Sample Size Calculation for an Individual Stepped-Wedge Randomized Trial.

In the individual stepped-wedge randomized trial (ISW-RT), subjects are allocated to sequences, each sequence being defined by a control period followed by an experimental period. The total follow-up time is the same for all sequences, but the duration of the control and experimental periods varies among sequences. To our knowledge, there is no validated sample size calculation formula for ISW-RTs unlike stepped-wedge cluster randomized trials (SW-CRTs). The objective of this study was to adapt the formula used for SW-CRTs to the case of individual randomization and to validate this adaptation using a Monte Carlo simulation study. The proposed sample size calculation formula for an ISW-RT design yielded satisfactory empirical power for most scenarios except scenarios with operating characteristic values near the boundary (i.e., smallest possible number of periods, very high or very low autocorrelation coefficient). Overall, the results provide useful insights into the sample size calculation for ISW-RTs.

Do patients with type 2 diabetes mellitus included in randomised clinical trials differ from general-practice patients? A cross-sectional comparative study.

OBJECTIVES: To compare the characteristics of patients with type 2 diabetes mellitus in general practice and those included in randomised controlled trials on which clinical practice guidelines are based. DESIGN: Cross-sectional comparative study. SETTING: We asked 45 general practitioners from three French Departments to identify the 15 patients with type 2 diabetes mellitus they most recently saw in consultation. In parallel, we selected randomised controlled trials included in the Cochrane systematic review on which the clinical practice guidelines for type 2 diabetes mellitus were based. PARTICIPANTS: We included 675 patients with type 2 diabetes mellitus, and data were collected from 23 randomised controlled trials, corresponding to 36 059 patients. OUTCOME MEASURES: Characteristics of general-practice patients were extracted from medical records by a unique observer. The same baseline characteristics of patients included in randomised controlled trials from the Cochrane systematic review were extracted and meta-analysed. We assessed standardised differences between these two series of baseline characteristics. A difference greater than 0.10 in absolute value was considered meaningful. RESULTS: General-practice patients were older than randomised controlled trial patients (mean (SD) 68.8 (1.1) vs 59.9 years (standardised difference 0.8)) and had a higher body mass index (mean (SD) 31.5 (6.9) vs 28.2 kg/m2 (standardised difference 0.5)) but smoked less (11.0% vs 29.3% (standardised difference -0.6)). They more frequently used antihypertensive drugs (82.1% vs 37.5% (standardised difference 1.2)) but less frequently had a myocardial infarction (7.6% vs 23.1% (standardised difference -1.1)). CONCLUSIONS: Patients with type 2 diabetes mellitus cared for in general practice differ in a number of important aspects from patients included in randomised controlled trials on which clinical practice guidelines are based. This situation hampers the applicability of these guidelines. Future randomised trials should include patients who better fit the 'average' general-practice patient with type 2 diabetes mellitus to help improve the translation of study findings in daily practice.

Why and when should we cluster randomize?

A cluster randomized trial is defined as a randomized trial in which intact social units of individuals are randomized rather than individuals themselves. Outcomes are observed on individual participants within clusters (such as patients). Such a design allows assessing interventions targeting cluster-level participants (such as physicians), individual participants or both. Indeed, many interventions assessed in cluster randomized trials are actually complex ones, with distinct components targeting different levels. For a cluster-level intervention, cluster randomization is an obvious choice: the intervention is not divisible at the individual-level. For individual-level interventions, cluster randomization may nevertheless be suitable to prevent group contamination, for logistical reasons, to enhance participants' adherence, or when objectives pertain to the cluster level. An unacceptable reason for cluster randomization would be to avoid obtaining individual consent. Indeed, participants in cluster randomized trials have to be protected as in any type of trial design. Participants may be people from whom data are collected, but they may also be people who are intervened upon, and this includes both patients and physicians (for example, physicians receiving training interventions). Consent should be sought as soon as possible, although there may exist situations where participants may consent only for data collection, not for being exposed to the intervention (because, for instance, they cannot opt-out). There may even be situations where participants are not able to consent at all. In this latter situation a waiver of consent must be granted by a research ethics committee.

The intentions of French health university students to recommend and to receive the HPV vaccine are mainly influenced by vaccine knowledge, confidence in vaccines and personal HPV vaccination.

