Epidemiology meets econometrics: using time-series analysis to observe the impact of bed occupancy rates on the spread of multidrug-resistant bacteria

The Impact of an Antimicrobial Stewardship Program on Days of Therapy in the Pediatric Center: An Interrupted Time-Series Analysis of a 19-Year Study

BACKGROUND

We aimed to analyze the effects of an antimicrobial stewardship program (ASP) on the proportion of antimicrobial-resistant pathogens in bacteremia, antimicrobial use, and mortality in pediatric patients.

METHODS

A retrospective single-center study was performed on pediatric inpatients under 19 years old who received systemic antimicrobial treatment from 2001 to 2019. A pediatric infectious disease attending physician started ASP in January 2008. The study period was divided into the pre-intervention (2001-2008) and the post-intervention (2009-2019) periods. The amount of antimicrobial use was defined as days of therapy per 1,000 patient-days, and the differences were compared using delta slope (= changes in slopes) between the two study periods by an interrupted time-series analysis. The proportion of resistant pathogens and the 30-day overall mortality rate were analyzed by the χ².

RESULTS

The proportion of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae bacteremia increased from 17% (39 of 235) in the pre-intervention period to 35% (189 of 533) in the post-intervention period (P < 0.001). The total amount of antimicrobial use significantly decreased after the introduction of ASP (delta slope value = -16.5; 95% confidence interval [CI], -30.6 to -2.3; P = 0.049). The 30-day overall mortality rate in patients with bacteremia did not increase, being 10% (55 of 564) in the pre-intervention and 10% (94 of 941) in the post-intervention period (P = 0.881).

CONCLUSION

The introduction of ASP for pediatric patients reduced the delta slope of the total antimicrobial use without increasing the mortality rate despite an increased incidence of ESBL-producing gram-negative bacteremia.

The association between bed occupancy rates and hospital quality in the English National Health Service

We study whether hospitals that exhibit systematically higher bed occupancy rates are associated with lower quality in England over 2010/11-2017/18. We develop an economic conceptual framework to guide our empirical analysis and run regressions to inform possible policy interventions. First, we run a pooled OLS regression to test if high bed occupancy is associated with, and therefore acts as a signal of, lower quality, which could trigger additional regulation. Second, we test whether this association is explained by exogenous demand-supply factors such as potential demand, and unavoidable costs. Third, we include determinants of bed occupancy (beds, length of stay, and volume) that might be associated with quality directly, rather than indirectly through bed occupancy. Last, we use a within-between random-effects specification to decompose these associations into those due to variations in characteristics between hospitals and variations within hospitals. We find that bed occupancy rates are positively associated with overall and surgical mortality, negatively associated with patient-reported health gains, but not associated with other indicators. These results are robust to controlling for demand-supply shifters, beds, and volume. The associations reduce by 12%-25% after controlling for length of stay in most cases and are explained by variations in bed occupancy between hospitals.

Impact of colonization pressure on acquisition of extended-spectrum β-lactamase-producing Enterobacterales and meticillin-resistant Staphylococcus aureus in two intensive care units: a 19-year retrospective surveillance

BACKGROUND

Colonization pressure is a risk factor for intensive care unit (ICU)-acquired multi-drug-resistant organisms (MDROs).

AIM

To measure the long-term respective impact of colonization pressure on ICU-acquired extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) and meticillin-resistant Staphylococcus aureus (MRSA).

METHODS

All patients admitted to two ICUs (medical and surgical) between January 1997 and December 2015 were included in this retrospective observational study. Rectal and nasal surveillance cultures were obtained at admission and weekly thereafter. Contact precautions were applied for colonized or infected patients. Colonization pressure was defined as the ratio of the number of MDRO-positive patient-days (PDs) of each MDRO to the total number of PDs. Single-level negative binomial regression models were used to evaluate the incidence of weekly MDRO acquisition.

FINDINGS

Among the 23,423 patients included, 2327 (10.0%) and 1422 (6.1%) were colonized with ESBL-PE and MRSA, respectively, including 660 (2.8%) and 351 (1.5%) acquisitions. ESBL-PE acquisition increased from 0.51/1000 patient-exposed days (PEDs) in 1997 to 6.06/1000 PEDs in 2015 (P<0.001). In contrast, MRSA acquisition decreased steadily from 3.75 to 0.08/1000 PEDs (P<0.001). Controlling for period-level covariates, colonization pressure in the previous week was associated with MDRO acquisition for ESBL-PE (P<0.001 and P=0.04 for medical and surgical ICU, respectively), but not for MRSA (P=0.34 and P=0.37 for medical and surgical ICU, respectively). The increase in colonization pressure was significant above 100/1000 PDs for ESBL-PE.

