Facility characteristics

There were between 46 and 48 NHSN-reporting DoD hospitals from 2017 to 2021 with 47 in 2021. Compared to all hospitals reporting to NHSN, DoD facilities were smaller on average (24/47 DoD facilities had 50 or fewer beds, compared to 2,105/5,067 non-DoD facilities, RR = 1.23, 95% CI 0.93–1.63) (Table 1).^{Reference O’Leary, Neuhauser, McLees, Paek, Tappe and Srinivasan15,Reference O’Leary, van Santen, Webb, Pollock, Edwards and Srinivasan16} Of the 21 DoD teaching hospitals, 13 were graduate teaching and eight were major teaching (Table 2). Thirty-four of the hospitals were within the U.S. and 13 were outside.

Table 1.

Bed size comparison of Department of Defense (DoD) and National Healthcare Safety Network (NHSN) reporting national hospitals

Abbreviations: DoD, Department of Defense; NHSN, National Healthcare Safety Network.

^a Data from O’Leary et al. (2017).^{Reference O’Leary, van Santen, Webb, Pollock, Edwards and Srinivasan16}

^b Data from O’Leary et al. (2024).^{Reference O’Leary, Neuhauser, McLees, Paek, Tappe and Srinivasan15}

^c DoD hospitals are included in the nationally reporting facilities.

Table 2.

Department of Defense (DoD) hospital characteristics based on 2021 National Healthcare Safety Network (NHSN) data and supplemental survey facilities

Abbreviations: DoD, Department of Defense; HHS, Department of Health and Human Services; ICU, intensive care unit; Min, minimum; Max, maximum; NHSN, National Healthcare Safety Network; Std. Dev., standard deviation.

^a Major teaching facilities have a program for medical students and post-graduate medical training (residencies/fellowships), while graduate teaching facilities only have post-graduate training. (Definition from NHSN Patient Safety Component Manual).⁸

^b Supplemental survey data not provided due to risk of facility identification.

Statistical significance of bivariate associations between facility characteristics is reported in Table 3, and significant associations are described below. Hospital location was associated with Service, teaching status, and size. Half of Air Force hospitals (5/10 were overseas versus 41.2% of Navy hospitals (7/17, RR 0.82, 95% CI 0.36 – 1.91), 11.1% of Army hospitals (2/18, RR 3.71, 95% CI 0.89–15.41; Navy comparator), and none of the five Joint hospitals. Only one of 14 overseas hospitals was a teaching hospital, compared with 21 of 36 hospitals located in the U.S. (RR 0.12, 95% CI 0.12–0.83). Twelve of 14 overseas hospitals had ≤ 50 beds compared with 15 of 36 hospitals located in the U.S. (RR 2.06, 95% CI 1.32–3.20), and none of the three largest hospitals were overseas. Hospital size was also associated with teaching status: 19/22 teaching hospitals had >50 beds compared to 4/28 non-teaching hospitals (RR 6.05, 95% CI 2.40–15.21). While of borderline statistical significance, the Navy tended to have more small hospitals (12/17) than the other Services (15/33, RR 1.55, 95% CI 0.96–2.52). (Appendix 2)

Table 3.

Statistically significant bivariate associations between facility characteristics and supplemental survey variables

Abbreviations: ASP, antibiotic stewardship program; Q, question (from the supplemental survey).

^a “Unknown” responses removed.

* Statistically significant (p < .05).

^# Borderline statistically significant (.05 ≤ p ≤ .06).

- Not applicable.

Fisher’s exact test p-values are shown; Associations of one facility characteristic with another appear twice in the chart.

See Appendix 2 for additional data on these associations.

Supplemental survey

Forty of 47 (85.1%) DoD hospitals completed the supplemental survey. Duplicate responses were received for three hospitals; responses from the person with longer tenure in the ASP were kept. More respondents (n = 28, 70.0%) reported that they were the ASP Pharmacist Leader, 11 (27.5%) were the Physician Leader, and 1 (2.5%) was the Infection Prevention and Control Leader. As seen in Table 2, there was a significant difference between survey completion status and facility size; the seven non-respondent facilities all had ≤ 50 beds. Region was significantly associated with survey completion; details were not included due to risk of facility identification. No other facility characteristics significantly varied by survey completion status.

Survey results indicated that most hospitals started ASPs in 2017 or prior: 9 hospitals (22.5%) in 2017 and 11 (27.5%) prior to 2017. The “unknown” category (n = 10) was removed for bivariate analyses. There was a significant relationship between when an ASP started and categorical number of beds. The three largest hospitals started ASPs earlier, in 2017 or prior. There was a significant association between when the ASP started and medical affiliation; teaching hospitals started ASPs earlier.

