Reducing bias in trials due to reactions to measurement: experts produced recommendations informed by evidence

When a test is more than just a test: Findings from patient interviews and survey in the trial of a technology to measure antidepressant medication response (the PReDicT Trial)

BACKGROUND

A RCT of a novel intervention to detect antidepressant medication response (the PReDicT Test) took place in five European countries, accompanied by a nested study of its acceptability and implementation presented here. The RCT results indicated no effect of the intervention on depression at 8 weeks (primary outcome), although effects on anxiety at 8 weeks and functioning at 24 weeks were found.

METHODS

The nested study used mixed methods. The aim was to explore patient experiences of the Test including acceptability and implementation, to inform its use within care. A bespoke survey was completed by trial participants in five countries (n = 778) at week 8. Semi-structured interviews were carried out in two countries soon after week 8 (UK n = 22, Germany n = 20). Quantitative data was analysed descriptively; for qualitative data, thematic analysis was carried out using a framework approach. Results of the two datasets were interrogated together.

OUTCOMES

Survey results showed the intervention was well received, with a majority of participants indicating they would use it again, and it gave them helpful extra information; a small minority indicated the Test made them feel worse. Qualitative data showed the Test had unexpected properties, including: instigating a process of reflection, giving participants feedback on progress and new understanding about their illness, and making participants feel supported and more engaged in treatment.

INTERPRETATION

The qualitative and quantitative results are generally consistent. The Test's unexpected properties may explain why the RCT showed little effect, as properties were experienced across both trial arms. Beyond the RCT, the qualitative data sheds light on measurement reactivity, i.e., how measurements of depression can impact patients.

Randomised pilot and feasibility trial of a group intervention for men who perpetrate intimate partner violence against women

BACKGROUND

There is a need for robust evidence on the effectiveness and cost-effectiveness of domestic abuse perpetrator programmes in reducing abusive behaviour and improving wellbeing for victim/survivors. While any randomised controlled trial can present difficulties in terms of recruitment and retention, conducting such a trial with domestic abuse perpetrators is particularly challenging. This paper reports the pilot and feasibility trial of a voluntary domestic abuse perpetrator group programme in the United Kingdom.

METHODS

This was a pragmatic individually randomised pilot and feasibility trial with an integrated qualitative study in one site (covering three local-authority areas) in England. Male perpetrators were randomised to either the intervention or usual care. The intervention was a 23-week group programme for male perpetrators in heterosexual relationships, with an average of three one-to-one sessions, and one-to-one support for female current- or ex-partners delivered by third sector organisations. There was no active control treatment for men, and partners of control men were signposted towards domestic abuse support services. Data were collected at three-monthly intervals for nine months from male and female participants. The main objectives assessed were recruitment, randomisation, retention, data completeness, fidelity to the intervention model, and acceptability of the trial design.

RESULTS

This study recruited 36 men (22 randomly allocated to attend the intervention group programme, 14 to usual care), and 15 current- or ex-partners (39% of eligible partners). Retention and completeness of data were high: 67% of male (24/36), and 80% (12/15) of female participants completed the self-reported questionnaire at nine months. A framework for assessing fidelity to the intervention was developed. In interviews, men who completed all or most of the intervention gave positive feedback and reported changes in their own behaviour. Partners were also largely supportive of the trial and were positive about the intervention. Participants who were not allocated to the intervention group reported feeling disappointed but understood the rationale for the trial.

CONCLUSIONS

It was feasible to recruit, randomise and retain male perpetrators and female victim/survivors of abuse and collect self-reported outcome data. Participants were engaged in the intervention and reported positive benefits. The trial design was seen as acceptable.

TRIAL REGISTRATION

ISRCTN71797549, submitted 03/08/2017, retrospectively registered 27/05/2022.

Digital Medication Management in Polypharmacy

BACKGROUND

Inappropriate drug prescriptions for patients with polypharmacy can have avoidable adverse consequences. We studied the effects of a clinical decision-support system (CDSS) for medication management on hospitalizations and mortality.

METHODS

This stepped-wedge, cluster-randomized, controlled trial involved an open cohort of adult patients with polypharmacy in primary care practices (=clusters) in Westphalia-Lippe, Germany. During the period of the intervention, their medication lists were checked annually using the CDSS. The CDSS warns against inappropriate prescriptions on the basis of patient-related health insurance data. The combined primary endpoint consisted of overall mortality and hospitalization for any reason. The secondary endpoints were mortality, hospitalizations, and high-risk prescription. We analyzed the quarterly health insurance data of the intention- to-treat population with a mixed logistic model taking account of clustering and repeated measurements. Sensitivity analyses addressed effects of the COVID-19 pandemic and other effects.

