Poor Compliance Is a Major Factor in Unstable Outpatient Control of Anticoagulant Therapy

Kumar, S.; Haigh, J. R. M.; Rhodes, Laura A.; Peaker, S.; Davies, J. A.; Roberts, B. E.; Feely, M.

doi:10.1055/s-0038-1646892

Cited by 84 publications

(37 citation statements)

References 15 publications

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“…Previous studies have shown that adherence to warfarin therapy is significantly associated with anticoagulation (INR) control [3,10,11]. It is recommended that future studies are required in order to examine such effect on the population.…”

Section: Knowledge Of Warfarin Therapymentioning

confidence: 99%

“…The improper use of warfarin is associated with unintentional bleeding and thrombosis as well as the lack of patients' knowledge, concurrent disease states, diet, and poor adherence to warfarin therapy [2][3][4]. Warfarin-associated intracerebral hemorrhage [5], with a 50 % mortality rate, is one of the most severe adverse drug events (ADEs).…”

Section: Introductionmentioning

confidence: 99%

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Association between Oral Anticoagulation Knowledge, Anticoagulation Control, and Demographic Characteristics of Patients Attending an Anticoagulation Clinic in Saudi Arabia: A Cross-Sectional Prospective Evaluation

Mayet

2015

Trop. J. Pharm Res

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%) had good knowledge of warfarin (scored ≥ 75 %), but only 35 patients (33.3 %) had good anticoagulation control (TTR ≥ 75 %). An association was observed between patients with no formal education and poor warfarin knowledge (p = 0.012). Smoking history was also linked with warfarin knowledge (p = 0.025). INR control results significantly differed by marital status with divorced/widow status displaying poor INR control (p = 0.028). Lastly, no association was found between good knowledge and good INR control (OR 1.35, 95 %;

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Section: Knowledge Of Warfarin Therapymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Association between Oral Anticoagulation Knowledge, Anticoagulation Control, and Demographic Characteristics of Patients Attending an Anticoagulation Clinic in Saudi Arabia: A Cross-Sectional Prospective Evaluation

Mayet

2015

Trop. J. Pharm Res

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“…Low-dose phenobarbital is frequently used as a chemical marker because of its long half-life. Recently, Kumar et al (1989) used this method in patients on warfarin therapy, and concluded that poor compliance is a major cause of instability. In our Thrombosis Service the majority of patients use the longacting coumarin derivative phenprocoumon (Marcoumar ® ).…”

mentioning

confidence: 99%

“…The older methods such as interviewing the patient, pill counts and measurements of the drug concentration in plasma all have disadvantages. A recently introduced method is to add a low-dose chemical marker to the tablet (Pullar et al, 1988;Kumar, 1989). Low-dose phenobarbital is frequently used as a chemical marker because of its long half-life.…”

mentioning

confidence: 99%

The role of compliance as a cause of instability in oral anticoagulant therapy

Meer¹,

Briët²,

Vandenbroucke³

et al. 1997

Br J Haematol

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Summary.To assess the role of non-compliance as a cause of instability in patients on oral anticoagulant therapy, a follow-up study of stably and instably anticoagulated patients and of patients beginning oral anticoagulant therapy was performed. Compliance was assessed by pill counting and with the use of pill bottles in the cap of which a microprocessor registered the exact date and time of opening of the bottle. (In)stability of oral anticoagulant therapy was expressed as the number of INRs and as the time spent within the target range and by squared sigma. Subsequently, as a pilot study, a randomized intervention study in instable, non-compliant patients was performed in which these patients were or were not informed about the real nature of the cap of the pill bottle.Nineteen stable and 19 unstable patients and 30 patients beginning therapy were followed for 3 months or less until therapy stopped. Compliance was better in the previously stably anticoagulated patients, although differences were small. Poor compliance was not a major cause of instability in patients starting therapy. Although the pilot intervention study was too small to assess the role of the special pill bottle, it was shown that compliance can be positively affected.

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“…Subsequently we have used it to assess compliance in a number of clinical situations (Bignell et al, 1988;Kumar et al, 1989a;Penn et al, 1988;Pullar etal., 1988a,c) and have shown it to be more effective than traditional methods (Pullar et al, 1988a(Pullar et al, , 1989. Low-dose phenobarbitone is a suitable pharmacological indicator for a number of reasons.…”

Section: Introductionmentioning

confidence: 99%

The prediction of steady‐state plasma phenobarbitone concentrations (following low‐dose phenobarbitone) to refine its use as an indicator of compliance.

Pullar

Kumar

Chrystyn

et al. 1991

Brit J Clinical Pharma

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1. A model for predicting the steady‐state plasma concentration of phenobarbitone following low‐dose phenobarbitone used as an indicator of compliance was derived using data for 10 healthy volunteers. 2. Each volunteer was given a single 30 mg oral dose of phenobarbitone and the pharmacokinetics were described. Subsequently, volunteers were given phenobarbitone 2 mg daily for 28 days and a further pharmacokinetic profile determined during and after this period. 3. An initial predicted estimate of steady‐state plasma drug concentration was made using each volunteer's demographic details. This estimate was revised by Bayesian analysis using single timed samples (24, 48, 72 or 96 h) following the single dose. 4. The model was tested on a further 10 healthy volunteers given a single 8 mg dose and who were subsequently given 2 mg daily for 28 days. 5. The revised estimate of peak steady‐ state plasma phenobarbitone concentration utilising the 96 h post‐ single dose concentration (356 ng ml‐1) was least biased (mean prediction error +/‐ 95% CI = 10.6 +/‐ 19.8 ng ml‐1) and most precise (root mean square error +/‐ 95% CI = 28.3 +/‐ 19.0 ng ml‐1). In all cases the peak or trough steady‐state drug concentration was within 13% of the predicted value. 6. The model reflected compliance accurately in a further eight volunteers with simulated partial (two‐thirds) compliance. 7. The use of a predictive model using Bayesian analysis to estimate expected steady‐state plasma phenobarbitone concentrations could increase further the usefulness of low‐dose phenobarbitone as an indicator of compliance.

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Poor Compliance Is a Major Factor in Unstable Outpatient Control of Anticoagulant Therapy

Cited by 84 publications

References 15 publications

Association between Oral Anticoagulation Knowledge, Anticoagulation Control, and Demographic Characteristics of Patients Attending an Anticoagulation Clinic in Saudi Arabia: A Cross-Sectional Prospective Evaluation

Association between Oral Anticoagulation Knowledge, Anticoagulation Control, and Demographic Characteristics of Patients Attending an Anticoagulation Clinic in Saudi Arabia: A Cross-Sectional Prospective Evaluation

The role of compliance as a cause of instability in oral anticoagulant therapy

The prediction of steady‐state plasma phenobarbitone concentrations (following low‐dose phenobarbitone) to refine its use as an indicator of compliance.

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