Methodological challenges in assessment of current use of warfarin among patients with atrial fibrillation using dispensation data from administrative health care databases

Sinyavskaya, Liliya; Matteau, Alexis; Johnson, Sarasa M.A.; Durand, Madéleine

doi:10.1002/pds.4570

Cited by 6 publications

(7 citation statements)

References 21 publications

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“…Indeed, we previously reported that for up to 75% of warfarin dispensations, the gaps were no longer than three days. 5 In our study population, the incidence rates of major bleeding were among the lowest of those reported in previous observational studies of individuals with NVAF. 10 This can be explained by a more restrictive definition in our study that included only those bleeding events requiring hospitalization.…”

Section: Discussioncontrasting

confidence: 48%

“…This suggests that in our study population, there were few individuals on warfarin having long gaps between dispensations. Indeed, we previously reported that for up to 75% of warfarin dispensations, the gaps were no longer than three days 5 …”

Section: Discussionmentioning

confidence: 99%

“…3 However, the days supplied may be vulnerable to exposure misclassification when comparing therapies with different medication use patterns, such as warfarin and direct oral anticoagulants (DOACs). 4,5 Individuals on warfarin need frequent dosing adjustments. The true duration of warfarin supply may last longer than the recorded supply due, for example, to pill splitting.…”

Section: Introductionmentioning

confidence: 99%

“…In pharmacoepidemiological studies, the definition of exposure duration using the days supplied is considered more reliable compared to other methods 3 . However, the days supplied may be vulnerable to exposure misclassification when comparing therapies with different medication use patterns, such as warfarin and direct oral anticoagulants (DOACs) 4,5 …”

Section: Introductionmentioning

confidence: 99%

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Defining the duration of the dispensation of oral anticoagulants in administrative healthcare databases

Sinyavskaya

Renoux

Durand

2021

Pharmacoepidemiology and Drug

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Purpose: In clinical practice, warfarin therapy requires frequent dose adjustments. In pharmacy claims, the days supplied value may not reflect the true duration of warfarin dispensation. This may affect the measures of association comparing the safety of direct oral anticoagulants (DOACs) versus warfarin.Methods: Using Quebec healthcare administrative databases, we formed a cohort of 55 230 patients newly treated with oral anticoagulants between 2010 and 2016. The duration of dispensations was defined using two approaches: the recorded days supplied value, and the longitudinal coverage approximation (data-driven) that may account for individual variation in drug usage patterns. Propensity scores adjusted Cox proportional hazards regression models were used to estimate the hazard ratio (HR) of major bleeding with dabigatran or rivaroxaban versus warfarin.Results: Using the days supplied, the mean (and standard deviation) dispensation durations for dabigatran, rivaroxaban, and warfarin were 19 (15), 19 (14), and 13 (12) days, respectively. Using the data-driven approach, the durations were 20 (16), 19 (15), and 15 (16) days, respectively. The choice of the approach had no impact on the HR estimates.Conclusions: In our settings, the data-driven approach closely approximated the recorded days supplied value for the standard dose therapies such as dabigatran and rivaroxaban. For warfarin, the data-driven approach captured more variability in the duration of dispensations compared to the days supplied value, which may better reflect the true drug-taking behavior of warfarin. Both approaches may provide valid estimates when comparing the safety of DOACs versus warfarin.

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Section: Discussioncontrasting

confidence: 48%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Defining the duration of the dispensation of oral anticoagulants in administrative healthcare databases

Sinyavskaya

Renoux

Durand

2021

Pharmacoepidemiology and Drug

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“…A common approach involves imputing a dose of 1 unit per day, which has been shown to be reliable for certain antihypertensive medications 91 . However, this approach is less reliable for drugs with variable dosages such as β blockers and warfarin and induces variability in the calculation with these agents 99 . Given that information on the prescribed daily dose is fundamental for accurately assessing the duration of medication exposure, custodians of administrative databases should consider collecting this information to better support research on medication use and associated outcomes.…”

Section: Discussionmentioning

confidence: 99%

Towards better reporting of the proportion of days covered method in cardiovascular medication adherence: A scoping review and new tool TEN‐SPIDERS

