This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for PRIDE: Preventing Respiratory Illnesses During Childhood Study (NCT00927264), a randomized na study. The primary outcome is Air Nicotine Levels.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00927264 |
| Phase | NA |
| Condition | Tobacco Smoke Pollution |
| Allocation | Randomized |
| Design model | Factorial |
| Masking | Single |
| Enrollment | 350 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Johns Hopkins University |
| Results posted | Yes |
2. Clinical Question
Population
Children enrolled in a Head Start program and living in households that include a smoker were the focus of the study. The registry describes the primary outcome as an indicator of the child’s exposure to environmental tobacco smoke. It does not give further eligibility details in the record.
Intervention
Caregivers in the Behavioral arm were to receive a home-based motivational interviewing intervention for environmental tobacco smoke reduction plus an educational program for smoke reduction. Both parts are described as behavioral interventions in the registry.
Comparator
Caregivers in the Education Only arm were to receive the educational program for environmental tobacco smoke reduction, without the motivational interviewing intervention. This makes the recorded arm contrast an addition of motivational interviewing to education, rather than a comparison with no program.
Primary question
The primary outcome was air nicotine levels, measured at baseline and 3, 6 and 12 months. The registry describes air nicotine as an indicator of the child’s exposure to environmental tobacco smoke. The clinical question is whether the posted air-nicotine results differ between the randomized arms over those assessments. The registry record does not report the outcome values or an arm comparison, so it does not answer that question statistically.
3. Trial Design
PRIDE, or Preventing Respiratory Illnesses During Childhood Study, is registered as NCT00927264. Its official title is “A+ Head Start Intervention for Smoke Free Homes.” Johns Hopkins University is listed as the sponsor. The registry describes the study as randomized, single-masked and factorial, with phase recorded as NA. Enrollment is 350, and the status is completed. The recorded start is 2009-01 and the primary completion is 2013-01.
The intervention was aimed at caregivers of children enrolled in Head Start whose households included a smoker. The Behavioral arm combined a home-based motivational interviewing intervention for environmental tobacco smoke reduction with an educational program. The Education Only arm received the educational program alone. Thus, the comparison concerns the motivational interviewing component added to education. The record does not explain the factorial structure further, so the factors, their levels, and any interaction analyses are not reported in the registry record.
The primary outcome was air nicotine levels, described as a measure of a child’s exposure to environmental tobacco smoke. The recorded unit is mg/m^3, and the planned assessments are baseline, 3, 6 and 12 months. The outcome is summarized using medians and inter-quartile ranges. The registry also lists secondary outcomes relating to the child’s cotinine levels, parent-reported respiratory function, parent or caregiver-reported health care use, and reported endorsement of a home smoking ban. Outcome values for these measures are not reported in the registry record.
Although the study is marked completed, completion status alone does not establish whether the primary result was favorable, precise, or statistically distinguishable between arms. The posted results do not report a statistical analysis count or the primary outcome values, and they do not establish how the factorial label was incorporated into the analysis.
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 had to complete a baseline assessment prior to randomization and reported information for themselves and the targeted child due to the young age of the child. 350 caregivers were recruited but only 330 were randomized because 20 did not complete the baseline assessment.
Overall Study
| Stage | Behavioral | Education Only |
|---|---|---|
| STARTED | 165 | 165 |
| COMPLETED | 109 | 140 |
| NOT COMPLETED | 56 | 25 |
Analysis population for the primary outcome, as defined in the registry: The number analyzed differs at each time point due to missing data. Reasons for missing data include unable to contact
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: Eligible caregivers had to be the parent or legal guardian of a child aged 6 months to 6 years, who reported one or more smokers living in the home, and who spoke English. The enrolled caregiver did not have to be the smoker.
