Family-Focused, Stress-Reduction Program to Improve the Health Care of Urban Children With Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Family-Focused, Stress-Reduction Program to Improve the Health Care of Urban Children With Asthma (NCT00384813), a randomized phase 2 study. The primary outcome is Mean Score on the Family Asthma Management System Scale (FAMSS).

2. Clinical Question

The clinical rationale recorded for the study is that stress and anxiety may negatively affect children with asthma, and that reducing stress for children and their families may support asthma care and reduce asthma symptoms. The intervention was intended to address family stress and asthma management together. The primary outcome, however, is a score about family asthma management; it is not a direct measure of stress, anxiety, or asthma symptoms.

The comparison therefore asks whether the average reported management score differed between two behavioral-program groups at the specified follow-up. The study enrolled 43 participants. The registry record does not report enough detail to define the age range, recruitment setting beyond the urban-family focus, or the full eligibility criteria. Nor does it report results for every possible clinical measure. The primary comparison should be read as evidence about this outcome at this follow-up, rather than as a complete assessment of all aspects of asthma health or family well-being.

3. Trial Design

This was a Phase 2, randomized, single-masked, parallel-group trial sponsored by Emory University. The registry record lists a total enrollment of 43 and a completed study status. The listed study dates run from 2007-01 to primary completion in 2009-04. These record details describe the trial structure and timing, but do not give the full operational protocol.

Participants were allocated to one of two behavioral interventions: the Project ASPIRE Home-Based Family Intervention or Project ASPIRE Enhanced Treatment As Usual. The enhanced usual-treatment arm is described as including one home visit. The record does not specify who was masked, how masking was maintained, or whether masking applied to outcome rating. It also does not report the allocation-generation or concealment procedures.

The primary outcome was assessed at 4 months from baseline. Posted group results include 21 participants for the home-based intervention and 20 for enhanced treatment as usual. Those outcome denominators do not account for the full enrollment listed in the record; the reasons for the difference are not reported in the registry record. The adverse-event record lists its own at-risk counts, which should not be assumed to be the same analysis population as the primary outcome.

The study is described as a program-development and evaluation effort focused on family stress and pediatric asthma management. The registry record does not report the original sample-size justification, detailed recruitment or retention procedures, the analysis population, or a full statistical analysis plan. As a result, the randomized parallel-group structure is clear, while several details needed to reconstruct implementation and analysis are not available 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: Caregivers of children meeting initial eligibility criteria were interviewed briefly by phone; those answering affirmatively to either of two stress questions were invited to participate in a Screening Assessment. Caregivers with an elevated score on a stress measure were invited to participate in the trial.

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.

6. Primary Endpoint

The registry lists the primary outcome as Mean Score on the Family Asthma Management System Scale (FAMSS), measured over 4 months from baseline.

The primary endpoint is the mean score on the Family Asthma Management System Scale (FAMSS) at 4 months from baseline. The measure is based on a semi-structured clinical interview with open-ended questions about how a family manages pediatric asthma. The interview is recorded and rated using a standard manual across seven core subscales and two optional subscales; the description also characterizes the score as an average of the subscales used to form a total score.

Scores are based on subscales rated from 1 to 9, with higher scores indicating better asthma management. The endpoint is therefore intended to capture multiple domains of family management rather than one isolated behavior or a direct measure of symptoms. An average score can provide a compact summary of the domains used in scoring, but it may conceal differences among those domains. The record does not say which optional subscales were used for each participant or report separate primary results by subscale.

This measure is relevant to the program’s stated focus on improving family asthma care. Its interpretation should remain specific to management as assessed by the interview and rating process. It should not be treated as a direct measure of stress reduction, asthma symptoms, or broader health outcomes.

7. Results Posted in the Registry

• 1: Home-based Family Intervention: mean 4.90 versus 4.10 on control; difference 0.80 (95% CI -0.02 to 1.62), standardized effect d = 0.60; z-test p = 0.056.

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean score describe? For a continuous outcome such as FAMSS, a group mean is the average of participants’ scores in that group. It provides a concise description of the group’s typical score but does not show the full distribution. Participants may have scores above or below the mean, and the registry record does not post the individual-level score distribution. Because higher FAMSS scores indicate better management, the direction of a mean difference can be interpreted using that scale convention.

What is the standard error? A standard error describes the sampling uncertainty in an estimated mean. In general, it reflects how much an estimate would vary across repeated samples under the statistical assumptions used. It is not the same as the spread of individual participant scores. The reported values are standard errors, not standard deviations. The record does not post the group standard deviations for this outcome, and the distinction matters: a standard error concerns precision of the mean, whereas a standard deviation describes variation among observations.

