Testing Preliminary Effectiveness of a Training to Support CHWs Outreach on Dental to African American Caregivers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Testing Preliminary Effectiveness of a Training to Support CHWs Outreach on Dental to African American Caregivers (NCT05511935), a randomized na study. The primary outcome is Knowledge Pretest Score.

2. Clinical Question

3. Trial Design

This was a randomized, parallel-group study with no masking recorded. One group was exposed to GRIN training, described as professional development for community health workers on dental health. The control group was unexposed and received no intervention. The registry lists the study phase as NA and the status as completed. Enrollment is recorded as 143.

The study’s stated aim was to explore the impact of an online training program intended to help community health workers conduct effective outreach supporting the dental health of African American youth through their caregivers. That description identifies the broad program objective; it does not establish that every endpoint directly measures outreach behavior or dental health in youth. The primary outcome posted is a participant knowledge score.

The study started on 2022-01-01, and the primary completion date was 2022-08-15. The registry’s baseline knowledge results list 62 participants in the GRIN group and 45 in the control group. The record does not explain the relationship between those endpoint counts and overall enrollment, including whether differences reflect eligibility for the measure, missing observations, or another reason.

Details such as the randomization procedure, concealment of group assignment, training duration, follow-up schedule, and the rationale for the planned enrollment are not reported in the registry record. The record also does not report a detailed protocol or a complete account of which participants were included in each analysis. These omissions limit how fully the conduct and analysis can be reconstructed from the registration information alone.

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.

Overall Study

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Knowledge Pretest Score, measured over Baseline.

The primary endpoint is the Knowledge Pretest Score at baseline. Participants answered 12 multiple-choice questions about oral health. Their answers were combined into a composite score from 0 to 100: a score of 0 represents no correct answers, and a score of 100 represents all questions answered correctly. The endpoint is summarized as a mean and standard deviation for each group. A higher score represents more correct answers on the knowledge questions.

A knowledge measure is used to describe one aspect of the subject matter the training aims to address. In this study, it offers a way to characterize participants’ oral-health knowledge and to compare the groups at baseline. It is not itself a measure of caregiver outreach, youth dental health, or whether knowledge was retained after training. The record does not report a separate primary endpoint measuring those outcomes.

Because the endpoint is explicitly labeled a pretest and its timeframe is baseline, the posted group comparison should be read as a comparison of baseline scores. A baseline difference, or lack of a clear difference, does not by itself estimate the effect of the training. The registry record does not report a baseline-adjusted post-training estimate as the primary result.

7. Results Posted in the Registry

• Exposed to GRIN Training: mean 64.92 versus 66.67 on control; difference -1.75 (95% CI -8.80 to 5.30), standardized effect d = -0.09; z-test p = 0.626.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a continuous score, so the registry summarizes each group with a mean and standard deviation. The mean describes the group’s average score, while the standard deviation describes how dispersed individual scores are around that average. These are different summaries: a mean difference compares group averages, whereas the standard deviation describes variation among participants within a group.

What does the mean difference represent?

The recalculated comparison uses the difference between the training-group mean and the control-group mean. With that ordering, a negative value means the training-group average is lower at baseline; a positive value would mean it is higher. The reported estimate is -1.75 points. This is an unadjusted comparison of the posted group summaries, not an adjusted model estimate. It does not account for other participant characteristics or establish a causal effect.

What does the t-test assess?

A two-sided t-test assesses whether the data are inconsistent with a null hypothesis of no difference in group means, allowing for differences in either direction. The registry reports a two-sided t-test for the sponsor’s final-values analysis. A p-value describes how unusual the data, or more extreme data, would be under the null model and its assumptions. It is not the probability that the null hypothesis is true, and it does not measure the probability that the training is beneficial or harmful.

The recalculated p-value uses the posted summary statistics and is labeled unadjusted. It should not be mistaken for a substitute for a prespecified sponsor analysis or for a model that accounts for design details not available in the record. The registry record does not report enough detail to determine whether the sponsor used covariate adjustment, handled missing observations in a particular way, or applied other modeling choices beyond the stated t-test.

Why are confidence intervals useful?

A confidence interval gives a range of values that are reasonably compatible with the data under the statistical method used. It conveys the estimate’s uncertainty and is often more informative than a significance test alone. For the recalculated baseline contrast, the interval includes zero and extends in both directions. Thus, the data do not distinguish clearly between a lower or higher training-group mean, and the range still permits differences that may matter substantively. A confidence interval is not a guarantee that the true value lies inside a particular realized interval.