CONCLUSION

Colonization pressure contributed to the increasing incidence of ESBL-PE but not MRSA. This study suggests that preventive control measures should be customized to MDROs.

Characteristics of late-onset sepsis in the NICU: does occupancy impact risk of infection?

OBJECTIVE

Infants in neonatal intensive care units (NICUs) are vulnerable to a variety of infections, and occupancy in the unit may correlate with risk of infection.

STUDY DESIGN

A retrospective cohort of infants admitted to the NICUs between 1997 and 2014. Survival analysis was used to model the relative hazard of sepsis infection in relation to two measures of occupancy: 1) the average census and 2) proportion of infants <32 weeks gestation in the unit.

RESULT

There were 446 (2.3%) lab-confirmed cases of bacterial or fungal sepsis, which steadily declined over time. For each additional percentage of infants <32 weeks gestation, there was an increased hazard of 2% (hazard ratio 1.02, 95% confidence interval: 1.00, 1.03) over their NICU hospitalization. Census was not associated with risk for infection.

CONCLUSION

During times of a greater proportion of infants <32 weeks gestation in the NICU, enhanced infection-control interventions may be beneficial to further reduce the incidence of infections.

Integration of advanced practice providers into the Israeli healthcare system

Many countries around the world have integrated various types of Advanced Practice Providers (APPs) into their healthcare systems. The main motivating factors for recognizing and developing APPs worldwide include physician shortages and the need for improved access or delivery (US, France, Belgium, Scotland, Switzerland), reduced residency hours (US, UK), shortages in underserved regions (US, Canada, Finland, Australia), and cost containment (Germany, Netherlands, UK, US). Israel is experiencing a shortage of physicians in peripheral geographic regions and in critical medical specialties. Recent by-laws approved by the Knesset (Parliament), combined with Israel Ministry of Health (MOH) policies, have thus far been unable to fully address the shortages. To understand the potential contribution of APPs in Israel, we evaluated the international historical foundations and development of APP roles. We assessed how APPs have impacted healthcare in other countries by analyzing public data and published international research about APP education, safety, quality of care, motivators, barriers, and impact. We found that APPs are recognized in dozens of countries, and have similar scopes of practice, graduate level education requirements (in developed countries), and clinical training. At the same time, there is wide variability among countries in the actual function and independence of the advanced practice nurse (APN), particularly the nurse practitioner (NP). APPs have been established as cost effective, safe healthcare providers who improve healthcare access. Israel has begun to introduce APPs, specifically NPs, in a variety of fields, including geriatrics, palliative care and diabetic care. We recommend a rapid expansion of existing and new APP roles into the Israeli healthcare system based on evidence and the recommendations of international evaluations by non-government organizations. By shifting the education to a university setting, mirroring successful, evidence-based, and established APP models found internationally, Israel could lessen the projected Israeli physician shortage, improve healthcare access in specific areas, and bolster existing resources towards a larger and richer pool of healthcare providers in Israel.

Colonization and infection with extended-spectrum β-lactamase-producing Enterobacteriaceae in ICU patients: what impact on outcomes and carbapenem exposure?

OBJECTIVES

It remains uncertain whether colonization and infection with ESBL-producing Enterobacteriaceae (ESBL-PE) affect the outcomes for ICU patients. Our objectives were to measure the effects of ESBL-PE carriage and infection on mortality, ICU length of stay (LOS) and carbapenem exposure in this population.

METHODS

A cause-specific hazard model based on prospectively collected data was built to assess the impact of ESBL-PE colonization and infection on competing risks of death and ICU discharge at day 28 in a multicentre cohort of ICU patients. Carbapenem exposure during the ICU stay was compared between infected carriers, uninfected carriers and non-carriers.

