A £160 Price Tag in a Text Message Cut Missed Hospital Appointments From 11.1% to 8.4%
Hallsworth et al. (2015) tested eight reminder texts on London NHS patients. Stating the cost of a no-show beat '9 out of 10 people attend' and a vaguer cost line.
In this article3 sections
Trial One began in November 2013 at a London NHS trust. Each patient received one of four texts five days before an outpatient appointment. The control told them to call the number on their appointment letter to cancel or rearrange. A second version wrote the phone number out. A third read “We are expecting you at [clinic] on [date] at [time]. 9 out of 10 people attend.” The fourth read “We are expecting you at [clinic] on [date] at [time]. Not attending costs NHS £160 approx.”
Trial One: four messages
Hallsworth and colleagues (PLoS ONE, 2015) randomized 10,111 reachable appointments across five specialities. Missed (“did not attend”) rates:
| Message | Missed rate |
|---|---|
| Control | 11.1% (284 of 2,566) |
| Phone number written out | 9.8% |
| Social norms (“9 out of 10 attend”) | 10.0% |
| Stated cost (£160) | 8.4% (206 of 2,445) |
The cost text cut the missed rate by 2.7 points, about a quarter in relative terms (odds ratio 0.74, 95% CI 0.61 to 0.89). The social-norms text was among the weaker arms, and it raised cancellations: 10.5% against 8.8% in the control (odds ratio 1.23, p = .03). Telling people that nearly everyone shows up may have made cancelling feel routine, though the trial did not test why.
Trial Two: pricing against vaguer pressure
Trial Two ran from March to May 2014 on 9,848 eligible appointments, with the £160 text as the control.
| Message | Missed rate | Versus £160 text |
|---|---|---|
| £160 cost (control) | 8.2% | n/a |
| “Not attending wastes NHS money” | 9.9% | odds ratio 1.22, p = .046 |
| “Please be fair to others waiting” | 10.7% | odds ratio 1.33, p < .01 |
| “…or we will record as a missed appt” | 9.6% | odds ratio 1.18, p = .07 |
The vague cost line trailed the priced one, though only just: the confidence interval (1.00 to 1.48) touches 1, and no correction was applied for comparing several arms. The appeal to fairness fared worst. A threat to record the miss, a consequence with no number attached, did not reach significance.
One reading is that a stated price is a fact for the recipient to weigh, while the other lines are attitudes that can be waved off. The trial compared wordings, so it cannot say which psychology produced the gap. It also had no arm that sent nothing at all, so it says nothing about how much any reminder adds.
Where the finding stops
Only about 20% of eligible patients had accurate mobile records, so the reminded group may differ from everyone else. The site was a single London trust, where the authors say missed rates are higher than in much of England. Messages went out five days ahead, longer than in most earlier studies, which may let any effect fade. Nobody could confirm the texts were read, and Trial One was registered after it began, within a six-week window the ethics committee permitted.
A price can also change how a penalty is read: in a well-known daycare experiment, a late-pickup fine was treated as a fee. What a reminder should lead with also mattered in New York’s redesigned court summons. Messages between friends raise a related question, taken up in a Q&A on how much detail to include.