Why does the analysis use a continuous-outcome comparison?

The score combines the knowledge-question responses into a scale, and the registry reports group means and standard deviations. Comparing means is a direct way to summarize the average score difference. The interpretation depends on the score being meaningfully summarized by its arithmetic mean and on the method’s assumptions being reasonable. The record does not report diagnostic checks or details about the distribution of scores. The bounded 0-to-100 scale also means the outcome cannot extend indefinitely in either direction, although no distributional analysis is posted.

What does standardization add?

A standardized effect expresses a mean difference relative to the pooled standard deviation, placing the contrast on a scale that is less tied to the original score units. The recalculated standardized effect is -0.093. It is a derived, unadjusted summary based on the posted group statistics. It does not replace the score-point estimate or its confidence interval, and it should not be interpreted as a clinically meaningful threshold. The registry record does not report a prespecified threshold for an important knowledge-score difference.

What are the limits of the recalculation?

The recalculated comparison uses the posted means, standard deviations, and group sizes. It is a simple unadjusted re-calculation and cannot recreate analysis choices that are not described in the registry. The record’s sponsor analysis is reported separately as a two-sided t-test of mean difference in final values. The primary endpoint, however, is labeled a baseline pretest. The record does not clarify whether the final-values analysis refers to this same measurement occasion or to another outcome time. This uncertainty limits direct interpretation of the sponsor result alongside the primary baseline comparison.

In general, over-dispersion means that the observed variability is greater than a model assumes. If a model underestimates variability, standard errors can be too small and intervals too narrow; if variability is modeled appropriately, uncertainty is better represented. This is a general statistical consideration, not a finding about this study: the registry record does not report an over-dispersion assessment or a model for this continuous endpoint.

10. Confidence Intervals and Precision

The recalculated mean difference is -1.75 points, with a 95% confidence interval from -8.796 to 5.296. The interval crosses zero, so the data are compatible with a small difference in either direction as well as a range of larger differences. It does not support a precise conclusion that the baseline group means are equal. The unadjusted p-value of 0.626 likewise does not provide strong evidence against a null hypothesis of no mean difference, but it does not quantify the size of the differences that remain plausible.

Precision depends on the amount of information in the analysis and the variability of scores. The registry reports 62 participants in the training group and 45 in the control group for this outcome, with standard deviations of 20.03 and 17.04, respectively. The interval reflects uncertainty in the group-mean contrast, not the spread of individual scores; the standard deviations describe that within-group spread.

The sponsor’s reported 95% confidence interval for the final-values analysis is -5.57 to 9.06 around a mean difference of 1.75. It also includes zero and allows differences in either direction. The two intervals come from comparisons described differently in the registry, so they should not be treated as interchangeable estimates without clarification of outcome timing and group ordering. The record does not explain that relationship. Overall, the posted intervals leave substantial uncertainty about the magnitude and direction of the mean difference.

11. 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 based on the observed effect and are not the trial’s original enrollment target or a reconstruction of its design rationale. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect used for each illustration is a stated fraction of the observed effect: 100%, 75%, or 50%.

The 80% power column gives the number of participants per arm that the planning calculation estimates would be needed to have an 80% chance of detecting the specified effect if that effect were the true effect, under the stated assumptions. The 90% column gives the corresponding planning count for a 90% chance. For 100% of the observed effect, the figures are 1,819 and 2,435 participants per arm for 80% and 90% power. For 75% of the observed effect, they are 3,233 and 4,328; for 50%, they are 7,274 and 9,738.

The curve’s general message is the relationship between effect size and the planning count: smaller effects require more participants to detect with the same target power, all else held constant. These calculations are particularly sensitive to the observed effect used as their starting point. They should not be read as evidence about the study’s achieved power or as a guarantee that a future study will attain a particular result. This is not observed power. The registry record does not report the trial’s original sample-size justification or design assumptions.