| Characteristic | Unit | Behavioral | Education Only | Total |
|---|---|---|---|---|
| Participants analysed | 165 | 165 | 330 | |
| Age, Continuous: child age | years | 3.81 (SD 0.81) | 3.71 (SD .82) | 3.76 (SD 0.82) |
| Age, Continuous: caregiver age | years | 32.07 (SD 8.6) | 32.12 (SD 9.18) | 32.09 (SD 8.87) |
| Sex: Female, Male: Child Gender – Female | Participants | 87 | 78 | 165 |
| Sex: Female, Male: Child Gender – Male | Participants | 78 | 87 | 165 |
| Sex: Female, Male: Caregiver Gender – Female | Participants | 140 | 148 | 288 |
| Sex: Female, Male: Caregiver Gender – Male | Participants | 25 | 17 | 42 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 153 | 149 | 302 |
| Race (NIH/OMB): White | Participants | 10 | 9 | 19 |
| Race (NIH/OMB): More than one race | Participants | 2 | 7 | 9 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 165 | 165 | 330 |
6. Primary Endpoint
The registry lists the primary outcome as Air Nicotine Levels, measured over Measured at Baseline, 3, 6 and 12 months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | mg/m^3 |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is air nicotine level, recorded in mg/m^3. The registry identifies it as an indicator of the child’s exposure to environmental tobacco smoke. Nicotine in air is therefore used as an environmental measure relevant to the study’s aim of reducing smoke exposure in children’s homes. It is distinct from the child’s cotinine level, which is listed as a secondary outcome and reflects a separate measurement approach.
Air nicotine was assessed at baseline and 3, 6 and 12 months. The endpoint is summarized by median and inter-quartile range. In general, the median describes the central position of observed values, while the inter-quartile range describes the spread of the middle portion of those values. These summaries can be useful when a distribution is skewed or has extreme observations, but they do not by themselves quantify an adjusted treatment contrast or establish statistical uncertainty.
The registry says the number analyzed differs across assessment times because of missing data, with inability to contact among the stated reasons. It does not report the actual median or inter-quartile-range values, the number analyzed at each assessment, or an estimated difference between the arms. Consequently, the endpoint’s role and measurement schedule are described, but the posted results do not permit a quantitative interpretation of the primary outcome.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record establishes the study question and design, but it does not provide the primary air-nicotine results. In particular, it gives no median or inter-quartile-range values at baseline, 3, 6 or 12 months, and no reported comparison between the Behavioral and Education Only arms. It also lists 0 analyses. As a result, the registry record does not support a conclusion about the direction, size or statistical precision of the primary outcome contrast.
The planned contrast is understandable from the arm descriptions: caregivers in the Behavioral arm were to receive motivational interviewing plus education, while caregivers in the Education Only arm were to receive education alone. Any observed difference would therefore relate to the additional motivational interviewing component within the educational-program context. The record does not report whether this contrast was estimated, how it was modeled, or whether the factorial design influenced the analysis.
Air nicotine is described as an indicator of the child’s environmental tobacco smoke exposure. However, knowing the endpoint definition is not equivalent to knowing the result. Without arm-specific outcome summaries and an uncertainty measure, it is not possible to assess how different the measured exposure was between arms, how variable the observations were, or how compatible the results might be with a range of effects.
The registry states that the number analyzed differs at each time point because of missing data, including inability to contact participants. It does not give the analyzed counts or explain how missing observations were handled. This matters for interpretation because the available observations at an assessment may not represent all enrolled participants equally. The record does not report whether missingness was examined by arm or whether any sensitivity analyses were performed.
Safety information is reported separately from the primary outcome. The Behavioral and Education Only groups each list 165 participants at risk for serious adverse events and one affected participant. Other adverse events are listed for 13 participants in the Behavioral group and 10 in the Education Only group. The registry lists asthma hospitalization and broken leg hospitalization among the top serious adverse-event terms, each at 0.6%. These figures do not substitute for the missing primary outcome analysis, and the record does not describe a statistical comparison of adverse events.
