Key messages

• Administering a long-term antibiotic prophylaxis regimen, compared to administering a short-term antibiotic prophylaxis regimen probably decreases the risk of surgical site infection.
• Administering a long-term prophylactic antibiotic regimen, compared to administering a short-term prophylactic antibiotic regimen, may increase hospital stay longer than two days (low certainty of evidence).
• No studies were found that looked at mortality, systemic infection and adverse effects.

What is the evidence.
See evidence matrix  in Epistemonikos later

We identified five systematic reviews [1], [2], [3], [4], [5] including nine studies overall [6], [7], [8], [9], [10], [11], [12], [13], [14], of which all were randomized trials.

What types of patients were included*

All trials included patients that underwent orthognathic surgery, without distinction in the subtype of surgery. The trials included men and women with ages ranging from 15 to 48 years [6], [7], [8], [9], [10], [11], [12], [13], [14].

What types of interventions were included*

All trials evaluated long antibiotic prophylaxis regimens compared with short prophylaxis regimens. 

Long-term prophylactic regimens considered administration of antibiotics before the operation, on the day of the surgery, and for several additional postoperative days: two days [7], [13],12 three days 12], five days [6], [11], seven days [10], [14]. This information was not reported in two trials [8], [9].

Short-term prophylactic antibiotic regimens considered preoperative and during the same day (up to 24 hrs.) antibiotic administration [6], [7], [8], [9], [10], [11], [12], [13], [14]. Three trials used placebo within the regimen [6], [7], [13]. 

The antibiotics used by each trial were:

• Cefpiramide [12]
• Penicillin G [7], [10], [11], [13], [14]
• Penicillin V [7]
• Amoxicillin [6]
• Amoxicillin and clavulanic acid [11]
• Clindamycin [6], [10] (only in patients presenting penicillin allergy)

The routes of drug administration used were

• Endovenous: [12]
• Intramuscular and intravenous [13]
• Endovenous and oral [6], [7], [10], [11], [14] 

Two trials did not report the regimen, antibiotic or route of administration used [8], [9].

What types of outcomes 
were measured

• Surgical Site Infection
• Hospital Stay

To whom this evidence does and does not apply

• The results of this summary are applicable to patients who are undergoing orthognathic surgery; and especially to those who present an increased risk of infection, either by concomitant chronic pathologies, drug treatment or by factors inherent to the surgical act, such as magnitude of the osteotomies, exposure to oral fluids and operating time.

• All the selected outcomes are considered critical for decision making according to the opinion of the authors of this summary, which coincide in general with those evaluated by the systematic reviews.
• The outcome mortality was included in the summary of findings table because it is a relevant outcome for clinical experts, even though it is not a frequent outcome, and was not reported by the reviews either. This also applies to the outcome of adverse effects, which was included because it reports relevant information regarding complications or post-operative aspects associated with orthognathic surgery. However, they were not reported in the reviews.

• The evidence included for this summary shows a likely benefit in terms of reducing the risk of surgical site infection using a long-term antibiotic prophylaxis regimen compared to using a short-term one.
• On the other hand, the risk of a hospital stay longer than two days using a long-term prophylactic antibiotic regimen is unclear due to the certainty of the evidence. Therefore, we suggest caution when assuming conclusions on this matter.
• Based on the above, the risk/benefit balance is favorable towards the use of a long-term prophylactic antibiotic regimen.

• None of the trials conducted a cost analysis regarding the use of antibiotic prophylaxis. However, there is evidence that the additional costs associated with complications of orthognathic surgery can be considerable [1].

• Given the evidence presented in this summary, most patients and surgeons should prefer a long-term prophylactic antibiotic regimen rather than a short-term one, since with the long-term regimen, there is a likely reduction in the risk of infectious postoperative complications and thus in their socio-economic consequences. 
• Additionally, it is important to emphasize that this is valid as long as there is a correct and precise indication for antibiotic administration.

Differences between this summary and other sources

• The conclusions of this summary are consistent with four of the five identified systematic reviews [1], [2], [4], [5], which consider that the long-term prophylactic antibiotic regimen probably reduces the risk of surgical site infection compared to a short-term regimen.
• A systematic review [3] reports that the quality of the available evidence is not good enough, and therefore a determination cannot be made with sufficient certainty.
• The American Association of Oral and Maxillofacial Surgeons (AAOMS) [15] and British Association of Oral and Maxillofacial Surgeons (BAOMS) [16] clinical guidelines for orthognathic surgery suggest the judicious use of antibiotic prophylaxis to contribute to the reduction of possible postoperative complications, without making any distinction on the type of scheme to be used.

• Future research is likely to change the conclusions of this summary, especially in respect to hospital stay longer than two days, because of the uncertainty surrounding this outcome.
• We did not identify any ongoing systematic reviews or randomized clinical trials in the National Institute for Health Research's International prospective register of systematic reviews (PROSPERO) and the World Health Organization's International clinical trials registry platform, respectively.