Text2Breathe: Enhance Parent Communication to Reduce Pediatric Asthma Disparities: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Text2Breathe: Enhance Parent Communication to Reduce Pediatric Asthma Disparities (NCT03032159), a randomized na study. The primary outcome is Emergency Department Visits for Asthma Care.

2. Clinical Question

Text2Breathe was designed to examine whether a communication-focused program for parents of children with asthma was associated with differences in asthma-related outcomes compared with a control condition. The primary question concerns the number of emergency department visits for asthma care during 12 months. The registry record reports the outcome as a mean, with a standard deviation, for each study group.

3. Trial Design

Text2Breathe (NCT03032159) is recorded as a completed, randomized, parallel-group trial. The registry lists the allocation as randomized and the masking as single. It does not identify which people were masked, so the meaning of single masking for participants, providers, outcome assessors, or analysts is not reported in the registry record. The phase is listed as NA.

The registry gives an enrollment of 221. The posted primary outcome summaries include 91 participants in the control group and 77 in the Text2Breathe group. These are the group counts attached to the reported outcome, not an explanation of how enrollment relates to the analysis counts. The reasons for the difference between enrollment and the outcome counts are not reported in the registry record.

The control group received usual asthma care and reminder texts. The intervention group had brief communication-skills learning and asthma-related educational messages. Thus, the randomized contrast combines the additional communication learning and intervention messaging with the control condition; the record does not describe a separate group that received only one of those components.

The study start is recorded as 2015-08, and primary completion as 2020-03. The primary outcome timeframe is 12 months. The record lists Asthma Morbidity as a secondary outcome and reports one secondary endpoint result. It lists 7 outcome measures overall, but the registry record does not provide a reported statistical analysis plan or reported analyses. The original trial’s sample-size rationale, its planned analysis populations, and details of adherence or follow-up are not reported in the registry record.

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: Of the 661 potential parent participants screened for eligibility, 221 were eligible and randomized. Participants are unique parent/child dyads. The parents were enrolled, and each parent had a child that they provided data on. Those that were screened but excluded either did not meet inclusion criteria or declined to participate.

Overall Study

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: Parents enrolled into the control (usual care) group and intervention (Text2Breathe study group).

6. Primary Endpoint

The registry lists the primary outcome as Emergency Department Visits for Asthma Care, measured over 12 months.

The primary endpoint is the number of emergency department visits for asthma care during 12 months. It is reported as a mean and standard deviation for each group. This describes the average number of visits in each outcome group; it does not directly state how many participants had at least one visit, how visits were distributed among individuals, or whether visits were concentrated in a small number of participants.

Emergency department use is one way to quantify acute healthcare encounters related to asthma. In general, an outcome of this kind can capture differences in the frequency of urgent care use, while remaining distinct from symptom scores, routine care, and other measures of asthma morbidity. The registry describes this endpoint as a number of visits for asthma care, but does not report further details about how visits were identified, verified, or attributed to asthma.

The posted group means are 1.65 visits in the control group and 1.95 in the Text2Breathe group, with standard deviations of 1.7 and 2.7, respectively. The reported mean difference is 0.3 visits, expressed as Text2Breathe minus control. The interpretation therefore concerns the average count during the stated timeframe, rather than an individual participant’s experience or a broader measure of all asthma-related health.

7. Results Posted in the Registry

• Text2Breathe Study Group: mean 1.95 versus 1.65 on control; difference 0.30 (95% CI -0.40 to 1.00), standardized effect d = 0.14; z-test p = 0.399.

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.

Asthma Morbidity

• 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:
  • Text2Breathe Study Group: mean 4.45 versus 3.36 on control; difference 1.09 (95% CI -0.35 to 2.53), standardized effect d = 0.23; z-test p = 0.137.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Text2Breathe Study Group and the control. The interval gives the range of effects that remain compatible with the data.

