Promotion of Physical Activity in Adolescents With Intellectual and Developmental Disabilities: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Promotion of Physical Activity in Adolescents With Intellectual and Developmental Disabilities (NCT03684512), a randomized na study. The primary outcome is Change in Adolescent Physical Activity From Baseline to 6 Months.

2. Clinical Question

The registry describes a comparison of two strategies intended to increase moderate to vigorous physical activity. The central statistical question is about the difference between groups in change, rather than whether either group changed on its own. The posted mean changes were -3.2 minutes per day for the adolescent-only group and -0.6 minutes per day for the adolescent-and-parent group. The estimated between-group mean difference was 2.6 minutes per day, with the comparison expressed as adolescent-and-parent relative to adolescent-only.

This is a question about an average difference in change for the participants contributing valid measurements, not a prediction for every adolescent. The registry’s primary population definition requires valid accelerometer data at both time points. How participants without valid data were handled in the trial’s analyses is not reported in the registry record. The result therefore needs to be read alongside the stated measurement requirement and the uncertainty around the comparison, rather than as a complete account of outcomes for everyone enrolled.

3. Trial Design

The registry describes a completed, randomized, parallel-group trial with single masking. It lists an enrollment of 116. The listed study start was 2019-01-07, and the primary completion date was 2021-10-29. The sponsor was the University of Kansas. The phase is listed as NA. Further details about the randomization procedure, who was masked, or how masking was maintained are not reported in the registry record.

Participants were assigned to one of two behavioral approaches. In the adolescent-only arm, adolescents were asked to attend weekly group exercise sessions and individual support sessions and monitor daily physical activity. In the adolescent-and-parent arm, adolescents and a parent were asked to take part in those sessions and monitor the adolescent’s activity; parents also had access to a Parent Facebook group. The registry identifies the interventions as behavioral. It does not report further information about the amount of contact, adherence, or the delivery of these activities.

The primary endpoint was change in adolescent moderate to vigorous physical activity from baseline to 6 months, measured in minutes per day. The primary results include 42 adolescents in the adolescent-only group and 31 in the adolescent-and-parent group with valid accelerometer data at both assessments. These outcome-specific numbers are not the same as the enrollment figure. The registry record does not explain the difference or report a participant flow that would show why some enrolled participants are not represented in the primary outcome groups.

The registry also lists change in adolescent physical activity at 18 months and measures of parent activity, sedentary time, fitness, strength, motor ability, and quality of life. Details of the trial’s own sample-size justification, planned interim analyses, and statistical analysis plan are not reported in the registry record. The posted planning illustrations are based on the observed comparison, not on the original trial design.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Dyads of adolescents with intellectual disabilities and a parent.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Adolescents who had valid accelerometer data at both baseline and 6 months

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Participants were adolescents with an intellectual disability and a parent. Note 4 parents (AO: 2, A+P: 2) had 2 children who enrolled in the study together.

6. Primary Endpoint

The registry lists the primary outcome as Change in Adolescent Physical Activity From Baseline to 6 Months, measured over Change from baseline to 6 months.

The primary endpoint is mean change in adolescent moderate to vigorous physical activity from baseline to 6 months, in minutes per day. Moderate to vigorous physical activity, often abbreviated MVPA, refers to activity in the moderate or vigorous intensity ranges. In this trial it was assessed with an ActiGraph accelerometer worn during waking hours for 7 consecutive days, except during bathing and swimming.

Accelerometer records were considered valid if the device was worn for at least 8 hours on 3 days, including 1 weekend day. The primary outcome population was adolescents whose data met the validity requirement at both baseline and 6 months. This definition makes the measurement rules explicit, but it also means the endpoint summary applies to participants with usable data at both assessments. The registry record does not describe how missing or invalid measurements were handled in the trial’s analysis.

Change from baseline is useful for expressing how the measured activity level shifted during follow-up. Comparing mean change between randomized groups focuses on whether the average shift differed across the two assigned strategies. A group’s change alone does not answer that comparative question: both groups could change in the same direction while having little difference between them. The estimated between-group mean difference and its confidence interval are therefore central to interpreting the primary result.

The endpoint is an accelerometer-based measure, not a report of all physical activity in every setting. The device-wearing instructions and validity rule define which observations contribute, while the registry does not provide additional detail about processing accelerometer data or the exact intensity thresholds used.

