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Anesth Analg 2002;94:644-649
© 2002 International Anesthesia Research Society

ECONOMICS AND HEALTH SYSTEMS RESEARCH

The Effect of Outpatient Preoperative Evaluation of Hospital Inpatients on Cancellation of Surgery and Length of Hospital Stay

Wilton A. van Klei, MD MSc*{dagger}, Karel G.M. Moons, PhD*{dagger}, Charles L.G. Rutten, MD PhD{ddagger}, Anke Schuurhuis, MD*, Johannes T.A. Knape, MD PhD*, Cornelis J. Kalkman, MD PhD*, and Diederick E. Grobbee, MD PhD{dagger}

*Department of Peri-operative Care, Anesthesia, and Pain Management, and {dagger}Julius Center for General Practice and Patient Oriented Research, University Medical Center Utrecht, The Netherlands; and {ddagger}Department of Anesthesiology, Isala Clinics, Weezenlanden Hospital, Zwolle, The Netherlands

Address correspondence and reprint requests to Wilton van Klei, MD, MSc, Department of Peri-operative Care, Anesthesia, and Pain Management, hp E03.511, University Medical Center Utrecht, PO Box 85500, 3508 GA, Utrecht, The Netherlands. Address e-mail to w.a.vanklei{at}azu.nl


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 References
 
To evaluate the possible effects of outpatient preoperative evaluation (OPE) for new surgical patients who will be inpatients, we conducted an observational study at a university hospital in The Netherlands. Various outcomes before and after the introduction of an OPE clinic were compared. The study population comprised all 21,553 elective adult inpatients operated on between January 1, 1997 and December 31, 1999. Cardiac surgery, obstetric and pediatric patients, and patients operated on in same-day surgery were excluded. The main outcome measures were surgical cases canceled for medical reasons, rate of same-day admissions (who were expected to increase), and length of hospital stay. After introduction of OPE, the rate of cancellations for medical reasons decreased from 2.0% to 0.9% (adjusted odds ratio 0.7, 95% CI, 0.5–0.9). The rate of same-day admissions increased from 5.3% before to 7.7% after OPE introduction (adjusted odds ratio 1.2, 95% CI, 1.01–1.39), and the total hospital length of stay (in days) significantly decreased by a factor of 0.92 (0.90–0.94), which was partly the result of a reduction in preoperative admission time. We concluded that, although smaller than anticipated, the use of OPE for potential inpatients leads to a significant reduction of cancelled cases and of length of admission. Further increase of these benefits from OPE requires changes in institutional policy, such as forcing surgical departments to increase their number of same-day admissions.

IMPLICATIONS: An observational study was conducted to compare various outcomes before and after the introduction of outpatient preoperative evaluation (OPE). Although smaller than anticipated, OPE for potential inpatients leads to a significant reduction of canceled cases and of length of admission.


   Introduction
Top
 Abstract
 Introduction
Methods
 Results
 Discussion
 References
 
Traditionally, all surgical patients are hospitalized at least one day before their operation and then visited by the anesthesiologist for preoperative evaluation. The aim of preoperative evaluation is to estimate the risk of perioperative morbidity and mortality and to optimize the patients’ condition (1). Outpatient preoperative evaluation (OPE) saves costs to hospitals and society and improves quality of care (1–8). OPE allows for comprehensive assessment of the patient when additional investigations and optimization of the patient’s health status is still possible. Hence, OPE could reduce perioperative morbidity and prevent late operating room (OR) cancellations. Moreover, OPE is a prerequisite for outpatient surgery and same-day admissions.

Various studies have shown that the number of canceled operations decreases, and the number of same-day admissions increases, after OPE implementation (3–6,8,9). However, varying rates of reduction in surgery cancellations were reported, with different definitions of cancellations (1,10). Moreover, most studies included a relatively small number of patients, studied specific surgical populations only (e.g., ambulatory patients), or evaluated single effects of the introduction of OPE (such as admission length) (6–10).

We examined a range of effects of OPE in a large series of surgical inpatients. In particular, the effect OPE can have on the rate of OR cancellations, length of hospital stay, and same-day admissions was determined.


