Is it feasible to nest a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting programme? Results from a Born in Bradford’s Better Start (BiBBS) study

Is it feasible to nest a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting programme? Results from a Born in Bradford’s Better Start (BiBBS) study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Is it feasible to nest a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting programme? Results from a Born in Bradford’s Better Start (BiBBS) study Kate Mooney, Josie Dickerson, Charlie Welch, Kirsty Crossley, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8406001/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Background It is crucial to find pragmatic design alternatives to randomised trials to evaluate early childhood parenting interventions in practice, which can suffer from potentially low uptake and disappointment bias. In the first study of its kind, we assess the feasibility of nesting a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting intervention delivered to parents of 1-2-year-old children living in inner-city Bradford, England. The study evaluated: (1) whether TwiCS methodology can be implemented to create control and intervention arms, whilst documenting any incidences of contamination; (2) whether satisfactory rates of intervention uptake are achieved; and (3) whether satisfactory rates of retention of participants are achieved. Methods A stratified random sample of 240 mother-child dyads were selected from an eligible population in the Born in Bradford’s Better Start cohort. Mother-child dyads were individually randomised 1:1 to the intervention or control, with stratification by child age (1 or 2 years old at the time of randomisation) and ethnicity (White British, South Asian, or other). A Red Amber Green (RAG) rating system supported the assessment of each objective: red (not achieved), amber (partly achieved), and green (achieved). Results TwiCS methodology created balanced control and intervention arms, and 73% of parents could be contacted about the intervention (green), though rates of contamination were higher than desired (2%, amber). Satisfactory rates of intervention uptake could not be achieved: 43% of parents consented to a referral (amber), and 14% of parents enrolled in IY-T (red). Satisfactory rates of retention in the intervention may be achievable, as 80% of enrolled parents participated (amber), and all participating parents completed the intervention (green). Conclusions It was feasible to use TwiCS methodology to randomly select, allocate, and contact parents, and document contamination in this setting. However, intervention uptake was low, and this would need improving for a future TwiCS evaluating this intervention to be feasible. This study suggests a TwiCS is not a viable approach to evaluating early years interventions delivered >12 months after cohort recruitment. Other pragmatic and implementable methods of evaluation may be more feasible, such as quasi-experimental designs, or target trials. Trial registration The study was prospectively registered on ISRCTN (ISRCTN16150114). Feasibility trial within a cohort study parenting programme birth cohort Incredible Years Better Start Bradford Born in Bradford’s Better Start Full Text Additional Declarations Competing interest reported. TB is a voluntary Trustee for Children’s Early Intervention Trust (CEIT). Early Intervention Wales Training (EIWT) is owned by CEIT and offers training courses, including Incredible Years®(IY). Trustees do not benefit financially from trainings or CEIT/EIWT activities. No IY training in Bradford was conducted via CEIT/EIWT. Supplementary Files SupplementaryFileA.CONSORTChecklistsv1.0.doc.docx SupplementaryFileB.TWiCSSOPv1.0.doc Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 13 May, 2026 Reviewers agreed at journal 28 Apr, 2026 Reviewers invited by journal 27 Apr, 2026 Editor assigned by journal 11 Jan, 2026 Submission checks completed at journal 11 Jan, 2026 First submitted to journal 19 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8406001","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":574094337,"identity":"372cf905-58bd-4597-adc5-599454d14cb0","order_by":0,"name":"Kate Mooney","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA90lEQVRIiWNgGAWjYBACCSQ24wMgYQBhH8CnhRnOZjYgWQubBFFaJNvPH3zAmGMjZ87eY1bNU3HPmIH98ANmnjO4tUjzJDMbMG5LM7bsOWN2m+dMsRkDT5oBM88N3FrkGJLZJBi3HU7ccCPH7DZvW4INA0MOAzPPBzxa+B+z/wBruf/GrBishf8Nfi3SEslsDBBbeMyYgVrMGCRAtuBxmOSMx8YSiUC/GJxJK5accybBmE3imcHBOXi8L3E+8eGHj9ts5AyOH9744U1FgmE/f/LDB2+O4dYCBglgksOAiQdIsTHgjRUUwP6A8QeRSkfBKBgFo2BkAQD/3EudC8ymqQAAAABJRU5ErkJggg==","orcid":"","institution":"University