Strong Evidence of Factors Associated with Increased Risk of SSI
Strong evidence supports that the following factors are associated with an increased risk of infection:

• Anemia
• Duration of Hospital Stay
• Immunosuppressive Medications
• History of Alcohol Abuse
• Obesity
• Depression
• History of Congestive Heart Failure
• Dementia

There were eight high quality studies on the association of Anemia with the risk of SSI. Of these, five revealed an association between anemia and SSI. Four studies reviewed the risk of PJI and the 5th study reviewed the risk of infection and cervical spine fusion. Determinations were based on regression analyses of large data bases. Greenky et al 2012 identified the significant risk of anemia in PJI of development of SSI.

Duration of Hospital Stay
There were 11 high quality studies that examined the association between the length of hospital stay and the risk of SSI. Of these, seven revealed an association between increased length of stay and the risk of SSI. The studies were a range of multi-variant analysis and regression analysis. Three studies revealed that prolonged preoperative inpatient stays were related to increased risk of infection. Four studies revealed that prolonged post op hospitalization correlated with an increased risk of SSI. Longer hospital stays, including both pre-op and post-op stays correlated with increasing risk of SSI development.

Immunosuppressive Medication
Ten high quality studies were reviewed that looked at the effects of immunosuppressive agents. Of these, seven revealed a strong correlation between the use of immunosuppressive medications and an increased risk of SSI. These studies reviewed the effects of these medications on the risk of SSI associated with total joint replacement, spine surgery and ACL reconstruction. Momohara 2011 identified specifically that infliximab and etanercept combined with prolonged disease duration were associated with increased SSI risk. Giles 2006 identified increased risks of SSI associated with taking Tumor Necrosis Factor medications.

Alcohol abuse
Five high quality articles were reviewed. Three revealed a strong correlation between alcohol abuse and the risk of SSI. The articles used multi-variant analysis and looked a range of orthopaedic procedures and the effect of alcohol abuse on the risk of SSI on these procedures. Large multivariate studies from Cavanaugh 2015, Grammatico 2015 and Jain 2015, surveying thousands of patients, consistently show increased risks associated with increased alcohol consumption.

Fourteen high quality studies showed a correlation between obesity and the risk of SSI. These studies used multivariant analysis showing that increasing BMI correlated strongly with the risk of post op infection. All of the studies showed significantly increased risk of SSI that correlate well with increased BMI. Several studies identified additional risks associated with increased BMI over 40. These risks include cardiac, pulmonary and systemic complications in additional to the increased SSI risks.

Four high quality studies confirmed a correlation between depression and the risk of SSI. All four studies used regression analysis. In each of the multivariate studies a correlation between clinically detected depression and increased risks of surgical site infection was identified.

Congestive Heart Failure
Two high quality studies revealed a strong correlation between the risk of CHF and SSI. These studies were all multi-variant regression analysis studies. Patients with CHF also have a higher risk of other vascular problems.

Two large high quality studies using regression analysis revealed a strong correlation between Dementia and the risk of SSI in geriatric fractures patients. Dementia is an independent risk factor for occurrence of a surgical site infection

Four high quality studies revealed a high correlation between the diagnosis of HIV/AIDs and the risks of SSI. There was a strong correlation between the diagnosis of HIV/AIDs and the risk of infection. Boylan revealed an increased risk of SSI of 17%.


The Future of OrthoGuidelines


The OrthoGuidelines Process