Since 1990, more than 50% of all hospital-based surgeries performed in the United States have been performed on an outpatient basis . Many of these patients have their preoperative evaluation completed by the anesthesiologist on the day of their procedure. It is unclear whether healthy adults benefit from preoperative evaluation prior to the day of surgery [2-5], but it has been demonstrated that hospital efficiency is enhanced by early preoperative evaluation [6-9]. In particular, delays and cancellations are decreased when outpatients have been evaluated in a preoperative evaluation clinic prior to the day of operation [6,9]. (Macarthur A, Macarthur C, Bevan J. Preoperative assessment clinic reduces day surgery cancellations [abstract]. Anesthesiology 1991;75:A1109.)
In November 1994, our university-affiliated Department of Veterans Affairs Hospital established a perioperative unit for outpatients. This unit provides preoperative services, such as registration, preoperative evaluations, and preoperative holding, as well as post-surgical support for outpatients, including a Phase 2 recovery area. The most important single element of our program has been the interdisciplinary preoperative evaluation clinic for outpatients under the medical direction of an anesthesiologist and staffed by nursing personnel. Similar clinics have reported decreased laboratory utilization [9,10], lower surgical cancellation rates [9,11,12], and fewer and shorter hospitalizations [10,12]. The magnitude of inpatient cost savings attributable to reducing hospitalization has not been fully described. The purpose of this report is to document these savings and also to document the change in the cancellation rate that resulted after our clinic opened.
In anticipation of decreased inpatient surgical bed utilization and to create space for the perioperative unit, an 11-room (22-bed) inpatient surgical unit was closed during November 1994. No major structural changes or remodeling were required. Cross-training of existing staff allowed almost half of the former inpatient unit nurses to work in the new clinic.
Patients were referred to the preoperative evaluation clinic directly from outpatient surgical clinics after they had been evaluated by a surgeon and scheduled for operation (to take place within 30 days). They came with their medical record in hand, which at a minimum included a current surgeon's history and physical examination, and a signed operation consent form.
On arrival at the clinic, patients completed the Health Quiz (NELCOR, Pleasanton, CA) and underwent a nursing assessment before being evaluated by an anesthesiologist. Laboratory tests and consultations were then ordered by the anesthesiologist and, with few exceptions, were obtained in the clinic the same day. Next, written preoperative instructions were given to the patient, and teaching was completed by the nursing staff. The night before operation, patients were called by clinic personnel with final instructions. Patients returned to the perioperative unit on the day of surgery for final preparation before being transported to the main operating room. After surgery, patients who had received spinal or general anesthesia completed Phase I recovery in the main postanesthesia care unit. Patients who received only local anesthesia or had procedures requiring minimal sedation went directly to the perioperative unit after surgery. Outpatients completed Phase 2 recovery in the perioperative unit prior to discharge to home.
Inpatient and outpatient surgical volume and cancellation rates from December 1993 to May 1994 (control period) were compared with similar data from the 6-mo period (December 1994 to May 1995) after the opening of the perioperative unit. Since outpatient surgery volume and cancellation rates had been stable during the 2 yr preceding the opening of the unit, all changes after November 1994 were assumed to be directly related to establishing the unit.
Estimated cost savings were calculated using utilization review data and current hospital ward costs. Salary data were obtained from our fiscal service. From 1993 utilization review data, we determined the average length of stay for patients who had inpatient surgical procedures at our hospital that could have been performed on an outpatient basis. Since surgical inpatient length of stay was stable during the 2 yr preceding the opening of the unit, we presumed the length of inpatient stay for these procedures in 1995 would remain unchanged. We multiplied the average inpatient length of stay by current surgical ward costs per day to estimate the inpatient hospitalization costs saved per outpatient procedure. The additional number of outpatient operations performed from December 1994 to May 1995 compared with the control period was multiplied by the estimated savings per procedure to calculate total inpatient savings. We then subtracted the cost of operating the perioperative unit to calculate the net savings.
chi squared analysis was used to determine whether the proportion of inpatient and outpatient operations or cancellations changed significantly after opening the preoperative evaluation clinic.
During the 6 mo immediately after the opening of the perioperative unit, the number of outpatient operations increased by 420 from 104 to 524 Figure 1, Table 1. The average age of patients seen in the unit was 55 yr (range 19-87 yr). Utilization review data revealed that patients previously admitted to the inpatient surgical ward for procedures commonly performed in the community on an outpatient basis stayed an average of 4.76 days. The average cost per inpatient day of care on our surgery wards in May 1995 was $570. Thus, the estimated inpatient ward savings were as follows: 420 patients times 4.76 days/patient times $570 per day = $1,140,000.