12. 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 = -1.750; pooled standard deviation σ = 18.835.
2. n = 2 × (1.96 + 0.842)² × 18.835² / -1.750² = 1,818.4, rounded up to 1,819 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 <- -1.75                      # observed difference in means
sigma <- 18.8349131996432                     # 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(5511935)
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 = 1,819 (80% power), 2,435 (90% power)
 75% of observed effect: n per arm = 3,233 (80% power), 4,328 (90% power)
 50% of observed effect: n per arm = 7,274 (80% power), 9,738 (90% power)
power.t.test: 1819.4 
Simulated power at n = 1,819 per arm: 0.801 (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.

13. Analyses Reported by the Sponsor

The sponsor reports a two-sided t-test for mean difference in final values. The reported estimate is 1.75, with a 95% confidence interval from -5.57 to 9.06 and p = 0.64. The recalculated unadjusted baseline contrast is -1.75, with a 95% confidence interval from -8.796 to 5.296 and p = 0.626. Both comparisons are compatible with no mean difference, and their p-values are close, but they are not identical analyses as described in the registry.

The opposite signs can reflect the order in which groups are subtracted: reversing the order reverses the sign of a mean difference. The registry does not state which subtraction order underlies the sponsor’s reported value. It also describes the primary endpoint as a baseline pretest, while the sponsor analysis is labeled final values. The record does not clarify whether these refer to the same time point or how the sponsor analysis relates to the primary endpoint.

The recalculation is an unadjusted comparison derived from posted group summaries. The sponsor analysis is the result reported in the registry, but the available description does not provide further details about its analytic population, missing-data handling, or adjustments. The two results should therefore be presented as distinct reported analyses rather than silently treated as exact replications of one another.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures and 12 analyses. It lists one secondary outcome, Satisfaction at Posttest Score. The record does not explain why the number of analyses differs from the number of outcome measures, how the posted analysis relates to every registered outcome, or whether any outcomes or analyses were omitted from the results record.

Multiplicity arises when several outcomes, time points, or statistical comparisons are examined. With many tests, the chance of at least one apparently unusual result can increase, even if no true effects exist. Statistical approaches can address this issue, but the registry record does not report a multiplicity strategy, a hierarchy among outcomes, or whether any adjustment was made. The number of measures alone does not establish that the analyses were all independent or that a particular correction was required.

The record does not report how missing outcome data were handled, whether all randomized participants were included in each analysis, or whether analyses followed an intention-to-treat principle. Although overall enrollment is recorded as 143, the baseline knowledge outcome lists 62 participants in the training group and 45 in control. The reason for the difference between the enrollment figure and the outcome-specific counts is not reported in the registry record. It would be inappropriate to assume that the difference reflects withdrawals, missing questionnaires, exclusions, or any specific event.

Details of the statistical analysis plan, including prespecified covariates, model diagnostics, treatment of incomplete observations, and any interim analyses, are not reported in the registry record. These omissions make it difficult to assess whether the reported comparisons were selected from a larger set of possible analyses or how robust they are to analytic decisions. The posted results can be interpreted as reported summaries, while conclusions about analysis populations and unreported outcomes must remain limited.

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 0% reporting threshold.

The registry reports zero serious adverse events in the GRIN training group among 62 participants at risk and zero in the control group among 45 participants at risk. It also reports zero other adverse events in each group, with the same group-specific at-risk counts. Deaths are reported as zero in both groups. No serious adverse-event terms are listed.

These entries describe the adverse-event counts recorded in the registry. They do not establish that no adverse experiences occurred outside the definitions, collection process, or reporting period used by the study. The record does not describe the safety-monitoring procedures, how events were elicited, or the time period covered by these counts. It also does not provide details on the severity or nature of non-serious events because none are listed.

Zero recorded events should be read as a count, not as proof that an intervention is free of risk. The study’s purpose was to explore training for community health workers’ outreach, and the posted safety figures are limited to the groups and event categories recorded. They do not answer broader questions about safety beyond this study’s reporting.

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

The posted baseline data describe oral-health knowledge scores in the two randomized groups before the outcome time point identified as pretest. The training group’s mean was 64.92 and the control group’s mean was 66.67. The recalculated unadjusted difference is -1.75 points, with a 95% confidence interval from -8.796 to 5.296 and p = 0.626. The estimated difference is small relative to the full score scale, but its uncertainty means the data do not establish equality or precisely identify the direction of a baseline difference.

