Warfarin-induced skin necrosis in HIV-1-infected patients with tuberculosis and venous thrombosis.
BACKGROUND
At the turn of the century, only 300 cases of warfarin-induced skin necrosis (WISN) had been reported. WISN is a rare but potentially fatal complication of warfarin therapy. There are no published reports of WISN occurring in patients with HIV-1 infection or tuberculosis (TB).


METHODS
We retrospectively reviewed cases of WISN presenting from April 2005 to July 2008 at a referral hospital in Cape Town, South Africa.


RESULTS
Six cases of WISN occurred in 973 patients receiving warfarin therapy for venous thrombosis (0.62%, 95% CI 0.25 - 1.37%). All 6 cases occurred in HIV-1-infected women (median age 30 years, range 27 - 42) with microbiologically confirmed TB and venous thrombosis. All were profoundly immunosuppressed (median CD4+ count at TB diagnosis 49 cells/microl, interquartile range 23 - 170). Of the 3 patients receiving combination antiretroviral therapy, 2 had TB-IRIS (immune reconstitution inflammatory syndrome). The median interval from initiation of antituberculosis treatment to venous thrombosis was 37 days (range 0 - 150). The median duration of parallel heparin and warfarin therapy was 2 days (range 1 - 6). WISN manifested 6 days (range 4 - 8) after initiation of warfarin therapy. The international normalised ratio (INR) at WISN onset was supra-therapeutic, median 6.2 (range 3.8 - 6.6). Sites of WISN included breasts, buttocks and thighs. Four of 6 WISN sites were secondarily infected with drug-resistant nosocomial bacteria (methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter, extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae) 17 - 37 days after WISN onset. In 4 patients, the median interval from WISN onset to death was 43 days (range 25 - 45). One of the 2 patients who survived underwent bilateral mastectomies and extensive skin grafting at a specialist centre.


CONCLUSIONS
This is one of the largest case series of WISN. We report a novel clinical entity: WISN in HIV-1 infected patients with TB and venous thrombosis. The occurrence of 6 WISN cases in a 40-month period may be attributed to (i) hypercoagulability, secondary to HIV-1 and TB: (ii) short concurrent heparin and warfarin therapy; and (iii) high loading doses of warfarin. Active prevention and appropriate management of WISN are likely to improve the dire morbidity and mortality of this unusual condition.
Bhaijee
F
F
Groote Schuur Hospital, Cape Town. fbhaijee@gmail.com
Wainwright
H
H
Meintjes
G
G
Wilkinson
R J
RJ
Todd
G
G
De Vries
E
E
Pepper
D J
DJ
D000328:Adult; D000925:Anticoagulants / Q000009:adverse effects*; D015897:Comorbidity; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D006801:Humans; D009336:Necrosis / Q000139:chemically induced; D012189:Retrospective Studies; D012867:Skin / Q000187:drug effects / Q000473:pathology*; D014376:Tuberculosis / Q000453:epidemiology*; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology; D020246:Venous Thrombosis / Q000453:epidemiology*; D014859:Warfarin / Q000009:adverse effects*
D000925:Anticoagulants; D014859:Warfarin