Clinical characteristics associated with poor outcome in patients acutely infected with Influenza A

We sought to identify certain clinical characteristics associated with a poor clinical outcome in patients acutely infected with Influenza A.

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).

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.

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.