Kaohsiung J Med Sci August 2007 • Vol 23 • No 8 395 Usually, fewer people work in hospitals on weekends
than on weekdays. Such shortfalls in hospital staffing
levels lead to less effective hospital functioning, and undoubtedly a lower quality of patient care on week-ends. For instance, earlier studies have shown that neonatal mortality is higher for babies born on week-ends than among those born on weekdays [1–3]. A large study involving all acute care hospitals in Ontario, Canada, over a 10-year period showed that patients with serious medical conditions have a sig-nificantly increased mortality rate if they are admitted Received: December 4, 2006 Accepted: February 14, 2007
Address correspondence and reprint requests to: Dr Jhi-Jhu Hwang, Division of Pulmonary and Critical Care Medicine, Kaohsiung Medical University Hospital, 100 Tzyou 1stRoad, Kaohsiung 807, Taiwan.
E-mail: jjhwang@ms4.hinet.net
A
DMISSION
T
IME AND
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UTCOMES OF
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ATIENTS
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EDICAL
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ARE
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Chau-Chyun Sheu,1Jong-Rung Tsai,1Jen-Yu Hung,1Chih-Jen Yang,1Hsin-Chia Hung,2
Inn-Wen Chong,1,3Ming-Shyan Huang,1,4and Jhi-Jhu Hwang1,3
1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Kaohsiung
Medical University Hospital, 3Faculty of Respiratory Care,4Department of Internal Medicine,
Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, and
2Graduate Institute of Health Care, Meiho Institute of Technology, Pingtung, Taiwan.
Studies have shown that weekend or night admissions to intensive care units (ICUs) are associated with increased mortality in critically ill patients. Our study aimed to evaluate the effects of admis-sion time and day on patient outcomes in a medical ICU equipped with patient management guide-lines, and staffed by intensivists on call for 24 hours, who led the morning rounds on all days of the week but did not stay in-house overnight. The study enrolled 611 consecutive patients admitted to a 26-bed medical ICU in a university hospital during a 7-month period. We divided them into two groups, which we labeled as “office hours” (08:00–18:00 on weekdays) and “non-office hours” (18:00–08:00 on weekdays, and all times on weekends) according to their ICU admission times. The clinical outcomes were compared between the groups. The effects of admission on weekends, at night, and various days of the week on hospital mortality were also evaluated. Our results showed that there were no significant differences in ICU and hospital mortalities between patients admitted during office hours and those admitted during non-office hours (27.2% vs. 27.4%,
p= 1.000; 38.9% vs. 37.6%, p = 0.798). The ICU length of stay, ICU-free time within 21 days, and
length of stay in the hospital were also comparable in both groups. Among the 392 patients requir-ing mechanical ventilation, the ventilator outcomes were not significantly different between those in the office-hour group and the non-office-hour group. Multivariate logistic regression analyses showed that the adjusted odds of hospital mortality were not significantly higher for patients admit-ted to our ICU on weekends, at night, or on any days of the week. In conclusion, our results showed that non-office-hour admissions to our medical ICU were not associated with poorer ICU, hospital, and ventilator outcomes, compared with office-hour admissions. Neither were time of day and day of the week admissions to our ICU associated with significant differences in hospital mortality.
Key Words:admission, critical care, intensive care unit, mortality, time factor (Kaohsiung J Med Sci 2007;23:395–404)
on weekends [4]. A similar study in California also found that patients admitted to hospitals on weekends have a higher risk-adjusted mortality than patients admitted on weekdays [5].
Since good quality care for critically ill patients relies more on the availability of adequate medical staff, immediate diagnostic studies, early therapeutic procedures, and appropriate treatments, the “week-end effect” on hospital mortality was expected to be stronger for patients admitted to intensive care units (ICUs) than for those admitted to wards. A cohort study in Finland using a national ICU database showed that weekend admissions, as compared with weekday ad-missions, are associated with increased mortality in critically ill patients [6]. Data from the Mayo Clinic also showed that weekend ICU admissions are asso-ciated with a higher hospital mortality rate than week-day ICU admissions [7]. In addition, a “night effect”, similar to the “weekend effect”, was also observed among patients requiring ICU admission [6,8]. Another study on emergency admissions to a pediatric ICU also demonstrated an increased risk of death for pedi-atric patients admitted with shock, congenital cardio-vascular diseases, or cardiac arrest during evening hours [9].
