Research method
Randomized Controlled Trial
33 studies
A randomized controlled trial assigns people by chance to an intervention or a comparator, then measures the same outcomes in both arms. Randomisation is meant to balance known and unknown confounders at baseline so that later differences can be attributed to the assigned treatment rather than to who signed up. The result is a contrast — a difference in minutes walked, a quality score, a PHQ-9 change — whose credibility still depends on retention, blinding, and whether the outcome is a behaviour people report or an event the trial was powered to count.
Clinicians reach for an RCT when they need to know whether a programme, drug, app or training actually changes outcomes, not merely whether people who already use it look healthier. It answers 'does this assignment cause a difference over this follow-up?' Its main limitation in this library is that many trials are short, rely on self-report, and lose people unevenly, so a statistically significant contrast is not the same as a durable hard-endpoint benefit.
Studies
33
Findings
5
6 supporting · 0 challenging · 0 qualifying citations
Open tensions
2
Currently
What we know
- Behaviour-change RCTs in this set often show a clear advantage while the intervention is running and a weaker or gone contrast once it stops. Insufficiently active adults randomised to a 50-day Facebook walking programme increased walking by about 155 min/week during the programme, but between-group advantages were not maintained three months after the app ended; Text4Heart raised lifestyle adherence at 3 months (AOR 2.55) without a significant 6-month difference.
- Some service-delivery trials are designed as non-inferiority tests rather than superiority tests. Orthopaedic patients randomised to videoconference versus usual outpatient visits had quality-score differences whose 90% CI (0.05–0.17) stayed inside the pre-specified non-inferiority margin, with all video visits completed as planned.
- Adjunctive digital CBT can move a validated symptom score without proving remission or long-term relapse prevention. Adults with antidepressant-refractory major depression randomised to add a smartphone CBT app scored about 2.5 PHQ-9 points lower at week 9 (SMD 0.40) and were more likely to meet response criteria; remission and side-effect differences were not significant.
- Intention-to-treat mixed models can still leave a trial hard to interpret when dropout is large and unequal. NHS Choices users randomised to MoodGYM versus wait-list showed adjusted WEMWBS advantages of about 2.5 points at 6 weeks and 2.9 at 12 weeks, but attrition was 73.5% in the intervention arm versus 26.9% in control.
- Not every paper that uses randomisation is an intervention RCT. A Copenhagen Mendelian-randomisation analysis of BMI and ischaemic heart disease uses genotype as an instrumental variable for BMI rather than randomly assigning a diet or drug, so the causal claim is about genetically influenced BMI, not about a treatment protocol.
Largest unresolved question
Trials disagree on what a 'positive' result is allowed to be. The orthopaedic telemedicine trial treats staying inside a non-inferiority margin as success, whereas the Facebook walking, Text4Heart, Kokoro-app and MoodGYM trials are powered to show the intervention beating control on a change score. A student who reads only superiority language will misread a successful non-inferiority trial as 'no difference, so it failed.'
Procedure
How it works
The main stages of the method. Specific protocols and analysis choices vary between studies.
Define eligibility and the outcomes
Before assignment, the trial states who can enter and what will be counted — minutes walked, a symptom score, a quality-of-life scale, or a hard event. An underpowered hard endpoint cannot be rescued by a significant score on a different measure.
Assign by chance
Eligible people are randomised to the intervention or a comparator so that known and unknown baseline confounders should balance. Randomisation is an assignment method. It does not keep the arms comparable if later dropout or unblinded reporting differs by arm.
Deliver the intervention and the comparator
One arm receives the programme, drug, app, or training; the other receives usual care, placebo, or an active control. Blinding, when it is possible, is what stops knowledge of assignment from shaping a subjective outcome.
Follow up and retain
The same outcomes are measured on a schedule. Differential attrition — people leaving one arm more than the other — reopens confounding after randomisation and is a known weak point of many trials in this library.
Estimate the contrast
The result is a difference between arms, often analysed as randomised (intention-to-treat). A statistically significant change on a reported score is still only that contrast, over that follow-up, in those who contributed data.
Do not read a score change as a hard event
An RCT answers whether this assignment caused a difference on the measured outcomes. A PHQ-9 or lifestyle-adherence contrast is not proof of fewer heart attacks, remissions, or deaths, and a benefit seen during the programme need not persist after it stops.
Common misconceptions
Randomisation guarantees that the groups stay comparable until the end of the trial.
It balances baseline assignment. Differential dropout, as in MoodGYM's 73.5% versus 26.9% attrition, and unblinded quality-of-life reporting, as in the heart-failure telemonitoring trial, can reopen confounding after randomisation.
