Field note · Appointments
The cheapest fix for missed appointments is one line in a text message.
Every no-show pitch ends with a product. This one ends with a sentence. Two randomised controlled trials across 19,959 NHS patients tested what happens when the reminder text says what the appointment costs, and the answer was a quarter fewer missed appointments.
The short answer
In two randomised controlled trials at Barts Health NHS Trust, adding the specific cost of the appointment to the standard SMS reminder cut the did-not-attend rate from 11.1% to 8.4% — a relative reduction of about a quarter. A second trial confirmed that a specific figure beats vague language about cost. Total sample: 19,959 patients.
If you run a diary — a dental practice, a clinic, a salon, a garage, a surveyor’s round — somebody has tried to sell you something for no-shows. Deposits. An app. Increasingly, an AI that rings people.
Before any of that, there is a change that has been tested properly and costs nothing: put the number in the text.
What exactly changed in the message?
The control group got the trust’s standard reminder. The intervention group got the same message with the appointment’s approximate cost to the NHS added — a specific figure, £161, rather than a general appeal.
That is the whole intervention. No app, no deposit, no call.
Does it matter whether the number is specific?
Yes, and that is the second trial. It compared a specific cost against general language about cost, in the same trust, across 9,848 more patients. Specific won: 8.2% against 9.9%.
“Missed appointments cost the NHS money” is a slogan. “This appointment costs £161” is a fact about the reader’s Tuesday. Only one of them moved the number.
What this means if you are not the NHS
Two honest caveats before you copy it. This was a hospital outpatient setting, where the cost lands on a public service rather than on the patient’s own bill — a private practice is asking a different question, because the client already knows they are paying. And it was 2013–14, before reminder fatigue had done another decade of work.
What transfers is the mechanism, not the number: a specific, concrete consequence beats a general appeal. The version to test in a private diary is the one that names what the slot is worth and what happens to it — the chair time, the person who could not have it, the notice you need to fill it.
So when does an AI earn its place here?
After the free change, not before. The sequence we would run:
- Fix the wording. One line, specific, in the existing reminder. Measure for a month against the month before.
- Then look at coverage. If a large share of your enquiries or confirmations arrive outside opening hours and go unanswered, that is a different problem and it is worth arithmetic — there is a calculator here for exactly that.
- Then automate the chase, narrowly: confirm, remind, rebook, hand to a named person. Four verbs.
Doing it in that order costs you a month and tells you whether steps two and three are worth anything. Doing it in the opposite order buys you a system whose effect you can no longer measure, because you changed everything at once.
Questions people actually ask
How do you reduce no-shows without charging deposits?
The best-evidenced change is the wording of the reminder. Two randomised controlled trials at Barts Health NHS Trust found that stating the specific cost of the appointment in the SMS reminder cut did-not-attend rates from 11.1% to 8.4%, and that a specific figure outperformed general language about cost. Nothing was installed and nothing was charged.
Do SMS appointment reminders actually work?
Reminders themselves are well established. What these trials add is that the content matters as much as the reminder: the same message with a specific cost figure added performed significantly better than the standard text, with an odds ratio of 0.74 (95% CI 0.61–0.89, p<0.01) across 10,111 patients.
Does this apply to a private practice rather than the NHS?
Partly. The setting was NHS outpatients, where the cost falls on a public service rather than the patient, and the trials ran in 2013–14. The transferable finding is the mechanism — a specific, concrete consequence beats a general appeal — rather than the exact percentage. Test your own wording for a month before buying anything.
Should I buy AI reception for no-shows?
Not first. Change the reminder wording and measure it for a month; it is free and it is the intervention with a randomised trial behind it. If a large share of your enquiries still arrive and go unanswered outside hours, do the arithmetic on what that is worth before buying, and scope any system to four verbs: answer, qualify, book, hand over.
Sources
- Hallsworth M et al., Stating Appointment Costs in SMS Reminders Reduces Missed Hospital Appointments: Findings from Two Randomised Controlled Trials, PLOS ONE, 10.1371/journal.pone.0137306. Trial one Nov 2013 – Jan 2014, n = 10,111: 11.1% vs 8.4% DNA, OR 0.74 (95% CI 0.61–0.89, p<0.01). Trial two Mar – May 2014, n = 9,848: specific 8.2% vs general 9.9%, OR 1.22 (95% CI 1.00–1.48, p = 0.046). Barts Health NHS Trust, five outpatient specialties. — peer-reviewed randomised controlled trials, primary
- The three-step sequence — wording first, arithmetic second, automation third — is Noxia’s own and is not part of the study. — our opinion, labelled
Checked 8 September 2026. Numbers that move — leaderboards, live indices — are re-checked every 30 days; annual datasets and rules in force every six months; dated research once a year. If something here has gone stale before we got to it, tell us and we will correct it and say what changed.
Change the sentence first. Ring us if it does not work.
If a month of better wording does not move your number, the problem is somewhere else and we will help you find where before selling you anything.
Talk to us about this