RESULTS

Among the 16,734 included patients, 594 (3.5%) were ESBL-PE carriers, including 98 (16.4%) with one or more ESBL-PE infections during the ICU stay. After adjustment for baseline and time-dependent confounders, ESBL-PE infections increased the probability of death at day 28 [adjusted cause-specific hazard ratio (aCSHR), 1.825, 95% CI 1.235-2.699, P = 0.0026] and the ICU LOS (aCSHR for discharge alive at day 28, 0.563, 95% CI 0.432-0.733, P < 0.0001). ESBL-PE carriage without infection extended the LOS (aCSHR, 0.623, 95% CI, 0.553-0.702, P < 0.0001), without affecting mortality (aCSHR, 0.906, 95% CI, 0.722-1.136, P = 0.3916). Carbapenem exposure increased in both infected and uninfected carriers when compared with non-carriers (627, 241 and 69 carbapenem days per 1000 patient days, respectively, P < 0.001).

CONCLUSIONS

ESBL-PE infections increased carbapenem consumption, LOS and day 28 mortality. ESBL-PE infections were rather infrequent in carriers; however, even ESBL-PE carriage without infection increased carbapenem exposure and delayed discharge, thereby amplifying the selective pressure and the colonization pressure in the ICU.

Control of extended-spectrum β-lactamase-producing Enterobacteriaceae nosocomial acquisition in an intensive care unit: A time series regression analysis

BACKGROUND

This study was undertaken to determine the temporal relationship between implementation of different interventions in an intensive care unit (ICU) and control of endemic nosocomial acquisition of extended-spectrum β-lactamase Enterobacteriaceae (ESBLE).

METHODS

This was a prospective observational study with time-series analysis of the monthly incidence of ESBLE and its predictors. In November 2007, after a 14-month baseline period, an intervention consisting of restriction of third-generation cephalosporins (3 GC) and increased use of alcohol-based hand rubs was implemented. In January 2008, an increased health care worker (HCW):patient ratio was also implemented. In March 2010, the ICU was closed, and patients were moved to a clean ICU.

RESULTS

The first intervention resulted in global reduction in 3 GC and increased use of alcohol-based hand rub. A significant change in ESBLE incidence was observed in a full segmented univariate regression analysis (mean change in level, -0.91 ± 0.19; P < .0001). After ICU closure, there was a dramatic reduction in ESBLE acquisition. According to the multivariate model, the ICU closure was the main protective factor. Before ICU closure, an increase in the HCW:patient ratio of 0.1 point tended to be associated with a decreased risk of ESBLE acquisition (relative risk, 0.28; 95% confidence interval, 0.06-1.25; P = .09).

CONCLUSIONS

This study shows that ICU closure was associated with, but not necessarily the reason for, control of ESBLE cross-transmission in a nonoutbreak setting. Environmental ESBE sources may play a role in cross-transmission.

Impact of neonatal intensive care bed configuration on rates of late-onset bacterial sepsis and methicillin-resistant Staphylococcus aureus colonization

BACKGROUND

Infections cause morbidity and mortality in neonatal intensive care units (NICUs). The association between nursery design and nosocomial infections is unclear.

OBJECTIVE

To determine whether rates of colonization by methicillin-resistant Staphylococcus aureus (MRSA), late-onset sepsis, and mortality are reduced in single-patient rooms. DESIGN Retrospective cohort study.

SETTING

NICU in a tertiary referral center.

METHODS

Our NICU is organized into single-patient and open-unit rooms. Clinical data sets including bed location and microbiology results were examined over 29 months. Differences in outcomes between bed configurations were determined by χ2 and Cox regression.

PATIENTS

All NICU patients.

RESULTS

Among 1,823 patients representing 55,166 patient-days, single-patient and open-unit models had similar incidences of MRSA colonization and MRSA colonization-free survival times. Average daily census was associated with MRSA colonization rates only in single-patient rooms (hazard ratio, 1.31; P=.039), whereas hand hygiene compliance on room entry and exit was associated with lower colonization rates independent of bed configuration (hazard ratios, 0.834 and 0.719 per 1% higher compliance, respectively). Late-onset sepsis rates were similar in single-patient and open-unit models as were sepsis-free survival and the combined outcome of sepsis or death. After controlling for demographic, clinical, and unit-based variables, multivariate Cox regression demonstrated that bed configuration had no effect on MRSA colonization, late-onset sepsis, or mortality.

