The purpose of this article is to evaluate, using two pairwise case-control studies, attributable mortality linked to hospital-acquired ventilator-associated pneumonia (HA-VAP) complicating the intensive care unit (ICU) stay of patients exhibiting severe community-acquired pneumonia (CAP).
Over an 11-year period, 498 patients with severe CAP were collected. Among them, 43 exhibited HA-VAP. In a first case-control study, these patients were matched with control on the basis of six confounding variables known to be general ICU prognosis factors. In a second case-control study, six variables specifically linked to CAP prognosis were used for matching.
In the two case-control studies, each case patient was matched with one control patient. In the first analysis, success of matching was achieved in 198 of 258 (77%) variables used for matching. In the second analysis, matching was successful for 242 of 258 (94%) confounding variables used. Eighteen patients died, compared with, respectively, 6 (P = .003) and 7 (P = .01) controls. Attributable mortality of HA-VAP was similar in the two pairwise analyses, respectively, 28% (risk ratio = 3.0; 95% confidence interval, 1.32 to 6.82) and 26% (risk ratio = 2.57; 95% confidence interval, 1.2 to 5.52).
When confounding factors were controlled, HA-VAP appeared to increase mortality of severe CAP requiring ICU admission.