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document
Warfarin for atrial fibrillation . The patient 's perspective . OBJECTIVE To determine the minimal clinically important difference ( MCID ) of warfarin therapy for the treatment of nonvalvular atrial fibrillation from the perspective of patients using 2 different elicitation methods . DESIGN All patients completed 2 face-to-face interviews , which were 2 weeks apart . For each interview , they were randomized to receive 1 of 2 elicitation methods : ping-ponging or starting at the known efficacy . SETTING The practices of 2 university-affiliated family medicine centers ( 8 physicians each ) , 14 community-based family physicians , and 2 cardiologists . PATIENTS Sixty-four patients with nonvalvular atrial fibrillation who were initiated with warfarin therapy at least 3 months before the study . INTERVENTION During each interview , the patients ' MCIDs were determined by using ( 1 ) a pictorial flip chart to describe atrial fibrillation ; the consequences of a minor stroke , a major stroke , and a major bleeding episode ; the chance of stroke if not taking warfarin ; the chance of a major bleeding episode if taking warfarin ; examples of the inconvenience , minor side effects , and costs of warfarin therapy ; and then ( 2 ) 1 of the 2 elicitation methods to determine their MCIDs ( the smallest reduction in stroke risk at which the patients were willing to take warfarin ) . Patients ' knowledge of their stroke risk , acceptability of the interview process , and factors determining their preferences were also assessed . MAIN RESULTS Given a baseline risk of having a stroke in the next 2 years , if not taking warfarin , of 10 of 100 , the mean MCID was 2.01 of 100 ( 95 % confidence interval , 1.60-2.42 ) . Fifty-two percent of the patients would take warfarin for an absolute decrease in stroke risk of 1 % over 2 years . Before eliciting their MCIDs , patients showed poor knowledge of their stroke risk , which improved afterward . The interview process was well accepted by the patients . The MCID using the ping-ponging elicitation method was 1.015 of 100 smaller compared with use of the starting at the known efficacy method ( P = .01 ) . CONCLUSIONS We were able to determine the MCID of warfarin therapy for the prevention of stroke from the perspective of patients with nonvalvular atrial fibrillation . Their MCIDs were much smaller than those that have been implied by some experts and clinicians . The interview process , using the flip chart approach , appeared to improve the patients ' knowledge of their disease and its consequences and treatment . The method used to elicit the patients ' MCIDs can have a clinically important effect on patient responses . The method used in our study can be generalized to other conditions and , thus , could be helpful in 3 ways : ( 1 ) from a clinical decision-making perspective , it could facilitate patient-physician communication ; ( 2 ) it could clarify the patient perspective when interpreting the results of previously completed trials ; and ( 3 ) it could be used to derive more clinically relevant sample sizes for randomized treatment trials .
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Intervention_Pharmacological
Warfarin
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Intervention_Pharmacological
warfarin therapy
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Intervention_Pharmacological
warfarin
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Intervention_Pharmacological
warfarin
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Intervention_Pharmacological
warfarin therapy
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Outcome_Other
minimal clinically important difference ( MCID )
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Outcome_Physical
a pictorial flip chart to describe atrial fibrillation ; the consequences of a minor stroke , a major stroke , and a major bleeding episode ;
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Outcome_Physical
chance of stroke if not taking warfarin ;
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Outcome_Physical
chance of a major bleeding episode if taking warfarin ;
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Outcome_Adverse-effects
minor side effects
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Outcome_Other
costs of warfarin therapy
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Outcome_Physical
stroke risk
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Outcome_Mental
knowledge of their stroke risk
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Outcome_Mental
MCID
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Outcome_Mental
MCID
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Outcome_Mental
patients ' knowledge of their disease and its consequences and treatment .
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Outcome_Mental
MCIDs
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Participant_Condition
atrial fibrillation
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Participant_Condition
nonvalvular atrial fibrillation
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Participant_Sample-size
Sixty-four
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Participant_Condition
nonvalvular atrial fibrillation
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Participant_Condition
nonvalvular atrial fibrillation