Comparing Cetaphil Restoraderm System Versus Standard Skin Care in Infants: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparing Cetaphil Restoraderm System Versus Standard Skin Care in Infants (NCT01375205), a randomized na study. The primary outcome is Percentage of Participants With Cumulative Atopic Dermatitis Diagnosed by Investigator at 12 Months.

2. Clinical Question

This question concerns the percentage of infants with a diagnosed event by a stated follow-up time, rather than the timing of diagnosis or a continuous measure of skin condition. It therefore compares the occurrence of the diagnosis between the randomized groups. The trial also listed secondary outcomes including age at onset of eczema, filaggrin mutation status, transepidermal water loss, skin hydration, skin pH, and high emollient use. Results for those secondary outcomes are not reported in the registry record.

The registry describes the study as a randomized pilot trial. That context matters when interpreting the comparison: the primary result is an estimate from the participants with posted outcome data, and the registry record notes loss to follow-up by 12 months. The posted percentages describe the observed groups; they do not by themselves establish how outcomes would differ in a broader population or under other skin-care routines.

3. Trial Design

The study was randomized, single-masked, and used a parallel-group model. Participants were assigned to Cetaphil Restoraderm or standard skin care, with each group following a different skin-care routine. The registry record lists an enrollment of 100 and classifies the study as a pilot trial. Its status is completed. The recorded study start is 2011-06, and primary completion is recorded as 2014-10.

The Cetaphil group was instructed to apply moisturizer once daily and bathe the infant with the Cetaphil cleanser. In the standard-care group, moisturizer could be applied as often as desired, alongside use of the Johnson & Johnson cleanser. These routines differ in product and in the stated moisturizer-use instructions. The comparison therefore concerns the assigned skin-care regimens as described in the registry, not an isolated ingredient or a single product used under identical instructions.

The primary endpoint was cumulative atopic dermatitis diagnosed by an investigator described as blinded, assessed at 12 months. The word blinded indicates that the investigator assessing this outcome was masked, but the specific masking procedures and which other people were masked are not reported in the registry record. The registry identifies the overall trial masking as single.

Although 100 participants were enrolled, the arm counts attached to the primary outcome are 38 for Cetaphil Restoraderm and 32 for standard care. The record states that around 28% of subjects enrolled were lost to follow-up by 12 months. It does not explain the full accounting of participant flow, the reasons for missing follow-up, or whether the outcome counts reflect a prespecified analysis population. The trial's original sample-size justification and design assumptions are not reported in the registry record.

The listed sponsor was Oregon Health and Science University. The registry names atopic dermatitis as the condition and includes secondary measures of skin barrier and hydration, as well as other outcomes. A randomized parallel design allows an outcome comparison between groups assigned to different care routines, while single masking of the investigator can reduce the influence of knowledge of assignment during outcome assessment. Those design features do not resolve uncertainty due to missing follow-up or the limited precision of the observed comparison.

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:

Analysis population for the primary outcome, as defined in the registry: Around 28% of subjects enrolled were lost to follow-up by 12 months

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 Percentage of Participants With Cumulative Atopic Dermatitis Diagnosed by Investigator at 12 Months, measured over 12 months.

The primary endpoint is the percentage of participants with cumulative atopic dermatitis diagnosed by an investigator at 12 months. The registry describes the diagnosis as being made by a blinded investigator. A cumulative percentage records whether the event was observed by the stated time; it does not describe how quickly the diagnosis occurred or the duration or severity of symptoms.

This type of binary endpoint is useful when the research question concerns whether an event occurred by a defined follow-up time. It produces an interpretable group-level summary: the proportion of participants with the diagnosis in each arm. For this trial, the posted values are 13.2% in the Cetaphil Restoraderm group and 25.0% in the standard-care group. The outcome counts attached to those groups are 5 of 38 and 8 of 32, respectively.