If the intervention works during the programme, the benefit will persist after it stops.
The Facebook walking trial's between-group walking advantage was gone three months after the app ended, and Text4Heart's lifestyle-adherence contrast was no longer significant at 6 months.
A statistically significant symptom-score difference means the trial proved fewer heart attacks, remissions, or deaths.
Kokoro-app moved PHQ-9 without a significant remission difference; Text4Heart did not prove fewer hard cardiac events; the telemonitoring trial was explicitly underpowered for hard endpoints.
Related
Claim ledger
What the evidence shows
Drawn from 33 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.
Behaviour-change RCTs in this set often show a clear advantage while the intervention is running and a weaker or gone contrast once it stops. Insufficiently active adults randomised to a 50-day Facebook walking programme increased walking by about 155 min/week during the programme, but between-group advantages were not maintained three months after the app ended; Text4Heart raised lifestyle adherence at 3 months (AOR 2.55) without a significant 6-month difference.
Study Role Design N Population Outcome Facebook team walking RCT Supports RCT50-day Facebook app + pedometer vs wait-list; teams of friends N=110 · 51 intervention, 59 control Insufficiently active adults organized in Facebook friend teams Self-reported MVPA/walking at 8 and 20 weeks Do heart texts improve lifestyle adherence? Supports RCTText4Heart 24-week mHealth cardiac rehabilitation plus usual care vs usual care alone N=123 · 61 intervention, 62 control New Zealand adults with coronary heart disease Adherence to recommended lifestyle behaviours at 3 and 6 months Some service-delivery trials are designed as non-inferiority tests rather than superiority tests. Orthopaedic patients randomised to videoconference versus usual outpatient visits had quality-score differences whose 90% CI (0.05–0.17) stayed inside the pre-specified non-inferiority margin, with all video visits completed as planned.
Adjunctive digital CBT can move a validated symptom score without proving remission or long-term relapse prevention. Adults with antidepressant-refractory major depression randomised to add a smartphone CBT app scored about 2.5 PHQ-9 points lower at week 9 (SMD 0.40) and were more likely to meet response criteria; remission and side-effect differences were not significant.
Intention-to-treat mixed models can still leave a trial hard to interpret when dropout is large and unequal. NHS Choices users randomised to MoodGYM versus wait-list showed adjusted WEMWBS advantages of about 2.5 points at 6 weeks and 2.9 at 12 weeks, but attrition was 73.5% in the intervention arm versus 26.9% in control.
Not every paper that uses randomisation is an intervention RCT. A Copenhagen Mendelian-randomisation analysis of BMI and ischaemic heart disease uses genotype as an instrumental variable for BMI rather than randomly assigning a diet or drug, so the causal claim is about genetically influenced BMI, not about a treatment protocol.
Debates
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.
Trials disagree on what a 'positive' result is allowed to be. The orthopaedic telemedicine trial treats staying inside a non-inferiority margin as success, whereas the Facebook walking, Text4Heart, Kokoro-app and MoodGYM trials are powered to show the intervention beating control on a change score. A student who reads only superiority language will misread a successful non-inferiority trial as 'no difference, so it failed.'
Trials disagree on what a 'positive' result is allowed to be. The orthopaedic telemedicine trial treats staying inside a non-inferiority margin as success, whereas the Facebook walking, Text4Heart, Kokoro-app and MoodGYM trials are powered to show the intervention beating control on a change score. A student who reads only superiority language will misread a successful non-inferiority trial as 'no difference, so it failed.'
- Video orthopaedics non-inferior to clinic
- Facebook team walking RCT
- Can a CBT phone app help stubborn depression?
Study Role Design N Population Outcome Video orthopaedics non-inferior to clinic Supports RCTVideoconference orthopaedic consultations vs usual hospital outpatient visits; non-inferiority N=389 · 389 patients; 559 consultations analysed Orthopaedic outpatients referred for specialist consultation Specialist-rated consultation quality (non-inferiority) Facebook team walking RCT Supports RCT50-day Facebook app + pedometer vs wait-list; teams of friends N=110 · 51 intervention, 59 control Insufficiently active adults organized in Facebook friend teams Self-reported MVPA/walking at 8 and 20 weeks Can a CBT phone app help stubborn depression? Supports RCTKokoro-app smartphone CBT plus antidepressant switch vs medication change alone N=164 · ITT; primary outcome at week 9 in 163/164 (99.4%) Adults in Japan with antidepressant-refractory major depression PHQ-9 at week 9
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
Unblinded patient-reported outcomes and attention effects pull in the opposite direction from hard clinical events. Phone telemonitoring improved MLHFQ in a 100-person heart-failure trial that was not powered for hospitalisation or death, while Text4Heart's lifestyle gains were self-reported and LDL differences were only borderline.