Recently, Arabi et al [10] demonstrated that clinical outcomes are consistent for patients admitted during weekdays, weeknights, and weekends to an ICU when it is staffed by on-site certified intensivists 24 hours a day, 7 days a week. However, for most ICUs world-wide, on-site availability of qualified intensivists is reduced on weekends and weeknights compared with weekdays. This is largely because of economic con-straints and the paucity of qualified intensivists. With recent advances in critical care medicine, increased standard care for critically ill patients has been estab-lished and successfully transformed into hospital- or ICU-based management guidelines [11–20]. Moreover, the wide availability of telecommunication systems makes it easier for on-call intensivists to participate in the decision-making process for managing newly admitted critically ill patients. We hypothesized, there-fore, that the time and day of admission does not influ-ence the outcomes of patients admitted to a “closed” medical ICU equipped with patient management guidelines, if it can be staffed by intensivists on call for 24 hours, who lead the morning rounds on all days of the week but do not stay in-house overnight. The pres-ent study aimed to compare the hospital mortality,
ICU mortality, and other clinical outcomes of patients admitted to our medical ICU at different times of the day and on different days of the week.
M
ATERIALS ANDM
ETHODSSetting and patients
This study was approved by the institutional review board (IRB) of Kaohsiung Medical University Hospital, and the need for written informed consent was waived by the IRB. Eligible participants for analysis were adult patients admitted to a 26-bed medical ICU in a university hospital between February 1, 2006 and August 31, 2006. Patients who were later transferred to another ICU for any reason, those requesting com-fort care only, and patients re-admitted to the ICU within the same hospital stay were excluded from the present study.
The critical care in our medical ICU was provided by two service teams comprising attending physicians, critical care fellows, resident physicians, critical care pharmacists, critical care nurses, and respiratory ther-apists. The attending physicians, all of whom were qualified specialists in both pulmonology and critical care medicine, worked as full-time dedicated inten-sivists in the medical ICU. The bedside patient rounds led by the attending intensivists were made in the morning from 08:30 to 11:30, all days of the week. The attending intensivists did not stay in-house at night, but were available for guidance in patient care by phone and for coming to the ICU if needed. Resident physicians from the Department of Internal Medicine staffed the ICU at a constant level 24 hours a day, 7 days a week. The nurse-to-patient ratio was maintained at 1:2 at all times. Patient management guidelines and protocols, including an intensive insulin infusion protocol, feeding protocol, pain control, sedation and paralysis protocol, lung protective ventilatory strategy, ventilator weaning protocol, management guidelines for hospital-acquired and ventilator-associated pneu-monia, and management guidelines for severe sepsis and septic shock were implemented in our ICU, and were driven by resident physicians, critical care nurses, and respiratory therapists.
Patients with prolonged mechanical ventilation (> 21 days of mechanical ventilation) were transferred to the respiratory care center, a step-down ICU, for con-tinuous critical care if their conditions were stable.
As a result, only a small number of patients stayed in our ICU for more than 21 days.
Data collection and study design
The baseline characteristics and clinical outcomes of all patients were retrospectively collected by reviewing their medical records. Patient characteristics includ-ing age, sex, Acute Physiology and Chronic Health Evaluation (APACHE) II scores, primary reasons for ICU admission, and sources were routinely recorded upon admission to our ICU. Those included in our study were grouped into two groups, the office-hour group and the non-office-hour group, according to their ICU admission times. The hospital, ICU, and ventilator outcomes were compared between these two groups. To determine the effects of time of the day and day of the week admissions on hospital mor-tality, the patients were further grouped into various categories according to their ICU admission times and days. The time intervals for grouping categories were defined as shown in Table 1. The crude and adjusted odds of hospital mortality among patients admitted to the ICU at different times of the day and on different days of the week were also analyzed.
Outcome measurements
Hospital mortality was the primary endpoint in this study. Secondary endpoints included ICU mortal-ity, ICU length of stay (LOS), hospital LOS, ICU-free days within 21 days, ventilator days, ventilator-free
days within 21 days, and prolonged mechanical ventilation.
