The cost-effectiveness of an outpatient anesthesia consultation clinic before surgery: a matched Hong Kong cohort study

Abstract

Background: Outpatient anesthesia clinics are well established in North America, Europe and Australia, but few economic evaluations have been published. The Perioperative Systems in Hong Kong are best described as a hybrid model of the new and old systems of surgical care. In this matched cohort study, we compared the costs and effects of an outpatient anesthesia clinic (OPAC) with the conventional system of admitting patients to the ward a day before surgery for their pre-anesthesia consultation. A second objective of the study was to determine the patient's median Willingness To Pay (WTP) value for an OPAC.

Methods: A total of 352 patients were matched (1:1) on their elective surgical procedure to either the clinic group or to the conventional group. The primary outcome was quality of recovery score and overall perioperative treatment cost (US$). To detect a difference in the joint cost-effect relationship between groups, a cost-effectiveness acceptability curve (CEAC) was drawn. A modified Poisson regression model was used to examine the factors associated with patients willing to pay more than the median WTP value for an OPAC.

Results: The quality of recovery scores on the first day after surgery between the clinic and conventional groups were similar (mean difference, -0.1; 95% confidence interval (CI), -0.6 to 0.3; P = 0.57). Although the preoperative costs were less in the clinic group (mean difference, -$463, 95% CI, -$648 to -$278 per patient; P <0.001), the total perioperative cost was similar between groups (mean difference, -$172; 95% CI, -$684 to $340 per patient; P = 0.51). The CEAC showed that we could not be 95% confident that the clinic was cost-effective. Compared to the conventional group, clinic patients were three times more likely to prefer OPAC care (relative risk (RR) 2.75, 95% CI, 2.13 to 3.55; P <0.001) and pay more than the median WTP (US$13) for a clinic consultation (RR 3.27, 95% CI, 2.32 to 4.64; P <0.001).

Conclusions: There is uncertainty about the cost-effectiveness of an OPAC in the Hong Kong setting. Most clinic patients were willing to pay a small amount for an anesthesia clinic consultation.

Keywords: Cost-effectiveness analysis; Outpatient anesthesia clinic; Patient satisfaction; Perioperative system.

Figure 1

Conventional and Perioperative System preprocedural processes at Prince of Wales Hospital, Hong Kong. There are three types of patient groups: Day only admissions (patients admitted and discharged on the same day after elective surgery), Day of surgery admissions (patients admitted on the day of elective surgery and then stay in hospital for at least one night) and Inpatients (patients admitted before the day of surgery and then discharged on the same day or afterwards following surgery). The Perioperative System was operational in 2006 but a dedicated pre-anesthetic clinic space was not available until July 2008.

Figure 2

Cost-effectiveness acceptability curves. These were derived from comparing incremental total perioperative cost and incremental preoperative cost per incremental Quality of Recovery Score.