How should the group contrast be read? The unadjusted recalculation compares the posted group means. It gives a mean difference of 0.8, expressed in FAMSS scale units, in the direction of the home-based intervention group having the higher mean. This calculation uses the posted summary statistics and does not adjust for additional variables. It is not the same as the registry’s reported regression coefficient. The record reports a linear regression analysis, but does not describe its covariates, model specification, handling of baseline score, or other analytical choices. Those details are not reported in the registry record.

What does a confidence interval add? In general, a confidence interval represents a range of values that are compatible with the observed data under the method’s assumptions. It communicates both the estimated direction and the uncertainty around the estimate. For the unadjusted mean difference, the interval runs from just below zero to 1.622. Because it includes zero, the data do not clearly distinguish a positive difference from no difference under that calculation. The interval is not a range containing a known true value with certainty, and it does not by itself account for unreported design or analysis choices.

What does the p value say? In general, a p value measures how unusual the observed data, or more extreme data, would be under a specified null hypothesis and statistical model. The unadjusted recalculation has p = 0.056. The registry’s linear regression analysis reports p = 0.23. Those values refer to different analyses and should not be treated as interchangeable. Neither p value gives the probability that the null hypothesis is true, nor does either quantify the practical importance of a score difference.

Why can analysis methods yield different estimates? An unadjusted comparison uses the group summaries without adjustment. Regression can estimate a contrast conditional on variables included in its model, or can reflect a different parameterization. In general, differences in adjustment, outcome handling, or analysis populations can affect estimates and uncertainty. The record does not report enough detail to say which, if any, of these explains the difference between the unadjusted recalculation and the reported coefficient. There is no posted confidence interval for the regression coefficient to assess its precision in the same way.

Why does variation matter? General statistical methods often account for how much observations vary within groups when estimating uncertainty. If outcomes show more variation than a model expects, uncertainty estimates can be too small unless the analysis allows for that extra variation; this issue is often called over-dispersion in settings where that concept applies. The FAMSS endpoint is continuous, and the record does not report a variance diagnostic or a specific over-dispersion assessment. No claim about such a problem can be made from the posted summary alone.

What is not established by the method description? The record lists one reported analysis and five outcome measures, but does not provide a complete statistical analysis plan. It does not report the trial’s original sample-size justification, interim analyses, a missing-data method, or a clearly defined analysis population. Those omissions limit independent evaluation of whether every design and analysis decision was prespecified and how incomplete outcome data were handled. General explanations of statistical methods do not fill in those missing trial-specific details.

10. Confidence Intervals and Precision

The unadjusted mean difference is 0.8 FAMSS units. Its confidence interval extends from slightly below zero to 1.622. The lower endpoint being just below zero is important: the interval includes a null difference, even though the point estimate favors a higher average score in the home-based intervention group. The interval also reaches values meaningfully above zero on the scale, so the available estimate permits a range of possible differences rather than pinpointing one value.

A confidence interval is a measure of statistical precision under the calculation’s assumptions. It is not a guarantee that the true effect lies within the interval, and it does not incorporate uncertainties that are not represented by the calculation. Here, the interval comes from an unadjusted recalculation based on posted group summaries, not from the registry’s reported regression analysis. The registry record does not post a confidence interval for the regression coefficient, so its precision cannot be evaluated from a corresponding interval in the record.

The posted standard errors are 0.293 for the home-based intervention mean and 0.3 for the enhanced treatment as usual mean. These describe uncertainty in the estimated means, not the range of individual participants’ scores. The primary-outcome groups include 21 and 20 participants, respectively. That amount of information leaves the group comparison subject to appreciable uncertainty, as reflected in the interval spanning zero. The record does not report a prespecified clinically important difference for FAMSS, so statistical precision cannot be translated into a judgment about clinical importance.

The unadjusted p value is 0.056, while the reported regression analysis gives p = 0.23. Because the analyses differ and the regression interval is not posted, the two values should not be merged into a single precision statement. Both should be interpreted alongside the estimate, endpoint definition, and missing analysis details.

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 sample-size figures are planning illustrations based on the observed effect, not the trial’s original design assumptions. The figures are participants per arm, not total events. They assume a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. They use the stated fraction of the observed effect as the effect to detect. The registry record does not report the original sample-size justification or the trial’s own planning assumptions.

For planning for 100% of the observed effect, the illustration gives 45 participants per arm for 80% power and 60 participants per arm for 90% power. For planning for 75% of the observed effect, it gives 79 participants per arm for 80% power and 106 participants per arm for 90% power. For planning for 50% of the observed effect, it gives 177 participants per arm for 80% power and 237 participants per arm for 90% power.

In plain language, the 80% power column describes the planned number of participants per arm under which the calculation would have an 80% chance of detecting the specified effect if that effect were real and the assumptions held. The 90% power column uses a higher chance of detection and therefore has larger participant counts for each effect assumption. Planning for a smaller effect requires more participants, because a smaller group difference is harder to distinguish from sampling variation.

