The Sexunzipped Trial: Optimizing the Design of Online Randomized Controlled Trials
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Abstract
The Sexunzipped Trial: Optimizing the Design of Online Randomized Controlled Trials
Background
There is huge potential for sexual health promotion using digital interventions, and interventions are increasingly being evaluated online. Online research offers the advantage of ease of access to large numbers of participants, the facility for automated randomization, automated reminders and automated data collection, and facility for blind allocation to intervention or control. However, there are concerns over repeat registration to obtain incentives, the quality of self-reported data, and potential high drop-out from online trials.
Objectives
• To assess the feasibility of online recruitment, online consent, participant identity verification, randomization and concealment of allocation, online data collection, and data quality
• To assess the effect on response rates at 3 month follow-up of two different levels of incentive payment (£10 and £20)
• To assess the effect on overall response rates at 3 month follow-up of requesting a Chlamydia urine sample by post in addition to an online sexual health questionnaire
Methods
2,041 young people aged 16 to 21 registered for the Sexunzipped online trial between November 2010 and March 2011. Most participants were recruited via an advert on Facebook (84%), 9% via friends or relatives, 4% via email, and 2% through school or college. Participants filled in baseline demographic and sexual health questionnaires online, and were then randomized to the interactive intervention website (Sexunzipped) or to an information-only control website. Participants were also randomly allocated to a postal request for a urine sample for genital Chlamydia testing (or no request); and receipt of a lower (£10) or higher (£20) shopping voucher incentive for 3 month outcome data. Participant identity was checked by requesting dates of birth at baseline and again at three month follow-up. The primary outcome for this feasibility study was retention of valid participants at 3 month follow-up, i.e. completion of the online questionnaire only, or online questionnaire and Chlamydia urine sample. We also analyzed measures of feasibility and process including numbers recruited by source; number of rejected ID verifications; and numbers responding to email and postal follow-up prompts by incentive and allocation to Chlamydia urine sample pot. Statistical analyses were conducted using STATA Version 12 (StataCorp LP, Texas, USA).
Results
The majority of participants (91%) were aged between 18 and 20 at enrolment, from all areas of the UK. Most were White (90%), in education or training (77%), and 63% of the sample were female. A total of 79/2041 entries (3.9%) were invalid registrations on the basis of contact details (n=12); discrepant dates of birth (n=66); or incoherent responses (n=1); and a further 4% of participants gave inconsistent responses to sexual health questions concerning condom use. The larger (£20) incentive boosted response rates at follow-up from 71% to 77% for the online sexual health questionnaire (p=0.20), and from 41% to 47% for postal Chlamydia urine testing (p=0.19), but these increases were not statistically significant. Requesting a Chlamydia sample as well as the online questionnaire reduced the proportion of complete data at 3 month follow-up from 75% to 42% (p< 0.0001).
Conclusions
It was cheap and efficient to recruit young people to this online trial, mostly via Facebook. Our procedures for obtaining online consent, verifying participant identity, randomization and concealment of allocation worked well. Online sexual health questionnaire data quality appears to have been good. Multiple methods of participant contact (by email and post), requesting online questionnaire data only, and a higher incentive increased the follow-up rates at 3 months.
Background
There is huge potential for sexual health promotion using digital interventions, and interventions are increasingly being evaluated online. Online research offers the advantage of ease of access to large numbers of participants, the facility for automated randomization, automated reminders and automated data collection, and facility for blind allocation to intervention or control. However, there are concerns over repeat registration to obtain incentives, the quality of self-reported data, and potential high drop-out from online trials.
Objectives
• To assess the feasibility of online recruitment, online consent, participant identity verification, randomization and concealment of allocation, online data collection, and data quality
• To assess the effect on response rates at 3 month follow-up of two different levels of incentive payment (£10 and £20)
• To assess the effect on overall response rates at 3 month follow-up of requesting a Chlamydia urine sample by post in addition to an online sexual health questionnaire
Methods
2,041 young people aged 16 to 21 registered for the Sexunzipped online trial between November 2010 and March 2011. Most participants were recruited via an advert on Facebook (84%), 9% via friends or relatives, 4% via email, and 2% through school or college. Participants filled in baseline demographic and sexual health questionnaires online, and were then randomized to the interactive intervention website (Sexunzipped) or to an information-only control website. Participants were also randomly allocated to a postal request for a urine sample for genital Chlamydia testing (or no request); and receipt of a lower (£10) or higher (£20) shopping voucher incentive for 3 month outcome data. Participant identity was checked by requesting dates of birth at baseline and again at three month follow-up. The primary outcome for this feasibility study was retention of valid participants at 3 month follow-up, i.e. completion of the online questionnaire only, or online questionnaire and Chlamydia urine sample. We also analyzed measures of feasibility and process including numbers recruited by source; number of rejected ID verifications; and numbers responding to email and postal follow-up prompts by incentive and allocation to Chlamydia urine sample pot. Statistical analyses were conducted using STATA Version 12 (StataCorp LP, Texas, USA).
Results
The majority of participants (91%) were aged between 18 and 20 at enrolment, from all areas of the UK. Most were White (90%), in education or training (77%), and 63% of the sample were female. A total of 79/2041 entries (3.9%) were invalid registrations on the basis of contact details (n=12); discrepant dates of birth (n=66); or incoherent responses (n=1); and a further 4% of participants gave inconsistent responses to sexual health questions concerning condom use. The larger (£20) incentive boosted response rates at follow-up from 71% to 77% for the online sexual health questionnaire (p=0.20), and from 41% to 47% for postal Chlamydia urine testing (p=0.19), but these increases were not statistically significant. Requesting a Chlamydia sample as well as the online questionnaire reduced the proportion of complete data at 3 month follow-up from 75% to 42% (p< 0.0001).
Conclusions
It was cheap and efficient to recruit young people to this online trial, mostly via Facebook. Our procedures for obtaining online consent, verifying participant identity, randomization and concealment of allocation worked well. Online sexual health questionnaire data quality appears to have been good. Multiple methods of participant contact (by email and post), requesting online questionnaire data only, and a higher incentive increased the follow-up rates at 3 months.
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