Oral Health Literacy and Oral Education: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Oral Health Literacy and Oral Education (NCT02436811), a randomized na study. The primary outcome is Changes in the Knowledge Score.

2. Clinical Question

3. Trial Design

The registry record describes a completed randomized, single-masked, parallel-group study. It lists an enrollment of 180 and describes three groups: written form instruction, standardized oral instruction, and control. The arm descriptions list 60 women in each group. The record does not specify who was masked or provide further details about allocation concealment or the randomization procedure.

Literacy in oral health was assessed before randomization using the BREALD-30 instrument. The brief summary says participants were categorized as having adequate literacy at 18 or higher, or low literacy below 18, and were randomly selected according to the score category in a specific intervention. The record does not clarify the full allocation procedure or provide results by literacy category.

The written group received a brochure about diet and oral health for children under two years of age. The standardized oral group received the same information in oral form from a trained individual. The control group received a leaflet about oral cancer. The study thus contrasts two ways of communicating a particular set of child oral-health and feeding information with an educational material on a different subject.

The knowledge statements were administered before the intervention, after a 15-minute break, and after a 4-week interval. Social, economic, and demographic information was to be evaluated at baseline. The registry record lists the study as completed, with a start date of 2014-10 and primary completion in 2015-12. Numerical outcome results and the number of participants assessed at each time point 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.

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 Changes in the Knowledge Score, measured over The nine statements were applied before the intervention (pre-test), after a 15-minute break, the statements were applied again (post-test). After a 4-week interval, the statement were applied once again..

The primary endpoint is change in a knowledge score, expressed in units on a scale. The score was based on nine statements developed and tested in a pilot study. The items concerned breastfeeding, supplemental feeding, sugar intake, bottle use, oral hygiene, and use of fluoride toothpaste. Responses used a three-level Likert format, with an additional “I don't know” option. A correct answer received a score of 1; incorrect answers, including “neither agree nor disagree” and “I don't know,” received a score of 0. The resulting score ranged from 0 to 9, with higher values indicating better outcomes.

Assessments were scheduled before the intervention, after a 15-minute break, and after a 4-week interval. This repeated assessment is intended to describe knowledge immediately after education and its retention at a later assessment. A score based on several statements can provide a concise summary of responses across the covered topics, though it does not show which individual topics were remembered or misunderstood. The registry record does not report observed scores, standard deviations, or the results of change comparisons. It also does not report additional information about the score's measurement properties beyond its development and testing in a pilot study.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes the outcome as a mean of a continuous measure, with standard deviation as the dispersion measure. A continuous score can take values across a defined range, and its mean describes the average score in a group. A standard deviation describes how dispersed individual scores are around that average. These summaries answer different questions: the mean locates the group average, while the standard deviation characterizes variation among participants. Neither summary alone gives the uncertainty around a comparison between groups.

What does repeated assessment contribute?

Each participant was scheduled to complete the knowledge statements before instruction, after a 15-minute break, and after a 4-week interval. Repeated measurements allow assessment of change within participants as well as differences in change between groups. Because measurements from the same participant are related, an analysis should account for that dependence rather than treat every score as unrelated. The brief summary names paired ANOVA and Student's t-tests as planned methods, with corresponding non-parametric tests in the event of non-normality. It does not specify which exact comparison each test was intended to address, how repeated assessments would be represented in the analysis, or how missing observations would be handled.

Why consider distributional assumptions?

General statistical explanation: Parametric methods such as t-tests and ANOVA use assumptions about the distribution of data or model errors. When those assumptions are sufficiently compatible with the data, the methods can estimate mean differences efficiently. If the data are markedly non-normal or contain influential extreme values, a non-parametric alternative may be considered. Non-parametric procedures often work with ranks or distributions rather than directly comparing means, so they may answer a somewhat different statistical question. The registry record says non-parametric tests would be used in the event of non-normality but does not specify diagnostic checks, decision criteria, or the selected alternatives.

What does a significance threshold mean?

The summary states a significance level of 5%. General statistical explanation: A significance threshold is a prespecified rule for judging how compatible observed data are with a null hypothesis under a chosen statistical model. A p-value is not the probability that a treatment works, that the null hypothesis is true, or that a result will repeat. Nor does a threshold describe the size or importance of an effect. The registry record does not provide p-values or state whether tests were one-sided or two-sided for the outcome analyses.

General statistical explanation: A confidence interval expresses uncertainty around an estimated quantity, such as a group difference. Its width reflects the precision of the estimate under the method used. Intervals that include values representing no difference can indicate that the data are compatible with a range of effects, but interpretation also depends on the interval's scale and assumptions. Confidence intervals for the primary outcome are not reported in the registry record.

Why are group comparisons important?

Within-group change can reflect the assigned material, but also changes common to all groups, repeated exposure to the same questions, or other influences over time. A comparison between groups helps distinguish changes associated with one assigned educational approach from changes occurring in a comparator group. A direct comparison of change requires the analysis to respect the repeated measurements and the randomized group assignment. The record does not report an effect estimate for any such contrast or specify a complete model for the multiple assessment times.

The registry record lists 180 as enrollment and describes 60 women per arm. Enrollment is not necessarily the same as the number with outcome data at every assessment. The numbers assessed at each time point, the treatment of withdrawals, and the analysis population are not reported in the registry record. These details affect how much information contributes to an estimate and how representative the analyzed participants may be of those enrolled.