Statistical analysis
All data were analyzed by the Statistical Package for the Social Sciences version 13.0 software (SPSS Inc., Chicago, IL, USA). Continuous data are presented as mean± standard deviation. Proportions are presented as number (%). Comparisons between groups were analyzed by using the unpaired two-tailed t test, Mann–Whitney U test, χ2test, or Fisher’s exact test as
appropriate. The association of patient characteristics with hospital mortality was analyzed by multivariate logistic regression. The effects of ICU admission time and day on hospital mortality was analyzed by univari-ate logistic regression for crude odds ratio (OR), and further analyzed by multivariate logistic regression for adjusted OR, using age, sex, APACHE II score, primary reason for admission, and patient source for adjust-ment. Statistical significance was defined as p< 0.05.
R
ESULTSPatient inclusion and baseline
characteristics
During the study period, there were 684 patients admitted to our medical ICU. After excluding 13 patients who were later transferred to other ICUs, 38 patients requesting for comfort care only, and
Table 1.Definition of time period of intensive care unit admission for grouping categories
Grouping category Definition
Workdays or weekends
Workdays 00:00–24:00, Monday to Friday
Weekends 00:00–24:00, Saturday, Sunday, and national holidays Daytime or nighttime
Daytime 08:00–18:00, 7 days a week
Nighttime 18:00–08:00, 7 days a week Office or non-office hours
Office hours 08:00–18:00 on weekdays
Non-office hours 18:00–08:00 on weekdays, and all times on weekends Days of the week 00:00–24:00, calendar days of the week
Time period of the day
Morning 08:00–12:00, 7 days a week
Afternoon 12:00–18:00, 7 days a week
Evening 18:00–24:00, 7 days a week
22 patients re-admitted to the ICU within the same hospital stay, a total of 611 patients were included for analysis. The baseline characteristics of these patients, including age, sex, APACHE II score, primary reason for admission, and patient source are shown in Table 2.
Office-hour admissions vs. non-office-hour
admissions
Two hundred and thirty-nine (39.1%) patients were admitted to the ICU during office hours, while 372 (60.1%) were admitted during non-office hours. There were no significant differences in baseline character-istics between patients admitted during office hours and those admitted during non-office hours (Table 2). The analyses of clinical outcomes in these two groups showed that the ICU mortality rate was 27.2% for patients admitted during office hours, not significantly different from 27.4% for patients admitted during non-office hours (p= 1.000). The hospital mortality rates were also similar in both groups (38.9% vs. 37.6%, p= 0.798). In addition, there were no significant differ-ences in ICU LOS, ICU-free days within 21 days, and hospital LOS between these two groups. For the 392 patients requiring mechanical ventilation, the average ventilator days and ventilator-free days were similar for patients admitted during office hours and non-office hours (8.7± 6.9 days vs. 8.1 ± 7.2 days, p = 0.437; 6.0 ± 7.5 days vs. 5.8±7.8 days, p=0.814). The proportions of
patients requiring prolonged mechanical ventilation were also similar in both groups (16.5% vs. 14.3%,
p= 0.215) (Table 3).
Association of baseline characteristics
with hospital mortality
Multivariate logistic regression analysis showed that the APACHE II score was an independent risk factor for hospital mortality (OR=1.12; 95% confidence inter-val [CI]=1.09–1.15). Patients admitted to the ICU for bleeding had higher hospital mortality (OR=2.68; 95% CI= 1.30–5.49), while patients admitted for heart dis-eases had significantly lower hospital mortality (OR= 0.31; 95% CI= 0.11–0.86), using patients admitted for severe sepsis or septic shock as the reference category. Regarding the sources of ICU admissions, patients admitted from wards had a significantly higher hospi-tal morhospi-tality rate (OR=1.93; 95% CI=1.28–2.91), while patients transferred from other hospitals had lower hospital mortality (OR=0.59; 95% CI=0.28–1.25), using patients admitted from the emergency department as the reference category (Table 4).
