Publications by authors named "Patrick C K Ng"

3 Publications

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A retrospective study of antithrombotic therapy use in an outpatient haemodialysis unit.

J Clin Pharm Ther 2021 Jun 15. Epub 2021 Jun 15.

Department of Pharmacy, University Health Network, Toronto, Ontario, Canada.

What Is Known And Objective: Patients on haemodialysis (HD) are at increased risk of both bleeding and thrombotic events, due to comorbidities and nature of dialysis treatment. However, there is a lack of research on evidence-based treatment strategies and prescribing patterns for antithrombotic therapies (ATT) in this population. To characterize ATT use and its main indications in an outpatient HD unit.

Methods: A single-centre retrospective chart review was conducted in a Toronto outpatient HD unit (n = 329). Medical histories, number of ATTs and corresponding indications were collected from adult patients prescribed at least one ATT from 1 October 2019 to 31 December 2019, inclusive.

Results And Discussion: Of 329 patients in the unit, a total of 135 (41%) patients were on at least one ATT. Of these 135 patients, 80% were on monotherapy (55% antiplatelet, 25.1% anticoagulant), 12.6% were on dual antiplatelet therapy (DAPT), and 7.4% were on a antiplatelet and anticoagulant combination. Primary indications for ATT in our cohort were coronary artery disease (CAD; 55%), atrial fibrillation (18.5%) and venous thromboembolism (VTE; 17%). Described ATT use was in-line with current clinical guidelines. Monotherapy was primarily used in our HD cohort, whereas few patients were on dual therapy. Low-dose aspirin was the most common antiplatelet prescribed for secondary prevention of cardiovascular events. Warfarin monotherapy was primarily indicated for VTE, and DAPT aspirin/clopidogrel was the most commonly prescribed for CAD.

What Is New And Conclusion: Our characterization of ATT use in this HD cohort demonstrates that ATT is often prescribed for a number of different CVD reasons. Overlapping and confounding indications for prescribing ATTs, lack of randomized controlled trials and unclear clinical guidelines mean that individualized risk-benefit assessments for ATT use are still needed to provide care for these high-risk patients. More research to address the safety and efficacy of ATTs is warranted to develop more robust evidence-based treatment guidelines for the HD population.
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June 2021

Development and Validation of Nine Deprescribing Algorithms for Patients on Hemodialysis to Decrease Polypharmacy.

Can J Kidney Health Dis 2020 29;7:2054358120968674. Epub 2020 Oct 29.

Department of Pharmacy, University Health Network, Toronto, ON, Canada.

Background: Polypharmacy is ubiquitous in patients on hemodialysis (HD), and increases risk of adverse events, medication interactions, nonadherence, and mortality. Appropriately applied deprescribing can potentially minimize polypharmacy risks. Existing guidelines are unsuitable for nephrology clinicians as they lack specific instructions on how to deprescribe and which safety parameters to monitor.

Objective: To develop and validate deprescribing algorithms for nine medication classes to decrease polypharmacy in patients on HD.

Design: Questionnaires and materials sent electronically.

Participants: Nephrology practitioners across Canada (nephrologists, nurse practitioners, renal pharmacists).

Methods: A literature search was performed to develop the initial algorithms via Lynn's method for development of content-valid clinical tools. Content and face validity of the algorithms was evaluated over three interview rounds using Lynn's method for determining content validity. Canadian nephrology clinicians each evaluated three algorithms (15 clinicians per round, 45 clinicians in total) by rating each algorithm component on a four-point Likert scale for relevance; face validity was rated on a five-point scale. After each round, content validity index of each component was calculated and revisions made based on feedback. If content validity was not achieved after three rounds, additional rounds were completed until content validity was achieved.

Results: After three rounds of validation, six algorithms achieved content validity. After an additional round, the remaining three algorithms achieved content validity. The proportion of clinicians rating each face validity statement as "Agree" or "Strongly Agree" ranged from 84% to 95% (average of all five questions, across three rounds).

Limitations: Algorithm development was guided by existing deprescribing protocols intended for the general population and the expert opinions of our study team, due to a lack of background literature on HD-specific deprescribing protocols. There is no universally accepted method for the validation of clinical decision-making tools.

Conclusions: Nine medication-specific deprescribing algorithms for patients on HD were developed and validated by clinician review. Our algorithms are the first medication-specific, patient-centric deprescribing guidelines developed and validated for patients on HD.
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October 2020

Investigation of the Optic Nerve Head Morphology Influence to the Optic Nerve Head Biomechanics - Population Specific Model.

Annu Int Conf IEEE Eng Med Biol Soc 2019 Jul;2019:5374-5377

Glaucoma is an eye disorder potentially leading to permanent blindness through the damage of optic nerves at the optic nerve head (ONH). As a critical region of optic nerve damage, the porous Lamina Cribrosa (LC) in the ONH plays a critical role in determining whether optic nerves passing through will experience apoptosis in response to shear stress. The primary cause of shear stress to the LC is the increase in intraocular pressure (IOP). Since morphology governs how mechanical stresses distributes, LC morphology could be an important factor in determining the risks of glaucoma development and progression. The current project aims at investigating how anterior LC surface morphology impacts its response to shear stress caused by IOP. Results of the current study show that steeper LC morphologies could be associated with increased average shear stress on the anterior LC surface. The effect of LC morphology was comparable to that of IOP. This highlights the potential significance of LC morphology on the distribution of IOP-induced shear stress and calls for further investigation in this area.
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July 2019