IIE Transactions (2008) 40, 800819Copyright C IIEISSN: 0740-817X print / 1545-8830 onlineDOI: 10.1080/07408170802165880

Appointment scheduling in health care: Challengesand opportunities

DIWAKAR GUPTA1, and BRIAN DENTON2

1Graduate Program in Industrial & Systems Engineering, Department of Mechanical Engineering, University of Minnesota,111 Church Street S.E., Minneapolis, MN 55455, USAE-mail: guptad@me.umn.edu2North Carolina State University, Edward P. Fitts Department of Industrial & Systems Engineering, 111 Lampe Drive, Raleigh,NC 27695, USAE-mail: bdenton@ncsu.edu

Received August 2006 and accepted December 2007

Appointment scheduling systems are used by primary and specialty care clinics to manage access to service providers, as well as byhospitals to schedule elective surgeries. Many factors affect the performance of appointment systems including arrival and servicetime variability, patient and provider preferences, available information technology and the experience level of the scheduling staff.In addition, a critical bottleneck lies in the application of Industrial Engineering and Operations Research (IE/OR) techniques. Themost common types of health care delivery systems are described in this article with particular attention on the factors that makeappointment scheduling challenging. For each environment relevant decisions ranging from a set of rules that guide schedulers toreal-time responses to deviations from plans are described. A road map of the state of the art in the design of appointment managementsystems is provided and future opportunities for novel applications of IE/OR models are identified.

Keywords: Appointment scheduling, health care operations management, access rules

1. Introduction

The health care industry represents approximately 15% ofthe gross domestic product of the United States. Health careexpenditures are growing at a rate such that the amount ofpublic money needed to finance health care, which currentlystands at 45% of all health care expenditures, is expected todouble by 2050. Americans who are covered by employer-sponsored plans have experienced double digit increases inpremiums as employers shift a greater portion of rapidly ris-ing health care costs to the employees (Economist, 2004).When we add factors such as an aging population, increas-ing demand for chronic care and strained public and privatehealth care budgets to this mix, it is no surprise that there isa growing pressure on health service providers to improveefficiency.

Appointment scheduling systems lie at the intersectionof efficiency and timely access to health services. Timely ac-cess is important for realizing good medical outcomes. It isalso an important determinant of patient satisfaction. Theability to provide timely access is determined by a varietyof factors that include fundamental questions about how

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many and which types of physical assets and equipment ahealth system should invest in, how should it allocate re-sources among multiple sites, how should it staff each clinicor hospital site, what rules best determine which providersand patients receive higher priority access to resources, andhow appointments are scheduled. The focus of this articleis on appointment scheduling. We do not consider ques-tions pertaining to the size of facilities, equipment and staff,and to resource allocation in multiple-service-site systems.(An example of such issues can be found in Chao et al.(2003)).

Scheduled patient encounters include primary and spe-cialty care visits, as well as elective surgeries. In each of theseenvironments, the process of scheduling appointments (as-signing a specific time when the patient is scheduled to startreceiving care) is different, which we will describe shortly.In addition, there are unscheduled encounters that includewalk-ins and urgent or emergency cases. The former, oc-curring mostly in primary care clinics, can be directed to analternate facility if the clinic in question is heavily booked.However, urgent specialty care and surgical patients oftenneed to be treated as soon as possible. The goal of a well-designed appointment system is to deliver timely and conve-nient access to health services for all patients. Appointmentsystems also smooth work flow, reduce crowding in waiting

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rooms and allow health systems to honor patient andprovider preferences while matching supply and demand.

