Are SMS vouchers or posted vouchers more effective for increasing response rates in a work-related survey in people with persistent pain?

ISRCTN	ISRCTN93103453
DOI	https://doi.org/10.1186/ISRCTN93103453
ClinicalTrials.gov (NCT)	Nil known
Clinical Trials Information System (CTIS)	Nil known
Protocol serial number	NRC 326732
Sponsor	Campus Kristiania
Funder	Norges Forskningsråd

Submission date: 13/06/2022
Registration date: 25/07/2022
Last edited: 14/05/2024

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Injury, Occupational Diseases, Poisoning

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Record updated in last year

Plain English summary of protocol

Background and study aims
Response rates are important in trials as high response rates mean that the sample is more likely to be reflective of the population from which it was drawn. While vouchers are known to increase response rates in trials, little work has been done to explore whether the method of delivery affects response. We will explore whether receiving vouchers by SMS message or in the post has a large effect on response rates.

Who can participate?
Those consenting to participate in a cohort study of the impact of being unemployed with persistent pain, with the chance of being offered an intervention to help people from the population to return to work and for which NOK 200 of high street vouchers are being offered as an incentive to complete questionnaires.

What does the study involve?
The study involves randomising participants to receive their vouchers either by SMS or by post

What are the possible benefits and risks of participating?
This is a methods trial comparing two ways of receiving vouchers and not a health care intervention, thus no benefits or risks are identified.

Where is the study run from?
Kristiania University College (Norway)

When is the study starting and how long is it expected to run for?
May 2022 to April 2023

Who is funding the study?
Research Council of Norway (Norway)

Who is the main contact?
Professor Robert Froud (Norway)
RobertJames.Froud@kristiania.no

Contact information

Prof Robert Froud
Principal investigator

Kristiania University College
Prinsens gate 7-9
Oslo
0107
Norway

ORCID ID	0000-0002-9193-2297
Phone	+47 41 26 73 69
Email	RobertJames.Froud@kristiania.no

Study information

Primary study design	Interventional
Study design	Randomized controlled trial
Secondary study design	Randomised parallel trial
Study type	Participant information sheet
Scientific title	Are SMS vouchers or posted vouchers more effective for increasing response rates in a work-related survey in people with persistent pain?
Study acronym	SPOST
Study objectives	Is there a large difference between SMS vouchers or posted vouchers for increasing response rates in a work-related survey in people with persistent pain?
Ethics approval(s)	Approval 16/05/2022, Regional Committees for Medical and Health Research Ethics (Gullhaugveien 1-3, 0484, Oslo, Norway; +47 22 84 55 22; rek-sorost@medisin.uio.no), ref: 402918.
Health condition(s) or problem(s) studied	Pain
Intervention	Current interventions, as of 17/01/2023: We will study the follow-up rate at three months for people enrolled in a cohort randomised study (ISRCTN85437524) and who are offered vouchers to participate. We will randomise all participants, regardless of what arm they are in, in a cohort randomised approach to receive the vouchers either by SMS or by post. The objective is to see if there is a large difference (ie of 30% or more) in follow-up rate at three months with one or other of the voucher offer methods. If no difference is detected then SMS would be preferred as it is less expensive and has a lower carbon footprint. _____ Previous interventions: We will study the follow-up rate at six months (primary) and 12 months (secondary) for people enrolled in a cohort randomised study (ISRCTN85437524) and who are offered vouchers to participate. We will randomise all participants, regardless of what arm they are in in the cohort randomised approach to receive the vouchers either by SMS or by post. The objective is to see if there is a large difference (ie of 30% or more) in follow-up rates with one or other of the voucher offer methods. If no difference is detected then SMS would be preferred as it is less expensive and has a lower carbon footprint.
Intervention type	Behavioural
Primary outcome measure(s)	Current primary outcome measure as of 17/01/2023: Follow-up response rate, measured using the number of three-month follow-up questionnaires received divided by the number of baseline measurements received. _____ Previous primary outcome measure: Follow-up response rate, measured using the number of three-month follow-up questionnaires received divided by the number of baseline measurements sent at three-months
Key secondary outcome measure(s)	Current secondary outcome measures as of 17/01/2023: Follow-up response rates, measured using the number of six- and 12-month follow-up questionnaires received divided by the number of baseline questionnaires, may be subsequently conducted. _____ Previous secondary outcome measures: Follow-up response rates, measured using the number of six- and 12-month follow-up questionnaires received divided by the number of baseline questionnaires sent at six- and 12-months
Completion date	30/04/2023

Eligibility

Participant type(s)	Other
Age group	Adult
Sex	All
Target sample size at registration	58
Total final enrolment	101
Key inclusion criteria	Participants in cohort randomised trial ISRCTN85437524
Key exclusion criteria	Participants not in ISRCTN85437524
Date of first enrolment	15/06/2022
Date of final enrolment	16/01/2023

Locations

Countries of recruitment

Norway

Study participating centre

Kristiania University College

Prinsens gate 7-9
Oslo
0107
Norway

Results and Publications

Individual participant data (IPD) Intention to share	Yes
IPD sharing plan summary	Available on request
IPD sharing plan	After completion of the ReISE project and all peer-reviewed publications and disseminations will be complete and published, anonymised/de-identified data will be available upon reasonable request to the data custodian at Kristiania University College. De-identified data will be stored in a secure database for this purpose. Protocol, data from intervention, and statistical analysis plan can be delivered upon reasonable request to principal investigator. RobertJames.Froud@kristiania.no

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes
Study website	Study website	11/11/2025	11/11/2025	No	Yes

Editorial Notes

14/05/2024: The intention to publish date was changed from 31/12/2024 to 31/03/2025.
27/02/2024: The intention to publish date was changed from 01/08/2023 to 31/12/2024.
17/01/2023: The following changes were made to the trial record:
1. The interventions were changed.
2. The primary outcome measure was changed.
3. The secondary outcome measures were changed.
4. The total final enrolment was added.
16/06/2022: Trial's existence confirmed by the Norwegian Regional Committees for Medical and Health Research Ethics.