The registry posts one secondary endpoint result: Asthma Morbidity, defined as maximum symptom days over 12 months. The means are 3.36 in the control group and 4.45 in the Text2Breathe group. The posted mean difference is 1.09, with a confidence interval spanning values below and above zero; the unadjusted p-value is 0.137. These results are not a separate confirmation of the primary endpoint. They describe a different measure of asthma morbidity, using its own outcome scale and comparison.

The direction of the secondary mean difference is toward a higher reported mean in Text2Breathe, as is the direction of the primary mean difference for emergency department visits. However, the outcomes are distinct, and similarity in direction does not show that one result explains the other or that either reflects a causal effect. The registry record does not report a joint analysis of the endpoints or an explanation of how symptom days and emergency department visits relate within participants.

Unadjusted secondary findings generally carry less weight than a prespecified primary result because secondary outcomes may be numerous and are often evaluated alongside other comparisons. Considering multiple results without a reported plan for multiplicity can increase the chance of apparently notable findings by chance. Here, the registry lists 7 outcome measures, posts one secondary result, and lists no reported analyses. The record does not describe which secondary analyses were planned, whether adjustments for multiple testing were intended, or how the posted secondary measure was selected. The single secondary result should therefore be treated as supporting context rather than as decisive evidence about the primary question or the study’s broader aim.

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

• Asthma Morbidity

9. Statistical Interpretation

10. Statistical Methods Explained

The registry reports the primary outcome as a continuous measure summarized by a mean and standard deviation. Although the underlying outcome is a count of visits, the posted comparison uses a mean difference rather than a comparison of event rates or proportions. The contrast is Text2Breathe minus control: a positive value indicates a higher group mean in Text2Breathe, while a negative value indicates a lower group mean. This direction convention makes the sign interpretable, but does not establish that the observed difference is attributable to the assigned intervention.

What does a mean difference describe?

A mean is the arithmetic average of the observed values in a group. A mean difference describes the separation between two such averages in the units of the outcome. Here, the unit is ED visits over the 12-month timeframe, and the posted mean difference is 0.3. This is not a relative change, an individual-level effect, or a comparison of the percentage of participants with any visit. The registry record does not post the underlying participant-level counts, so it is not possible to inspect skewness, clusters of repeat visits, or the number of zero counts from these summaries.

What does the standard deviation tell readers?

The standard deviation describes spread of observed values around a group mean. The posted values are 1.7 in control and 2.7 in Text2Breathe. In general, a larger standard deviation indicates more dispersion in the observations, but it does not reveal the full distribution or say whether unusual values are present. In a count outcome, the distribution may be asymmetric or include many zero values. The registry record does not report distribution plots or other details that would show whether a mean-based model’s assumptions were checked.

In general, over-dispersion occurs when count data vary more than a simple model’s assumptions would expect. It can affect standard errors and the reliability of model-based comparisons if the analysis does not account for that extra variability. This is a general statistical consideration for visit counts, not a claim about the model used in Text2Breathe: the registry record does not report a fitted model or its assumptions. No particular count-data method should be attributed to the trial on the basis of the posted summaries.

How should the unadjusted comparison be read?

The comparison is an unadjusted summary-statistic calculation using the posted means and standard deviations. It gives a straightforward estimate of the difference between the reported group averages and an associated interval and p-value. “Unadjusted” means the reported comparison does not account for additional covariates in the posted calculation. The registry record lists no reported analyses, so it is not possible to confirm whether the trial investigators conducted a separate adjusted primary analysis, what variables they might have considered, or whether another analysis was prespecified.

Random allocation is intended, in general, to support comparable groups at the time of assignment. It does not remove the need to understand outcome availability, follow-up, adherence, and analysis choices. The outcome counts posted for the primary measure are 91 for control and 77 for Text2Breathe, while the registry enrollment is 221. The record does not state why those counts differ, how missing outcomes were handled, or whether the posted groups include all randomized participants. The posted descriptive comparison should therefore be understood in light of this reporting gap.