of York","correspondingAuthor":true,"prefix":"","firstName":"Kate","middleName":"","lastName":"Mooney","suffix":""},{"id":574094346,"identity":"85878767-3065-4d19-af5e-0d96f4c1bc75","order_by":1,"name":"Josie Dickerson","email":"","orcid":"","institution":"Bradford Teaching Hospitals NHS Foundation Trust","correspondingAuthor":false,"prefix":"","firstName":"Josie","middleName":"","lastName":"Dickerson","suffix":""},{"id":574094347,"identity":"5b1157eb-efc5-4b18-84c4-ad3f9c371b8c","order_by":2,"name":"Charlie Welch","email":"","orcid":"","institution":"University of York","correspondingAuthor":false,"prefix":"","firstName":"Charlie","middleName":"","lastName":"Welch","suffix":""},{"id":574094348,"identity":"5ce0b98d-9f23-41bf-8378-9a19a8a2fa1a","order_by":3,"name":"Kirsty Crossley","email":"","orcid":"","institution":"Bradford Teaching Hospitals NHS Foundation Trust","correspondingAuthor":false,"prefix":"","firstName":"Kirsty","middleName":"","lastName":"Crossley","suffix":""},{"id":574094349,"identity":"a274d409-1c8b-4019-a04f-9568cdcf62a4","order_by":4,"name":"Matthew Walker","email":"","orcid":"","institution":"Bradford Teaching Hospitals NHS Foundation Trust","correspondingAuthor":false,"prefix":"","firstName":"Matthew","middleName":"","lastName":"Walker","suffix":""},{"id":574094360,"identity":"07364779-670b-4929-8031-ec7b5df8eaaa","order_by":5,"name":"John Wright","email":"","orcid":"","institution":"Bradford Teaching Hospitals NHS Foundation Trust","correspondingAuthor":false,"prefix":"","firstName":"John","middleName":"","lastName":"Wright","suffix":""},{"id":574094362,"identity":"88f3e3c2-779c-488c-a0ab-fa98d0b957d0","order_by":6,"name":"Tracey Bywater","email":"","orcid":"","institution":"University of York","correspondingAuthor":false,"prefix":"","firstName":"Tracey","middleName":"","lastName":"Bywater","suffix":""},{"id":574094364,"identity":"69752894-a95b-4b25-b2cd-bf60a0da2888","order_by":7,"name":"Sarah Blower","email":"","orcid":"","institution":"University of York","correspondingAuthor":false,"prefix":"","firstName":"Sarah","middleName":"","lastName":"Blower","suffix":""}],"badges":[],"createdAt":"2025-12-19 14:53:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8406001/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8406001/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101751544,"identity":"15d8eb7f-8327-454c-a7ab-9c6e9c740103","added_by":"auto","created_at":"2026-02-03 10:21:12","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":646170,"visible":true,"origin":"","legend":"","description":"","filename":"FeasibilityTwiCSv1.1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8406001/v1_covered_da05b2ba-b791-4dd1-8b29-8c748926141b.pdf"},{"id":101487817,"identity":"61c1a275-4c61-49c6-99aa-2c379c65a173","added_by":"auto","created_at":"2026-01-30 09:29:52","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":34685,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFileA.CONSORTChecklistsv1.0.doc.docx","url":"https://assets-eu.researchsquare.com/files/rs-8406001/v1/affe366c06e8210d48f38c7c.docx"},{"id":101487818,"identity":"7897191d-930d-45cf-9743-fef69e636ac1","added_by":"auto","created_at":"2026-01-30 09:29:52","extension":"doc","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":110080,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFileB.TWiCSSOPv1.0.doc","url":"https://assets-eu.researchsquare.com/files/rs-8406001/v1/1405d7304d77b87a2deac443.doc"}],"financialInterests":"Competing interest reported. TB is a voluntary Trustee for Children’s Early Intervention Trust (CEIT). Early Intervention Wales Training (EIWT) is owned by CEIT and offers training courses, including Incredible Years®(IY). Trustees do not benefit financially from trainings or CEIT/EIWT activities. No IY training in Bradford was conducted via CEIT/EIWT.","formattedTitle":"Is it feasible to nest a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting programme? Results from a Born in Bradford’s Better Start (BiBBS) study","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"pilot-and-feasibility-studies","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pafs","sideBox":"Learn more about [Pilot and Feasibility Studies](http://pilotfeasibilitystudies.