The planning assumptions described in the registry summary refer to an illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such assumptions concern hypothetical planning rather than an observed treatment effect or the trial's original design. The registry record does not report a sample-size justification for the trial itself, and any planning illustration should not be interpreted as observed power or as evidence that a particular effect was established.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome was assessed at multiple time points, and the study has three groups. Those features create more than one possible contrast or analysis. The registry summary notes that the primary outcome has several categories or time points and is not reduced to one comparison. The registry record does not report a multiplicity adjustment, a hierarchy of comparisons, or which contrast was designated as the principal test. Without those details, the nominal significance level alone does not describe the overall chance of a false positive across all analyses.

Outcome completion is also important for repeated measurements. A participant may have a baseline score but not a later score, and the number with observations at each assessment can affect the analysis. The registry record does not report missing-data counts, reasons for missingness, methods for handling incomplete measurements, or whether all randomized participants were included in an analysis. It also does not report an intention-to-treat or per-protocol population definition.

The study description says social, economic, and demographic information would be evaluated at baseline, but it does not specify a covariate-adjustment plan for the primary outcome. Whether analyses were adjusted, and which variables were included, are not reported in the registry record. The record also does not report interim analyses or a detailed statistical analysis plan. These omissions make it difficult to determine how the reported analysis, if any, related to the full set of planned comparisons and available observations.

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

The study's score operationalizes knowledge through correct responses to statements on child feeding and oral health. Its definition makes the outcome understandable, and the repeated assessment schedule distinguishes immediate post-instruction performance from later retention. However, the score is not a direct measure of behavior, child health, or the practical use of the information. The registry record does not report results for those outcomes.

The written and standardized oral groups received information about children's diet and oral health, whereas the control group received oral-cancer education. A comparison between these groups would therefore be a comparison of assigned educational materials and topics, not simply written versus spoken communication under otherwise identical content. The registry record does not report results that would establish the relative performance of these approaches.

The record's hypothesis refers to written instruction and literacy, but the statement is incomplete and no literacy-stratified outcome estimates are reported. The threshold categories used to classify literacy do not, by themselves, reveal whether effects differ by literacy. Evidence for such a difference would require an analysis that directly evaluates variation in the intervention contrast across literacy levels.

Because outcome means, variability, uncertainty estimates, and test results are not reported in the registry record, no conclusion about the magnitude, direction, or precision of a score difference can be drawn from this record. Completion status and the planned statistical methods do not establish the outcome of the study. The available information describes what was intended to be measured and compared, not what the observed data showed.

12. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between how information is delivered and what information is delivered. The written and standardized oral groups were assigned the same child oral-health and feeding content in different formats, while the control group received a leaflet on oral cancer. The design therefore makes the written-versus-oral contrast conceptually different from either intervention-versus-control contrast. Keeping these questions separate matters when defining the estimand: the particular group difference a study aims to estimate.

Repeated measurement is also central. The score was assessed before instruction, after a 15-minute break, and after a 4-week interval. These observations address immediate response and subsequent retention, but are correlated within participants and represent distinct time-specific questions. Analysis should account for that dependence and make clear which time contrast is being estimated. The registry record does not report the chosen contrast or its estimate.

The literacy assessment adds a potential effect-modification question: whether the relative score pattern across instruction groups differs by literacy category. That is not answered simply by observing scores within categories; it requires a direct comparison of effects across literacy levels. The record's incomplete hypothesis statement and absence of literacy-specific results leave that question unresolved.

Finally, this record illustrates the difference between a detailed outcome definition and an interpretable result. The scoring rules and schedule are described, but without outcome estimates and their uncertainty, readers cannot assess the observed pattern. Clear reporting of contrasts, missing observations, analysis populations, and multiplicity would help connect the randomized design to the conclusions that the data support.

13. 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 limitation for interpreting this study from the registry record is that numerical primary outcome results are not reported. Group means, standard deviations, changes over time, between-group contrasts, confidence intervals, and p-values are absent. The direction, size, and precision of any score differences therefore cannot be evaluated.

The planned outcome has repeated assessments, but the record does not give the number of participants with scores at each assessment or explain how incomplete observations were handled. It also does not identify the analysis population. These omissions prevent assessment of attrition and of whether the analyzed participants, if an analysis was conducted, remained comparable across groups.

The registry summary names Student's t-tests and paired ANOVA, with non-parametric tests in case of non-normality, but does not define the exact primary contrast, analysis model, assumptions checks, or procedure for selecting alternatives. The handling of multiple time points and group comparisons is not reported. The record does not report whether analyses were adjusted for baseline characteristics or how the literacy categories were incorporated into analyses.

There is a further interpretive limitation in the control condition: its leaflet addressed oral cancer, while the intervention materials addressed child feeding and oral health. The record does not describe a comparator receiving the same content in a different format. Consequently, intervention-versus-control comparisons would involve differences in topic as well as the assigned educational approach. The identity of the masked party and details of allocation concealment are also not reported in the registry record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Oral Health Literacy and Oral Education — NCT02436811.
• Registry record last updated 2016-05-06; status last verified 2016-04.
• Results first posted 2016-05-06.
• 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.

17. Record Summary

NCT02436811, titled Oral Health Literacy and Oral Education, is recorded as a completed randomized, single-masked, parallel-group study sponsored by Universidade Federal do Paraná. The record lists enrollment of 180 and describes written instruction, standardized oral instruction, and a control group. The arm descriptions list 60 women in each group.

The primary outcome was a knowledge score from nine statements, ranging from 0 to 9, assessed before instruction, after a 15-minute break, and after a 4-week interval. The planned analysis summary names Student's t-tests and paired ANOVA, with corresponding non-parametric tests if the data were non-normal, and states a 5% significance level.

The registry record does not report numerical primary outcome results, group comparisons, uncertainty estimates, missing-data handling, or analysis populations. Its description supports interpretation of the question and measurement plan, but not conclusions about observed score changes or differences between groups.