INTRODUCTION: Despite documented effectiveness in preventing several cancers, genital warts and safety of Human Papillomavirus (HPV) vaccine, immunization coverage among French adolescents remains far from the 80 % target. University health students (HS) in France may promote HPV vaccine through a national service (Service Sanitaire des Etudiants en Santé). We aimed to evaluate intentions to recommend the HPV vaccine to friends and relatives, to receive HPV vaccine, and to identify factors associated with these attitudes. METHODS: We conducted a cross-sectional survey in five French Universities from October 2019 to February 2020, using a self-administered online questionnaire. We used bivariable and multivariable logistic regression models to identify determinants of behavior around HPV vaccine: (i) individual intention for vaccination, and (ii) vaccine recommendation to friends and relatives. RESULTS: Among the 732 respondents (180 men, 552 women), 305 (41.7%) reported previous HPV vaccination (54.5 % among women), 504 (68.9%) would recommend the HPV vaccine to friends and relatives, 532 (72.7%) respondents would be vaccinated today if it was recommended for them. Intentions to recommend or to receive the HPV vaccine were less frequent in nursing students compared to medical and pharmacy students. After adjustment for demographical factors, HPV vaccine knowledge was associated with intention [aOR 1.30 (95%-confidence interval, 1.15-1.47)] and recommendation [1.26 (1.10-1.45)], respectively. Additionally, adjusting for knowledge about HPV infections, and confidence in vaccines in general was associated with vaccine intention [1.55, (1.30-1.84)] and recommendation [1.52 (1.24-1.86)]. HPV-vaccinated HS were more prone to recommend the HPV vaccine to friends and relatives [10.9 (6.6-17.9)]. CONCLUSION: A majority of HS would accept and/or recommend HPV vaccines. HS with greater knowledge about the HPV vaccine were more prone to recommend it. Strengthening knowledge about HPV and its vaccination is probably necessary before their Involvement in a HPV immunization program.

Can Biomarkers Correctly Predict Ventilator-associated Pneumonia in Patients Treated With Targeted Temperature Management After Cardiac Arrest? An Exploratory Study of the Multicenter Randomized Antibiotic (ANTHARTIC) Study.

IMPORTANCE: Ventilator-associated pneumonia (VAP) frequently occurs in patients with cardiac arrest. Diagnosis of VAP after cardiac arrest remains challenging, while the use of current biomarkers such as C-reactive protein (CRP) or procalcitonin (PCT) is debated. OBJECTIVES: To evaluate biomarkers' impact in helping VAP diagnosis after cardiac arrest. DESIGN SETTING AND PARTICIPANTS: This is a prospective ancillary study of the randomized, multicenter, double-blind placebo-controlled ANtibiotherapy during Therapeutic HypothermiA to pRevenT Infectious Complications (ANTHARTIC) trial evaluating the impact of antibiotic prophylaxis to prevent VAP in out-of-hospital patients with cardiac arrest secondary to shockable rhythm and treated with therapeutic hypothermia. An adjudication committee blindly evaluated VAP according to predefined clinical, radiologic, and microbiological criteria. All patients with available biomarker(s), sample(s), and consent approval were included. MAIN OUTCOMES AND MEASURES: The main endpoint was to evaluate the ability of biomarkers to correctly diagnose and predict VAP within 48 hours after sampling. The secondary endpoint was to study the combination of two biomarkers in discriminating VAP. Blood samples were collected at baseline on day 3. Routine and exploratory panel of inflammatory biomarkers measurements were blindly performed. Analyses were adjusted on the randomization group. RESULTS: Among 161 patients of the ANTHARTIC trial with available biological sample(s), patients with VAP (n = 33) had higher body mass index and Acute Physiology and Chronic Health Evaluation II score, more unwitnessed cardiac arrest, more catecholamines, and experienced more prolonged therapeutic hypothermia duration than patients without VAP (n = 121). In univariate analyses, biomarkers significantly associated with VAP and showing an area under the curve (AUC) greater than 0.70 were CRP (AUC = 0.76), interleukin (IL) 17A and 17C (IL17C) (0.74), macrophage colony-stimulating factor 1 (0.73), PCT (0.72), and vascular endothelial growth factor A (VEGF-A) (0.71). Multivariate analysis combining novel biomarkers revealed several pairs with p value of less than 0.001 and odds ratio greater than 1: VEGF-A + IL12 subunit beta (IL12B), Fms-related tyrosine kinase 3 ligands (Flt3L) + C-C chemokine 20 (CCL20), Flt3L + IL17A, Flt3L + IL6, STAM-binding protein (STAMBP) + CCL20, STAMBP + IL6, CCL20 + 4EBP1, CCL20 + caspase-8 (CASP8), IL6 + 4EBP1, and IL6 + CASP8. Best AUCs were observed for CRP + IL6 (0.79), CRP + CCL20 (0.78), CRP + IL17A, and CRP + IL17C. CONCLUSIONS AND RELEVANCE: Our exploratory study shows that specific biomarkers, especially CRP combined with IL6, could help to better diagnose or predict early VAP occurrence in cardiac arrest patients.

Effectiveness of a School- and Primary Care-Based HPV Vaccination Intervention: The PrevHPV Cluster Randomized Trial.