Each of primary care, specialty care and hospital serviceshave certain unique features that give rise to different chal-lenges for managing appointments. In the primary care set-ting, the vast majority of patients require services that canbe performed within a fixed time length. Therefore, primarycare clinics tend to divide available provider time into equal-length time slots such that, by and large, patients needs canbe accommodated in a standard appointment slot. For cer-tain types of visits that require more time, clinics may assignmultiple appointment slots. The appointment schedulingproblem then reduces to that of finding a suitable matchamong the available time slots of providers in the clinic,provider prescribed restrictions on how available slots maybe filled and patients preferences for day/time of week aswell as for a particular service provider. (An example ofprovider restrictions on the use of available slots is the limitthat many providers place on the number of physical examsor new patients that can be scheduled in any given session.)Still, the problem of matching supply and demand is noteasy because different patients have different perceptionsof the urgency of their need and different day-of-week andtime-of-day preference patterns.

Patient service times in specialty care clinics tend to varymore depending on the patients diagnoses and other char-acteristics. Therefore, provider time may not be divided intostandard time slots. Moreover, many specialty services re-quire a referral from the primary care physician. In suchcases, appointments are booked by the medical assistantof the referring doctor. Bookings may occur at periodicintervals (e.g., at the end of each day). Appointment man-agement for specialty care clinics is further complicated be-cause of two reasons: (i) the need to reserve capacity forurgent appointment requests that must be treated soon af-ter they occur; and (ii) the need to realize high utilizationof more-expensive specialists time.

Scheduling surgical appointments is even more complex.Procedure times are variable, several pre-surgery appoint-ments may be required for necessary medical exams and avariety of service providers/resources have to be simulta-neously scheduled in order to deliver the desired services.For example, in addition to the team of surgeons, a prop-erly equipped surgery room, specialized nursing staff andanesthesiologists have to be available at the desired starttime. Therefore, surgery scheduling sometimes occurs intwo stages. Patients first choose from a menu of availabletime windows (each may be a week long) during which theyprefer to have the procedure performed. The physiciansoffice later confirms a specific day and surgery start time,which we refer to as the appointment. Surgeons typicallyneed to fit all procedures scheduled for a day within a blockof operating room time that is assigned for their use. Theyhave preferences with respect to which types of proceduresthey like to perform on specific days and times of week. Suchconsiderations can further complicate scheduling. Finally,

a significant proportion of overall demand in a variety ofsurgical specialty areas is from urgent patients who need tobe treated as soon as possible.

In all three environments, a patient who schedules an ap-pointment faces two types of access delays. Indirect (virtual)waiting time is the difference between the time that a patientrequests an appointment and the time of that appointment.Direct (captive) waiting time is the difference between a pa-tients appointment time (or his/her arrival time if he/sheis tardy) and the time when he/she is actually served by theservice provider. In contrast, in a system with no appoint-ments, e.g., when a service provider accepts only walk-insor urgent cases, patients experience only direct waiting. In-direct waiting is usually orders of magnitude greater thandirect waiting. Whereas direct waiting is an inconvenienceto the patient, excessive indirect wait can pose a serioussafety concern (Murray and Berwick, 2003).

A well-designed appointment system achieves small di-rect waiting times for unscheduled (especially urgent/emergency) episodes without increasing the direct waitingtimes of scheduled patients or lowering resource utilization.This is accomplished by specifying various rules that de-termine which types of patients may access available serviceprovider resources at what times. We refer to such rules asaccess rules and include them within the scope of this ar-ticle. Access rules also reduce the negative impact of indi-rect waiting on scheduled urgent appointments by reservingsome capacity exclusively for their use.

Appointment systems can be a source of dissatisfaction,both for the patients and for the providers. Patients areimpacted by the lack of availability of timely and conve-nient appointment slots, especially when their need is ur-gent. Clinicians are impacted by the uncertainty in the num-ber of patient appointments from day to day, and the mixof appointments on any given day. These factors can af-fect clinicians earnings as well as their job satisfaction lev-els. In many instances, clinicians can handle high-prioritydemand, and variations in case mix, only by stretchingtheir schedules to absorb demand variationi.e., by shrink-ing lunch time, pushing back dinner and double booking(work