CONCLUSIONS

MRSA colonization rate was impacted by hand hygiene compliance, regardless of room configuration, whereas average daily census affected only infants in single-patient rooms. Single-patient rooms did not reduce the rates of MRSA colonization, late-onset sepsis, or death.

Unplanned 3-day re-attendance rate at Emergency Department (ED) and hospital's bed occupancy rate (BOR)

Background

Unplanned re-attendance at the Emergency Department (ED) is often monitored as a quality indicator of the care accorded to patients during their index ED visit. High bed occupancy rate (BOR) has been considered as a matter of reduced patient comfort and privacy. Most hospitals in Singapore operate under BORs above 85 %. This study aims to explore factors associated with the unplanned 3-day ED re-attendance rate and, in particular, if higher BOR is associated with higher 3-day unplanned ED re-attendance rate.

Methods

This was a multicenter retrospective study using time series data. Three acute tertiary hospitals were selected from all six adult public hospitals in Singapore based on data availability. Daily data from year 2008 to 2013 were collected from the study hospitals’ information systems. These included: ED visit date, day of week, month, year, public holiday, daily hospital BOR, daily bed waiting time (BWT) at ED (both median and 95th percentile), daily ED admission rate, and 3-day ED re-attendance rate. The primary outcome of the study was unplanned 3-day ED re-attendance rate from all reasons. Both univariate analysis and generalized linear regression were respectively applied to study the crude and adjusted association between the unplanned 3-day ED re-attendance rate and its potential associated factors. All analyses were conducted using SPSS 18 (PASW 18, IBM).

Results

The average age of patients who visited ED was 35 years old (SD = 2), 37 years old (SD = 2), and 40 years old (SD = 2) in hospitals A, B, and C respectively. The average 3-day unplanned ED re-attendance rate was 4.9 % (SE = 0.47 %) in hospital A, 3.9 % (SE = 0.35 %) in hospital B, and 4.4 % (SE = 0.30 %) in hospital C. After controlling for other covariates, the unplanned 3-day ED re-attendance rates were significantly associated with hospital, time trend, day of week, daily average BOR, and ED admission rate. Strong day-of-week effect on early ED re-attendance rate was first explored in this study. Thursday had the lowest re-attendance rate, while Sunday has the highest re-attendance rate. The patients who visited at ED on the dates with higher BOR were more likely to re-attend the ED within 3 days for hospitals A and B. There was no significant association between BOR and ED re-attendance rate in hospital C.

Conclusions

A study using time series data has been conducted to explore the factors associated with the unplanned 3-day ED re-attendance rate. Strong day-of-week effect was first reported. The association between BOR and the ED re-attendance rate varied with hospital.

Hospital bed occupancy for rotavirus and all cause acute gastroenteritis in two Finnish hospitals before and after the implementation of the national rotavirus vaccination program with RotaTeq®

Background

Vaccination-impact studies of the live-attenuated pentavalent oral vaccine Rotateq® have demonstrated that the burden of rotavirus gastroenteritis has been reduced significantly after the introduction of RotaTeq® vaccination, but less is known about the benefit of this vaccination on hospital overcrowding.

Methods

As part of an observational surveillance conducted during the RV seasons 2000/2001 to 2011/2012, we analysed hospital discharge data collected retrospectively from two Finnish hospitals (Oulu and Tampere), concerning ICD 10 codes A00-09 (acute gastroenteritis, AGE) and A08.0 (rotaviral acute gastroenteritis RV AGE). We estimated the reduction in the number of beds occupied and analysed the bed occupancy rate, for RV AGE and all cause AGE, among 0–16 year-old children, before and after the implementation of the RV immunisation program.

Results

The rate of bed days occupied for RV AGE was reduced by 86% (95% CI 66%-94%) in Tampere and 79% (95% CI 47%-92%) in Oulu after RV vaccination implementation. For all cause AGE, reduction was 50% (95% CI 29% to 65%) in Tampere and 70% (95% CI 58% to 79%) in Oulu. Results were similar among 0–2 year-old children. This effect was also observed on overcrowding in both hospitals, with a bed occupancy rate for all cause AGE >25% in only 1% of the time in Tampere and 9% in Oulu after the implementation of the immunisation program, compared to 13% and 48% in the pre-vaccination period respectively. After extrapolation to the whole country, the annual number of prevented hospitalizations for all cause AGE in the post-vaccination period in Finland was estimated at 1,646 and 2,303 admissions for 0–2 and 0–16 year-old children respectively.

