Taiwan National Health Insurance (NHI) was established in 1995 and includes 99% of the 23 million Taiwanese residents due to mandatory, universal enrollment. The NHIRD collects and maintains all participant demographic data and diagnoses according to the International Classification of Disease, ninth revision (ICD-9-CM), as well as all procedures and medications.
Quintiles IMS or IMS Health is an organization that samples drug sales in each country through multiple supply routes to retail pharmacies and hospitals. Drug sales for the entire country are projected by the sampled data using patented projection methodology (1)
To estimate the rate of nosocomial infections, the Taiwan CDC revised the previous surveillance system and launched the TNIS. The TNIS collects data on nosocomial infections in hospital ICUs. The detailed methodology of data collection and inclusion criteria for each year is described in annual reports issued by the Taiwan CDC.
The clinical data of patients with nosocomial infections (eg, pathogen, types of infection, age, or hospital setting) are collected from the TNIS. Types of nosocomial infections in TNIS include pneumonia, surgical site, urinary tract, bloodstream, and others. Only infections with identifiable bacterial etiology are included.
The incidence of nosocomial bacterial infections in the ICUs is calculated by dividing the total number of episodes of nosocomial bacterial infections by the number of patient-days in a given group. The number of patient-days is the sum of the number of days in the ICU of a given population (by age or hospital setting). Only participated hospitals are included in the analyses. Information of length of stay in hospitals that participated in TNIS is extracted from the NHIRD.
The proportion of bacterial species in each infection type is also calculated. The percentage is calculated by dividing the number of infection episodes caused by a specific bacterium by the number of total infection episode. Bacterial pathogens include Enterococcus spp. and Staphylococcus spp. as well as Acinetobacter spp., Enterobacter spp., Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The sum of the percentage from each bacterium is more than 100% because one episode of infection may be caused by multiple pathogens.
Hospital settings (medical centers and regional/local hospitals) are defined in accordance with the NHI administration and Interior Ministry, respectively. There is only one medical center in Eastern Taiwan and the NHI administration prohibits the dissemination of information on specific hospitals. Therefore, this medical center is categorized as a regional/local hospital.
Data on inpatient antibiotic consumption are derived from the NHIRD. Only systemic use (oral or intravenous form) of antibiotics is included in analyses. Consumption is measured by the Defined Daily Doses (DDD) of antibiotics divided by the number of patient-days or population-days in a given group.
The DDD of each antibiotic is calculated according the ATC codes. The DDD of an antibiotic that is not indicated by the ATC is designated based on the mechanism of action and structure of the medication (DDD Table). The number of patient-days is the sum of hospitalization duration (days) of a given population (defined by age, area, or hospital setting). The number of population-days is defined by the number of Taiwanese residents multiplied by 365 days. The number of Taiwanese residents in a given group (age or area) is based on data issued by the Interior Ministry.