7. Results Posted in the Registry

• Adolescent and Parent (A+P): mean -0.60 versus -3.20 on control; difference 2.60 (95% CI -3.68 to 8.88), standardized effect d = 0.19; z-test p = 0.417.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change in Adolescent Moderate to Vigorous Physical Activity From Baseline to 18 Months

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Adolescent and Parent (A+P): mean 7.60 versus -1.50 on control; difference 9.10 (95% CI -4.20 to 22.40), standardized effect d = 0.35; z-test p = 0.180.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Adolescent and Parent (A+P) and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists secondary measures covering adolescent physical activity at 18 months, parent physical activity, sedentary time for adolescents and parents, cardiovascular fitness, muscular strength, motor ability, and quality of life. The numerical secondary comparison described in detail is the adolescent moderate to vigorous physical activity change from baseline to 18 months. Its estimate points in the same general direction as the primary comparison, but its confidence interval includes no difference. It should be read as an additional, uncertain comparison rather than as independent confirmation.

The primary endpoint concerns the 6-month change in adolescent activity, while the 18-month measure extends the activity question to a later follow-up. Together, the two measures can describe whether the observed pattern is similar across follow-up times, but they do not by themselves establish a durable effect. The registry does not provide enough information about participant retention, missing data, or the analysis plan to determine how comparable the contributing groups are at the two time points.

For the other listed secondary measures, numerical estimates and detailed comparisons are not reported in the registry record. Although the registry lists eight secondary outcome measures, the reported-analyses field is empty. This means the available record does not establish which analyses were prespecified, whether all planned secondary comparisons were conducted, or whether any multiplicity adjustment was used.

Unadjusted secondary findings generally carry less weight than a prespecified primary comparison because testing many outcomes can increase the chance of seeing an apparently notable result by chance. This is a general statistical concern, not evidence that any particular secondary finding is false. Secondary outcomes can still be useful for describing patterns and generating questions for future work, but interpretation should account for their exploratory status and the lack of reported analysis details. The secondary data do not change the principal reading of the primary estimate: the between-group difference remains uncertain.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change in Adolescent Moderate to Vigorous Physical Activity From Baseline to 18 Months
• Change in Parent Physical Activity
• Change in Sedentary Time
• Change in Parent Sedentary Time
• Change in Cardiovascular Fitness
• Change in Muscular Strength
• Change in Motor Ability
• Change in Quality of Life

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is a measured quantity expressed in minutes per day. For this kind of outcome, a mean summarizes the average change within each group, and the between-group mean difference summarizes the contrast in those average changes. The posted arm estimates are -3.2 minutes per day for adolescent-only and -0.6 minutes per day for adolescent-and-parent. The comparison is defined in the direction adolescent-and-parent minus adolescent-only, giving an estimated mean difference of 2.6 minutes per day.

What does the mean difference represent?

The mean difference is a contrast between group averages, not a count of participants who improved and not a measure of the change for a typical individual. Its interpretation depends on the direction used for the comparison. In this result, a positive estimate means the mean change is higher in the adolescent-and-parent group than in the adolescent-only group. The estimate is small relative to the spread of individual changes, and the confidence interval shows that the observed data are compatible with a range of possible between-group differences.

Why report standard deviations?

A standard deviation describes how spread out observations are around a group mean. The posted standard deviations for the primary change are 14.8 minutes per day in the adolescent-only arm and 12.5 minutes per day in the adolescent-and-parent arm. They describe variation among observations, not uncertainty in the mean difference itself. That uncertainty is represented by the confidence interval for the comparison. General statistical point: when observations vary widely, estimates of group means and differences can be less precise unless the amount of information is sufficient to estimate them closely.

How should the confidence interval be read?

The confidence interval for the mean difference extends from -3.677 to 8.877 minutes per day. In general, a confidence interval is a range of values compatible with the data under the statistical method used. It communicates uncertainty in a way that keeps the direction and possible size of the effect visible. Here the range includes zero, which corresponds to no between-group mean difference, as well as values in both directions. The registry does not state the confidence level or provide full details of the calculation, so no level should be inferred from the record alone.

What does the p-value add?

The unadjusted p-value is 0.417. In general, a p-value measures how unusual data at least as inconsistent with a specified null model would be if that model held, under the assumptions of the test. It is not the probability that the null hypothesis is true, and it does not measure the probability that the result will replicate. Because this is an unadjusted p-value, it should not be treated as accounting for the trial’s multiple outcomes or any unreported analysis choices. The registry does not report the test procedure or a prespecified analysis plan.

Why can over-dispersion matter?