Importance: The human papillomavirus (HPV) vaccine is safe and effective, yet vaccination coverage remains below public health objectives in many countries. Objective: To examine the effectiveness of a 3-component intervention on HPV vaccination coverage among adolescents aged 11 to 14 years 2 months after the intervention ended, each component being applied alone or in combination. Design, Setting, and Participants: A cluster randomized trial with incomplete factorial design (PrevHPV) was conducted between July 1, 2021, and April 30, 2022, in French municipalities receiving 0, 1, 2, or 3 components of the intervention. Randomization was stratified by school district and municipalities' socioeconomic level. Analyses were carried out on 11- to 14-year-old adolescents living in all participating municipalities, regardless of what had been implemented. Intervention: The PrevHPV intervention had 3 components: (1) educating and motivating 11- to 14-year-old adolescents in middle schools, along with their parents; (2) training general practitioners (GPs) on up-to-date HPV information and motivational interviewing techniques; and (3) free HPV vaccination at school. Main Outcomes and Measures: The primary outcome was HPV vaccination coverage (≥1 dose) 2 months after the intervention ended among 11- to 14-year-old adolescents living in participating municipalities, based on the French national reimbursement database and data collected during the trial in groups randomized to implement at-school vaccination. Results: A total of 91 municipalities comprising 30 739 adolescents aged 11 to 14 years (15 876 boys and 14 863 girls) were included and analyzed. Half the municipalities were in the 2 lowest socioeconomic quintiles and access to GPs was poor in more than two-thirds of the municipalities. Thirty-eight of 61 schools (62.3%) implemented actions and 26 of 45 municipalities (57.8%) had at least 1 trained GP. The median vaccination coverage increased by 4.0 percentage points (IQR, 2.0-7.3 percentage points) to 14.2 percentage points (IQR, 9.1-17.3 percentage points) at 2 months. At-school vaccination significantly increased vaccination coverage (5.50 percentage points [95% CI, 3.13-7.88 percentage points]) while no effect was observed for adolescents' education and motivation (-0.08 percentage points [95% CI, -2.54 to 2.39 percentage points]) and GPs' training (-1.46 percentage points [95% CI, -3.44 to 0.53 percentage points]). Subgroup analyses found a significant interaction between at-school vaccination and access to GPs, with a higher effect when access was poor (8.62 percentage points [95% CI, 5.37-11.86 percentage points] vs 2.13 percentage points [95% CI, -1.25 to 5.50 percentage points]; P = .007 for interaction). Conclusions and Relevance: In this cluster randomized trial, within the context of the late COVID-19 pandemic period and limited school and GP participation, at-school HPV vaccination significantly increased vaccination coverage. The trial did not show a significant effect for training GPs and education and motivation, although it may be observed after more time has elapsed after the intervention. Trial Registration: ClinicalTrials.gov Identifier: NCT04945655.

Optimizing Communication on HPV Vaccination to Parents of 11- to 14-Year-Old Adolescents in France: A Discrete Choice Experiment.

BACKGROUND: With the aim to optimize communication during HPV vaccination campaigns in France, we elicited parental preferences around HPV vaccination. METHODS: We conducted a single-profile discrete choice experiment (DCE) among parents of 11- to 14-year-old middle-school pupils, who completed an anonymous, self-administered, internet-based questionnaire during 2020-2021. The DCE comprised five attributes (vaccine-preventable disease, justification of optimal age, information on safety, indirect protection and coverage) of vaccination against an unnamed disease that were presented to respondents in ten choice tasks, or scenarios. We use fixed effect logit models to estimate attribute weights on theoretical vaccine acceptance, and random effect linear regression to estimate attribute coefficients on vaccine eagerness (decision and decision certainty). We estimated marginal effects of attributes on expected vaccine acceptance. RESULTS: Vaccination scenarios were accepted by 55.6-89.2% of the 1291 participants. The largest marginal effects on expected vaccine acceptance in the full sample arose from prevention of cancer versus genital warts (+ 11.3 percentage points); from a "severe side effect suspicion that was not scientifically confirmed" versus a statement about "more benefits than risks" (+ 8.9 percentage points), and information on 80% vaccine coverage in neighbouring countries versus on "insufficient coverage" (+ 4.2 percentage points). Explaining the early age of vaccination by sexual debut had a strong negative impact among French monolingual parents with lower education level (vs age-independent, OR 0.48, 95% CI 0.27-0.86), but not other socio-economic groups. After removing low-quality responses (unvaried certainty and short questionnaire completion), among serial non-demanders with children not vaccinated against HPV, only disease elimination impacted vaccine eagerness positively (coefficient 0.54, 0.06-1.02). DISCUSSION: Using DCEs to elicit parents' preferences around communication messages, notably on cancer prevention, vaccine coverage and information about vaccine safety, could help to optimize HPV vaccination promotion efforts.