These results do not show whether GRIN training increased knowledge after training. They also do not demonstrate whether community health workers conducted more effective outreach, whether caregiver understanding changed, or whether dental health among youth changed. The primary measure is a baseline knowledge score, not a direct measure of any of those later outcomes. The registry’s separate sponsor analysis is described as a final-values comparison, but the record does not clarify its timing or relationship to the baseline endpoint.

A non-significant comparison is not proof that two groups are equivalent. Equivalence requires an appropriate design and a prespecified range of differences considered sufficiently small; such a margin is not reported in the registry record. Likewise, the planning illustrations based on the observed effect do not establish the study’s original intended power or provide evidence of an effect.

The most defensible reading is descriptive and limited: the record posts baseline group summaries and an uncertain unadjusted comparison. Any conclusion about a training effect would require an appropriate post-training comparison, clear outcome timing, and sufficient information about analysis populations and missing data. Those details are not reported for the primary endpoint in the registry record. No medical advice or conclusion about treatment effectiveness follows from these statistics.

17. Why This Trial Matters Statistically

This study illustrates why the timing and definition of an endpoint matter as much as the statistical test. The primary measure is explicitly a baseline pretest. A between-group comparison at baseline describes the groups at that point, but it is not an estimate of what happened after the training. When a study is intended to assess a training program, readers need to distinguish baseline characterization from a post-training contrast or a comparison of change over time.

The result also shows why a confidence interval adds useful context to a p-value. The recalculated estimate is near zero, and the unadjusted p-value is not small, but the interval still allows a range of differences in both directions. That uncertainty cautions against interpreting a non-significant result as proof of no difference. It also highlights the value of reporting a clear, clinically or practically interpretable scale and a prespecified threshold for a difference that would matter. No such threshold is reported in the registry record.

Finally, the record provides an example of how group ordering and analysis timing affect apparent comparisons. The sponsor’s reported mean difference has the reverse sign from the unadjusted recalculation, while the endpoint is described as baseline and the sponsor analysis as final values. Careful reporting of contrast direction, measurement time, analysis population, and missing-data handling would make results easier to compare and interpret. These are general statistical reporting principles, not findings that the training had or lacked an effect.

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.

The main trial-specific limitation is that the primary endpoint is a baseline knowledge score, while the study aim concerns an online training intended to support outreach. A baseline score does not measure change after exposure. The registry record does not post a primary post-training knowledge comparison or an estimate of training-related change for this endpoint. The sponsor analysis is described as final values, but its relationship to the baseline pretest is not explained.

The outcome-specific group counts are 62 for GRIN and 45 for control, while total enrollment is recorded as 143. The reason for the difference is not reported in the registry record. Without a participant flow or analysis-population description, it is not possible to determine how many randomized participants contributed to each outcome or why some may not have contributed.

The record does not report detailed eligibility criteria, randomization procedures, allocation concealment, the training duration, follow-up timing, or the full content of the intervention. It also does not report the original sample-size justification, a prespecified analysis plan, missing-data procedures, multiplicity handling, or whether there were interim analyses. These gaps constrain evaluation of risk of bias and reproducibility.

The posted primary comparison is an unadjusted baseline comparison, and the sponsor’s analysis description does not give enough detail to reconstruct all analytic choices. The record also lists more outcome measures than analyses and does not explain the relationship between them. These are limitations in what can be established from the registry record; they should not be taken as evidence that any particular procedure was or was not used.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Testing Preliminary Effectiveness of a Training to Support CHWs Outreach on Dental to African American Caregivers — NCT05511935.
• Registry record last updated 2024-11-07; status last verified 2024-11.
• Results first posted 2024-11-07.
• 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

NCT05511935 is a completed, randomized, parallel-group study with no masking recorded. It examined GRIN professional development training for community health workers, compared with a control group receiving no intervention. The stated goal was to support outreach concerning the dental health of African American youth through caregivers.

The primary posted outcome is baseline oral-health knowledge, scored from 0 to 100. The mean was 64.92 in the training group and 66.67 in control. The recalculated unadjusted mean difference, training minus control, was -1.75, with a 95% confidence interval from -8.796 to 5.296 and p = 0.626. The sponsor separately reports a final-values t-test with a mean difference of 1.75, a 95% confidence interval from -5.57 to 9.06, and p = 0.64.

The registry records enrollment of 143 and reports zero serious adverse events, zero other adverse events, and zero deaths in both groups. Details needed to interpret the endpoint counts, post-training effects, missing data, and analysis populations are not reported in the registry record.