These are planning illustrations, not observed power. They are based on the effect estimated in this trial and do not show the probability that this completed trial produced a correct result. Their relevance depends on whether the assumed effect, allocation, statistical approximation, and other planning conditions are suitable for a future study.

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 = 0.800; pooled standard deviation σ = 1.342.
2. n = 2 × (1.96 + 0.842)² × 1.342² / 0.800² = 44.2, rounded up to 45 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 <- 0.800000000000001                      # observed difference in means
sigma <- 1.34218134737105                     # 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(384813)
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 = 45 (80% power), 60 (90% power)
 75% of observed effect: n per arm = 79 (80% power), 106 (90% power)
 50% of observed effect: n per arm = 177 (80% power), 237 (90% power)
power.t.test: 45.2 
Simulated power at n = 45 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 registry’s reported sponsor analysis is a linear regression comparing the two groups. It gives a regression coefficient of .33 and p = 0.23. A confidence interval for this coefficient is not posted. The record does not describe the regression model in enough detail to identify the covariates, the coefficient’s precise interpretation, or the assumptions used for inference.

The unadjusted recalculation from the posted means gives a difference of 0.8, a confidence interval extending from just below zero to 1.622, and p = 0.056. This is a simple comparison based on group summary statistics. It is not a reproduction of the sponsor’s regression analysis and may not estimate precisely the same quantity. Without the model details, the reason for the difference cannot be determined from the registry record.

The two analyses should therefore be reported separately. The recalculation is useful for understanding the posted group means and the uncertainty around their unadjusted contrast; the registry result is the reported regression analysis. The record does not indicate a discrepancy flag for these results, but that does not make the estimands or methods identical. The regression p value should not be substituted for the unadjusted p value, or vice versa, and the missing regression confidence interval limits comparison of precision.

14. Multiplicity, Missing Data and Analysis Populations

The registry record lists five outcome measures and identifies two secondary outcomes: the Parenting Stress Index - SF (PSI-SF) and the Brief Symptom Inventory (BSI). It reports one analysis. The primary endpoint is the mean FAMSS score at 4 months from baseline. The record does not report results for every outcome measure in the information available, nor does it state whether additional analyses were conducted but not posted.

When a study evaluates multiple outcomes or makes multiple comparisons, the chance of obtaining at least one apparently notable result can increase. In general, multiplicity procedures can control that risk by adjusting interpretation or statistical thresholds. The registry record does not report a multiplicity adjustment, a hierarchy for outcome testing, or a plan for prioritizing secondary outcomes. It is therefore not possible to determine whether the reported p values were intended as confirmatory tests or how multiple outcomes were considered.

The record reports a linear regression for the primary comparison but does not provide the model specification or a complete analysis plan. It does not report an interim-analysis plan or whether any interim analyses occurred. The original sample-size justification is also not reported in the registry record. These details matter because choices about monitoring, analysis, and outcome selection can affect how a reported result should be interpreted.

The outcome group counts are 21 and 20, whereas total enrollment is 43. The record does not explain the difference or state whether participants without posted endpoint results were missing, excluded, or handled in another way. It does not report a missing-data method, an intention-to-treat definition, a per-protocol population, or other analysis-population definitions. The registry record therefore does not establish how missing outcomes or departures from assigned intervention were treated.

These are reporting limits, not evidence that a particular analysis choice was made incorrectly. They constrain evaluation of multiplicity, missing data, and the relationship between the randomized groups and the analyzed participants. Conclusions should remain tied to the posted primary comparison and the analysis details that are actually reported.

15. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The adverse-event record lists 23 participants at risk in the home-based family intervention group and 20 in enhanced treatment as usual. It reports zero serious adverse events in each group and zero other adverse events in each group. Death counts are not reported in the registry record. The adverse-event counts should be read using these listed at-risk denominators, rather than assuming they match the primary-outcome analysis counts.

A reported count of zero means that the registry record lists no events of that type among the participants counted as at risk. It does not prove that an event is impossible, that every event was captured, or that the interventions have no safety concerns. The record does not describe adverse-event collection methods, event definitions beyond the serious and other categories, or the observation period for these counts. It also does not list serious-event terms.

These figures are descriptive safety reporting for the groups and denominators recorded. They do not support a broader safety conclusion beyond the reported counts, particularly because the study’s total enrollment was 43 and details about ascertainment and follow-up are not available in the registry record.

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

The posted primary outcome shows higher average FAMSS scores in the home-based family intervention group than in the enhanced treatment as usual group at 4 months from baseline: 4.9 compared with 4.1. Since higher scores indicate better asthma management, the observed mean scores favor the home-based intervention in direction. The unadjusted mean difference is 0.8, but its confidence interval extends from just below zero to 1.622 and its p value is 0.056.