What do the p-value and confidence interval contribute?

In general, a p-value describes how incompatible the observed data are with a specified null model, under the assumptions of the analysis. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of a difference. The primary unadjusted p-value is 0.399. A confidence interval communicates uncertainty around an estimate: its span indicates which values are relatively compatible with the data and analysis assumptions. The registry’s interval for the primary mean difference includes zero, along with both negative and positive differences.

These inferential summaries rely on the calculation and its assumptions. The record does not report an analysis plan, a model, a confidence-level label, handling of missing data, or a multiplicity plan. The interval and p-value should thus be read as the posted unadjusted comparison, not as a complete account of all trial analyses. The registry discrepancy indicator is false; there is no flagged conflict between the posted summary and a separate sponsor analysis in this record.

What is the role of secondary outcomes?

The posted secondary endpoint is Asthma Morbidity, expressed as maximum symptom days over 12 months and summarized as a mean and standard deviation. In general, secondary outcomes can add context about outcomes beyond the primary endpoint, but they do not replace the primary question. When several outcomes or analyses are considered, the chance of finding a nominally unusual result can increase unless the analysis plan addresses multiplicity. The record lists 7 outcome measures and one posted secondary result, but no reported analyses or multiplicity method. The secondary comparison is therefore descriptive and exploratory in context; the record does not establish how it was prioritized in the original trial plan.

11. Confidence Intervals and Precision

Precision concerns how tightly an estimate is determined by the observed data and the analysis. The primary mean difference is 0.3 ED visits, and its reported confidence interval extends from a negative value to a positive value. Because zero lies within that interval, the posted data are compatible with no mean difference as well as with differences in either direction under the unadjusted analysis. The interval’s span also indicates that the estimate is not pinpointed to a single small range of values.

A confidence interval is not a guarantee that the true effect lies within its bounds, nor does it assign a probability to any one value. In general, it summarizes the uncertainty that would arise from repeated use of the same procedure under its assumptions. The registry record does not state the confidence level, so no particular level should be inferred from the posted bounds.

The primary outcome group standard deviations are 1.7 for control and 2.7 for Text2Breathe, and the outcome counts are 91 and 77, respectively. Variation in outcomes and the amount of available data both affect precision in general. The registry record does not explain why these outcome counts are below the enrollment figure or provide missing-data analyses, so the effect of outcome availability on the uncertainty cannot be assessed from the posted results alone.

The unadjusted p-value of 0.399 is consistent with the interval spanning zero, but it is not a measure of precision or practical importance on its own. A non-small p-value does not demonstrate equivalence or rule out potentially meaningful differences. The registry record does not report an equivalence margin or a prespecified precision target. The interval should therefore be used to communicate uncertainty, rather than to claim that the groups had the same outcome.

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 expressed as participants per arm, not as total events. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effects used for the illustrations are 100%, 75%, and 50% of the observed effect. These are planning scenarios based on the observed effect, not the assumptions used to design the original trial; the original design assumptions are not reported in the registry record.

For 100% of the observed primary effect, the illustration gives 856 participants per arm for 80% power and 1,146 participants per arm for 90% power. For 75% of the observed effect, the corresponding figures are 1,521 and 2,036 participants per arm. For 50% of the observed effect, they are 3,422 and 4,581 participants per arm. The columns describe different planning targets: 80% power means a design with an 80% chance of detecting the specified effect under the stated assumptions, and 90% power means a 90% chance, if those assumptions and effect are correct.

Smaller effects require more participants to detect under otherwise unchanged assumptions. The figures are not estimates of how many people were needed under the original protocol, and they are not observed power. They are illustrations calculated from the effect observed in this trial. As the observed estimate itself is uncertain, these figures should not be treated as a definitive design recommendation.

