Nosocomial infections: decade-specific risk.

Although the elderly are thought to be at increased risk for acquiring nosocomial infections (NIs), the degree of risk has not been carefully quantified. We determined the decade-specific risks of NIs. The rate was constant at approximately 10 per 1,000 discharged patients from birth to 40 to 49 years. Thereafter the rate rose logarithmically and peaked at greater than 100 per 1,000 discharges after 70 years. Of all NIs, 64% occurred after 60 years of age. Yet, this elderly group made up only 23% of hospitalized patients. In conclusion, while the elderly comprise a small fraction of hospitalized patients, they account for the majority of nosocomial infections.