   Methods
Top
 Abstract
 Introduction
 Methods
Results
 Discussion
 References
 
Patients.
The study population comprised of 21,553 elective adult surgical inpatients in which 24,685 elective, noncardiac OR visits were scheduled. Inpatients are postoperative patients admitted postoperatively after same-day admit surgery and patients already admitted preoperatively. All patients were admitted between January 1, 1997 and December 31, 1999 to the University Medical Center of Utrecht, a 1080-bed teaching hospital in The Netherlands. Obstetric and pediatric cases were not included because most of these OR visits were in the adjacent children’s hospital. Because they were already submitted to OPE since the mideighties, patients operated on in same-day surgery, who were discharged within 8 h after surgery, were also excluded.

OPE was gradually introduced in June 1997 with orthopedic surgery, plastic surgery, and urology. It was then introduced in the years after to other various specialties such as gynecology and vascular surgery in October 1998, ear-nose-throat and dental surgery in May 1999, neurosurgery in June 1999, and general and eye surgery in October 1999. Across all surgical specialties, the occurrence of several outcomes before and after the implementation of an OPE clinic was compared.

Preoperative Evaluation.
Before the introduction of OPE, the anesthesiologist visited the patient on the ward the day before surgery. The medical history and physical examination were obtained, and the patient was informed about anesthesia. After OPE was introduced, patients visited the OPE clinic on average 3 wk before the surgery date. At this clinic, each patient was evaluated by the anesthesiologist using an extensive questionnaire, additional medical history, and a physical examination. Subsequently, a specially trained nurse informed the patient about the perioperative care.

Outcomes.
The primary outcome of this study was the rate of surgical cases canceled for medical reasons. A case was considered canceled if scheduled at 1 PM on the day before surgery, but not performed on the planned date.

The secondary outcome was measured by the rate of same-day admissions, the average number of (preoperative) admission days, the rate of patients that made a preoperative visit to an internist, cardiologist, or pulmonologist ("consultative specialists"), the rate of postoperative intensive care unit (ICU) admissions, and the rate of additional preoperative testing, such as laboratory tests. A same-day admission was defined as a patient admitted and operated on the same day for nonemergency reasons. Preoperative admission days were the number of days between the admission day and the day of surgery. Although some patients were operated on more than once within one admission, for this outcome, the first OR visit was always taken. Postoperative ICU admission was defined as admission into the ICU on the day of surgery or until the seventh postoperative day.

Data Collection.
Beginning January 1, 1997, 6 mo before the first OPE clinic was started, we documented every surgical procedure whether it was before or after the introduction of OPE and whether it was performed as scheduled or canceled. For each canceled procedure, the surgical specialty, the reason for cancellation, and sex and age of the patient were documented. For cases not canceled, the same data were obtained, as well as data about the (preoperative) length of admission, preoperative visits by these patients to consultative specialists, the additional tests, and postoperative ICU admission. A time window of 100 days before the day of surgery was chosen for visits to consultative specialists and additional testing. For patients who visited a consultative specialist more than once within these 100 days, only the most recent visit was counted. The same was done for each additional test.

Analysis.
The odds ratio and a 95% CI were used to estimate the difference in rate of OR cancellation before and after the introduction of OPE. To adjust for age, sex, and date of introducing OPE, multivariable logistic regression analysis was used. The variable "date of introduction" was categorized into five period groups (i.e., June 1997, October 1998, May 1999, June 1999, and October 1999) and was included as four indicator variables, with the first period as the reference group. This adjustment for the date of introduction was made because the distribution of specialties in the period before the introduction of OPE differed from the distribution in the period after OPE introduction. This could have influenced the studied associations. This same analytical approach was used to compare the rate of same-day admissions, the rate of preoperative visits by patients to consultative specialists, the rate of preoperative chest radiographs and electrocardiograms (ECGs), and the rate of postoperative ICU admissions.

To determine whether admission times (estimated in days using midnight census) and the number of preoperative laboratory tests significantly changed after OPE introduction, the differences in means before and after OPE were estimated. Multivariable linear regression analysis was used to adjust these differences again for age, sex, and introduction date. After log transformation, the two variances (before and after OPE) of the log admission time were equal. Therefore, to quantify whether the admission time before and after OPE introduction was significantly changed; we used Student’s t-test based on the log admission time (11).


   Results
Top
 Abstract
 Introduction
 Methods
 Results
Discussion
 References
 
Before the introduction of OPE, 14,148 patients were scheduled for surgery, and 7405 patients were scheduled after OPE introduction (Table 1). In these 21,553 adult patients, 24,685 OR visits were scheduled (16,219 before and 8466 after OPE introduction; some patients were scheduled more than once). The number of patients operated on for the first time was 13,162 before and 7024 after OPE introduction.