RESULTS

688 primary care practices were randomized, and data were obtained on 42 700 patients over 391 994 quarter years. No significant reduction was found in either the primary endpoint (odds ratio [OR] 1.00; 95% confidence interval [0.95; 1.04]; p = 0.8716) or the secondary endpoints (hospitalizations: OR 1.00 [0.95; 1.05]; mortality: OR 1.04 [0.92; 1.17]; high-risk prescription: OR 0.98 [0.92; 1.04]).

CONCLUSION

The planned analyses did not reveal any significant effect of the intervention. Pandemicadjusted analyses yielded evidence that the mortality of adult patients with polypharmacy might potentially be lowered by the CDSS. Controlled trials with appropriate follow-up are needed to prove that a CDSS has significant effects on mortality in patients with polypharmacy.

Examining reactivity to the measurement of physical activity and sedentary behavior among women in midlife with elevated risk for cardiovascular disease

OBJECTIVES

To estimate the extent of reactivity to measurement of physical activity (PA) and sedentary behavior among women in midlife with elevated risk for cardiovascular disease (CVD).

DESIGN

Secondary analysis of a 10-day observational study of PA and sedentary behavior.

MAIN OUTCOME MEASURES

PA (steps, minutes of light PA, total minutes of moderate-to- vigorous PA [MVPA]) and percent time in sedentary behavior per day were assessed using ActiGraph GT3X tri-axial accelerometers in 75 women in midlife with elevated CVD risk (e.g. hypertension; MAge = 51.61, MBMI = 34.02 kg/m2). Two-level multilevel models were used to test for evidence of reactivity, with the addition of random effects to test for evidence of individual differences in observed trends.

RESULTS

All outcomes showed linear trends across days (ps < 0.001), though this masked what appeared to be meaningful dropoff after Day 1 or Day 2 (with little difference between subsequent days; srs ranging from 0.15 to 0.32). The random effect was significant only for percent time in sedentary behavior (χ2[1] = 10.40, p = 0.02).

CONCLUSIONS

Consistent small to medium effects were found for all PA and sedentary behavior outcomes, underscoring the importance of considering measurement reactivity in populations with elevated CVD risk.

Effectiveness of internet-delivered dialectical behavior therapy skills training on executive functions among college students with borderline personality traits: a non-randomized controlled trial

Given the enormous influence of emotions on cognitive processes, individuals with borderline personality disorder (BPD) suffer from marked deficits in higher-order thinking abilities. Considering the prevalence of BPD among college students, this study aimed to investigate the changes in perceived executive functioning among college students with traits/presence of BPD undergoing internet-delivered dialectical behavior therapy skills training (DBT-ST) that included the mindfulness and emotion regulation modules. An internet-delivered version of DBT-ST was opted for, as technological advancements in the present era promote the use of online platforms for psychotherapy. This non-randomized controlled trial consisted of 36 college students with traits/presence of BPD. The intervention group attended 13 sessions of DBT-ST, and the control group attended 13 sessions of behavioral activation. Perceived executive functioning was assessed using the Behavior Rating Inventory of Executive Functions for Adults. A 2-way repeated measures analysis of variance was used to evaluate the treatment impact on the outcome variable. Results showed that the DBT-ST group had larger improvements in their abilities to initiate, plan, and organize current and future-oriented task demands and to organize their everyday environment, compared to the control group. Both, the DBT-ST group and the control group demonstrated improvements in emotional control, working memory, and their abilities to shift and task monitor. Findings suggest that the internet-delivered version of DBT-ST, consisting of the mindfulness and emotion regulation modules, can foster notable improvements in executive functions among college students with traits/presence of BPD. Improved executive functioning is one of the several multifaceted outcomes of dialectical behavior therapy.

Device-based physical activity measures for population surveillance-issues of selection bias and reactivity

Background

Device-based measurement in physical activity surveillance is increasing, but research design choices could increase the risk of self-selection bias and reactive behaviour. The aim of this study is to compare the self-reported physical activity profiles of four different samples: participants in a large national survey, participants in a telephone-based survey of non-responders, participants in the large national survey who accepted the invitation to device-based measuring, and the same sample during the week of monitoring.