General: comparing event percentages gives a direct description of the observed frequency in each group. A relative measure or a difference between group risks can express the contrast in other ways, but each depends on the same underlying event data and answers a somewhat different descriptive question. The choice of measure should be read alongside its uncertainty, not as a guarantee of what would occur for a new set of participants.

The endpoint is one part of a broader set of planned outcomes. The record lists secondary outcomes concerning eczema onset, emollient use, filaggrin mutation status, transepidermal water loss, skin hydration, and skin pH, but results for those outcomes are not reported in the registry record. The primary result therefore addresses the stated diagnosis endpoint, not every dimension of skin condition named in the study record.

7. Results Posted in the Registry

• Cetaphil Restoraderm: 13.2% (5/38) versus 25.0% (8/32) on control; risk difference -11.8 percentage points (95% CI -30.3 to 6.6), risk ratio 0.53 (0.19–1.45); unadjusted two-proportion z-test p = 0.204.

8. Statistical Interpretation

9. Statistical Methods Explained

The posted comparison is an unadjusted comparison of a binary outcome: whether atopic dermatitis was diagnosed by 12 months. The arm-level results are percentages of participants with the event. The risk-difference estimate compares the event risk in the Cetaphil Restoraderm arm with the event risk in standard care. Its negative direction reflects a lower observed risk in the Cetaphil group. The comparison also reports relative measures, but the registry's main interpretation should remain anchored in the primary outcome and the uncertainty around the group contrast.

What does a risk difference describe?

General: a risk difference is the event proportion in one group minus the event proportion in another group, using a stated group order. A value of zero corresponds to equal observed risks. A negative estimate in this comparison means the observed event percentage was lower in the Cetaphil arm than in the standard-care arm. The estimate is a contrast between the observed groups, not an individual prediction, and its size should be considered with its confidence interval.

The posted risk-difference estimate is -0.118. Its confidence interval runs from -0.303 to 0.066. This interval includes zero, so it does not exclude no difference. The point estimate alone can look more definite than the underlying data warrant; the interval shows that the estimated contrast is imprecise and is compatible with both a negative and a positive difference.

What does the p-value say?

The unadjusted p-value is 0.204. General: a p-value assesses the compatibility of observed data with a specified null hypothesis under the assumptions of a statistical test. It is not the probability that the null hypothesis is correct, the probability that a result occurred by chance, or a measure of clinical importance. A relatively large p-value does not prove equivalence or absence of an effect. A p-value also does not communicate the range of plausible effect sizes as directly as a confidence interval.

The registry provides an unadjusted comparison. An adjusted statistical model, covariate adjustment, or stratified analysis is not reported in the registry record. The record also does not state the test procedure used to obtain the p-value, so the calculation should not be described as a specific named test. The posted result can be discussed as an unadjusted estimate and p-value without inferring unreported analytic details.

Why can a binary outcome be informative?

General: binary outcomes reduce each participant's result to whether an event occurred within the defined period. They are straightforward to communicate as percentages, but they discard information about timing, severity, and variation within each category. A time-to-event analysis could address timing, but such an analysis is not reported for the primary endpoint in the registry record. The endpoint specified is the cumulative percentage diagnosed at 12 months.

The primary outcome uses participants with posted arm denominators of 38 and 32, alongside counts of 5 and 8. These observed counts are small enough that individual outcomes contribute visibly to the group percentages. General: with fewer observed events, estimates of event risks and contrasts can be uncertain, particularly when follow-up is incomplete. This general point does not identify the cause of uncertainty in this trial; the registry does not give enough information to separate the contribution of sample size, outcome frequency, and missing follow-up.

How should the confidence interval be read?

General: a confidence interval is a range of estimates generated by a statistical procedure that reflects sampling variability under its assumptions. It helps distinguish a precise estimate from one that permits a broad range of effect sizes. It does not account automatically for selection bias, outcome misclassification, deviations from assigned care, or other limitations. The posted interval crosses zero and includes both directions of difference, so the sign of the point estimate should not be treated as conclusive.