Dalli

Kilkenny

Arnet

et al. 2022

Brit J Clinical Pharma

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Although medication adherence is commonly measured in electronic datasets using the proportion of days covered (PDC), no standardized approach is used to calculate and report this measure. We conducted a scoping review to understand the approaches taken to calculate and report the PDC for cardiovascular medicines to develop improved guidance for researchers using this measure. After prespecifying methods in a registered protocol, we searched Ovid Medline, Embase, Scopus, CINAHL Plus and grey literature (1 July 2012 to 14 December 2020) for articles containing the terms “proportion of days covered” and “cardiovascular medicine”, or synonyms and subject headings. Of the 523 articles identified, 316 were reviewed in full and 76 were included (93% observational studies; 47% from the USA; 2 grey literature articles). In 45 articles (59%), the PDC was measured from the first dispensing/claim date. Good adherence was defined as 80% PDC in 61 articles, 56% of which contained a rationale for selecting this threshold. The following parameters, important for deriving the PDC, were often not reported/unclear: switching (53%), early refills (45%), in‐hospital supplies (45%), presupply (28%) and survival (7%). Of the 46 articles where dosing information was unavailable, 59% reported how doses were imputed. To improve the transparent and systematic reporting of the PDC, we propose the TEN‐SPIDERS tool, covering the following PDC parameters: Threshold, Eligibility criteria, Numerator and denominator, Survival, Presupply, In‐hospital supplies, Dosing, Early Refills, and Switching. Use of this tool will standardize reporting of the PDC to facilitate reliable comparisons of medication adherence estimates between studies.

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Real‐world on‐treatment and initial treatment absolute risk differences for dabigatran vs warfarin in older US adults

Webster‐Clark

Stürmer

Edwards

et al. 2020

Pharmacoepidemiology and Drug

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PurposeTrials and past observational work compared dabigatran and warfarin in patients with atrial fibrillation, but few reported estimates of absolute harm and benefit under real‐world adherence patterns, particularly in older adults that may have differing benefit‐harm profiles. We aimed to estimate risk differences for ischemic stroke, death, and gastrointestinal bleeding after initiating dabigatran and warfarin in older adults (a) when patients adhere to treatment and (b) under real‐world adherence patterns.MethodsIn a 20% sample of nationwide Medicare claims from 2010 to 2015, we identified beneficiaries aged 66 years and older initiating warfarin and dabigatran. We followed individuals from initiation until death or October 2015 (initial treatment, IT) and separately censored individuals' follow‐up after drug switches and gaps in supply (on‐treatment, OT). We applied inverse probability of treatment and standardized morbidity ratio weights, as well as inverse probability of censoring weights, to estimate two‐year risk differences (RDs) for dabigatran vs warfarin.ResultsWe identified 10,717 dabigatran and 74,891 warfarin initiators. Weighted OT RDs suggested decreased ischemic stroke risk for dabigatran vs warfarin; IT RDs indicated increased or no change in ischemic stroke risk. Regardless of follow‐up approach and weighting strategy, risk of death appeared lower and risk of gastrointestinal bleeding appeared higher when comparing dabigatran vs warfarin.ConclusionsDabigatran use was associated with lower risks of mortality and ischemic stroke in routine care when older adults stayed on treatment. IT analyses suggested that these benefits may be diminished under real‐world patterns of switching and discontinuation.

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Methodological challenges in assessment of current use of warfarin among patients with atrial fibrillation using dispensation data from administrative health care databases

Abstract: Greater refill gaps for warfarin may reflect inadequate capture of the period covered by the number of dispensed pills recorded in administrative data. A time-dependent definition of exposure using dispensation data would lead to greater misclassification of warfarin than DOACs use.

Cited by 6 publications

References 21 publications

Defining the duration of the dispensation of oral anticoagulants in administrative healthcare databases

Defining the duration of the dispensation of oral anticoagulants in administrative healthcare databases

Towards better reporting of the proportion of days covered method in cardiovascular medication adherence: A scoping review and new tool TEN‐SPIDERS

Real‐world on‐treatment and initial treatment absolute risk differences for dabigatran vs warfarin in older US adults

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