Purpose: We sought to identify certain clinical characteristics associated with a poor clinical outcome in patients acutely infected with Influenza A.
Methods: We performed a retrospective chart review of inpatients with acute Influenza A infection comparing a poor outcome group (POG; n=27), defined as patients who died and/or developed respiratory failure or shock, with a usual outcome group (UOG; n=105).
Results: Compared with the UOG, the POG had a significantly greater percentage of patients with: a history of chronic obstructive pulmonary disease (41% vs 20%), coronary artery disease (63% vs 38%), congestive heart failure (44% vs 23%), transient ischemic attack (TIA) or stroke (44% vs 21%), chronic renal insufficiency (22% vs 8%) and dialysis (11% vs 1%). Shortness of breath as a chief complaint (74% vs 44%), lower initial oxygen saturations (0.86 vs 0.92), as well as higher mean respiratory rates (28/minute vs 22/minute) occurred more frequently in the POG. The POG also had a greater frequency of CHF/ vascular congestion (26% vs 8%), and interstitial involvement (22% vs 6%) on admission chest roentgenogram. Independent predictors of poor outcome identified by multivariate analysis included low oxygen saturation on admission, history of TIA or stroke, and history of dialysis.
Conclusions: The presence of certain comorbidities as well as clinical and radiographic evidence of respiratory compromise on admission may be helpful in identifying high-risk patients acutely infected with Influenza A.