Methods

In October 2020, 163,133 Danish adults participated in a national survey and of those 39,480 signed up for device-based measurements. A balanced random sample (n = 3,750) was invited to wear an accelerometer of whom 1,525 accepted the invitation. Additionally, a short telephone-based survey on 829 non-responders to the national survey was conducted. Sociodemographic characteristics and self-reported weekly frequencies of physical activity across four domains are compared.

Results

The participants in the national survey were older, more often female, and more often not working. Participants in the telephone-based survey were younger, more often doing unskilled work, and were more often active at home and at work. The participants in the device-based sample were more often active during transport and leisure in the national survey, and participants categorized in the most active category increased during the week of monitoring from 29.0% to 60.7% and from 58.5% to 81.7% for active transport and leisure activities, respectively.

Conclusion

Recruiting a population representative sample for device-based measurement of physical activity is challenging, and there is a substantial risk of sample selection bias and measurement reactivity. Further research in this area is needed if device-based measures should be considered for population physical activity surveillance.

A systematic review and meta-analysis of studies of reactivity to digital in-the-moment measurement of health behaviour

Self-report measures of health behaviour have several limitations including measurement reactivity, i.e., changes in people's behaviour, cognitions or emotions due to taking part in research. This systematic review investigates whether digital in-the-moment measures induce reactivity to a similar extent and why it occurs. Four databases were searched in December 2020. All observational or experimental studies investigating reactivity to digital in-the-moment measurement of a range of health behaviours were included if they were published in English in 2008 or later. Of the 11,723 records initially screened, 30 publications reporting on 31 studies were included in the qualitative synthesis/ 7 studies in the quantitative synthesis. Eighty-one percent of studies focused on reactivity to the measurement of physical activity indicators; small but meaningful pooled effects were found (Cohen's ds: 0.27-0.30). Only a small number of studies included other behaviours, yielding mixed results. Digital in-the-moment measurement of behaviour thus may be as prone to reactivity as self-reports in questionnaires. Measurement reactivity may be amplified by (1) ease of changing the behaviour (2) awareness of being measured and social desirability, and (3) resolving discrepancies between actual and desired behaviour through self-regulation.

Recruitment interventions for trials involving adults lacking capacity to consent: methodological and ethical considerations for designing Studies Within a Trial (SWATs)

BACKGROUND

The number of interventions to improve recruitment and retention of participants in trials is rising, with a corresponding growth in randomised Studies Within Trials (SWATs) to evaluate their (cost-)effectiveness. Despite recognised challenges in conducting trials involving adults who lack capacity to consent, until now, no individual-level recruitment interventions have focused on this population. Following the development of a decision aid for family members making non-emergency trial participation decisions on behalf of people with impaired capacity, we have designed a SWAT to evaluate the decision aid in a number of host trials (CONSULT). Unlike in recruitment SWATs to date, the CONSULT intervention is aimed at a 'proxy' decision-maker (a family member) who is not a participant in the host trial and does not receive the trial intervention. This commentary explores the methodological and ethical considerations encountered when designing such SWATs, using the CONSULT SWAT as a case example. Potential solutions to address these issues are also presented.

DISCUSSION

We encountered practical issues around informed consent, data collection, and follow-up which involves linking the intervention receiver (the proxy) with recruitment and retention data from the host trial, as well as issues around randomisation level, resource use, and maintaining the integrity of the host trial. Unless addressed, methodological uncertainty about differential recruitment and heterogeneity between trial populations could potentially limit the scope for drawing robust inferences and harmonising data from different SWAT host trials. Proxy consent is itself ethically complex, and so when conducting a SWAT which aims to disrupt and enhance proxy consent decisions, there are additional ethical issues to be considered.

CONCLUSIONS

Designing a SWAT to evaluate a recruitment intervention for non-emergency trials with adults lacking capacity to consent has raised a number of methodological and ethical considerations. Explicating these challenges, and some potential ways to address them, creates a starting point for discussions about conducting these potentially more challenging SWATs. Increasing the evidence base for the conduct of trials involving adults lacking capacity to consent is intended to improve both the ability to conduct these trials and their quality, and so help build research capacity for this under-served population.

Effectiveness of an Online Programme to Tackle Individual's Meat Intake through SElf-regulation (OPTIMISE): A randomised controlled trial

PURPOSE

A reduction in meat intake is recommended to meet health and environmental sustainability goals. This study aimed to evaluate the effectiveness of an online self-regulation intervention to reduce meat consumption.