Crude and adjusted odds of hospital
mortality by time of day and day of the
week of ICU admissions
To determine the effects of time of day and day of the week of ICU admissions on hospital mortality, the
Table 2.Baseline characteristics of patients by time of admission
Total patients Office hours Non-office hours
p* (n= 611) (n= 239) (n= 372)
Age (yr) 66.0± 15.1 66.2± 15.6 65.9± 14.8 0.778 Sex (male) 360 (58.9%) 147 (61.5%) 213 (57.25%) 0.313 APACHE II score 21.7± 9.4 21.9± 9.4 21.6± 9.4 0.734
Primary reason for admission 0.204
Severe sepsis or septic shock 288 (47.1%) 110 (46.0%) 178 (47.9%) Acute respiratory failure 129 (21.1%) 52 (21.8%) 77 (20.7%) Bleeding 47 (7.7%) 24 (10.0%) 23 (6.2%) Heart disease 34 (5.6%) 16 (6.7%) 18 (4.8%) Post-resuscitation 37 (6.1%) 15 (6.3%) 22 (5.9%) Other 76 (12.4%) 22 (9.2%) 54 (14.5%) Patient source 0.007 Emergency department 312 (51.1%) 119 (49.8%) 193 (51.9%) Wards 219 (35.8%) 93 (38.9%) 126 (33.9%) Other hospitals 52 (8.5%) 11 (4.6%) 41 (11.0%) Other ICUs 28 (4.6%) 16 (6.7%) 12 (3.2%)
patients were further grouped into various categories according to their ICU admission times and days. Univariate logistic regression analyses showed that the hospital mortalities of non-office-hour admissions, weekend admissions, and night admissions were not significantly different from that of office-hour admis-sions, weekday admisadmis-sions, and day admisadmis-sions, re-spectively (OR= 0.95, 0.91, 1.08; 95% CI = 0.68–1.32, 0.62–1.35, 0.78–1.50). Multivariate logistic regression analyses also showed that there were no significant differences in adjusted odds of hospital mortality between patients admitted to the ICU during office
hours vs. non-office hours, on weekdays vs. weekends, and at daytime vs. nighttime. Moreover, there were no significant differences in hospital mortality between patients admitted to the ICU on different days of the week. Even after adjustment for confounding factors, days of the week admissions to the ICU were not asso-ciated with significant differences in hospital mortality (Table 5).
The results also showed that patients admitted to the ICU in the afternoon had the lowest adjusted odds of hospital death (OR= 0.67; 95% CI = 0.32–1.38), com-pared with those admitted in the morning (OR= 1),
Table 4.Multivariate logistic regression analysis showing the association of baseline characteristics of patients with hospital mortality
OR (95% CI) p
Age (yr) 1.01 (0.99–1.02) 0.172
Sex (female) 0.72 (0.49–1.07) 0.106
APACHE II score 1.12 (1.09–1.15) < 0.001
Primary reason for admission 0.007
Severe sepsis or septic shock* 1
Acute respiratory failure 1.18 (0.72–1.94) 0.506
Bleeding 2.68 (1.30–5.49) 0.007 Heart disease 0.31 (0.11–0.86) 0.024 Post-resuscitation 2.07 (0.86–4.98) 0.103 Other 1.13 (0.61–2.06) 0.704 Patient source Emergency department* 1 Wards 1.93 (1.28–2.91) 0.002 Other hospitals 0.59 (0.28–1.25) 0.170 Other ICUs 0.96 (0.37–2.46) 0.929
*The reference category in logistic regression analysis. OR= odds ratio; CI = confidence interval; APACHE = Acute Physiology and Chronic Health Evaluation; ICUs = intensive care units.
Table 3.Clinical outcomes of patients by time of admission
Clinical outcome Office hours Non-office hours p (n= 239) (n= 372)
ICU outcomes
ICU mortality 65 (27.2%) 102 (27.4%) 1.000
ICU LOS 8.0± 6.4 7.3± 6.3 0.149
ICU-free days within 21 days 9.0± 7.8 9.6± 7.9 0.364 Hospital outcome
Hospital mortality 93 (38.9%) 140 (37.6%) 0.798
Hospital LOS 22.6± 21.7 20.8± 20.5 0.303
Patients requiring mechanical ventilation (n= 392) 162 (67.8%) 230 (61.8%) 0.142
Ventilator days 8.7± 6.9 8.1± 7.2 0.437
Ventilator-free days within 21 days 6.0± 7.5 5.8± 7.8 0.814 Prolonged mechanical ventilation 26 (16.5%) 32 (14.3%) 0.215 ICU = intensive care unit; LOS = length of stay.