General statistical point: over-dispersion occurs when observed variability exceeds what a chosen model assumes. For a continuous endpoint analyzed through means, the corresponding concern is whether the variability and distribution assumed by the method describe the observations adequately. If variation is larger or more irregular than assumed, standard errors and confidence intervals can be misleading. The record reports arm standard deviations and a pooled standard deviation of 13.87 for the comparison, but does not report diagnostic checks or model details. There is not enough information in the registry record to assess distributional assumptions or determine whether a different model was considered.

What does the sample-size illustration estimate?

The planning figures use the observed effect as a starting point and show participant counts per arm under stated assumptions. The listed planning scenarios consider 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. These are prospective planning illustrations, not evidence about the achieved power of this completed trial. The trial’s original design assumptions and sample-size justification are not reported in the registry record. General statistical point: a smaller target effect is harder to distinguish from background variation and therefore usually requires more participants, all else equal.

The registry also lists secondary outcomes and a primary assessment at 6 months. For secondary outcomes, the listed registry analyses count is 0, and no reported analyses are identified. This limits the available basis for evaluating whether outcomes were analyzed according to a prespecified hierarchy or whether multiplicity was handled in a particular way. The distinction matters because several outcomes can create multiple opportunities for apparently notable findings, especially when each is interpreted without adjustment. The record does not say whether the research team conducted analyses not included in the registry results.

Finally, the primary endpoint is based on valid accelerometer data at both assessments. That is a measurement inclusion rule, not a description of the analysis population in all other respects. The registry does not say whether the primary comparison was intention-to-treat, whether data were imputed, or whether other models adjusted for baseline or participant characteristics. Without those details, the most direct interpretation is of the posted arm means and unadjusted comparison for the stated valid-data population.

11. Confidence Intervals and Precision

The estimated mean difference in primary change is 2.6 minutes per day, comparing adolescent-and-parent with adolescent-only. Its confidence interval extends from -3.677 to 8.877 minutes per day. This range is wide enough to include zero and values on either side, so the data do not pin down a single direction or a narrow magnitude for the group contrast.

Confidence intervals are useful because they display both the point estimate and its uncertainty. General statistical explanation: a confidence interval is constructed using a method that, over repeated samples under its assumptions, has a stated long-run coverage property. The registry record does not state the confidence level or enough methodological detail to verify the interval’s construction. The appropriate reading is therefore to focus on the posted limits without assigning an unreported confidence level.

The interval is compatible with a negative difference as well as a positive difference. A negative difference would place the adolescent-and-parent mean change lower than the adolescent-only mean change under the comparison direction used; a positive difference places it higher. Because zero falls within the interval, the posted results also remain compatible with no difference. This uncertainty is consistent with the unadjusted p-value of 0.417, although a p-value and a confidence interval communicate uncertainty in different ways.

The arm standard deviations of 14.8 and 12.5 minutes per day describe observed dispersion in change. The comparison’s pooled standard deviation is 13.87. These measures help put the mean difference in context, but they do not remove uncertainty or show how the results are distributed among individual participants. The standard errors reported for the two arm means are 2.284 and 2.245; the registry does not provide further details about the calculation method.

Precision is also affected by which observations are represented. The primary summaries include adolescents with valid accelerometer data at both baseline and 6 months, with 42 in one arm and 31 in the other. How many randomized participants lacked eligible data, why data were unavailable, and whether missingness was related to activity are not reported in the registry record. Those unknowns limit interpretation beyond the measured-data population.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. They are illustrations computed from the observed effect, not the trial’s own design calculation. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the target effect is the stated fraction of the observed effect. The trial’s original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the planned participants per arm under those assumptions for a design with an 80% chance of detecting the chosen target effect if that effect is the true one. The 90% power column uses a higher target chance of detection. These are design-planning concepts: power is calculated before a study, for a specified effect size and analysis assumptions. The figures are not observed power for the completed trial.

The rows use 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect as the target. The illustration indicates that targeting a smaller effect requires more participants per arm under the same general planning framework. This is a general consequence of trying to distinguish a smaller signal from variability: additional information is needed to achieve a similar chance of detection. The observed estimate is uncertain, so planning directly from it should not be mistaken for a definitive estimate of the effect a future trial should target.

