Division of Emergency Medicine, Stanford University.
West J Emerg Med. 2010 Dec;11(5):435-41.
The aim of this study was to determine the rate of infection at which it is cost-effective to treat dog bite wounds with antibiotics.
Our study was composed of two parts. First we performed a randomized, double-blind controlled trial (RCT) to compare the infection rates of dog bite wounds in patients given amoxicillin-clavulanic acid versus placebo. Subjects were immunocompetent patients presenting to the emergency department (ED) with dog bite wounds less than 12 hours old without suspected neurovascular, tendon, joint or bone injury, and who had structured follow-up after two weeks. Second, we developed a cost model with sensitivity analysis to determine thresholds for treatment.
In the RCT, primary outcomes were obtained in 94 patients with dog bites. The overall wound infection rate at two weeks was 2% [95% CI 0 to 7%]. Two of 46 patients (4%) receiving no antibiotics developed infections, while none of the 48 patients (0%) receiving prophylactic antibiotics developed an infection (absolute reduction 4% [95% CI -1.0 to 4.5%]). Using a sensitivity analysis across a rate of infections from 0-10%, our cost model determined that prophylactic antibiotics were cost effective if the risk of wound infection was greater than 5% and antibiotics could decrease that risk by greater than 3%.
Our wound infection rate was lower than older studies and more in line with current estimates. Assuming that prophylactic antibiotics could provide an absolute risk reduction (ARR) of 3%, it would not be cost effective to treat wounds with an infection rate of less than 3% and unlikely that the ARR would be achievable unless the baseline rate was greater than 5%, suggesting that only wounds with greater than 5% risk of infection should be treated. Future work should focus on identifying wounds at high-risk of infection that would benefit from antibiotic prophylaxis.
本研究旨在确定治疗犬咬伤时使用抗生素的成本效益感染率。
我们的研究由两部分组成。首先，我们进行了一项随机、双盲对照试验（RCT），比较给予阿莫西林克拉维酸和安慰剂的犬咬伤患者的感染率。研究对象为免疫功能正常的患者，他们在急诊科就诊时因犬咬伤，伤后不到 12 小时，无疑似神经血管、肌腱、关节或骨损伤，且在两周后有结构性随访。其次，我们建立了一个成本模型，并进行了敏感性分析，以确定治疗的阈值。
在 RCT 中，94 名犬咬伤患者获得了主要结局。两周时的总体伤口感染率为 2%[95%CI 0 至 7%]。未接受抗生素治疗的 46 名患者中有 2 名（4%）发生感染，而接受预防性抗生素治疗的 48 名患者中无一例（0%）发生感染（绝对减少 4%[95%CI-1.0 至 4.5%]）。使用感染率在 0%至 10%之间的敏感性分析，我们的成本模型确定，如果伤口感染的风险大于 5%，并且抗生素可以将该风险降低 3%以上，那么预防性抗生素是具有成本效益的。
我们的伤口感染率低于旧的研究，更符合当前的估计。假设预防性抗生素可以提供 3%的绝对风险降低（ARR），那么治疗感染率低于 3%的伤口就没有成本效益，除非基线率大于 5%，否则不太可能实现 ARR，这表明只有感染风险大于 5%的伤口才需要治疗。未来的工作应集中在确定需要抗生素预防的高感染风险的伤口。