T
able 5.
Hospital mortality rates, cr
ude and adjusted odds of hospital mortality by time of the day and day of the week of ICU admission
s
ICU admission time
Hospital mortality (%) Cr ude OR (95% CI) p Adjusted OR (95% CI) † p Of fice or non-of fice hours Of fice hours* 93/239 (38.9%) 1 1 Non-of fice hours 140/372 (37.6%) 0.95 (0.68–1.32) 0.751 1.09 (0.74–1.61) 0.662 W
orkdays or weekends Weekdays*
182/471 (38.6%) 1 1 W eekends 51/140 (36.4%) 0.91 (0.62–1.35) 0.636 0.79 (0.50–1.25) 0.310
Day or night Day*
117/314 (37.3%) 1 1 Night 116/297 (39.1%) 1.08 (0.78–1.50) 0.648 1.46 (0.99–2.14) 0.056
Day of the week Monday*
38/93 (40.9%) 1 1 T uesday 36/96 (37.5%) 0.87 (0.48–1.56) 0.636 0.80 (0.41–1.60) 0.534 W ednesday 38/96 (39.6%) 0.95 (0.53–1.70) 0.858 0.80 (0.40–1.61) 0.535 Thursday 30/83 (36.1%) 0.82 (0.45–1.51) 0.521 0.71 (0.35–1.44) 0.342 Friday 40/103 (38.8%) 0.92 (0.52–1.63) 0.772 1.17 (0.60–2.25) 0.650 Satur day 28/80 (35.0%) 0.78 (0.42–1.45) 0.429 0.68 (0.33–1.41) 0.302 Sunday 23/60 (38.3%) 0.90 (0.46–1.75) 0.755 0.73 (0.34–1.57) 0.418 T
ime period of the day Morning*
22/54 (40.7%) 1 1 Afternoon 95/260 (36.5%) 0.84 (0.46–1.52) 0.561 0.67 (0.32–1.38) 0.275 Evening 78/205 (38.0%) 0.89 (0.49–1.65) 0.718 1.02 (0.49–2.13) 0.963 Midnight 38/92 (41.3%) 1.02 (0.52–2.03) 0.947 1.09 (0.48–2.49) 0.840 *The r efer
ence category in logistic r
egr
ession analysis;
†adjustment was made for age, sex,
Acute Physiology and Chr
onic Health Evaluation
II scor e, primary r eason for admis sion, and patient sour ce. ICU = intensive car e unit; OR = odds ratio; CI = confidence interval.
and patients admitted in the middle of the night had the highest adjusted odds of hospital death (OR=1.09; 95% CI= 0.48–2.49). However, the differences did not reach statistical significance.
D
ISCUSSIONThe results of our study showed that non-office-hour admissions to our ICU were not associated with poorer clinical outcomes. There were no significant differences in ICU mortality, hospital mortality, ICU LOS, hospital LOS, ventilator days, and prolonged mechanical ven-tilation between patients admitted during office hours and those admitted during non-office hours. More-over, both univariate and multivariate logistic regres-sion analyses showed that the hospital mortality rates were not significantly higher for patients admitted to our ICU on weekends, at night, or on any day of the week. This implies that our ICU functioned consistently 24 hours a day and 7 days a week.
Our study showed that 22.9% of ICU admissions occurred during the weekends and 48.6% occurred during the night. As a result, a remarkably high pro-portion (60.1%) of patients was admitted to our ICU during non-office hours. This is similar to other reports that 65.6–69% of ICU admissions occurred during weekends or at night [10,21]. Since accurate diagnoses and appropriate management during the first few hours after ICU admission are crucial for the clinical outcomes of critically ill patients, it is very important to maintain consistent ICU function during non-office hours.
