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Key issues include construct validity when grouping participants with prior psychotic episodes under “early episode,” understated treatment contamination, modest outcomes with wide confidence intervals and lack of a priori power calculation, and psychometric concerns from an ad hoc simplification of the PSP scale. The authors call for standardized definitions, contamination-resistant designs, validated instruments, and further cost-effectiveness evaluation.",{"@graph":69,"@context":122},[70,84,105],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/correspondence-concerns-on-construct-validity-and-contamination-in-the-lay-care-study/434834/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/correspondence-concerns-on-construct-validity-and-contamination-in-the-lay-care-study/434834.png","ImageObject",300,407,{"name":92,"@type":93},"Cipher","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-11-01","2026-09-29",true,{"@type":102,"interactionType":103,"userInteractionCount":39},"InteractionCounter",{"@type":104},"ViewAction",{"@type":106,"mainEntity":107},"FAQPage",[108,114,118],{"name":109,"@type":110,"acceptedAnswer":111},"What primary construct validity concern is raised about the Lay-CARE trial?","Question",{"text":112,"@type":113},"Participants with a history of one or two psychotic episodes are grouped under the label “early episode,” which diverges from standard first-episode definitions and blurs interpretive clarity about intervention timing and impact.","Answer",{"name":115,"@type":110,"acceptedAnswer":116},"How is treatment contamination addressed, and what do the authors suggest?",{"text":117,"@type":113},"The correspondence argues that potential contamination is understated given fluid and unstructured care pathways. It recommends contamination-adjusted or per-protocol analyses and sensitivity analyses to strengthen conclusions.",{"name":119,"@type":110,"acceptedAnswer":120},"What statistical and outcome-related limitations are highlighted?",{"text":121,"@type":113},"Reported improvements are modest with wide confidence intervals, and the absence of an a priori sample size calculation may leave the study underpowered. One statistically significant finding is described as mitigation of deterioration rather than true improvement.","https://schema.org",{"og:url":83,"og:type":124,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":126,"canonical":83},"index,follow",{"doc_id":128,"site_id":62},434834,1791080910,{"code":4,"msg":5,"data":131},{"doc_id":128,"user_id":132,"nickname":92,"user_avatar":133,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":134,"file_id":135,"file_url":136,"file_type":137,"file_size":138,"view_count":39,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":8,"language":139,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":140,"faqs":141,"seo_title":142,"seo_description":67,"update_tm":143,"read_time":81,"preview_page_count":4},687208528416,"https://ap-avatar.wpscdn.com/davatar_9964176cb1d06d4a9deccf72a44ae3dc","Correspondence   \nConcerns on construct validity and contamination in the Lay-CARE study  \nYilin Jiang,a,∗,c Narina A. Samah,a,c and Heng Zhoub,c  \naFaculty of Educational Sciences and Technology, Universiti Teknologi Malaysia, Skudai, 81310, Johor, Malaysia bStudent Affairs Department, Chongqing Medical University, Yuzhong, 400016 Chongqing, China  \nWe read with interest the recent article1 by Jirapramukpitak and Supanya evaluating a lay health worker-delivered case management programme for early psychosis in Bangkok. While the trial addresses an important gap in early intervention services in lowresource settings, we believe several methodological and interpretative issues warrant further attention.  \nFirst, the study’s inclusion of individuals with a history of one or two psychotic episodes—spanning a wide age range and varied illness duration—raises concerns about construct validity. By grouping potentially chronic or relapsed patients under the label “early episode,” the trial departs from standard definitions of first-episode psychosis and dilutes interpretive clarity regarding intervention timing and impact.2  \nSecond, while the authors acknowledge that seven participants in the usual care group received lowintensity case management (LICM) components due to caregiver distress, the potential for treatment contamination is understated. In settings where care pathways are fluid and unstructured, this crossover isnot unexpected, but its analytical implications are significant. Per-protocol or contamination-adjusted intention-to-treat analyses would have strengthened the robustness of conclusions. Retaining these participants in the included in the analysis (ITT) framework without sensitivity analyses may bias treatment effects towards the null.  \nThird, the reported improvements—for example, a 6% absolute increase in socially useful activity—are modest and accompanied by wide confidence intervals. Without an a priori sample size calculation, the study may be underpowered to detect clinically meaningful effects. Furthermore, the most statistically significant finding—reduced aggressive/disturbing behaviour—reflects mitigation of deterioration rather than improvement, warranting a more cautious interpretation.  \nFinally, the ad hoc simplification ofthe Personal and Social Performance (PSP) scale raises psychometric  \nconcerns. The reduction of the original six-point response to three categories was not followed by revalidation, and the scale’s use in linear regression without testing ordinal assumptions may compromise the validity of effect estimates.3  \nIn sum, while the Lay-CARE model is promising, stronger conceptual precision, contamination control, and statistical caution are needed before efficacy claims can be made. Future studies should adopt standardized definitions of early psychosis, contamination-resistant designs (e.g., cluster randomisation), and validated instruments sensitive to change. Additionally, the costeffectiveness of the model warrants further investigation.4 It remains to be confirmed whether this approach can genuinely reduce government expenditures while maintaining a patient-centred framework.  \nContributors  \nAll the authors have contributed equally to conceptualisation, writingoriginal draft, and writing-review and editing.  \nDeclaration of interests  \nWe declare no competing interests.  \nReferences  \n1 Jirapramukpitak T, Supanya S. Lay health worker-delivered case management for early episodes of psychosis in Bangkok, Thailand (Lay-CARE): a single-centre, pragmatic, randomised controlled trial. Lancet Reg Health Southeast Asia. 2025;38:100617. [https://doi](https://doi). org/10.1016/j.lansea.2025.100617 .  \n2 Drake RJ, Husain N, Marshall M, et al. Effect of delaying treatment of first-episode psychosis on symptoms and social outcomes: a longitudinal analysis and modelling study. Lancet Psychiatry. 2020;7(7):602–610. [https://doi.org/10.1016/s2215-](https://doi.org/10.1016/s2215-)[ ](https://doi.","cbCaikGo5mjOKTN2","https://ap.wps.com/l/cbCaikGo5mjOKTN2","pdf",106980,"English","# Correspondence\n## Concerns about construct validity\n## Concerns about contamination and analysis\n## Concerns about effect size and statistical power\n## Psychometric concerns with PSP scale\n## Overall conclusions and recommendations\n## Contributors\n## Declaration of interests\n## References","[{\"question\":\"What primary construct validity concern is raised about the Lay-CARE trial?\",\"answer\":\"Participants with a history of one or two psychotic episodes are grouped under the label “early episode,” which diverges from standard first-episode definitions and blurs interpretive clarity about intervention timing and impact.\"},{\"question\":\"How is treatment contamination addressed, and what do the authors suggest?\",\"answer\":\"The correspondence argues that potential contamination is understated given fluid and unstructured care pathways. It recommends contamination-adjusted or per-protocol analyses and sensitivity analyses to strengthen conclusions.\"},{\"question\":\"What statistical and outcome-related limitations are highlighted?\",\"answer\":\"Reported improvements are modest with wide confidence intervals, and the absence of an a priori sample size calculation may leave the study underpowered. One statistically significant finding is described as mitigation of deterioration rather than true improvement.\"}]","Correspondence - Concerns on construct validity and contamination in the Lay-CARE study | PDF",1790670760]