METHODS

One hundred and fifty one adult meat eaters were randomised 1:1 to a multi-component self-regulation intervention or an information-only control. The study lasted 9 weeks (1-week self-monitoring; 4-week active intervention; and 4-week maintenance phase). The intervention included goal-setting, self-monitoring, action-planning, and health and environmental feedback. Meat intake was estimated through daily questionnaires in weeks 1, 5 and 9. The primary outcome was change in meat consumption from baseline to five weeks. Secondary outcomes included change from baseline to nine weeks and change in red and processed meat intake. We used linear regression models to assess the effectiveness of all the above outcomes.

RESULTS

Across the whole sample, meat intake was 226 g/day at baseline, 118 g/day at five weeks, and 114 g/day at nine weeks. At five weeks, the intervention led to a 40 g/day (95%CI - 11.6,- 67.5, P = 0.006) reduction in meat intake, including a 35 g/day (95%CI - 7.7, - 61.7, P = 0.012) reduction in red and processed meat, relative to control. There were no significant differences in meat reduction after the four-week maintenance phase (- 12 g/day intervention vs control, 95% CI 19.1, - 43.4, P = 0.443). Participants said the intervention was informative and eye-opening.

CONCLUSION

The intervention was popular among participants and helped achieve initial reductions in meat intake, but the longer-term reductions did not exceed control.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04961216, 14th July 2021, retrospectively registered.

Demographic and psychosocial correlates of measurement error and reactivity bias in a four-day image-based mobile food record among adults with overweight and obesity

Improving dietary reporting among people living with obesity is challenging as many factors influence reporting accuracy. Reactive reporting may occur in response to dietary recording but little is known about how image-based methods influence this process. Using a 4-day image-based mobile food record (mFRTM), this study aimed to identify demographic and psychosocial correlates of measurement error and reactivity bias, among adults with BMI 25-40kg/m2. Participants (n=155, aged 18-65y) completed psychosocial questionnaires, and kept a 4-day mFRTM. Energy expenditure (EE) was estimated using ≥4 days of hip-worn accelerometer data, and energy intake (EI) was measured using mFRTM. Energy intake: energy expenditure ratios were calculated, and participants in the highest tertile were considered to have Plausible Intakes. Negative changes in EI according to regression slopes indicated Reactive Reporting. Mean EI was 72% (SD=21) of estimated EE. Among participants with Plausible Intakes, mean EI was 96% (SD=13) of estimated EE. Higher BMI (OR 0.81, 95%CI 0.72-0.92) and greater need for social approval (OR 0.31, 95% CI 0.10-0.96), were associated with lower likelihood of Plausible Intakes. Estimated EI decreased by 3% per day of recording (IQR -14%,6%) among all participants. The EI of Reactive Reporters (n=52) decreased by 17%/day (IQR -23%,-13%). A history of weight loss (>10kg) (OR 3.4, 95% CI 1.5-7.8), and higher percentage of daily energy from protein (OR 1.1, 95%CI 1.0-1.2) were associated with greater odds of Reactive Reporting. Identification of reactivity to measurement, as well as Plausible Intakes, is recommended in community-dwelling studies to highlight and address sources of bias.

Effectiveness of a digital intervention versus alcohol information for online help-seekers in Sweden: a randomised controlled trial

BACKGROUND

The ubiquity of Internet connectivity, and widespread unmet needs, requires investigations of digital interventions for people seeking help with their drinking. The objective of this study was to test the effectiveness of a digital alcohol intervention compared to existing online resources for help seekers.

METHODS

This parallel randomised controlled trial included 2129 risky drinkers with access to a mobile phone and aged 18 years or older. Randomised sub-studies investigated consent procedures and control group design. Simple computerised randomisation was used. Participants were aware of allocation after randomisation; research personnel were not. The digital intervention was designed around weekly monitoring of alcohol consumption followed by feedback and tools for behaviour change. Primary outcomes were total weekly consumption (TWC) and frequency of heavy episodic drinking (HED), measured 2 and 4 months post-randomisation.

RESULTS

Between 25/04/2019 and 26/11/2020, 2129 participants were randomised (intervention: 1063, control: 1066). Negative binomial regression was used to contrast groups, with both Bayesian and maximum likelihood inference. The posterior median incidence rate ratio (IRR) of TWC was 0.89 (95% CI = 0.81;0.99, 98.2% probability of effect, P-value = 0.033) at 2 months among 1557 participants and 0.77 (95% CI = 0.69;0.86, > 99.9% probability of effect, P-value < 0.001) at 4 months among 1429 participants. For HED, the IRR was 0.83 (95% CI = 0.75;0.93, > 99.9% probability of effect, P-value = 0.0009) at 2 months among 1548 participants and 0.71 (95% CI = 0.63;0.79, probability of effect > 99.9%, P-value < 0.0001) at 4 months among 1424 participants. Analyses with imputed data were not markedly different.