Organization factors proved to have great impact on the clinical outcomes of patients requiring ICU admission. Among them, the presence of intensivists in the ICU has been regarded as increasingly important for the quality of care of critically ill patients. For exam-ple, changing from an “open” to a “closed” ICU format improved patient outcomes [22]. Young and Birkmeyer [23] reviewed the current literature and reported that intensivist-model ICUs are associated with 15–60% of relative reductions in mortality rates. Another review of the literature by Pronovost et al [24] showed that high-intensity ICU physician staffing (mandatory intensivist consultation or closed ICU) is associated with reduced hospital and ICU mortality and hospital and ICU LOS, compared with low-intensity ICU physician staffing (no intensivist or elective intensivist consultation).
The 2003 Society of Critical Care Medicine guide-lines for adult ICUs have recommended a 24-hour in-house coverage by intensivists who are dedicated to the care of ICU patients and do not have conflicting responsibilities [25]. However, it is difficult for most institutions to reach such staffing levels in their ICUs. A cross-sectional survey of Canadian adult ICUs showed that only 15% of adult and pediatric ICUs have in-house intensivists overnight [26]. Fortunately, there are other ways to improve the quality of ICU care. Studies have demonstrated improved outcomes when protocols are implemented into critical care [27]. We have developed and successfully implemented several protocols and guidelines for the management of critically ill patients in our ICU, including an intensive insulin infusion protocol, feeding protocol, pain control, sedation and paralysis protocol, lung protective ventilatory strategy, ventilator weaning protocol, management guidelines for hospital-acquired and ventilator-associated pneumonia, and manage-ment guidelines for severe sepsis and septic shock. These protocols and guidelines, driven by resident physicians, critical care nurses, and respiratory thera-pists, helped our ICU maintain a constant quality of care, particularly during nights when intensivists did not stay house. One of the major roles of in-tensivists in our ICU was to develop and renew the patient management protocols and guidelines according to the best available evidence-based medi-cine, as well as to educate the members of the critical care team to be familiar with these protocols and guidelines.
Although the differences were not significant, the adjusted odds of hospital death were higher for patients admitted to the ICU at night, compared to those ad-mitted during the day (OR= 1.46; 95% CI = 0.99–2.14;
p= 0.056). On the other hand, the adjusted odds of
hospital death were not higher for patients admitted to the ICU on weekends, compared with those admitted on weekdays (OR= 0.79; 95% CI = 0.50–1.25; p = 0.31). These results were somewhat compatible with the staffing pattern in our ICU where resident physicians and critical care nurses staffed the ICU in-house at constant levels all the time, while dedicated inten-sivists led the morning rounds on all days of the week but did not stay in-house overnight. In our ICU, there were fewer ICU admissions (data not shown) and no conferences on weekends. With the same staffing lev-els, the lighter workload might result in better patient
care and, therefore, lower hospital mortality for patients admitted on weekends.
In addition, the observation that the adjusted odds of hospital mortality were higher for morning admis-sions than for afternoon admisadmis-sions, and were higher for midnight admissions than for evening admis-sions implied that there might be “morning effects” and “sleep deprivation effects” beyond the effect of staffing levels. Routine morning service and teaching rounds, case conferences, and journal clubs in our ICU were all held in the morning. Moreover, more proce-dures were performed in the morning than in other time periods. Such a heavy workload might be asso-ciated with the poorer outcomes for patients admit-ted in the morning than in the afternoon, even though the staffing levels were equal in both time periods. In addition, studies have shown that sleep deprivation of physicians is associated with a decline in perform-ance [28–30]. As the in-house resident physician shifts in our ICU were > 24 hours in duration, the sleep-deprivation effects might explain the slightly higher adjusted mortality rate for patients admitted at around midnight than earlier in the evening.
The present study has certain limitations in that only a small number of patients were included for analysis, and the data were collected from a single ICU in one medical center. However, this is the first study reporting the effects of time and day factors of ICU admission on patient outcomes in Taiwan. We report on our experience and hope it will contribute to the continuous improvement in the quality of critical care in Taiwan.
In conclusion, our results showed that non-office-hour vs. office-non-office-hour admissions were not associated with poorer ICU, hospital, or ventilator outcomes in a medical ICU equipped with patient management guidelines, and staffed by intensivists on call for 24 hours, who led the morning rounds on all days of the week but did not stay in-house overnight. More-over, time of day and day of the week admissions to our ICU were not associated with significant differences in hospital mortality.
R
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404 Kaohsiung J Med Sci August 2007 • Vol 23 • No 8
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