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P181 Patient-led remote intracapillary pharmacokinetic sampling (fingerPRICKS) for therapeutic drug monitoring in patients with Inflammatory Bowel Disease

Chee, D.(1,2);Nice, R.(3);Hamilton, B.(1,2);Jones, E.(4);Hawkins, S.(2);Redstone, C.(2);Cairnes, V.(2);Pohl, K.(2);Chanchlani, N.(1,2);Lin, S.(1,2);Kennedy, N.(1,2);Ahmad, T.(1,2);Goodhand, J.(1,2);McDonald, T.(1,3);

(1)IBD Pharmacogenetics Group, University of Exeter, Exeter, United Kingdom;(2)Royal Devon and Exeter Hospital NHS Foundation Trust, Department of Gastroenterology, Exeter, United Kingdom;(3)Royal Devon and Exeter Hospital NHS Foundation Trust, Department of Blood Sciences Laboratory, Exeter, United Kingdom;(4)University of Bath, Department of Sciences, Bath, United Kingdom

Background

Because of COVID-19 public health restrictions, telemedicine has replaced conventional outpatient follow up for most patients with chronic immune-mediated inflammatory disorders treated with biologic drugs. Innovative solutions to facilitate remote therapeutic drug monitoring are therefore required. Low-volume intracapillary blood sampling can be undertaken by patients at home and samples returned by post to central laboratories.

Methods

We sought to report the effect of the COVID-19 pandemic on requests for therapeutic drug monitoring and the equivalence, acceptability and effectiveness of low-volume intracapillary fingerprick sampling compared to conventional venepuncture. Drug and antidrug antibody levels were measured using standard ELISAs.

Results

Therapeutic drug monitoring requests for adalimumab (96.5 [70.5 - 106] per week to 52 [33.5 - 57.0], p < 0.001) but not infliximab (184.5 [161.2 - 214.2] to 161 [135 - 197.5], p = 0.34) reduced during the first UK stay-at-home lockdown compared with the preceding six months.  

Fingerprick sampling was equivalent to conventional venepuncture for adalimumab (Figure 1), infliximab, vedolizumab, and ustekinumab drug and anti-adalimumab and -infliximab antibody levels. The median (IQR) volume of serum obtained using intracapillary sampling was 195µL (130-210). More than 87% (90/103) patients agreed that intracapillary testing was easy and 69% (71/103) preferred it to conventional venepuncture (Figure 2).   

In routine care, 75.3% (58/77) patients returned two blood samples within 14 days to permit remote assessment of biologic therapeutic drug monitoring.   

Figure 1: Adalimumab drug Linear regression and Bland Altman plot    Left: Linear regression analysis of venous vs capillary adalimumab drug level results (mg/L), Slope 1.02 [0.90 - 1.14]. Right: Bland Altman plot of mean of venous and capillary adalimumab drug measurement against percentage difference between TEa vs observed mean % difference. 

Figure 2: Questionnaire acceptability response data    Patient acceptability questionnaire response results by 5-point Likert scale. (A) Itemised proportional responses, grouped by domain. (B) Cumulative agreement per respondent; +1/+2 points for agree/strongly agree, 0 for neither agree nor disagree, -1/-2 for disagree/strongly disagree.

Conclusion

Therapeutic drug monitoring can be undertaken using patient-led remote intracapillary blood sampling and has the potential to be a key adjunct to telemedicine in patients with immune-mediated inflammatory diseases.

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