Healthcare Information Systems to Assess Influenza Outbreaks: An analysis of the 2009 H1N1 Epidemic in Buenos Aires

To determine whether a private HIS could have detected the influenza epidemic outbreaks earlier through changes in morbidity and mortality patterns.

Data Source included a health information system (HIS) from an academic tertiary health care center integrating administrative and clinical applications. It used a local interface terminology server which provides support through data autocoding of clinical documentation. Specific data subsets were created to compare the burden of influenza during the epidemiological week (EW) 21 to 26 for years 2007 to 2009 among 150,000 Health Maintenance Organization members in Argentina. The threshold for identifying an epidemic was considered met when the weekly influenza-like illness (ILI) rate exceeded 200 per 100,000 visits. Case fatality rates and mortality rates of severe acute respiratory infection (SARI) from 2007 to 2009 were retrospectively compared. Case fatality rates and mortality rates for A/H1N1 influenza 2009 also were estimated.

The HIS detected the outbreak in EW 23 while the government Ministry of Health (MoH) gave a national epidemic alert during EW 25. The number of visits for ILI increased more than fourfold when comparing 2009 to the period 2007-2008. The SARI mortality rate in 2009 was higher than in 2008 (RR 2.8; 95%CI 1.18-6.63) and similar to that of 2007 (RR 1.05; 95%CI 0.56-1.49). 2009 was the first year with mortalities younger than 65 years attributable to SARI. The estimated A/H1N1 case fatality rate for SARI was 6.2% (95%CI 2.5 to 15.5) and A/H1N1 mortality rate was 6 per 100,000 (95%CI 0 to 11.6).

Our HIS detected the outbreak two weeks before than the MoH gave a national alert. The information system was useful in assessing morbidity and mortality during the 2009 influenza epidemic H1N1 outbreak suggesting that with a private-public integration a more real-time outbreak and disease surveillance system could be implemented.