ASP leaders in the DoD civilian/contractor employment category (hereafter civilian) were in their roles longer than military ASP leaders (Table 4). When asked if ASP leaders were more often assigned or requested to be in the role, 15 (37.5%) responded assigned, 9 (22.5%) said evenly requested and assigned, 7 (17.5%) responded that both occur but more often assigned, 5 (12.5%) said both but more often requested, and 4 (10.0%) said requested. When asked what proportion of ASP members were pharmacists, 27 (67.5%) reported 1–25%, followed by 10 (25.0%) reporting 26–50%. There was a statistically significant association between Region and proportion of pharmacists in the ASP, driven by Region 4 which has the most hospitals. While not statistically significant, there may be a weak association with proportion of time ASP pharmacist leaders spend on stewardship activities and hospital teaching status; less time was spent at non-teaching hospitals.

Table 4.

Comparing Antibiotic Stewardship Program (ASP) leader employment categories and roles with tenure and ASP proportions by employment category

^a Only 4 “unknown” responses were recorded: 2 military – other type of leader; 1 civilian/contractor – physician; 1 civilian/contractor – other type of leader.

^b Calculated with 1 = 0–1 year; 2 = >1–2 years; 3 = >2 years-3 years; 4 = >3 years-4 years; 5 = >4 years.

When asked if an ASP leader was available on a daily basis, 35 (85.0%) replied “yes;” responses were not associated with facility characteristics. All respondents were asked on average what percent of time did physician and pharmacist ASP leaders dedicate to antimicrobial stewardship activities; 30 (75.0%) answered that physician leaders spent 1–25% of their time, and 8 (20.0%) said 26–50% of their time. Pharmacist leaders spent more time on ASP activities than physicians, but still the majority (23 (57.5%)) reported an average of 1–25% of time on ASP activities; 9 (22.5%) 26–50% of time, 2 (5.0%) 51–75% of time, and 6 (15.0%) 76–100% of time. There was no correlation with categorical number of beds or variation by level for number of admissions, number of patient days, or continuous number of beds with the reported proportion of time ASP leaders spent on stewardship activities.

Core Elements adherence

From 2017 to 2021, between 4,940 and 5,053 hospitals responded to the NHSN annual survey,¹⁴ including 46 to 48 DoD hospitals, meaning DoD represents approximately 1.0% of nationally reporting facilities (Table 5). Reporting facility participation varies year-to-year, thus comparisons over time do not compare the same facilities. National and DoD average percent CE adherence was very high overall, though the largest deficiencies over time were in Education, followed by Tracking and Reporting (Fig. 1). There were differences between national and DoD average adherence, with DoD lower than national levels for several CEs: −1.9% Education, −1.3% for both Action and Tracking, and −4.5% for having all seven CEs in place. For 2021, DoD was above national levels at 100% adherence for the procedural CEs of Action, Tracking, Reporting, and Education, and DoD was 0.7% higher for programs with all seven CEs in place. DoD was lower than national adherence for the structural CEs: −1.0% Leadership, −2.5% Accountability, and −0.9% Pharmacy Expertise. In 2021, Pearson’s χ² tests showed that adherence differences between national and DoD hospitals were not significant (p = 0.484 Leadership, 0.199 Accountability, 0.543 Pharmacy Expertise, 0.480 Action, 0.356 Tracking, 0.456 Reporting, 0.551 Education). Adherence for 2021 was high and thus not able to be stratified by levels of facility characteristics.

Table 5.

National and Department of Defense (DoD) adherence to CDC Core Elements, 2017–2021 and Priority Elements, 2021

Abbreviations: CDC, Centers of Disease Control and Prevention; DoD, Department of Defense; NA, not applicable.

^a National Priority Elements data from O’Leary et al. (2024)^{Reference O’Leary, Neuhauser, McLees, Paek, Tappe and Srinivasan15} – denominators differ from the CDC Antibiotic Resistance & Patient Safety Portal (AR & PSP) because 6 states/territories were excluded from the AR & PSP but were included in the O’Leary manuscript (personal email communication with Neuhauser, Melinda); number of facilities not available.

DoD hospitals are included in the nationally reporting facilities; National Core Elements data from the AR & PSP.

Refer to Fig. 1 for a visual representation of these data.

Figure 1.

Percent of national and Department of Defense hospital adherence to CDC Core Elements, 2017–2021.

In 2021 for the Priority Elements, DoD hospitals reported lower adherence than national hospitals for four Priority Elements: −35.3% Leadership, −12.9% Accountability, −17.5% Pharmacy/Stewardship Expertise, and −14.8% Action; two Priority Elements were higher: +57.0% Tracking and +9.6% Reporting.^{Reference O’Leary, Neuhauser, McLees, Paek, Tappe and Srinivasan15} DoD hospitals met an average of 3.3 of the Priority Elements, with 3 (6.4%) meeting all Priority Elements; 9.5% of national hospitals met all six.^{Reference O’Leary, Neuhauser, McLees, Paek, Tappe and Srinivasan15} There were 8 DoD facilities (17.0%) meeting five of the Priority Elements and 9 (19.1%) meeting four. Thus, 36.2% of DoD hospitals met four or five Priority Elements, compared to 45.6% of national hospitals. In the MHS, there did not appear to be a facility size association with meeting all six Priority Elements.