Overall, the posted information allows a description of the randomized comparison, the outcome schedule and selected safety counts. It does not allow a statistical judgment about whether air nicotine differed between arms, how precisely any difference was estimated, or whether the observed pattern changed over follow-up.
9. Statistical Methods Explained
In general, a randomized trial assigns participants or other units to study arms by chance. Random assignment is intended to make the arms comparable, on average, with respect to both measured and unmeasured characteristics at the point of assignment. It does not ensure perfect balance in a particular trial, and it does not remove the need to report how outcomes were analyzed. The registry describes this study as randomized, but the method of sequence generation, concealment of assignment and unit of randomization are not reported in the registry record.
What does single masking mean in this record?
The design is labeled single-masked. The registry does not say which people were masked, whether masking applied to outcome assessment, or whether masking was maintained throughout follow-up. These details matter because knowledge of the assigned program can affect behavior, reporting, delivery of an intervention or assessment. The record describes a home-based motivational interviewing intervention and an educational program but does not specify masking procedures for caregivers, intervention staff or outcome assessors.
How should the factorial label be read?
The model is recorded as factorial, but the registry does not identify the factors or explain how they were combined in the analysis. The arm descriptions distinguish motivational interviewing plus education from education alone. Without additional details, it would be inappropriate to infer the factorial components, estimate an interaction, or assume that the primary comparison was analyzed using any particular factorial model. The posted information does not report the statistical model or a primary contrast estimate.
What do median and inter-quartile range communicate?
The primary endpoint is summarized as a median with an inter-quartile range. In general, the median locates the midpoint of ordered observations, and the inter-quartile range describes the spread between the central quartiles. These summaries are often useful when data are asymmetric or contain unusually high values. They are descriptive statistics, however, and do not by themselves answer whether the arms differ beyond what might be expected from sampling variability. That assessment generally requires a contrast and an uncertainty measure, such as a confidence interval, with an analysis appropriate to the design and outcome.
Over-dispersion is a general issue in statistical modeling when the observed variability is greater than a model assumes. If a model underestimates variability, its uncertainty estimates can be too narrow. That concept may be relevant to some count or clustered data, but the registry does not report a model for the air-nicotine outcome or identify over-dispersion as a concern in this study. It should not be assumed to have been present or addressed.
What can the planning assumptions tell readers?
The registry describes a sample-size planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms and a normal approximation. The illustration is described as detecting a stated fraction of the observed effect. It is explicitly not the trial’s own design calculation. No resulting participant counts are reported in the registry record, so none can be interpreted from the posted information.
Such an illustration is a planning aid, not observed power. In general, planning calculations estimate the sample size needed under specified assumptions about an effect and variability. They do not establish the probability that the completed trial found a result, and a calculation based on an observed effect does not replace a reported estimate and confidence interval. The record does not report the original sample-size justification, the effect assumption used for the trial’s design, or whether the study’s enrollment target was based on a particular primary analysis.
For time-to-event outcomes, the registry’s general planning note refers to total events using the Schoenfeld method; for other outcomes, it refers to participants per arm. The primary endpoint in this study is described as air nicotine levels, not a time-to-event outcome. The record does not state a separate time-to-event analysis for the primary endpoint.
What is absent from the reported analysis?
The registry lists 0 analyses and supplies no primary endpoint estimates, confidence intervals or p-values. It does not report whether the analysis was adjusted, how repeated measurements were handled, or whether the comparison was based on a change from baseline or values at individual follow-up assessments. General statistical methods can explain why those choices matter, but they cannot identify which approach this study used. The relevant method and results are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint was measured at baseline and 3, 6 and 12 months. Assessing the outcome at multiple times creates several possible comparisons. In general, when many outcomes, time points or contrasts are tested, the chance of at least one apparently notable result can increase unless the analysis plan addresses multiplicity. The registry record does not report a prespecified primary follow-up time, a multiplicity adjustment, a hierarchy of tests, or a rule for interpreting results across assessments. It also does not report any primary outcome analyses, so the impact of multiplicity on reported findings cannot be evaluated.
