Pandemic influenza A (2009 H1N1) in hospitalized patients in a Saudi Arabian hospital: epidemiology and clinical comparison with H1N1-negative patients.

Background And Objectives: The World Health Organization (WHO) declared that pandemic influenza A (H1N1) was a public health emergency of international concern in April 2009. Herein, we describe the characteristics of patients in a Saudi Arabian hospital with and without H1N1 infection.

Methods: We reviewed the records of patients admitted with influenza-like illness and compared confirmed pandemic H1N1 cases to the H1N1-negative patients admitted to the hospital. Infections due to the novel H1N1 virus were confirmed using real-time reverse transcriptase polymerase chain reaction (rRT-PCR).

Results: During the study period, a total of 165 patients were admitted with influenza-like illness and underwent rRT-PCR testing. Of these patients, 47 (28.4%) had confirmed novel H1N1 virus infection. Thus, the hospitalization incidence rate was 13.4 cases per 100,000 persons. The remaining patients had negative H1N1 rRT-PCR test results. The mean age±SD of the H1N1-positive patients was 30.3±28.5 years compared with 25.3±23 years for the H1N1-negative group (P=0.28). Severe obesity was observed in 6.7% and 8.5% of H1N1-positive and H1N1-negative patients, respectively (P=0.74). The clinical picture was similar between the two groups, except for the higher prevalence of nausea (25.5% vs. 11%) and diarrhea (21.3% vs. 7.6%) in the H1N1-positive group than in the H1N1-negative group (P=0.03) The mortality rate was low in both groups.

Conclusion: The clinical presentation and outcome are insufficient to differentiate between influenza-like illness (ILI) caused by H1N1 and that cause by other pathogens. In general, both groups had mild disease in this cohort of patients in Saudi Arabia.