Salaries and benefits to staff the perioperative unit, including one third of the physician director's salary, for the first 6 mo of operation were $253,173. We estimated a cost of $5000 for medications and supplies based on data from postanesthesia care unit charges . This gives an estimated net savings of $882,000 ($1,140,000 - [253,000 + 5000]). The largest single component of the savings resulted from decreased nursing salary costs. The 22-bed inpatient surgery ward formerly required staffing 24 hours per day, 365 days per year. Converting it to outpatient use required staffing only 14 hours per day (6 AM to 8 PM), 250 days per year. This allowed us to decrease nursing staff assigned to the perioperative unit from 16.2 to 7.4 full-time equivalents at a cost savings of $530,000 per year. The balance of the savings resulted primarily from decreased salary costs for other employees (pharmacy, laboratory, housekeeping, dietary, etc.). Not included in the savings were the cost of utilities and other expenses associated with decreased maintenance of the physical plant at night, on weekends, etc.
Outpatient cancellations decreased significantly (P < 0.001) from 26% prior to opening the perioperative unit to 6.6% during the first 6 mo after it was established. Inpatient cancellation rates (21% vs 19%) were stable during the 6 mo before and after opening the unit Table 2. The indications for cancellation were similar during the control period and the study period. One third of cancellations in both periods were for medical reasons with the remainder due to other factors, such as emergency surgery superseding elective surgery, patients having eaten prior to elective surgery, patients not having a companion for transportation home after outpatient surgery, and patients failing to appear on the day of surgery.
The benefits of outpatient preoperative evaluation clinics were recognized almost 50 years ago . However, these clinics were not widely used until recent years. The growth of outpatient surgery sparked an interest in them because they have been shown to increase efficiency and improve patient care [6-9]. In particular, preoperative consultation by the anesthesiologist has been associated with a lower proportion of patients subjected to unnecessary laboratory tests, electrocardiograms, and chest radiographs [9,10] and with lower surgical cancellation rates [9,11,12].
Of all these efficiencies, reductions in hospitalization have the greatest cost saving potential. Other studies have demonstrated decreased inpatient lengths of stay associated with establishing a preoperative evaluation clinic [5,10,15,16], but none of these studies have calculated the cost savings from both preoperative and postoperative reductions in length of stay. Booth  compared the cost of outpatient assessment followed by admission on the day of surgery with the cost of inpatient assessments on the day before surgery. Outpatient evaluation resulted in a savings of $366 per patient with 76% of this savings attributed to decreased nursing costs. In that study, the combined laboratory and radiology savings associated with outpatient evaluation resulted in a savings of only $26 per patient.
Without our utilization review data from 1993, we might have underestimated the number of inpatient days that were eliminated. Intuitively, one might expect outpatient preoperative evaluation to save only one or two days of hospitalization per patient. Our data suggest that we saved an average of 4.76 days of hospitalization per patient. A similar result was noted by Frost , who reported an average savings of 3.91 days per patient at her municipal hospital after a preoperative evaluation clinic was established. It is possible that such long perioperative lengths of stay are peculiar to health care institutions in the public sector, where until recently pressure to reduce length of stay has been minimal. Even if the potential reduction in length of stay in the private sector is only one day or less, considerable savings still can be achieved . Larger savings comparable to ours should also be possible in countries such as France and Switzerland, where government health care systems still provide per diem rather than per procedure reimbursement for surgical operations (Francois Clergue, MD, personal communication, Paris, France) and outpatient surgery is uncommon . The per diem payment system encourages inpatient preoperative evaluation and prolonged postoperative hospitalization.
Additional cost savings are also achieved by decreasing the cancellation rate. After the opening of our clinic, the outpatient cancellation rate fell from 26% to 6.6% (P < 0.001). These data are similar to those of Hand et al. , who reported a reduction in the cancellation rate of almost 50% after opening their outpatient clinic. Macarthur et al.1 noted that patients who attended their hospital preoperative clinic had a five times lower cancellation rate than those seen only in the surgeon's office. Booth  reported 60% fewer cancellations for patients evaluated as outpatients, but the resulting cost savings was only $20 per patient.
Our data demonstrate that establishing an outpatient preoperative evaluation clinic to facilitate outpatient surgery can result in large cost savings. These savings were possible even at our government-funded hospital, where patients have relatively limited financial resources, i.e., 71.6% have yearly incomes below $21,000. Our study did not include the economic cost of care by family members at home. A survey in 1993 from Great Britain revealed that 18% of patients undergoing short-stay procedures reported that their caretaker had to take time off work to perform the caring role . However, this expense is partially offset by the economic benefits to the patient, such as fewer days off from work.
In an era when cost-benefit analysis is applied to all aspects of medical practice , it is useful to know that establishing an outpatient preoperative evaluation clinic in a public sector institution can lead to substantial savings even in the first six months of operation. These savings have continued in the eight months (6/95-2/96) after our study as outpatient volume has increased to 50% of all surgeries. The greatest cost savings in our setting continue to be attributable to fewer and shorter hospitalizations . Although preoperative evaluation clinics have been directed by nurses  and by other physicians [3,5,8,23], the largest reductions in hospital stay are most consistently reported by interdisciplinary units such as ours where anesthesiologists have taken an active role [10,12,15,16,23]. This could be an important new source of employment for anesthesiologists .
The authors wish to acknowledge the advice of Dr. Stephen P. Fischer, Stanford University Hospital, whom we consulted prior to establishing our preoperative clinic for outpatients.
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