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WARFARIN-RELATED BLEEDING FOLLOWING OPEN HEART SURGERY IN NAIROBI
Abstract
Objectives: To review anticoagulant-related bleeding in heart valve patients on warfarin at
the Kenyatta National Hospital and to determine the variables associated with anticoagulantrelated
bleeding.
Design: A combined retrospective and prospective review of patients operated at the
Kenyatta National Hospital. Retrospective period from June 1973 to 31st July 1997, while
prospective period from August 1st 1997 to June 1st 2000.
Setting: Surgical Outpatient Department, Kenyatta National Hospital, Nairobi.
Main outcome measures: Linearised occurrence rate of anticoagulant-related bleeding and
the one- five- and ten- year bleed free rates. Independent risk factors associated with
anticoagulant-related bleeding determined using Cox's proportional hazards.
Results: Thirty one bleeding episodes were recorded in 150 patients followed up for a total
of 745 patient-years. The risk of occurrence of the first bleed was 16.0% ; while the risk of a
subsequent bleed increased thereafter with a 16.7%, 50% and 50% riskafter the first, second
and third bleeds respectively. The linearised rate for minor anticoagulant-related bleed was
4.16% per patient per year however, half the bleeds occurred within the first year of valve
implantation or previous bleeding episode. The one-, five- and ten- year bleed free rates for
all valves combined were 93%, 85% and 78% respectively. There was no statistically
signicant difference between the curves comparing the bleed free rates for the first and
second bleeding episodes (p=0.098). The number of valves implanted, the site of implant and
the time to the occurrence of bleeding were independent risk factors associated with the
occurrence of bleeding (p<.05).
Conclusion: The occurrence of anticoagulant-related bleeding is relatively common being
slightly above theinternationally reported range. Most episodes of bleeding will occur within
one year of hospital discharge or the previous bleeding episode. The riskof another bleeding
episode occurring increases with each episode with up to a 50% risk of re-bleed after the
second bleeding episode. In this study, the number of valves implanted, their position and the
time of occurrence of the bleed were risk factors to the occurrence of bleeding.
the Kenyatta National Hospital and to determine the variables associated with anticoagulantrelated
bleeding.
Design: A combined retrospective and prospective review of patients operated at the
Kenyatta National Hospital. Retrospective period from June 1973 to 31st July 1997, while
prospective period from August 1st 1997 to June 1st 2000.
Setting: Surgical Outpatient Department, Kenyatta National Hospital, Nairobi.
Main outcome measures: Linearised occurrence rate of anticoagulant-related bleeding and
the one- five- and ten- year bleed free rates. Independent risk factors associated with
anticoagulant-related bleeding determined using Cox's proportional hazards.
Results: Thirty one bleeding episodes were recorded in 150 patients followed up for a total
of 745 patient-years. The risk of occurrence of the first bleed was 16.0% ; while the risk of a
subsequent bleed increased thereafter with a 16.7%, 50% and 50% riskafter the first, second
and third bleeds respectively. The linearised rate for minor anticoagulant-related bleed was
4.16% per patient per year however, half the bleeds occurred within the first year of valve
implantation or previous bleeding episode. The one-, five- and ten- year bleed free rates for
all valves combined were 93%, 85% and 78% respectively. There was no statistically
signicant difference between the curves comparing the bleed free rates for the first and
second bleeding episodes (p=0.098). The number of valves implanted, the site of implant and
the time to the occurrence of bleeding were independent risk factors associated with the
occurrence of bleeding (p<.05).
Conclusion: The occurrence of anticoagulant-related bleeding is relatively common being
slightly above theinternationally reported range. Most episodes of bleeding will occur within
one year of hospital discharge or the previous bleeding episode. The riskof another bleeding
episode occurring increases with each episode with up to a 50% risk of re-bleed after the
second bleeding episode. In this study, the number of valves implanted, their position and the
time of occurrence of the bleed were risk factors to the occurrence of bleeding.
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