This combination of estimate and uncertainty does not establish a clear difference. The point estimate is one possible summary of the observed group contrast, while the confidence interval indicates that the data are compatible with a range of differences, including no difference. The registry’s separate regression analysis reports coefficient .33 and p = 0.23. Because the model details and regression confidence interval are not reported, this result cannot be fully aligned with the unadjusted calculation.

The endpoint measures family management as assessed through an interview and rating scale. It does not directly measure stress reduction, anxiety, asthma symptoms, or longer-term clinical outcomes. Although those topics form part of the study rationale, the primary result alone cannot establish changes in them. Nor does a group average indicate how every family’s management changed.

The randomized parallel-group design supports a comparative question, but interpretation is limited by the small number of posted primary-outcome participants, the difference between outcome counts and total enrollment, and missing details on the analysis population, missing data, and regression model. The record also does not report a clinically important difference for the scale. Statistical evidence and clinical importance are distinct: neither can be settled from the mean difference alone.

The result is best understood as an uncertain difference in average interview-rated asthma management at one follow-up. It is not a definitive conclusion about treatment benefit or lack of benefit, and it should not be extended to outcomes or populations not represented in the posted record.

17. Why This Trial Matters Statistically

This trial illustrates why an observed difference, a confidence interval, and a p value need to be read together. The home-based intervention group had a higher posted mean FAMSS score, but the unadjusted confidence interval includes zero and the unadjusted p value is 0.056. Reporting only the point estimate would leave out the uncertainty; reporting only the p value would leave out the direction and scale of the comparison.

It also shows why the estimand and analysis method matter. The simple mean difference is 0.8, while the registry’s linear regression reports coefficient .33 with p = 0.23. Those results come from differently described analyses, and the regression model is not detailed enough to explain their relationship. Statistical interpretation depends on knowing what quantity an analysis estimates, how it handles baseline information and other variables, and which participants are included.

The study further highlights the importance of distinguishing the endpoint from the broader rationale. Family stress, asthma symptoms, and asthma management are related ideas in the stated purpose, but the primary endpoint is an interview-rated management score. A result for that measure should not be treated as a result for every aspect of family or child health.

Finally, sample-size illustrations based on an observed effect are planning tools, not evidence of the power achieved by a completed trial. Their assumptions and the size of the effect targeted shape the participant counts. Together, these distinctions help readers separate what the data describe from what remains uncertain or unreported.

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 primary-outcome groups include 21 participants in the home-based family intervention and 20 in enhanced treatment as usual, while enrollment is listed as 43. The registry record does not explain this difference. Without a reported analysis population or missing-data approach, it is not possible to determine how the outcome counts relate to all randomized or enrolled participants.

The outcome is reported at 4 months from baseline, and no longer-term primary result is described in the record. The FAMSS is an interview-based measure rated across multiple subscales; the record does not identify which optional subscales were used for each participant or provide separate results by domain. It also does not report a clinically important difference or information about consistency of ratings.

The trial is described as randomized and single-masked, but the record does not say who was masked or provide allocation procedures. The sponsor’s linear regression result lacks a confidence interval and a detailed model description. The unadjusted recalculation is therefore not a substitute for a fully specified reported analysis. The record also does not report the original sample-size justification, multiplicity procedures, interim analyses, or handling of missing data.

The study’s focus is urban children with asthma and their families, but the record does not provide further population characteristics in the information reported. Generalizability to other settings or groups cannot be evaluated from these results alone. These limitations identify what cannot be assessed from the registry record; they do not establish that any particular design or analysis decision was inappropriate.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Family-Focused, Stress-Reduction Program to Improve the Health Care of Urban Children With Asthma — NCT00384813.
• Registry record last updated 2014-07-28; status last verified 2014-07.
• Results first posted 2014-07-28.
• 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

NCT00384813 is a completed, randomized, single-masked, parallel-group Phase 2 trial sponsored by Emory University. It enrolled 43 participants and compared the Project ASPIRE Home-Based Family Intervention with Project ASPIRE Enhanced Treatment As Usual, described as including one home visit. The study focused on asthma management for urban children and families.

The primary outcome was mean FAMSS score at 4 months from baseline. Posted means were 4.9 for the home-based intervention group and 4.1 for enhanced treatment as usual. The unadjusted recalculation gives a difference of 0.8, with an interval extending from just below zero to 1.622 and p = 0.056. The registry separately reports a linear regression coefficient of .33 with p = 0.23.

The record lists two secondary outcomes and five outcome measures. It reports zero serious and zero other adverse events in each group; death counts are not reported in the registry record. Key analysis details, including the original sample-size justification, missing-data handling, and regression specification, are not reported.