BACKGROUND: The H1N1/09 virus was reported to be similar to the seasonal flu. However, the World Health Organization (WHO) documented a substantial proportion of patients with H1N1/09 who developed severe illness and death particularly among those with underlying medical conditions. Presently, to our knowledge, there is no data in the Philippines where the demographic and clinical characteristics, risk factors and outcome of children positive for H1N1/09 virus were compared to those with influenza but were negative for H1N1/09.

OBJECTIVE: The objective of this study was to compare the demographic and clinical characteristics, risk factors, treatment and outcome of the two groups.

METHODS: A review was done of the charts of 162 patients who were tested for H1N1/09 virus by RT-PCR assay at the Makati Medical Center from May 5 to July 16, 2009. Demographic characteristics, risk factors, clinical features, treatment and outcomes were compared between the two groups. Categorical variables used between the two groups were compared using Fisher's exact test or Chi square test while quantitative variables were compared using T-test; odds ratio was determined.

RESULTS: A total of 162 patients were included in this study. The largest group of patients positive for H1N1/09 was from the age group of 11-15 years old (35.8%). Risk factors such as travel history and exposure to a confirmed case showed no association to having a positive H1N1/09 test. Clinical features such as fever (100%) and cough (82.1%) were the most common presenting symptoms for both groups. Majority of these patients were given supportive treatment and out of 162 subjects, 91.4 % were treated as outpatient. Clinical outcome showed one mortality from the case group and none from the controls.

CONCLUSION: Thus, the demographic characteristics and clinical findings were similar for both groups. Future studies are recommended to include those with influenza-like illness not tested for H1N1/09 virus.