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  		Table 1.  Characteristics of Elective Admitted Adult Patients Scheduled for Surgery Before and After OPE Introduction
 
In 96% of all cancellations, the reason for cancellation was documented (Table 2). After adjustment, the odds ratio for all cancellations together was 0.88 (95% CI, 0.76–1.02). The rate of cancellations for medical reasons only, which were expected to be influenced mostly by OPE, decreased from 1.95% to 0.93%, yielding an odds ratio of 0.5 (0.4–0.6) and a difference of 1.02% (95% CI, 0.07%–1.31%). After adjustment, the odds ratio was 0.7 (95% CI, 0.5–0.9).


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  		Table 2.  Number of Operating Room Cancellations for Different Reasons Before and After the Introduction of OPE (% Between Parenthesis) and Corresponding Odds Ratios
 
The admission time was skewly distributed; the overall mean was 8.6 days (SD 11.8) and the median 5 days. The preoperative and total admission time were significantly decreased after OPE introduction (P < 0.001). The preoperative admission time after OPE was 0.89 (95% CI, 0.88–0.91) times the value found before OPE, a relative decrease of 11%. For total admission time, this relative decrease was 8% (Table 3). After adjustment, similar ratios were found.


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  		Table 3.  Mean and Median Admission Time, Geometric Mean, and Estimated Ratio’s of Admission Time Before OPE Versus After OPE
 
The rate of same-day admissions increased from 5.26% (692/13,162) before to 7.72% (542/7024) after OPE introduction. This difference of 2.46% (95% CI, 1.73%–3.17%) yielded an odds ratio of 1.19 (95% CI, 1.01–1.39) after adjustment. Figure 1 shows the total rate of same-day admissions in our clinic per semester since 1997. At the end of 2000, the absolute rate of same-day admissions was 20%.



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  		Figure 1. Percentage of same-day admissions of total number of admissions per semester since 1997.

 
After adjustment for age, sex, and introduction date, the number of postoperative ICU admissions and visits to consultative specialists did not differ before and after OPE, but the number of preoperative ECGs performed and chest radiographs decreased significantly (Table 4). Also, the mean number of preoperative laboratory tests performed per patient decreased from 2.4 before to 1.5 tests after OPE introduction (difference 0.84; 95% CI, 0.81–0.88). After adjustment, this difference was 0.70 (95% CI, 0.66–0.74). The rate of patients in which no laboratory test was performed increased from 17% (2278/13,162) before to 37% (2295/7024) after OPE introduction (difference 15%; 95% CI, 14%–17%), yielding an odds ratio of 3.1 (95% CI, 2.8–3.4) after adjustment.


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  		Table 4.  Number of Postoperative ICU Admissions, Preoperative Visits by Patients to Consultative Specialists, ECG’s and Chest Radiographs Before and After OPE (% Between Parenthesis) and Odds Ratio’s
 

   Discussion
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
References
 
We evaluated the possible effects of the introduction of an OPE clinic for surgical inpatients. The number of OR cancellations for medical reasons (such as untreated hypertension) decreased by 30%. In addition, the length of hospital stay and the number of preoperative additional tests (e.g., ECGs, chest radiographs, and laboratory tests) were significantly reduced.

To appreciate these results, it should be noted that this study was nonrandomized; it compared the situation before and after the introduction of OPE. Although we made adjustments for several confounders (age, sex, and introduction date), it may well be that there were unmeasured differences between both groups that were responsible for the observed effects. Second, only the data on surgery cancellations were collected prospectively. Data on other outcomes were obtained from the hospital information system. Although these data appeared to be reliable, we have no information on error rates. However, errors in such data are likely to be nondifferential before and after OPE introduction.

Previous studies reported effects of OPE comparable to those observed here, including a reduction in canceled cases and in additional preoperative tests (3–9). The relative reduction in surgical cancellations ranged from 20% to 88%, but most studies included a relatively small number of patients. In one study from a university hospital in the United States, Fischer (5) reported a decrease from 1.96% to 0.21% (relative reduction, 88%) in cancellations for medical reasons in adult out- and inpatients and in the number of additional tests ordered. In our study, the observed effect was smaller, which is likely the result of differences in patient population (we included inpatients only). Several studies have also shown a reduction in preoperative length of admission (2,3,6,8). In most instances, this reduction resulted from an increased number of same-day admissions (up to >50%) or to an increase of patients that were operated on in ambulatory surgery. In our study, the increase in same-day admissions (from 5% to 20% one year after complete OPE introduction, Fig. 1) was much smaller. The observed decrease in postoperative admission length after introduction of OPE in our clinic has been less (8).

