Interventional
• Enrollment (Estimated): 35
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Adults aged 18 years or older.
• Current healthcare staff or staff volunteers.
• Already consented to use the routine dried blood spot (DBS) vitamin D service.
• Able and willing to provide all three sample types- routine DBS finger-prick sample, a Tasso+ upper-arm self-collected capillary sample, and a venous blood sample taken by a trained Trust phlebotomist.
• Able to give informed consent.
• Able to complete a short questionnaire in English.

Exclusion Criteria:

• • Participants will not be able to take part if any of the following apply:

  • Under 18 years of age
  • Not a member of staff or staff volunteer
  • Known difficulty with blood sampling, such as a history of fainting, severe needle phobia, or conditions that make venepuncture unsafe.
  • Skin conditions or injuries on the upper arm that would prevent safe use of the Tasso+ device.
  • Bleeding disorders or current use of anticoagulant medication that would make capillary or venous sampling unsafe.
  • Inability to give informed consent, including difficulty understanding the study information.
  • Inability to complete the short questionnaire in English, as this is needed to assess user experience.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Supportive Care
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Vitamin D sampling; Staff members having Vit D sampling using blood spot, venous samples, and sample collected using the device	Device: Vit D Tasso+; Blood collected using Tasso device

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Agreement between Tasso+ capillary serum and venous serum 25(OH)D	Continuous 25(OH)D₂ and 25(OH)D₃ concentrations (nmol/L)	From Study start date for up to 12 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
User acceptability	Pain, on a scale from 1-5 1= no pain. 5= worse pain	From Study start date for up to 12 months
User acceptability	Ease of Use: how easy or difficult each method was to complete 1= Very difficult, 5=Very easy Dried Bloodspot Venepuncture Tasso+	From study start date to 12 months
User acceptability	Clarity of Instructions: how clear were the instructions you were given? 1= Not clear at all, 5=Extremely clear Dried Bloodspot Venepuncture Tasso+	From Study start date for up to 12 months
User acceptability	Safety: How safe did each method feel to you ? 1= Very unsafe, 5=Very safe Dried Bloodspot Venepuncture Tasso+	From Study start date for up to 12 months
User acceptability	Your Preference: please rank the three collection methods 1= your favourite, 3=least preferred Dried Bloodspot Venepuncture Tasso+	From Study start date for up to 12 months
User acceptability	Willingness to self-collect: how willing would you be to collect your own sample using each method in the future? 1= Very willing, 5=Very willing Dried Bloodspot Venepuncture Tasso+	From Study start date for up to 12 months
Sample quality	Volume adequacy- minimum blood vol 200uL	From Study start date for up to 12 months
Sample quality	Pre analytical failure- % samples unacceptable for analysis due to inadequate volume or poor quality blood spot	From Study start date for up to 12 months
Laboratory workflow efficiency	Hands on time (hrs/mins)	From Study start date for up to 12 months
Laboratory workflow efficiency	Batch failures based on LCMSMS batch acceptance criteria- QC with +/- 2sd of mean, cal curve R value > 0.95	From Study start date for up to 12 months
Laboratory workflow efficiency	Repeat samples (%)	From Study start date for up to 12 months
Turnaround time (TAT)	Time from sample request to result authorisation	From Study start date for up to 12 months
Clinical classification agreement	Numerical agreement (statistically quantified by Passing and Bablok analysis)	From Study start date for up to 12 months
Clinical classification agreement	Vitamin D status category agreement (deficient / insufficient / replete) quantified statistically using Cohen's kappa analysis	From Study start date for up to 12 months

Collaborators and Investigators

• Sponsor: The Royal Wolverhampton Hospitals NHS Trust

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: July 14, 2026
• First Submitted That Met QC Criteria: August 19, 2026
• First Posted (Actual): August 24, 2026

Study Record Updates

• Last Update Posted (Actual): August 24, 2026
• Last Update Submitted That Met QC Criteria: August 19, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: Vitamin D Tasso
• Other Study ID Numbers: 2026LAB148

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No