16 To control for confounding agents, we included in the model, drugs that could potentially accelerate or reduce bleeding or occlusive tendency.
Aimed at minimizing these confounding agents - frequently not taken into consideration in previous studies - we evaluated the effect of the 4G/5G polymorphism of the PAI-1 gene on the occurrence of organ dysfunction, severity of the disease and mortality in a relatively homogenous cohort of patients: only Caucasian subjects with severe sepsis due to pneumonia were included in the study.
No confounding agent was involved in the occurrence of ANA and anti-dsDNA.
No confounding agent (such as statins) was involved in patients with myositis, myalgias or elevated creatinin phosphokinase.
A total of 400 serum canine samples, including 283 positive dogs for CVL from an endemic area, 86 clinically healthy dogs from a non-endemic area and 31 dogs seropositive for confounding infectious agents (Trypanosoma cruzi, Toxoplasma gondii, Neospora caninum, Babesia canis and Ehrlichia canis) were used for test validation.
In order to avoid anti-TNF-α agent as a confounding factor, patients under or who had previously received anti-TNF-α agent were excluded from this study.
However, we cannot rule out the presence of additional confounding infectious agents, for which we did not control.
After confounding from other antimicrobial agents was controlled for, fluoroquinolone use was significantly associated with an increased risk of developing CDAD (OR 12.7; 95% CI 2.6 to 61.6).
However, particularly in surgical patients, vasopressors may be required as a result of anesthetic agents, epidural anesthesia, blood loss, and so on, so that in the presence of infection it may be difficult to accurately distinguish the specific reason for vasopressor agents, thus confounding the diagnosis.
As noted above, however, even processes of tracking by means of simple heuristics can lead a tracker to make systematic misidentification errors and confound an apparent agent with a real agent.
Nonetheless, findings from Coble et al. (2002) suggest that the magnitude of bias due to confounding from exposure to multiple agents is likely to be minimal based on the proportion of farmers reporting exposure to agents including cleaning solvents and diesel exhaust.
