US population aging and demand for inpatient services.

US inpatient capacity increased until the 1970s, then declined. The US Census Bureau expects the population aged ≥65 years to more than double by 2050. The implications for national inpatient capacity requirements have not been quantified. Our objective was to calculate the number of hospital admissions that will be necessitated by population aging, ceteris paribus. We estimated 2011 nationwide age-specific hospitalization rates using data from the Nationwide Inpatient Sample and Census data. We applied these rates to the population expected by the Census Bureau to exist through 2050. By 2050, the US population is expected to increase by 41%. Our analysis suggests that based on expected changes in the population age structure by then, the annual number of hospitalizations will increase by 67%. Thus, inpatient capacity would have to expand 18% more than population growth to meet demand. Total aggregate inpatient days is projected to increase 22% more than population growth. The total projected growth in required inpatient capacity is 72%, accounting for both number of admissions and length of stay. This analysis accounts only for changes in the population's age structure. Other factors could increase or decrease demand, as discussed in the article.