Conclusions

This study demonstrated that universal RV vaccination is associated with a clear decrease in the number of bed days and occupancy rates for RV AGE and all cause AGE. Positive consequences include increase in quality of care and a better healthcare management during winter epidemics.

High bed occupancy rates: Are they a risk for patients and staff?

AIM

In order to produce empirical evidence on the relationship between high bed occupancy and its potential hazards, this study correlates bed occupancy rates with hospital patient safety and staff overload indicators.

METHODS

Data from nine medium to large scale public hospitals, all pertaining to the Hospital Foundation of Minas Gerais, Brazil, were gathered for the period January 2007 to June 2011. Indicators were aggregated by month, resulting in 486 observations (54 months × 9 hospitals). Bivariate linear regressions were performed, aiming to estimate the effect of bed occupancy rates on each response variable (hospital infection rates, institutional mortality and sick leave incidence). In addition, to directly test the hypothesis that bed occupancy rates over 85% are unsafe, it was included in the models as a categorical instead of continuous variable, using 85% as the cut-off value.

RESULTS

Bed occupancy rates showed an inverse correlation to mortality rates (b = -0.056; P < 0.001) and presented no significant correlation to the nosocomial infection rates (P = 0.512). High bed occupancy (>85%) was associated with a slight increment of short sick leaves, especially short leaves (<7 days) (+0.14%; P = 0.008).

CONCLUSIONS

The increase in hospital loading was unexpectedly associated with reduced institutional mortality and was not related to nosocomial infection incidences. High bed occupancy was associated to a slight increment of short sick leaves.

Bed occupancy rates and hospital-acquired infections--should beds be kept empty?

There is growing evidence that bed occupancy (BO) rates, overcrowding and understaffing influence the spread of hospital-acquired infections (HAIs). In this article, a systematic review of the literature is presented, summarizing the evidence on the adverse effects of high BO rates and overcrowding in hospitals on the incidence of HAIs. A Pubmed database search identified 179 references, of which 44 were considered to be potentially relevant for full-text review. The majority (62.9%) focused on methicillin-resistant Staphylococcus aureus-associated infection or colonization. Only 12 studies were found that provided a statistical analysis of the impact of BO on HAI rates. The median BO rate of the analysed studies was 81.2%. The majority of studies (75%) indicated that BO rates and understaffing directly influence the incidence of HAIs. Only three studies showed no significant association between BO rates and the incidence of HAIs. Interestingly, only one of the included studies detected a seasonal trend in the BO rate. The present review shows an association between BO rates and the spread of HAIs in various settings. Because the evidence on this topic is limited, we conclude that further research is needed in order to analyse the rationale of a threshold BO rate, because keeping beds empty is comparatively costly.

The importance of colonization pressure in multiresistant Acinetobacter baumannii acquisition in a Greek intensive care unit

INTRODUCTION

We investigated the role of colonization pressure on multiresistant Acinetobacter baumannii acquisition and defined patient-related predictors for carriage at admission and acquisition during hospitalization in intensive care unit (ICU) patients.

METHODS

This was a 12-month, prospective, cohort study of all patients admitted to a single ICU of a tertiary hospital. Screening samples were collected at ICU admission to identify imported carriers, and weekly during hospitalization to identify acquisition. Colonization pressure (carriers' patient-days × 100/all patients' patient-days) and the absolute number of carriers were calculated weekly, and the statistical correlation between these parameters and acquisition was explored. Multivariable analysis was performed to identify predictors for A. baumannii carriage at admission and acquisition during hospitalization. A. baumannii isolates were genotyped by repetitive-extragenic-palindromic polymerase chain reaction (PCR; rep-PCR).