CONCLUSIONS

A digital alcohol intervention produced self-reported behaviour change among online help seekers in the general population. The internal and external validity of this trial is strong, subject to carefully considered study limitations arguably inherent to trials of this nature. Limitations include higher than anticipated attrition to follow-up and lack of blinding.

TRIAL REGISTRATION

The trial was prospectively registered ( ISRCTN48317451 ).

Promoting an active choice among physically inactive adults: a randomised web-based four-arm experiment

BACKGROUND

Promoting active (i.e., conscious, autonomous, informed, and value-congruent) choices may improve the effectiveness of physical activity interventions. This web-based four-arm experimental study investigated the effect of promoting an active versus passive choice regarding physical activity on behavioural and psychological outcomes (e.g., physical activity intentions and behaviours, autonomy, commitment) among physically inactive adults.

METHODS

Dutch inactive adults were randomized into four groups: physical activity guideline only (control group G), guideline & information (GI), guideline & active choice (GA), or guideline & active choice & action planning (GA +). GA and GA + participants were stimulated to make an active choice by weighing advantages and disadvantages of physical activity, considering personal values, and identifying barriers. GA + participants additionally completed action/coping planning exercises. Passive choice groups G and GI did not receive exercises. Self-reported behavioural outcomes were assessed by a questionnaire pre-intervention (T0, n = 564) and at 2-4 weeks follow-up (T2, n = 493). Psychological outcomes were assessed post-intervention (T1, n = 564) and at follow-up. Regression analyses compared the outcomes of groups GI, GA and GA + with group G. We also conducted sensitivity analyses and a process evaluation.

RESULTS

Although promoting an active choice process (i.e., interventions GA and GA +) did not improve intention (T1) or physical activity (T2 versus T0), GA + participants reported higher commitment at T1 (β = 0.44;95%CI:0.04;0.84) and more frequently perceived an increase in physical activity between T0 and T2 (β = 2.61;95%CI:1.44;7.72). GA participants also made a more active choice at T1 (β = 0.16;95%CI:0.04;0.27). The GA and GA + intervention did not significantly increase the remaining outcomes. GI participants reported higher intention strength (β = 0.64;95%CI:0.15;1.12), autonomy (β = 0.50;95%CI:0.05;0.95), and commitment (β = 0.39;95%CI:0.04;0.74), and made a more active choice at T1 (β = 0.13;95%CI:0.02;0.24). Interestingly, gender and health condition modified the effect on several outcomes. The GA + intervention was somewhat more effective in women. The process evaluation showed that participants varied in how they perceived the intervention.

CONCLUSIONS

There is no convincing evidence of a beneficial effect of an active versus passive choice intervention on physical activity intentions and behaviours among inactive adults. Further research should determine whether and how active choice interventions that are gender-sensitized and consider health conditions can effectively increase physical activity.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04973813 . Retrospectively registered.

Supporting People With Type 2 Diabetes in the Effective Use of Their Medicine Through Mobile Health Technology Integrated With Clinical Care to Reduce Cardiovascular Risk: Protocol for an Effectiveness and Cost-effectiveness Randomized Controlled Trial

BACKGROUND

Type 2 diabetes is a common lifelong condition that affects over 400 million people worldwide. The use of effective medications and active self-management can reduce the risk of serious complications. However, people often have concerns when starting new medications and face difficulties in taking their medications regularly. Support provided by brief messages delivered through mobile phone-based SMS text messages can be effective in some long-term conditions. We have identified promising behavior change techniques (BCTs) to promote medication adherence in this population via a systematic review and developed SMS text messages that target these BCTs. Feasibility work has shown that these messages have fidelity to intended BCTs, are acceptable to patients, and are successful in changing the intended determinants of medication adherence. We now plan to test this intervention on a larger scale in a clinical trial.

OBJECTIVE

The aim of this trial is to determine the effectiveness and cost-effectiveness of this intervention for reducing cardiovascular risk in people with type 2 diabetes by comparing it with usual care.

