Hospital-Level Changes in Adult ICU Bed Supply in the United States

Abstract

Objectives: Although the number of intensive care beds in the United States is increasing, little is known about the hospitals responsible for this growth. We sought to better characterize national growth in intensive care beds by identifying hospital-level factors associated with increasing numbers of intensive care beds over time.

Design: We performed a repeated-measures time series analysis of hospital-level intensive care bed supply using data from Centers for Medicare and Medicaid Services.

Setting: All United States acute care hospitals with adult intensive care beds over the years 1996-2011.

Patients: None.

Interventions: None.

Measurements and main results: We described the number of beds, teaching status, ownership, intensive care occupancy, and urbanicity for each hospital in each year of the study. We then examined the relationship between increasing intensive care beds and these characteristics, controlling for other factors. The study included 4,457 hospitals and 55,865 hospital-years. Overall, the majority of intensive care bed growth occurred in teaching hospitals (net, +13,471 beds; 72.1% of total growth), hospitals with 250 or more beds (net, +18,327 beds; 91.8% of total growth), and hospitals in the highest quartile of occupancy (net, +10,157 beds; 54.0% of total growth). In a longitudinal multivariable model, larger hospital size, teaching status, and high intensive care occupancy were associated with subsequent-year growth. Furthermore, the effects of hospital size and teaching status were modified by occupancy: the greatest odds of increasing ICU beds were in hospitals with 500 or more beds in the highest quartile of occupancy (adjusted odds ratio, 18.9; 95% CI, 14.0-25.5; p < 0.01) and large teaching hospitals in the highest quartile of occupancy (adjusted odds ratio, 7.3; 95% CI, 5.3-9.9; p < 0.01).

Conclusions: Increasingly, intensive care bed expansion in the United States is occurring in larger hospitals and teaching centers, particularly following a year with high ICU occupancy.

Figure 1

Change in intensive care bed supply by year attributable to new hospitals, growing hospitals, shrinking hospitals and closed hospitals in the United States between 1997 and 2011 (left axis scale). The black dashed line shows the net annual change in intensive care bed supply. The light grey region shows the national intensive care bed supply (right axis scale). Note: Intensive care beds from hospitals with no change in a given year (compared to the prior year) are included in the right axis summary count.

Figure 2

Odds of increasing intensive care beds in subsequent year by hospital size and quartile of occupancy. Model adjusts for baseline number of intensive care beds, hospital academic status, hospital ownership, geographic region and urbancity. The reference category for comparisons is lowest quartile of intensive care occupancy and less than one hundred hospital beds. All comparisons have p-values <0.01, with exception of the comparison marked with an asterisk.

Figure 3

Odds of increasing intensive care beds in subsequent year by teaching status and quartile of occupancy. Model adjusts for baseline number of intensive care beds, total hospital beds, hospital ownership, geographic region and urbancity. The reference category for comparisons is lowest quartile of intensive care occupancy and non-teaching status. All comparisons have p-values <0.01, with exception of comparisons marked with asterisks.