Industry sponsorship bias in randomized controlled trials of digital cognitive behavioral therapy for insomnia: A meta research study based on the 2023 Brazilian Guidelines on the Diagnosis and Treatment of Insomnia in Adults

Viviane Akemi Kakazu¹Marcia Assis²Andrea Bacelar³Andréia Gomes Bezerra¹Giovanna Lira Rosa Ciutti¹Silvia Gonçalves Conway^4,5,6José Carlos Fernandes Galduróz¹Luciano Ferreira Drager⁷Mariana Pery Khoury^1,8Ingrid Porto Araújo Leite¹Ygor de Matos Luciano¹Dalva Poyares¹Sergio Tufik^1,9Gabriel Natan Pires^1*

• ¹Departamento de Psicobiologia, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil
• ²Clínica do Sono de Curitiba, Hospital São Lucas, Curitiba, Paraná, Brazil
• ³Clínica Bacelar - Neuro e Sono, Rio de Janeiro, Paraná, Brazil
• ⁴Instituto de Psiquiatria (IPq), Universidade de São Paulo, São Paulo, Rio Grande do Sul, Brazil
• ⁵Departamento de Otoneurologia, Universidade de São Paulo, SAO PAULO, Brazil
• ⁶AkasA - Formação e Conhecimento, SAO PAULO, Brazil
• ⁷Heart Institute (InCor), São Paulo, Sao Paulo, Brazil
• ⁸Universidade Santo Amaro, São Paulo, São Paulo, Brazil
• ⁹Instituto do Sono (Brazil), São Paulo, São Paulo, Brazil

Background: Industry sponsorship bias refers to the tendency of a study, most likely clinical trials, to produce results that favor the sponsor's interest. It is especially relevant in cases in which a study is funded by companies or organizations with a commercial interest in the product or technology being evaluated. Digital Cognitive Behavioral Therapy for Insomnia (dCBT-I) is a widely used nonpharmacological treatment, and research in this area is often funded by organizations that have a commercial interest in this treatment. This study aimed to assess whether industry sponsorship bias in dCBT-I trials is associated with more favorable outcomes. Methods: This study was based on the sample of randomized controlled trials (RCTs) included at the "2023 Brazilian Guidelines on the Diagnosis and Treatment of Insomnia in Adults". Inclusion criteria included 1. Diagnosis using ICSD-3, DSM-5, Insomnia Severity Index (ISI) or Athens Insomnia Scale (AIS). 2. dCBT-I as intervention. 3. Other forms of CBT-I or negative control groups as comparators, and 4. ISI as main outcome. Immediate post-treatment ISI data was extracted for both intervention and control groups in each included study, and the betweengroups Cohen's d effect size was calculated for each included study. Methodological quality was evaluated using the van Tulder scale. Results: Twenty-eight analyses of RCTs were included. Interventions such as SHUTi (Sleep Healthy Using the Internet) (39.28%) and Online CBT-I (28.57%) were the most common, with comparators such as minimal intervention (50%) and waiting list (32.14%). There was a significant association between the risk of sponsorship bias and open access publication [X²(1)=5.250; p=0.022], as well as between the risk of sponsorship bias and lower levels of methodological quality [X²(1)=4.861; p=0.027]. There was no correlation between risk of bias levels and Insomnia Severity Index (ISI) mean scores (the main indicator of outcomes) in the control and experimental groups. These results suggest that the risk of sponsorship bias may impact the methodological quality of studies and compliance with established standards. Conclusion: A greater risk of sponsorship bias was associated with lower methodological quality articles and open access publication.