Unblinded patient-reported outcomes and attention effects pull in the opposite direction from hard clinical events. Phone telemonitoring improved MLHFQ in a 100-person heart-failure trial that was not powered for hospitalisation or death, while Text4Heart's lifestyle gains were self-reported and LDL differences were only borderline.
Study Role Design N Population Outcome Phone telemonitoring in heart failure Supports RCTMobile telemonitoring plus usual care vs standard care for six months N=100 Adults with heart failure Minnesota Living with Heart Failure Questionnaire (MLHFQ) quality of life Do heart texts improve lifestyle adherence? Supports RCTText4Heart 24-week mHealth cardiac rehabilitation plus usual care vs usual care alone N=123 · 61 intervention, 62 control New Zealand adults with coronary heart disease Adherence to recommended lifestyle behaviours at 3 and 6 months
PaperFren reads this as a limit on how far one study travels — different assays, populations, or outcomes — not a forced fight between papers.
Timeline
How understanding moved
Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.
2026
Concept page published
Randomized Controlled Trial
Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Coverage edits are distinct from reviewed research changes and corrections. Dates record PaperFren updates; study publication dates appear in the timeline.
- Coverage updated · Concept page published
Papers
33 studies in this library bear on Randomized Controlled Trial, ordered by citations.
- SMS coaching for weight loss
Daily tailored text/MMS coaching produced about 2 kg more weight loss than print materials over 4 months in overweight adults.
- SASA! cut partner violence in Kampala
A Kampala cluster RCT found community mobilization (SASA!) associated with roughly 50% lower past-year physical IPV and male partner concurrency.
- Interdisciplinary frailty RCT
A 12-month multifactorial interdisciplinary program reduced frailty prevalence and improved mobility versus usual care in frail older adults in Sydney.
- Did India’s toilet campaign improve child health?
A village-randomized sanitation program raised latrine access and cut open defecation modestly but did not improve child diarrhea, parasites, anemia, or growth.
- Same-day ART start improves HIV outcomes
Rapid ART initiation raised 90-day treatment start and 10-month viral suppression versus standard multi-visit initiation.
- Deprexis online therapy reduced depression scores
An integrative online program (Deprexis) improved BDI depression symptoms versus delayed treatment in a large German internet RCT.
- Mediterranean diet and depression risk
Overall Mediterranean diet assignment did not significantly reduce depression; a nuts arm suggested benefit in diabetes subgroup analyses.
- Does higher BMI causally raise heart disease risk?
Genetic instruments for BMI suggest a causal increase in ischemic heart disease risk larger than simple observational estimates.
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- Literacy-friendly HF self-care trial
A literacy-sensitive outpatient heart failure education program improved knowledge and self-efficacy but did not clearly cut hospitalizations or quality-of-life scores versus usual care.
- Phone telemonitoring in heart failure
Mobile telemonitoring improved heart-failure quality of life over six months with strong adherence.
- Tele-orthopedics costs less than hospital visits
In a Norwegian RCT, remote orthopedic video visits cost less than hospital outpatient visits with similar QALY gains.
- Glucose Buddy app associated with improved type 1 HbA1c in a trial
Adults with poorly controlled type 1 diabetes using Glucose Buddy plus weekly educator texts lowered HbA1c versus usual care.
- Do heart texts improve lifestyle adherence?
A text-and-internet cardiac rehab program improved short-term lifestyle adherence after CHD, but the benefit faded by 6 months.
- Video orthopaedics non-inferior to clinic
Remote video orthopaedic consultations met the trial’s non-inferiority margin versus standard outpatient visits.
- PrEP adherence in Partners PrEP
In a Partners PrEP adherence substudy, median pill-count and MEMS adherence exceeded 97%, and counseling restored most low adherers to ≥80%.
- Phone telemonitoring after heart-failure flare
Home mobile-phone telemonitoring after acute heart-failure decompensation cut primary events and hospital days versus usual care.
- TB pillbox reminders beat SMS for doses
In a China cluster RCT, medication-monitor reminders cut poor TB adherence 40–50%, while text messages mainly reduced loss to follow-up.
- Digital pills cut blood pressure faster
Patients with uncontrolled hypertension and type 2 diabetes using digital medicines had larger 4-week SBP drops than usual care.
- Doctor communication training helps hypertension care
Training physicians in communication skills improved hypertensive patients’ health literacy, blood pressure control, adherence, and self-efficacy in an Iranian RCT.
- Does wireless BP monitoring boost patient activation’s benefits?