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/PAFS/default.aspx","title":"Pilot and Feasibility Studies","twitterHandle":"@MedicalEvidence","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Feasibility, trial within a cohort study, parenting programme, birth cohort, Incredible Years, Better Start Bradford, Born in Bradford’s Better Start","lastPublishedDoi":"10.21203/rs.3.rs-8406001/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8406001/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIt is crucial to find pragmatic design alternatives to randomised trials to evaluate early childhood parenting interventions in practice, which can suffer from potentially low uptake and disappointment bias. In the first study of its kind, we assess the feasibility of nesting a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting intervention delivered to parents of 1-2-year-old children living in inner-city Bradford, England.\u003c/p\u003e\n\u003cp\u003eThe study evaluated: (1) whether TwiCS methodology can be implemented to create control and intervention arms, whilst documenting any incidences of contamination; (2) whether satisfactory rates of intervention uptake are achieved; and (3) whether satisfactory rates of retention of participants are achieved.\u003c/p\u003e\n\u003cp\u003eMethods\u003c/p\u003e\n\u003cp\u003eA stratified random sample of 240 mother-child dyads were selected from an eligible population in the Born in Bradford’s Better Start cohort. Mother-child dyads were individually randomised 1:1 to the intervention or control, with stratification by child age (1 or 2 years old at the time of randomisation) and ethnicity (White British, South Asian, or other). A Red Amber Green (RAG) rating system supported the assessment of each objective: red (not achieved), amber (partly achieved), and green (achieved).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTwiCS methodology created balanced control and intervention arms, and 73% of parents could be contacted about the intervention (green), though rates of contamination were higher than desired (2%, amber). Satisfactory rates of intervention uptake could not be achieved: 43% of parents consented to a referral (amber), and 14% of parents enrolled in IY-T (red). Satisfactory rates of retention in the intervention may be achievable, as 80% of enrolled parents participated (amber), and all participating parents completed the intervention (green).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIt was feasible to use TwiCS methodology to randomly select, allocate, and contact parents, and document contamination in this setting. However, intervention uptake was low, and this would need improving for a future TwiCS evaluating this intervention to be feasible. This study suggests a TwiCS is not a viable approach to evaluating early years interventions delivered \u0026gt;12 months after cohort recruitment. Other pragmatic and implementable methods of evaluation may be more feasible, such as quasi-experimental designs, or target trials.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrial registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was prospectively registered on ISRCTN (ISRCTN16150114).\u003c/p\u003e","manuscriptTitle":"Is it feasible to nest a randomised Trial within a Cohort Study (TwiCS) to evaluate an early years parenting programme? Results from a Born in Bradford’s Better Start (BiBBS) study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-30 09:29:47","doi":"10.21203/rs.3.rs-8406001/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-13T14:53:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"317874239040072692820717418063260652464","date":"2026-04-28T14:35:23+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-28T03:24:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-12T04:49:35+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-12T04:47:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"Pilot and Feasibility Studies","date":"2025-12-19T14:25:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"pilot-and-feasibility-studies","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pafs","sideBox":"Learn more about [Pilot and Feasibility Studies](http://pilotfeasibilitystudies.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/PAFS/default.aspx","title":"Pilot and Feasibility Studies","twitterHandle":"@MedicalEvidence","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a0fc5dc3-c8f0-43f7-b35d-cd2053f28548","owner":[],"postedDate":"January 30th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-13T14:53:02+00:00","index":27,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-28T03:40:12+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-30 09:29:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8406001","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8406001","identity":"rs-8406001","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}