Multmedia Appendix 1. Summary of the 21 Web-based scheduling systems Service or Provider Names Features Assessment Methods Results Improved Metrics Choose and Book [1–3]  UK natonal appointment system for Natonal Health Service (NHS)  Supports Web-based appointments  Supports electronic referrals Retrospectve analysis of patent atendance data. [2] Appointments booked with “Choose and Book” had a signifcantly lower no-show rate than those made by traditonal appointment methods. This system optmized the referral process, reduced delays, and streamlined outpatent referral pathways.  Reduced no-show rate  Optmized the referral process  Reduced wait tme Holdsworth House Medical Practce [4]  Asynchronous  The appointment service is a component of the Australian practce’s “e-communicaton” system  Email-based  Appointments are confrmed by email or text messages Not reported This system was efcient and saved clinicians’ valuable tme. Many patents preferred to use this system.  Improved efciency  Reduced staf labor ZocDoc [5]  Real-tme  Medical appointment SaaS  Supports same-day appointments  Practces can track confrmed appointments, cancellatons, and missed appointments Retrospectve analysis of ZocDoc appointment records for 3 dermatology clinics over a 6- month period. Appointments booked with ZocDoc had a much lower no-show rate (6.9%) than those made by traditonal appointment methods at dermatology clinics.  Reduced no-show rate WAS [6]  Asynchronous  Proprietary appointment system for Xijing hospital in China  Patents receive appointment numbers to register their visits Follow-up telephone interviews with users. Patents using WAS were more satsfed than patents using the usual queuing method (71.7% vs. 49.0%, P<.001). The average invalid waitng tme for queuing and WAS were signifcantly diferent (86 minutes vs 7 minutes, P<.001).  Increased satsfacton  Reduced wait tme eTriage [7]  Real-tme  Web-based appointment service for sexual health clinics in the UK Questonnaire- based survey completed on atendance. 100% of patents can get an appointment within 48 hours, compared to 48% of patents using regular appointment methods. 70% of the users were satsfed with the service. 94% would recommend it to a friend. 96% would reuse it. It reduced the clinic’s and call center’s staf labor by releasing clinic capacity.  Improved patent satsfacton  Reduced wait tme  Reduced staf labor EppointmentPlus [8,9]  Real-tme  Medical appointment SaaS  Can integrate with the practce’s management sofware  Appointment tme slots are categorized by visit types Not reported This system kept doctors in control and reduced staf labor.  Reduced staf labor NexShed Scheduware [8]  Real-tme  Medical appointment SaaS  Can integrate with the practce’s management sofware  Can work together with traditonal scheduling  Can restrict the type and tme of appointments  Compatble with EHR systems from other vendors Not reported This system kept doctors in control and reduced staf labor.  Reduced staf labor Murray Hill Medical Group [10]  Real-tme  Patents can choose available appointment tmes but the amount of tme for the appointment is not revealed to them  Appointments will be confrmed by email  Patents will receive two reminders  Patents can view, cancel and reschedule appointments Not reported Patent satsfacton were improved and failed appointments were reduced. 95% of the patents who had used the Web-based appointment service would not use other appointment methods. About 50% of the appointments were made for the next day and 90% were made for within two weeks. It saved the medical group $170,000 annually due to the reducton of staf. Doctors’ empty appointment slots were flled overnight and thus income was increased. The no-show rate decreased to less than 1% from about 8% (phone-based appointments).  Improved satsfacton  Reduced no-show rate  Reduced wait tme  Reduced staf labor  Improved efciency  Increased revenue