The effects of the introduction of OPE in our hospital were smaller than anticipated. Despite the fact that OPE allowed same-day admissions, a number of specialists admitted patients to the ward one day before surgery for reasons of teaching medical students or routine additional tests. Obviously, to change these existing practice patterns, the incentives for all those concerned must be clear. It will take time to change habits, to define new clinical pathways to reduce variability between specialists, and to receive the full benefits from OPE. In this context, it should be noted that OPE was introduced gradually. We found that it took at least one year after entering patients in the OPE process before a change in practice pattern was evident in a particular surgical specialty. Because the present data suggest that our hospital has not yet extracted the maximal benefit from the OPE clinic, our institutional policy should possibly be changed, i.e., surgical departments should be urged to increase their number of same-day admissions.

The effects of OPE observed in our study most likely resulted from a better timing of the preoperative evaluation of surgical inpatients; OPE allows ample time for comprehensive assessment of the patient and treatment of comorbidity before the scheduled date of surgery. This reduces the number of late cancellations (within 24 h before surgery) because of newly discovered conditions (Table 2). Most preventable perioperative events are cardiopulmonary in origin (1,12–17). Because preoperative evaluation focuses on these organ systems, the observed reduction in cancellations for newly discovered cardiopulmonary disease was expected. The reduction in postoperative admission time was possibly the result of a reduction in morbidity; this is the result of a better preoperative optimization of the patients’ condition and the information given by nurses at our OPE clinic (18–20). Furthermore, by making OPE an integral component of perioperative care, the number of unnecessary preoperative tests will decrease considerably. In conclusion, OPE of hospital inpatients leads to an increase in the quality of perioperative care as a result of a reduction of canceled surgery, hospital admission time, and preoperative testing.


   Acknowledgments
 
The authors gratefully acknowledge Monique Pluer, OR coordinator at the University Medical Center Utrecht, who collected and documented the data about the canceled surgical cases from 1997 to 1999.


   References
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 References
 

  1. Roizen MF. Preoperative evaluation. In: Miller RD, ed. Anaesthesia. New York: Churchill Livingstone, 2000: 824–83.
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  6. Pollard J, Zboray A, Mazze R. Economic benefits attributed to opening a preoperative evaluation clinic for outpatients. Anesth Analg 1996; 83: 407–10.[ISI][Medline]
  7. Starsnic MA, Guarnieri DM, Norris MC. Efficacy and financial benefit of an anesthesiologist-directed university preadmission evaluation center. J Clin Anesth 1997; 9: 299–305.[ISI][Medline]
  8. Pollard J, Garnerin P. Use of outpatient preoperative evaluation to decrease length of stay for vascular surgery. Anesth Analg 1997; 85: 1307–11.[Abstract]
  9. Conway JB, Goldberg J, Chung F. Preadmission anaesthesia consultation clinic. Can J Anaesth 1992; 39: 1051–7.[Abstract/Free Full Text]
  10. Pollard J, Olson L. Early outpatient preoperative anesthesia assessment: does it help to reduce operating room cancellations? Anesth Analg 1999; 89: 502–5.[Abstract/Free Full Text]
  11. Zhou X, Gao S, Hui S. Methods for comparing the means of two independent log-normal samples. Biometrics 1997; 53: 1129–35.[ISI][Medline]
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  15. Van Aken H, Rolf N. Preoperative evaluation and preparation. The view of the anesthetist. Anaesthesist 1997;46:S80–4 [German, English summary].
  16. Wolters U. ASA classification and perioperative variables as predictors of postoperative outcome. Br J Anaesth 1996; 77: 217–22.[Abstract/Free Full Text]
  17. Schein O, Katz J. The value of routine preoperative testing before cataract surgery. N Engl J Med 2000; 342: 168–75.[Abstract/Free Full Text]
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Accepted for publication November 6, 2001.




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Lippincott, Williams & Wilkins Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999 HighWire Press