METHODS

The trial will be a 12-month, multicenter, individually randomized controlled trial in primary care and will recruit adults (aged ≥35 years) with type 2 diabetes in England. Consenting participants will be randomized to receive short SMS text messages intended to affect a change in medication adherence 3 to 4 times per week in addition to usual care. The aim is to test the effectiveness and cost-effectiveness of the intervention when it is added to usual care. The primary clinical outcome will be a composite cardiovascular risk measure. Data including patient-reported measures will be collected at baseline, at 13 and 26 weeks, and at the end of the 12-month follow-up period. With 958 participants (479 in each group), the trial is powered at 92.5% to detect a 4-percentage point difference in cardiovascular risk. The analysis will follow a prespecified plan. A nested quantitative and qualitative process analysis will be used to examine the putative mechanisms of behavior change and wider contextual influences. A health economic analysis will be used to assess the cost-effectiveness of the intervention.

RESULTS

The trial has completed the recruitment phase and is in the follow-up phase. The publication of results is anticipated in 2024.

CONCLUSIONS

This trial will provide evidence regarding the effectiveness and cost-effectiveness of this intervention for people with type 2 diabetes.

TRIAL REGISTRATION

ISRCTN Registry ISRCTN15952379; https://www.isrctn.com/ISRCTN15952379.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/32918.

Reducing bias in trials from reactions to measurement: the MERIT study including developmental work and expert workshop

BACKGROUND

Measurement can affect the people being measured; for example, asking people to complete a questionnaire can result in changes in behaviour (the 'question-behaviour effect'). The usual methods of conduct and analysis of randomised controlled trials implicitly assume that the taking of measurements has no effect on research participants. Changes in measured behaviour and other outcomes due to measurement reactivity may therefore introduce bias in otherwise well-conducted randomised controlled trials, yielding incorrect estimates of intervention effects, including underestimates.

OBJECTIVES

The main objectives were (1) to promote awareness of how and where taking measurements can lead to bias and (2) to provide recommendations on how best to avoid or minimise bias due to measurement reactivity in randomised controlled trials of interventions to improve health.

METHODS

We conducted (1) a series of systematic and rapid reviews, (2) a Delphi study and (3) an expert workshop. A protocol paper was published [Miles LM, Elbourne D, Farmer A, Gulliford M, Locock L, McCambridge J, et al. Bias due to MEasurement Reactions In Trials to improve health (MERIT): protocol for research to develop MRC guidance. Trials 2018;19:653]. An updated systematic review examined whether or not measuring participants had an effect on participants' health-related behaviours relative to no-measurement controls. Three new rapid systematic reviews were conducted to identify (1) existing guidance on measurement reactivity, (2) existing systematic reviews of studies that have quantified the effects of measurement on outcomes relating to behaviour and affective outcomes and (3) experimental studies that have investigated the effects of exposure to objective measurements of behaviour on health-related behaviour. The views of 40 experts defined the scope of the recommendations in two waves of data collection during the Delphi procedure. A workshop aimed to produce a set of recommendations that were formed in discussion in groups.

RESULTS

Systematic reviews - we identified a total of 43 studies that compared interview or questionnaire measurement with no measurement and these had an overall small effect (standardised mean difference 0.06, 95% confidence interval 0.02 to 0.09; n = 104,096, I² = 54%). The three rapid systematic reviews identified no existing guidance on measurement reactivity, but we did identify five systematic reviews that quantified the effects of measurement on outcomes (all focused on the question-behaviour effect, with all standardised mean differences in the range of 0.09-0.28) and 16 studies that examined reactive effects of objective measurement of behaviour, with most evidence of reactivity of small effect and short duration. Delphi procedure - substantial agreement was reached on the scope of the present recommendations. Workshop - 14 recommendations and three main aims were produced. The aims were to identify whether or not bias is likely to be a problem for a trial, to decide whether or not to collect further quantitative or qualitative data to inform decisions about if bias is likely to be a problem, and to identify how to design trials to minimise the likelihood of this bias.

LIMITATION

The main limitation was the shortage of high-quality evidence regarding the extent of measurement reactivity, with some notable exceptions, and the circumstances that are likely to bring it about.

CONCLUSION

We hope that these recommendations will be used to develop new trials that are less likely to be at risk of bias.

FUTURE WORK

The greatest need is to increase the number of high-quality primary studies regarding the extent of measurement reactivity.

STUDY REGISTRATION

The first systematic review in this study is registered as PROSPERO CRD42018102511.

FUNDING

Funded by the Medical Research Council UK and the National Institute for Health Research as part of the Medical Research Council-National Institute for Health Research Methodology Research Programme.