The registry lists 5 outcome measures in total and names secondary outcomes involving child cotinine, parent-reported respiratory function, health care utilization, and endorsement of a home smoking ban. It does not report results for those outcomes or explain how multiplicity across primary and secondary outcomes was handled. The analysis plan, including whether any outcomes were exploratory, is not reported in the registry record.
Missing data are specifically noted for the primary outcome: the number analyzed differs at each time point, and stated reasons include inability to contact participants. The record does not give the number missing at each assessment, whether missingness differed between arms, or the method used to handle missing observations. In general, missing-data methods rely on assumptions about why values are missing. When those assumptions are not examined, the available-case results may not fully represent all randomized participants.
The analysis population is also not defined in the registry results. It does not report whether analyses followed an intention-to-treat principle, included only participants with observed measurements, or used another population definition. The handling of withdrawals, protocol deviations and participants without follow-up measurements is not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Behavioral | 1 | 165 | 0.6% |
| Education Only | 1 | 165 | 0.6% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Behavioral | 13 of 165 |
| Education Only | 10 of 165 |
Most frequent serious adverse event terms
| Event term | Organ system | Behavioral | Education Only |
|---|---|---|---|
| Asthma Hospitalization | Respiratory, thoracic and mediastinal disorders | 1 of 165 | 0 of 165 |
| Broken Leg Hospitalization | Surgical and medical procedures | 0 of 165 | 1 of 165 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Behavioral | Education Only |
|---|---|---|---|
| Family Stress Related to Smoking | Social circumstances | 13 of 165 | 10 of 165 |
Serious events with the highest arm-level rate: asthma hospitalization (0.6%), broken leg hospitalization (0.6%).
The adverse-event information lists 165 participants at risk for serious adverse events in each group. One participant is listed as affected by a serious adverse event in the Behavioral group, and one in the Education Only group. For other adverse events, 13 participants are listed as affected in the Behavioral group and 10 in the Education Only group. The registry lists asthma hospitalization and broken leg hospitalization as top serious adverse-event terms, each reported as 0.6%.
These are descriptive counts in the posted safety record. They do not establish that the groups had equivalent safety profiles, nor do they provide a formal estimate of a between-group difference. The record does not specify the event definitions, whether participants could experience multiple events, the period used for each count, or the statistical approach to safety comparisons. The deaths field is null, so death information is not reported in the registry record.
Serious and other adverse events should be read as separate categories as reported, not combined. The registry’s selected serious-event terms are not a complete narrative of each event or its relationship to the intervention. No causal attribution should be inferred from these counts alone.
12. What the Result Does, and Does Not, Mean
The record’s main contribution is a clear description of the clinical question: whether adding home-based motivational interviewing to an educational program for environmental tobacco smoke reduction is associated with different air nicotine levels than education alone among children in households that include a smoker. The outcome was assessed at baseline and 3, 6 and 12 months and summarized using medians and inter-quartile ranges.
That description does not establish what happened to air nicotine. The primary values, analyzed counts by assessment, arm contrast and measures of statistical uncertainty are not reported in the registry record. The record therefore cannot show the magnitude or direction of any difference, how precisely it was estimated, or whether the pattern varied over time. Completed status and enrollment of 350 do not fill in those missing results.
The same distinction applies to the listed secondary outcomes. Their names indicate additional questions about cotinine, respiratory function, health care use and home smoking bans, but no outcome values or analyses are reported. The adverse-event counts offer limited descriptive safety information, but do not provide a comparative analysis or establish attribution.
In general, a trial result is most informative when readers can see the outcome estimates, uncertainty, analysis population, and methods used to address missing data and multiple comparisons. Those details help distinguish a small, imprecise estimate from a more precise finding and clarify which comparison the analysis supports. Here, the registry describes the design and measurement schedule but not the quantitative primary analysis.