The registry also posts risk-ratio and odds-ratio estimates with intervals. These are alternative scales for expressing a comparison of binary outcomes. General: a risk ratio compares event risks as a ratio, while an odds ratio compares event odds. Neither scale removes uncertainty, and values on different scales are not directly interchangeable. The primary result is easiest to anchor in the posted event percentages and risk-difference interval; no additional conclusion should be drawn from a different scale without considering its interval and interpretation.

What remains unknown about the analysis?

The registry record does not report the original statistical analysis plan, the trial's sample-size justification, whether interim analyses were conducted, the handling of missing outcomes, or the analysis population. It also does not report whether the primary analysis followed randomized assignment regardless of adherence. These omissions prevent a fuller assessment of the planned-versus-posted analysis and the extent to which the available comparison preserves the randomized groups.

The record lists 8 outcome measures, and 6 secondary outcomes are posted by name, but it reports 0 analyses. Results for the secondary outcomes are not reported in the registry record. Whether any multiplicity adjustment was specified or applied is also not reported in the registry record. These gaps mean that the primary endpoint should be interpreted on its own terms, without assuming how other outcomes or repeated analyses were handled.

10. Confidence Intervals and Precision

The point estimate favors a lower observed event percentage in the Cetaphil Restoraderm arm, but its confidence interval extends across zero. The interval therefore includes values consistent with a lower event risk in Cetaphil and values consistent with a higher event risk. Its span is an important part of the result: the direction and size of the underlying contrast are not estimated precisely enough to rule out either direction on the risk-difference scale.

The two arm percentages are based on 5 events among 38 participants in the Cetaphil group and 8 among 32 in standard care. These counts describe the participants included in the posted primary result. The total enrollment was 100, and around 28% of subjects enrolled were lost to follow-up by 12 months. The registry does not explain the complete accounting between enrollment, loss to follow-up, and the primary-outcome denominators. That missing detail limits interpretation of the precision because a confidence interval for the observed comparison does not itself account for possible bias from unobserved outcomes.

General: sampling precision concerns how much an estimate may vary across samples under the statistical model. A confidence interval conveys one component of that uncertainty. It does not incorporate every uncertainty about conduct or data completeness, and a narrow interval would not by itself eliminate bias. In this trial, the interval crosses zero and the record also reports substantial loss to follow-up, so both statistical uncertainty and completeness of outcome information deserve attention.

The registry record does not state a confidence level for the interval, so no confidence percentage should be inferred from the posted limits. Nor does the interval establish that the groups are equivalent. An equivalence conclusion would require a prespecified margin and an analysis designed for that purpose; such a margin and analysis are not reported in the registry record. The appropriate reading is that the observed estimate is uncertain and compatible with effects on either side of zero, with missing-data details also unavailable.

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 planning figures are planning illustrations based on the observed effect, not the trial's original design justification. For this comparison, the figures are participants per arm, not total events. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is specified as a fraction of the observed effect.

The 80% power column gives the planned number of participants per arm for a hypothetical study to have an 80% chance of detecting the stated effect under those assumptions, if that effect and the model assumptions were correct. The 90% power column gives the corresponding number per arm for a 90% chance. These are planning targets for a future study, not numbers of participants observed in this pilot.

For planning at 100% of the observed effect, the figures are 172 participants per arm for 80% power and 230 participants per arm for 90% power. For planning at 75% of the observed effect, they are 324 participants per arm for 80% power and 434 participants per arm for 90% power. For planning at 50% of the observed effect, they are 769 participants per arm for 80% power and 1,028 participants per arm for 90% power.

