Participants of health research studies such as cancer screening trials usually have better health than the target population. Data-enabled recruitment strategies might be used to help minimise healthy volunteer effects on study power and improve equity.
A computer algorithm was developed to help target trial invitations. It assumes participants are recruited from distinct sites (such as different physical locations or periods in time) that are served by clusters (such as general practitioners in England, or geographical areas), and the population may be split into defined groups (such as age and sex bands). The problem is to decide the number of people to invite from each group, such that all recruitment slots are filled, healthy volunteer effects are accounted for, and equity is achieved through representation in sufficient numbers of all major societal and ethnic groups. A linear programme was formulated for this problem.
The optimisation problem was solved dynamically for invitations to the NHS-Galleri trial (ISRCTN91431511). This multi-cancer screening trial aimed to recruit 140,000 participants from areas in England over 10 months. Public data sources were used for objective function weights, and constraints. Invitations were sent by sampling according to lists generated by the algorithm. To help achieve equity the algorithm tilts the invitation sampling distribution towards groups that are less likely to join. To mitigate healthy volunteer effects, it requires a minimum expected event rate of the primary outcome in the trial.
Our invitation algorithm is a novel data-enabled approach to recruitment that is designed to address healthy volunteer effects and inequity in health research studies. It could be adapted for use in other trials or research studies.

An ongoing challenge for forensic interviewers is to maximize their use of invitations, such as requests that the child \"tell me more about\" details mentioned by the child. Examining 434 interviews with 4- to 12-year-old children questioned about abuse, this study analyzed (1) faux invitations, in which interviewers prefaced questions with \"tell me\" but then asked a noninvitation, (2) negative recasts, in which interviewers started to ask an invitation but then recast the question as a wh- or option-posing question, and (3) other aspects of questions that may relate to productivity independent of their status as invitations. About one fourth of \"tell me\" questions were faux invitations, and over 80% of recasts were negative. The frequency of both faux invitations and negative recasts increased during the substantive phase of the interviews, and these were related to decreased productivity, increased nonresponsiveness, and increased uncertainty. In contrast, use of exhaustive terms (e.g., \"tell me everything\") and nonstatic questions (e.g., about actions) was related to increased productivity. The results suggest that training should teach interviewers when and how strategic use of invitations and other question types can elicit specific types of forensically relevant information.

BACKGROUND: The NHS Health Check (NHSHC) is a national programme for the prevention of non-communicable diseases. Patients aged 40-74 without an existing cardiovascular-related condition should be invited quinquennially. Uptake is lower than anticipated. We assessed the impact on uptake of two new behaviourally-enhanced leaflets (with the current national leaflet as a control), enclosed with the invitation letter: the first trial on the leaflet.
METHODS: A double-blind three-armed randomized controlled trial was conducted. The new leaflets were shorter (two pages, instead of four); one was loss-framed (\'don\'t miss out\') and the other was gain-framed (\'make the most of life\'). The participants were patients from 39 practices in Lewisham and 17 practices in NE Lincolnshire, who were allocated to interventions using a random-number generator and received one of the leaflets with their invitation letter from April-September 2018. The outcome measure was uptake of an NHSHC by November 2018. The trial was powered to detect a 2% effect.
RESULTS: Uptake was 17.6% in the control condition (n = 3677), 17.4% in the loss-framed condition (n = 3664), and 18.2% in the gain-framed condition (n = 3697). Leaflet type was not a significant predictor of NHSHC uptake in a logistic regression that controlled for demographic variables, with GP practice as a random effect. Statistically significant predictors of uptake included location (higher uptake in Lewisham), age (increased age was associated with increased attendance) and sex (higher uptake in females). The Bayes Factor comparing the null to a hypothesis of differences between conditions was 416, which is extreme evidence in favour of the null hypothesis.
CONCLUSIONS: There was no evidence for a meaningful effect of either a loss-framed or gain-framed behaviourally-informed leaflet type on uptake, which is surprising, given that behaviourally informed letters have improved uptake of NHSHCs. It is possible that people do not pay attention to leaflets that are enclosed with letters, or that the leaflet continues to support informed decision-making but this does not affect uptake.
BACKGROUND: Clinicaltrials.gov, NCT03524131. Registered May 14, 2018. Retrospectively registered.