Accordingly, the posted information supports interpretation of the trial’s planned comparison and certain recorded safety counts, but not a conclusion about the effect of the motivational interviewing component on the primary endpoint. It also cannot establish whether the study was sufficiently informative to rule in or rule out effects of particular sizes.
13. Why This Trial Matters Statistically
This trial raises a useful statistical distinction between a well-described question and an interpretable result. The registry identifies the randomized arms, the primary endpoint, its measurement schedule and the way the outcome was summarized. Yet the primary outcome values and statistical comparison are not reported. Without those, readers cannot judge the size or precision of the arm contrast, regardless of the completed status of the study.
The design also highlights why repeated assessments and missing follow-up matter. Air nicotine was measured at baseline and 3, 6 and 12 months, while the registry states that the number analyzed differs by time point because of missing data, including inability to contact participants. In general, an analysis must clarify how measurements across time are compared and how incomplete follow-up is handled. The registry does not report those decisions, so the consequences for interpretation cannot be assessed.
The listed median and inter-quartile range are appropriate descriptive forms for a distribution that may not be symmetric, but descriptive summaries alone do not quantify uncertainty about the contrast. An estimate and uncertainty interval would help readers understand the range of effects compatible with the data. Neither is reported for the primary endpoint.
Finally, the record includes a planning illustration based on an observed effect, but it is not the trial’s own design calculation. This distinction matters: retrospective planning illustrations are not evidence of observed power and do not replace reported estimates. The absent primary results leave the central efficacy question unresolved in the registry record, even though the study’s aims and intervention comparison are described.
14. 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 central limitation for interpreting this trial from the registry is that the primary outcome results are not reported. Air nicotine medians and inter-quartile ranges, arm-specific analyzed counts and a statistical contrast are absent. The record lists 0 analyses, so it is not possible to assess the effect’s direction, size or precision from the posted information.
The registry notes that the number analyzed varies across time points because of missing data, with inability to contact participants among the reasons. It does not report the extent or distribution of missingness, how missing observations were handled, or whether the missingness pattern differed by arm. This prevents an assessment of possible bias from incomplete follow-up.
Further design and analysis details are not reported in the registry record. These include the factorial components and their analytic role, the identity of the masked parties, the randomization and allocation procedures, the analysis population, the primary statistical model, adjustment for baseline values or repeated measurements, and any multiplicity strategy. The registry also does not report the original sample-size justification or the results of the listed secondary outcomes.
The safety record gives counts and selected serious-event terms, but does not describe event definitions, event timing, attribution, or formal comparisons. The deaths field is null. These limits mean that the posted safety information should be read descriptively rather than as a full comparative assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: PRIDE: Preventing Respiratory Illnesses During Childhood Study — NCT00927264.
- Registry record last updated 2017-08-24; status last verified 2017-08.
- Results first posted 2017-08-24.
- 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.
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18. Record Summary
NCT00927264, PRIDE: Preventing Respiratory Illnesses During Childhood Study, is registered as a completed randomized, single-masked, factorial study sponsored by Johns Hopkins University. Enrollment is 350; phase is listed as NA. The recorded start is 2009-01 and primary completion is 2013-01.
The study compared a home-based motivational interviewing intervention plus education for environmental tobacco smoke reduction with education alone. The primary outcome was air nicotine level in mg/m^3, summarized by median and inter-quartile range at baseline and 3, 6 and 12 months. The registry describes air nicotine as an indicator of the child’s exposure to environmental tobacco smoke.
The record notes varying analyzed numbers across time points because of missing data, including inability to contact participants. It lists 5 outcome measures and 0 analyses. Primary outcome estimates and secondary outcome results are not reported in the registry record. Safety counts are reported descriptively, including one serious adverse event in each arm.