Building an SMS Reminder Cadence That Actually Fills Screening Slots

Most sites already send some kind of reminder before a screening visit. The difference between a reminder program that moves the no-show rate and one that doesn't usually comes down to timing, wording, and what happens when someone replies.

Build the cadence around decision points

A single text the day before is the most common setup and the weakest. Participants drop out of a screening visit at three distinct moments: shortly after booking, when the details fade; a few days out, when work or childcare conflicts surface; and the morning of, when logistics get real. Send something at each of those points.

A cadence that works for most screening visits booked a week or more in advance:

1. Within an hour of booking. Confirm date, time, address, and who they're meeting. This is also your first deliverability test — if it bounces, you learn now instead of the morning of.
2. Three days before. Cover the prep items: fasting, medication list, insurance card, ride arrangements. Ask them to reply if the time no longer works.
3. The afternoon before. Short confirmation with a reply prompt.
4. Ninety minutes before. Parking instructions, building entrance, suite number, and a phone number they can call if they're lost.

For visits booked within 48 hours, collapse this to confirmation, night-before, and morning-of.

Write like a person at a clinic, not a system

The texts that get responses read like they came from a coordinator. Use the site name and the coordinator's first name. Avoid all-caps, avoid exclamation points stacked on study names, and keep each message under about 300 characters so it lands as one segment.

Two specifics that matter more than people expect:

• Name the building, not just the address. "Suite 210, the brick building behind the Walgreens" prevents more late arrivals than a street number.
• Say what the visit involves and how long it takes. Participants skip appointments they can't picture. "About 90 minutes — questionnaires, vitals, and a blood draw" sets expectations and reduces day-of anxiety cancellations.

Make replies easy and answer them fast

The reminder is only half the value. The other half is the reschedule you capture because someone could text back "can't make Tuesday" instead of calling during business hours. Sites that route inbound texts to a shared inbox a coordinator actually watches tend to convert a meaningful share of would-be no-shows into rebooked visits.

Set a response-time target — most sites can manage within two business hours — and decide in advance who covers it at lunch and after 4 p.m. An unanswered reply is worse than no text at all.

Track the right number

Don't measure text volume. Measure:

• No-show rate by referral source and by lead time from booking to visit
• Reply rate on the three-days-out message, which is your early warning signal
• Reschedules captured via text versus lost entirely

You'll often find no-shows concentrate in one source or in visits booked more than two weeks out. That tells you where to add a live phone call on top of the texts.

Keep the basics clean

Capture explicit consent to text at the point of first contact and log it. Honor STOP immediately and make sure the opt-out propagates to every list. Keep protocol details out of messages — name the site, not the indication — so a text read by someone else doesn't disclose a health condition. Send between 8 a.m. and 8 p.m. in the participant's time zone, and archive message history where your monitor can find it.