RESULTS

At ICU admission, 284 patients were screened for carriage. A. baumannii was imported in 16 patients (5.6%), and acquisition occurred in 32 patients (15.7%). Acquisition was significantly correlated to weekly colonization pressure (correlation coefficient, 0.379; P = 0.004) and to the number of carriers per week (correlation coefficient, 0.499; P <0.001). More than one carrier per week significantly increased acquisition risk (two to three carriers, odds ratio (OR), 12.66; P = 0.028; more than four carriers, OR, 25.33; P = 0.004). Predictors of carriage at admission were infection at admission (OR, 11.03; confidence interval (CI), 3.56 to 34.18; P < 0.01) and hospitalization days before ICU (OR, 1.09; CI, 1.01 to 1.16; P = 0.02). Predictors of acquisition were a medical reason for ICU admission (OR, 5.11; CI, 1.31 to 19.93; P = 0.02), duration of antibiotic administration in the unit (OR, 1.24; CI, 1.12 to 1.38; P < 0.001), and duration of mechanical ventilation (OR, 1.08; CI, 1.04 to 1.13; P = 0.001). All strains were multiresistant. Rep-PCR analysis showed one dominant cluster.

CONCLUSIONS

Acquisition of multiresistant A. baumannii in ICU patients is strongly correlated to colonization pressure. High levels of colonization pressure and more than two carriers per week independently increase acquisition risk. Patient-related factors, such as infection at admission and long hospitalization before the ICU, can identify imported A. baumannii carriers. Medical patients with extended administration of antibiotics and long duration of mechanical ventilation in the ICU were the most vulnerable to acquisition.

Economic implications of the dynamic relationship between antibiotic use and hospital-acquired infections

OBJECTIVES

The emergence and spread of antimicrobial resistance is still an unresolved problem worldwide. Recent evidence shows correlations between the volume of broad-spectrum antibiotics used in the hospital setting and the incidence of multidrug-resistant bacteria. According to this dynamic relationship, loss of antibiotic activity can be modeled as a negative externality of antibiotic consumption.

METHODS

The present study proposes to present an economic model describing the probability of antibiotic treatment failure as a function of antimicrobial use and alcohol-based hand-rub use. Furthermore, the results of recently conducted time-series analyses and cost-of-illness studies are applied to the model to determine the externalities of antibiotic consumption and alcohol-based hand-rub use with respect to the costs of hospital-acquired infections.

RESULTS

According to our calculations, the consumption of third-generation cephalosporins and fluoroquinolones is associated with the highest negative externalities (€143 and €101, respectively) because their use has been shown to be associated with most types of hospital-acquired infections. In contrast, the use of alcohol-based hand-rub solution for hand disinfection is associated with a positive externality of 41 cents per single disinfection of the hands.

CONCLUSIONS

The externalities presented in this work represent a possible application of cost-of-illness data to quantify the impact of antibiotic use on antimicrobial resistance. In addition, the results indicate that most economic research on the topic is biased in assuming the overall use of antibiotics to be responsible for the spread of antimicrobial resistance.

Understaffing, overcrowding, inappropriate nurse:ventilated patient ratio and nosocomial infections: which parameter is the best reflection of deficits?

BACKGROUND

In stressed and high-throughput systems, periodic overcrowding (high bed occupancy) and understaffing (low nurse:patient ratio) are widely described risk factors for nosocomial infections.

AIM

The impact of bed occupancy (patient:bed ratio), nurse:patient ratio and nurse:ventilated patient ratio on nosocomial bloodstream infections (BSI) and pneumonia were investigated in 182 intensive care units (ICU).

METHODS

The ICUs reported monthly data on device use and nosocomial device-associated infections to the German hospital surveillance system for nosocomial infections in 2007. Information on the number of healthcare workers on the ward per 24h in 2007 and structure parameters was obtained by questionnaires. The association between occupancy or staff parameters and the number of nosocomial infections per month was analysed using generalized estimating equation models.

FINDINGS

In total, 1313 cases of pneumonia and 513 cases of BSI were reported from 182 ICUs with 1921 surveillance months and 563,177 patient-days. Fewer nosocomial infections were associated with a higher nurse:ventilated patient ratio [adjusted incidence rate ratio 0.42 (95% confidence interval 0.32-0.55) for months with nurse:ventilated patient ratios >75th percentile compared with ≤ 25 th percentile]. Interestingly, the nurse:patient ratio was not a significant parameter with respect to the occurrence of BSI and pneumonia. High bed occupancy (>75th percentile) was associated with fewer nosocomial infections.

CONCLUSION

A staffing parameter that reflects the intensity of care, such as the nurse:ventilated patient ratio, may enable better evaluation of workload and resources, especially at a time when nursing resources are being reduced but nosocomial infections are increasing.