In hypertensive adults, a wireless self-monitoring program strengthened links between rising patient activation and better behaviours/BP control.
- MoodGYM improves population wellbeing
In a large UK web RCT, automated MoodGYM raised mental well-being versus wait-list control despite high intervention attrition.
- Web program increased older adults’ measured activity in a trial
A Dutch RCT found a web-based intervention raised daily activity ~46% and improved weight and HbA1c markers in inactive 60–70-year-olds.
- Can a CBT phone app help stubborn depression?
Adding a smartphone CBT program to a medication switch improved depressive symptoms more than switching antidepressants alone.
- Facebook team walking RCT
A 50-day team social-network pedometer program boosted walking/MVPA during the intervention, but gains were not maintained 3 months later.
- Child-care diet/activity RCT and zBMI
A seven-month child-care nutrition and activity intervention significantly reduced children's zBMI versus control centers.
- Coaching vs recommendations in IntelliCare
In a factorial RCT, coaching lowered anxiety more than self-guided use, while weekly app recommendations boosted depression improvement and app sessions.
- Fitbit wear during an activity trial
Survivors wore Fitbits most days and roughly doubled ActiGraph MVPA over 12 weeks in the intervention arm.
- iCBT for depression in diabetes
Unmodified clinician-supported iCBT beat treatment-as-usual on depression, anxiety, distress, and diabetes-specific distress in adults with diabetes.
- Dementia-carer internet support forum
Over 12 weeks on Alzheimer’s Society’s Talking Point forum, caregiving relationship quality improved but anxiety and depression scores did not.
- Automated e-therapy for anxiety disorders
People finishing Anxiety Online’s disorder-specific e-therapy programs showed significant pre–post gains on severity, quality of life, and confidence measures.
- Join2move usage drop-off
Patients with knee/hip OA used Join2move less than intended: 94% started, 46% hit 6/9 modules, only 19% finished all nine.
- Audio vs text produce-app RCT
A tailored mobile app’s audio messages raised fruit intake more than text or control, while vegetable intake showed no overall main effect.
- Propofol vs sevoflurane and breast cancer survival
In the CAN randomised trial, five-year overall survival after primary breast cancer surgery was essentially the same with propofol or sevoflurane maintenance anaesthesia.
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Questions
What is still open
Trials disagree on what a 'positive' result is allowed to be. The orthopaedic telemedicine trial treats staying inside a non-inferiority margin as success, whereas the Facebook walking, Text4Heart, Kokoro-app and MoodGYM trials are powered to show the intervention beating control on a change score. A student who reads only superiority language will misread a successful non-inferiority trial as 'no difference, so it failed.'
Unblinded patient-reported outcomes and attention effects pull in the opposite direction from hard clinical events. Phone telemonitoring improved MLHFQ in a 100-person heart-failure trial that was not powered for hospitalisation or death, while Text4Heart's lifestyle gains were self-reported and LDL differences were only borderline.
Ask PaperFren about Randomized Controlled Trial
Study this conceptflashcards and short-answer questions
Why can a trial that finds 'no significant difference' still be a success, and which paper in this set is built that way?
When the scientific claim is that a new service is not worse than usual care by more than a pre-specified margin, staying inside that margin is the success criterion. The orthopaedic videoconference trial analysed quality scores that way: the 90% CI for the difference stayed within the non-inferiority margin and every video visit ran as planned.
Using the Facebook walking and Text4Heart trials, explain what 'the intervention worked' does and does not mean once follow-up continues after the programme ends.
Both show a behavioural advantage while the programme is on (about 155 extra walking minutes per week; lifestyle-adherence AOR 2.55 at 3 months). Neither maintains a clear between-group lifestyle contrast after the stimulus fades (three months off-app; non-significant 6-month lifestyle difference). That is evidence about a time-limited behaviour change, not about a self-sustaining habit or fewer cardiac events.
How should a student read MoodGYM's ~2.5–2.9 point WEMWBS advantage together with its attrition figures?
The mixed-model ITT estimate favours MoodGYM, but 73.5% of the intervention arm dropped out versus 26.9% of wait-list controls. Differential attrition can bias even an ITT model if missingness is related to outcome, so the point estimate is not a clean causal effect for everyone assigned.
Distinguish an intervention RCT from the Copenhagen BMI–IHD Mendelian-randomisation paper. What is randomised in each case?
In the walking, telemedicine, Text4Heart, Kokoro-app and MoodGYM papers, investigators assign a programme or usual care by chance. In the BMI paper, nature has already assigned FTO, MC4R and TMEM18 alleles that shift BMI; the analysis uses those alleles as instruments. That supports a causal reading of BMI, not a claim that a particular weight-loss programme was tested.