title: Managing a mixed-registration-type appointment system in outpatient clinics.
abstract: BACKGROUND
  Improving outpatient resource utilization significantly enhances the efficiency of healthcare organizations. Substantial number of walk-in patients (average of 72% in our study) to outpatient services is a universal characteristic of Taiwan's healthcare organizations. Consequently, scheduling becomes extremely complicated and important. Selecting the right scheduling alternative, a healthcare organization can markedly improve operating efficiency of outpatient resources.
  
  
  OBJECTIVE
  This research applied simulation methodology to analyze several scheduling solutions and found that setting the appropriate arrival time interval for preregistered patients significantly impacts queuing problems in outpatient services.
  
  
  METHODS
  Using established simulation models, the effects of various scheduling policies on patients' throughput time and waiting times were revealed. Under alternative model A, the first 20 numbers are reserved for scheduled patients; after that, only even numbers are offered for scheduled ones. Odd numbers after 20 are left for walk-ins. Under alternative model B, front numbers were assigned to scheduled patients successively. The later numbers were left for walk-ins. Alternative model C assigned scheduled patients with even numbers and walk-ins with odd numbers in sequence. Finally, alternative model D was designed to examine the optimal scheduled time interval by conducting the model with different scheduled time intervals such as 3, 5, 7, 9, and 11 min.
  
  
  RESULTS
  The alternative sequence (alternative model C-assigning even numbers for scheduled patients and odd numbers for walk-in patients, or vice versa) significantly has the least throughput time (average: 34.9 min vs 55.2, 56.2, and 46.2 min) and waiting times (average: 14.7 min vs 34.9, 35.8, and 25.8 min) for walk-in patients compared with other registration strategies. Scheduling the appointments with flexible time interval (alternative model D) has the least throughput time (average: 24.2 min vs 28.4, 28.2, and 37.2 min) and waiting times (average: 8.0 min vs 12.5, 12.3, and 20.5 min) for scheduled patients compared with other registration strategies.
  
  
  CONCLUSIONS
  The findings of this research could be applied possibly to any outpatient clinic with mixed-registration-type (walk-in and scheduled), particularly which accounts for high percentage of walk-in patients.
authors.affiliation: Institute of Health Care Organization Administration, School of Public Health, National Taiwan University, No. 1, Sec. 1, Jen Ai Rd, Rm. 1512, 100, ROC, Taipei, Taiwan. susyi@ha.mc.ntu.edu.tw
authors.forename: Syi
authors.initials: S
authors.lastname: Su
authors.forename: Chung-Liang
authors.initials: CL
authors.lastname: Shih
mesh_terms: D001071:Appointments and Schedules; D017598:Efficiency, Organizational; D006751:Hospital Information Systems; D006782:Hospitals, Special / Q000458:organization & administration*; D006801:Humans; D017146:Models, Organizational; D010044:Outpatient Clinics, Hospital / Q000458:organization & administration* / Q000706:statistics & numerical data; D012984:Software; D012985:Software Design; D013624:Taiwan; D014572:Urology / Q000458:organization & administration*