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 = 0.300; pooled standard deviation σ = 2.215.
2. n = 2 × (1.96 + 0.842)² × 2.215² / 0.300² = 855.4, rounded up to 856 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 <- 0.3                      # observed difference in means
sigma <- 2.21460105466545                     # 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(3032159)
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 = 856 (80% power), 1,146 (90% power)
 75% of observed effect: n per arm = 1,521 (80% power), 2,036 (90% power)
 50% of observed effect: n per arm = 3,422 (80% power), 4,581 (90% power)
power.t.test: 856.4 
Simulated power at n = 856 per arm: 0.804 (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 record lists 7 outcome measures, identifies emergency department visits for asthma care as the primary endpoint, and posts Asthma Morbidity as a secondary outcome. It reports no analyses. A multiplicity strategy—such as a hierarchy among endpoints, adjustment of significance thresholds, or a distinction between confirmatory and exploratory comparisons—is not reported in the registry record. Without that information, the unadjusted p-values should not be interpreted as if they necessarily account for all outcomes or analyses considered during the trial.

Missing-data handling is also not reported. The primary endpoint summaries include 91 participants in control and 77 in Text2Breathe, while enrollment is recorded as 221. The record does not describe the number randomized to each group, the number with an observed primary outcome, reasons for unavailable outcomes, imputation, or sensitivity analyses. The adverse-event fields use different group counts, but the record does not explain how those sets relate to the primary-outcome groups. These reporting gaps prevent an assessment of whether outcome availability could affect the comparison.

The registry does not state whether the analysis followed intention-to-treat principles, whether participants were analyzed according to assigned group, or whether any per-protocol or other analysis population was used. Nor does it report covariate adjustment, clustering, repeated-measure handling, or a statistical model. These details matter because they determine which observations enter the analysis and how uncertainty is estimated. They should not be inferred from the randomized, parallel-group design alone.

Overall, the posted results permit a reading of the displayed group summaries and their unadjusted comparisons. They do not permit a full audit of prespecification, multiplicity, missingness, or analysis-population choices. Those items are not reported in the registry record.

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 adverse-event record lists zero serious adverse events in the control group among 110 participants at risk and zero in the Text2Breathe group among 111 participants at risk. It also lists zero other adverse events in each group, with the same at-risk counts, and zero deaths in each group. No serious-event terms are listed.

These entries describe what the registry record reports for the listed categories and at-risk groups. They do not establish that no adverse experiences occurred outside the recorded categories, that every participant was assessed in the same way, or that an event could not occur. The registry record does not give further detail on event collection, severity definitions beyond the listed serious category, attribution, or follow-up procedures. The adverse-event counts also differ from the primary-outcome group counts, and the reason is not reported in the registry record. The safety entries should therefore be read as registry-reported counts, not as a complete characterization of safety.

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

The posted results describe a randomized comparison in which the Text2Breathe group had a higher mean number of emergency department visits for asthma care than the control group over 12 months. The mean difference is 0.3 visits, and the unadjusted confidence interval spans values on both sides of zero. The unadjusted p-value is 0.399. The result is uncertain and does not establish a difference between the groups; it also does not establish that the groups are equivalent or that a difference is absent.

The findings do not show whether Text2Breathe reduced disparities. Reducing disparities is identified as an overarching study goal, but the posted primary endpoint is emergency department visits and the posted secondary endpoint is maximum symptom days. The record does not report a disparity-specific outcome or a comparison of effects across population subgroups. The results should not be taken as a direct test of the broader goal.

The intervention was a package that included communication-skills learning and asthma-related educational text messages, while control participants received usual care and reminder messages. The posted comparison cannot isolate the contribution of any single component. The registry record also does not provide information about message receipt, engagement, adherence, or changes in communication with providers. Those mechanisms cannot be inferred from the outcome summaries.