The associated curve should be read as a planning aid showing how required sample size changes with the chosen target effect under the stated assumptions. It does not reconstruct the trial’s original design, and the registry does not report whether the investigators used these assumptions when planning enrollment. In particular, the enrolled 116 should not be compared mechanically with a planning illustration to make a claim about the trial’s achieved power. The posted outcome sample also reflects the accelerometer validity requirement at both baseline and 6 months.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 2.600; pooled standard deviation σ = 13.875.
2. n = 2 × (1.96 + 0.842)² × 13.875² / 2.600² = 447.0, rounded up to 448 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 2.6                      # observed difference in means
sigma <- 13.8747617667658                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(3684512)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 448 (80% power), 599 (90% power)
 75% of observed effect: n per arm = 795 (80% power), 1,064 (90% power)
 50% of observed effect: n per arm = 1,789 (80% power), 2,394 (90% power)
power.t.test: 448 
Simulated power at n = 448 per arm: 0.796 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry identifies one primary outcome and lists multiple secondary outcome measures. When several outcomes or comparisons are evaluated, multiplicity becomes relevant: repeated testing can increase the chance that at least one result appears noteworthy even when there is no corresponding underlying difference. General statistical approaches may control the overall error rate, define a hierarchy of outcomes, or treat secondary analyses as exploratory. The registry record does not report whether any such approach was planned or used.

The posted primary p-value is unadjusted. It should be interpreted as a result for that comparison, not as a value corrected for the full set of outcomes or analyses. No reported analyses are identified in the registry, and the trial’s statistical analysis plan is not reported in the registry record. It is therefore not possible to determine from the record whether the primary comparison was selected before data review, whether additional outcomes were analyzed, or how the investigators handled multiple testing.

The primary outcome population is limited to adolescents with valid accelerometer data at baseline and 6 months. The registry does not report how many enrolled participants lacked valid data at either assessment, why data were missing or invalid, or whether the probability of having valid measurements differed by arm. It also does not describe imputation, sensitivity analyses, or the analysis population for the comparison. Those details matter because analyses restricted to participants with complete valid data can differ from analyses that include all randomized participants, especially if missingness is related to outcome or assignment.

Random allocation supports a fair comparison at assignment, but it does not by itself resolve missing outcome data or guarantee that the observed valid-data groups remain comparable. The record’s enrollment count and outcome-specific group counts are not accompanied by participant-flow explanations. It is not possible to tell whether exclusions arose from nonattendance, device-wear validity, withdrawal, or other reasons; those explanations are not reported in the registry record.

The registry also does not report interim analyses, stopping rules, or the original sample-size justification. These omissions do not prove that such procedures were absent; they mean their use cannot be assessed from the record. A careful reading should distinguish details that are posted—the randomized design, outcome definition, and reported estimates—from analysis decisions for which the registry offers no detail.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: covid 19 hospitalization (1.8%), pancreatitis (1.7%), tubulointerstitial nephritis (1.7%).

The registry reports serious adverse events and other adverse events by group, with separate numbers at risk. For serious adverse events, 59 were at risk in the adolescent-only group and 57 in the adolescent-and-parent group; 2 and 1 were affected, respectively. For other adverse events, the corresponding at-risk numbers were 59 and 57, with 1 and 2 affected. The registry reports 0 deaths in each group.

These figures are descriptive counts in the registry record. They do not establish that an intervention caused an event, and the record does not provide event timing, severity detail beyond the serious-event classification, or an analysis comparing safety between groups. The listed serious-event terms include COVID 19 Hospitalization at 1.8%, Pancreatitis at 1.7%, and Tubulointerstitial Nephritis at 1.7%. The record does not provide additional context for interpreting those percentages, such as the calculation denominator or event-level details.

At-risk counts and affected counts should be read as separate parts of the safety summary, not as a substitute for a full account of exposure or follow-up. The counts are small, and the registry does not report a statistical comparison or causal assessment of adverse events. They therefore describe what was posted rather than support a conclusion about comparative safety.

16. What the Result Does, and Does Not, Mean

The posted primary result is an estimate of the difference in mean change in adolescent moderate to vigorous physical activity between two assigned strategies. The point estimate is 2.6 minutes per day in the direction of a higher mean change for adolescent-and-parent relative to adolescent-only. The confidence interval, from -3.677 to 8.877 minutes per day, includes no difference and values in either direction. The result is therefore uncertain in both direction and size.

This does not establish that the approaches are equivalent. A confidence interval that includes zero is not proof that there is no difference; it indicates that the data are not precise enough to rule out a range that includes no difference. Nor does the point estimate alone establish a meaningful advantage. The registry does not report a threshold for what magnitude of change would be considered important, and no judgment about clinical importance can be derived from the comparison alone.

The result also does not show that either group’s activity was unchanged. The arm means represent observed average changes among adolescents with valid measurements at both assessments, and they should be understood as group summaries. Individual participants may have had changes that differed from their group mean. The registry does not provide individual-level distributions or responder counts.

