<abstract xmlns="http://www.w3.org/1999/xhtml">

<sec><h3>Background</h3>
<p>Current treatment for severe haemophilia includes prophylactic factor replacement to prevent bleeding. Coagulation factor products have significant inter-patient variability in pharmacokinetic (PK) parameters. Optimal management requires tailoring prophylaxis to individual PK parameters. Web-based Application for the Population Pharmacokinetic Service (WAPPS) is a tool that estimates individual PK values using a population approach. Despite its growing use to help guide dosing selection, few studies have investigated its clinical impact.</p>
</sec>
<sec><h3>Aim</h3>
<p>To investigate any change in prophylaxis regimen and hours per week where factor level is under 1%, pre- and post-PK testing using WAPPS, for paediatric patients with severe haemophilia.</p>
</sec>
<sec><h3>Methods</h3>
<p>A retrospective chart review was conducted for all paediatric patients with severe haemophilia receiving care between April 2013 and July 2018 at McMaster Children's Hospital who have used WAPPS. Data extracted included: patient demographics, PK data generated by WAPPS, prophylaxis regimen pre- and post-PK testing, and reason for regimen change. The number of hours per week where factor level was under 1% pre- and post-PK testing was calculated using WAPPS.</p>
</sec>
<sec><h3>Results</h3>
<p>Thirty-one patients were included; 42% (n=13) changed their prophylaxis regimen after PK testing. After using PK data to personalise prophylaxis recommendations, there was a decrease in the number of hours per week where factor level is under 1% (from an average of 13.1 hours/week to 11.8 hours/week), though not statistically significant (p=0.16).</p>
</sec>
<sec><h3>Conclusion</h3>
<p>PK data generated by WAPPS has direct impact by informing changes to prophylaxis recommendations. This individualised approach promotes patient-centred care and patient engagement without increasing the time spent with factor levels below 1%. It also confirms and validates clinical practice.</p>
</sec>
</abstract>

Background
Current treatment for severe haemophilia includes prophylactic factor replacement to prevent bleeding. Coagulation factor products have significant inter-patient variability in pharmacokinetic (PK) parameters. Optimal management requires tailoring prophylaxis to individual PK parameters. Web-based Application for the Population Pharmacokinetic Service (WAPPS) is a tool that estimates individual PK values using a population approach. Despite its growing use to help guide dosing selection, few studies have investigated its clinical impact.

Aim
To investigate any change in prophylaxis regimen and hours per week where factor level is under 1%, pre- and post-PK testing using WAPPS, for paediatric patients with severe haemophilia.

Methods
A retrospective chart review was conducted for all paediatric patients with severe haemophilia receiving care between April 2013 and July 2018 at McMaster Children's Hospital who have used WAPPS. Data extracted included: patient demographics, PK data generated by WAPPS, prophylaxis regimen pre- and post-PK testing, and reason for regimen change. The number of hours per week where factor level was under 1% pre- and post-PK testing was calculated using WAPPS.

Results
Thirty-one patients were included; 42% (n=13) changed their prophylaxis regimen after PK testing. After using PK data to personalise prophylaxis recommendations, there was a decrease in the number of hours per week where factor level is under 1% (from an average of 13.1 hours/week to 11.8 hours/week), though not statistically significant (p=0.16).

Conclusion
PK data generated by WAPPS has direct impact by informing changes to prophylaxis recommendations. This individualised approach promotes patient-centred care and patient engagement without increasing the time spent with factor levels below 1%. It also confirms and validates clinical practice.

Web-based Application for the Population Pharmacokinetic Service (WAPPS)'s impact on dosage selection: a single paediatric centre experience

The Journal of Haemophilia Practice

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Background
Current treatment for severe haemophilia includes prophylactic factor replacement to prevent bleeding. Coagulation factor products have significant...

	PATIENTS WHO HAVE CHANGED THEIR PROPHYLAXIS REGIMEN AFTER PK TESTING	PATIENTS WHO HAVE NOT CHANGED THEIR PROPHYLAXIS REGIMEN AFTER PK TESTING
Age
Mean ± SD	10.61 ± 4.16	9.89 ± 3.26
(Minimum, Maximum)	(2, 15)	(3, 15)

Weight (kg)
Mean ± SD	45.72 ± 20.83	37.52 ± 14.53
(Minimum, Maximum)	(14, 76.9)	(14.5, 66.2)

Height (cm)
Mean ± SD	149.12 ± 31.89	140.99 ± 20.75
(Minimum, Maximum)	(81, 184)	(95.8, 175)

CHANGES TO PROPHYLAXIS REGIMEN
DOSAGE	FREQUENCY	DRUG	NUMBER OF PATIENTS (N)
↑	↓	—	8
↑	—	—	1
↓	—	—	1
↓	↑	—	1
—	↑	—	1
—	—	Changed	1

Web-based Application for the Population Pharmacokinetic Service (WAPPS)'s impact on dosage selection: a single paediatric centre experience

Article Category: Clinical Research

Published Online: Jul 13, 2021

Page range: 80 - 85

DOI: https://doi.org/10.17225/jhp00179

Keywords
haemophilia A, haemophilia B, factor VIII, factor IX, children, pharmacokinetics

© 2021 Celia Kwan et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Data extracted from chart review

Patient demographics

Changes to prophylaxis regimen after WAPPS

Web-based Application for the Population Pharmacokinetic Service (WAPPS)'s impact on dosage selection: a single paediatric centre experience

Article Category: Clinical Research

Published Online: Jul 13, 2021

Page range: 80 - 85

DOI: https://doi.org/10.17225/jhp00179

Keywordshaemophilia A, haemophilia B, factor VIII, factor IX, children, pharmacokinetics

© 2021 Celia Kwan et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Figure 1

Data extracted from chart review

Patient demographics

Changes to prophylaxis regimen after WAPPS

Keywords
haemophilia A, haemophilia B, factor VIII, factor IX, children, pharmacokinetics