Finally, the posted summaries are limited by the absence of a reported statistical analysis plan, analysis populations, missing-data details, and multiplicity procedures. They apply to the recorded study groups and outcome definitions; they do not prove that the intervention would have the same results in other settings or populations. The registry record supports a cautious description of the observed means and uncertainty, not a clinical recommendation or a general conclusion about treatment effectiveness.

17. Why This Trial Matters Statistically

This trial raises several important statistical issues because it compares randomized groups on a count outcome but reports the primary result as a mean difference. That summary is easy to interpret in ED visits, yet a mean does not reveal whether the observed pattern reflects many participants with modest counts or a smaller number with repeated visits. The group standard deviations, particularly the larger spread in the Text2Breathe group, underscore why distributional information and suitable analysis choices matter for count data.

The result also illustrates the distinction between an estimate and its precision. The mean difference is positive, but the confidence interval spans zero and the unadjusted p-value is 0.399. A point estimate alone can obscure uncertainty; conversely, a p-value alone cannot show the range of effects compatible with the data. Reading the estimate, interval, group summaries, and reporting limitations together gives a more complete account of what the registry record supports.

Randomization is a design feature, not a substitute for transparent reporting of analysis populations, missing outcomes, or the planned statistical approach. Here, the enrollment figure and primary-outcome group counts do not match, and the record does not explain that difference. With no reported analyses or multiplicity strategy, readers cannot determine how the posted unadjusted comparisons relate to all analyses conducted or planned.

The study’s disparity-focused objective also illustrates why outcome choice matters. A trial can be motivated by inequities without its posted primary endpoint directly measuring whether those inequities changed. The record’s outcomes describe asthma-related utilization and morbidity, but do not report subgroup contrasts or a disparity measure. Statistical interpretation must remain tied to what was measured and reported.

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.

Several limitations specific to the posted Text2Breathe record affect interpretation. The primary endpoint is summarized by means and standard deviations, but participant-level distributions, numbers with no emergency visits, and patterns of repeated visits are not reported. Since the outcome is a count, these details could help readers understand how the group averages arose. The registry does not state whether an analysis suited to count distributions was used.

The posted primary outcome counts are 91 for control and 77 for Text2Breathe, compared with an enrollment of 221. The record does not explain the relationship among these figures, identify reasons for unavailable outcomes, or describe missing-data methods. It also does not report the original sample-size justification, although planning illustrations based on the observed effect are available. The trial’s original design assumptions therefore cannot be evaluated from the registry record.

Masking is recorded as single, but the masked party is not identified. The record gives no analysis plan, adjustment strategy, multiplicity approach, or analysis-population definition. It lists 7 outcome measures and posts one secondary result, without reported analyses. These omissions limit assessment of whether the posted comparisons were prespecified and how they fit among outcomes considered.

The intervention is described as a combination of brief communication learning and ongoing asthma-related texts. The record does not report intervention engagement or separate the effects of those components. It also does not post a direct measure of disparity change, despite identifying disparity reduction as an overarching goal. Consequently, the summaries are informative about the listed outcomes but cannot answer every question raised by the study rationale.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Text2Breathe: Enhance Parent Communication to Reduce Pediatric Asthma Disparities — NCT03032159.
• Registry record last updated 2024-12-03; status last verified 2024-11.
• Results first posted 2024-11-01.
• 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

Text2Breathe (NCT03032159) is a completed randomized, parallel-group study of communication support and asthma-related messaging for parents of children with asthma. The primary endpoint is emergency department visits for asthma care over 12 months. The posted mean difference is 0.3 visits in the direction of a higher mean in the Text2Breathe group; its confidence interval spans zero, and the unadjusted p-value is 0.399.

Asthma Morbidity, measured as maximum symptom days over 12 months, is posted as a secondary outcome. The registry lists no reported analyses, and details about missing outcomes, analysis populations, multiplicity, and the original sample-size assumptions are not reported in the registry record. The results should be read as uncertain, unadjusted summaries of the recorded outcomes.