The endpoint is based on accelerometer measurements over specified wear periods and validity criteria. It does not capture every possible aspect of activity, and the record does not provide additional details on processing or intensity thresholds. The primary comparison applies to the stated valid-data population; reasons that some enrolled participants are not included are not reported. This limits extension of the result to all enrolled adolescents.

The findings also cannot establish how the components of each program contributed to the observed comparison. The adolescent-and-parent strategy included parent participation and access to a Parent Facebook group, but adherence and exposure are not reported. The registry does not report adjusted analyses, multiplicity procedures, or the full analysis plan. The most defensible interpretation is descriptive: the posted estimate favors a higher average change in the adolescent-and-parent group, but the interval and available analysis details leave substantial uncertainty.

17. Why This Trial Matters Statistically

This trial raises a statistical question that is common in behavioral research: how to compare two multi-component approaches when the primary outcome is measured repeatedly and varies considerably between participants. The primary analysis focuses on the difference in mean change, which distinguishes a group comparison from a simple before-and-after description. That distinction is important because an observed change within one group does not by itself show that the group changed differently from its comparator.

The endpoint also illustrates how measurement rules define an analysis population. Accelerometer data had to meet a stated wear-time and valid-day threshold at both baseline and 6 months. Clear rules can improve consistency in measurement, but they make it important to report how many randomized participants met them and what happened to the others. The record gives the outcome-specific group counts but not a participant-flow explanation or missing-data analysis.

The uncertainty around the mean difference is another key statistical feature. The point estimate gives a compact summary, but the interval shows that multiple true differences remain compatible with the observed result. Reporting both helps prevent readers from treating a single estimate or p-value as a complete account of evidence.

Finally, the registry lists a range of secondary outcomes and a later assessment of adolescent activity. Such outcomes can broaden the questions a trial addresses, but they also make prespecification and multiplicity handling important. Those methods are not reported in the registry record. The case therefore illustrates why interpretation depends not only on the numerical estimate, but also on who contributed data, how uncertainty is conveyed, and whether the analysis choices can be assessed.

18. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

A central limitation of the available result is that the primary comparison represents adolescents with valid accelerometer data at both baseline and 6 months, not necessarily everyone enrolled or randomized. The registry lists enrollment of 116, while the primary endpoint summaries include 42 participants in the adolescent-only arm and 31 in the adolescent-and-parent arm. The record does not explain the participant flow between enrollment and the valid-data analysis population. Reasons for unavailable or invalid measurements, and whether they differed across groups, are not reported in the registry record.

The registry provides the primary arm means, standard deviations, mean difference, confidence interval, and unadjusted p-value, but does not report the full statistical analysis plan. Details such as baseline adjustment, the exact inferential procedure, and sensitivity analyses are not reported. The confidence level for the interval is also not stated in the record. These omissions constrain assessment of the analysis beyond the posted summaries.

Intervention delivery and adherence are not described in detail. The arm descriptions identify group exercise sessions, individual support sessions, physical activity monitoring, and parent access to a Facebook group, but the record does not report attendance, engagement, or variation in exposure. Consequently, the comparison cannot clarify which components participants received or how consistently they participated.

The registry lists several secondary outcomes, but detailed numerical results for most are not reported in the registry record. It also does not document multiplicity procedures, interim analyses, or the original sample-size justification. The absence of these details limits evaluation of how outcome selection and analysis decisions were made. These are limitations of the information available in the registry record, rather than proof that the study team did not conduct additional analyses or procedures.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Promotion of Physical Activity in Adolescents With Intellectual and Developmental Disabilities — NCT03684512.
• Registry record last updated 2023-07-03; status last verified 2023-06.
• Results first posted 2023-07-03.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

22. Record Summary

The registry describes a completed randomized, parallel-group, single-masked trial comparing remote physical activity approaches for adolescents with intellectual and developmental disabilities. One arm delivered the intervention to adolescents only; the other included a parent and offered parent access to a Facebook group. Enrollment was 116.

The primary endpoint was change in adolescent moderate to vigorous physical activity from baseline to 6 months, measured by accelerometer and limited to adolescents with valid data at both time points. The posted mean difference was 2.6 minutes per day, with a confidence interval from -3.677 to 8.877 and an unadjusted p-value of 0.417. The interval includes zero, leaving the direction and size of the between-group difference uncertain.

The registry also lists secondary outcomes, including adolescent activity at 18 months and measures of activity, fitness, strength, motor ability, and quality of life. The registry record does not report the trial’s original sample-size justification, full statistical analysis plan, or details of missing-data handling. The primary result should therefore be read as a comparison among the stated valid-data population, with substantial uncertainty and limited information about analysis decisions.