General: smaller effects are harder to distinguish from random variation, so studies designed to detect smaller effects generally require more participants when other assumptions are held fixed. The rising planning figures as the assumed fraction decreases illustrate that relationship. They should not be read as a recommendation or a forecast: the observed effect is itself uncertain, and the trial's own original design assumptions are not reported in the registry record. These figures are not observed power.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.250; treatment proportion p₁ = 0.132; average p̄ = 0.191.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5557 = 1.0891.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5493 = 0.4623.
4. n = (1.0891 + 0.4623)² / (-0.1184)² = 171.6, rounded up to 172 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
p0 <- 0.25                          # control proportion
p1 <- 0.131578947368421                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1375205)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 172 (80% power), 230 (90% power)
 75% of observed effect: n per arm = 324 (80% power), 434 (90% power)
 50% of observed effect: n per arm = 769 (80% power), 1,028 (90% power)
power.prop.test: 171.6 
Simulated power at n = 172 per arm: 0.810 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures and 6 secondary outcomes by name. The secondary outcomes include percentage of high emollient use, age at onset of eczema, filaggrin mutation status, transepidermal water loss, skin hydration measured by skin electrical capacitance, and skin pH. The registry record reports 0 analyses. Results for these secondary outcomes are not reported in the registry record.

Multiplicity arises when several outcomes or comparisons are tested. General: as the number of statistical tests increases, the chance of obtaining at least one small p-value under a set of null hypotheses may increase. Statistical plans can address this in different ways, but the registry record does not report whether a multiplicity strategy was planned or used. It is therefore not possible to say whether the primary p-value was adjusted, or how the secondary outcomes were intended to contribute to interpretation.

The record does not report an interim-analysis plan, the original statistical analysis plan, or whether analyses were prespecified. It also does not report the analysis population, missing-data procedures, or whether all randomized participants were included according to assigned group. The outcome description notes that around 28% of subjects enrolled were lost to follow-up by 12 months. Reasons for loss, outcome status among those participants, and any imputation or sensitivity analyses are not reported in the registry record.

These omissions matter because the posted outcome denominators are smaller than the enrollment and because interpretation depends on how participants without a recorded 12-month outcome were handled. The registry record does not provide enough detail to determine whether missingness differed by arm or was associated with diagnosis. The reported group percentages should therefore be understood as results for the posted outcome data, not assumed to represent a complete follow-up analysis of all enrollees.

Without the analysis plan and results for secondary outcomes, the primary comparison can be described, but the broader pattern of findings and the role of multiple testing cannot be assessed. No adjustment, interim analysis, or analysis population should be inferred from the information in the registry record.

14. 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 3% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: idiopathic intracranial hypertension (1.9%), rsv and stridor (1.9%).

The serious-adverse-event figures use groups of 54 participants at risk in the Cetaphil Restoraderm arm and 46 in standard care. Serious adverse events were reported as affecting 2 participants in the Cetaphil group and 0 in standard care. Deaths were 0 in both groups. Other adverse events were reported as affecting 30 participants in the Cetaphil group and 21 in standard care.

The serious-event terms listed among the leading terms are Idiopathic Intracranial Hypertension and RSV and Stridor, each recorded as 1.9%. The record does not make clear in this summary whether those terms refer to individual cases in a particular group, so they should not be assigned to an arm based on these figures alone.

These counts describe reported events during the study; they do not establish that a product caused an event. The registry record does not provide further details about event definitions, severity beyond the serious classification, timing, duration, or the assessment of relationship to an intervention. The at-risk denominators used for adverse-event reporting differ from the primary-outcome denominators, and the record does not explain that distinction. Comparisons should therefore be descriptive rather than treated as proof of a safety difference.

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

The posted primary results show a lower observed percentage of cumulative atopic dermatitis diagnosis in the Cetaphil Restoraderm group than in the standard-care group at 12 months: 13.2% compared with 25.0%. The unadjusted risk-difference interval includes zero, and the unadjusted p-value is 0.204. Together, these figures describe a difference in the observed data while leaving considerable uncertainty about the size and direction of the underlying contrast.

They do not establish that the skin-care routines caused the observed difference. The trial was randomized, and the primary assessment is described as made by a blinded investigator, but around 28% of subjects enrolled were lost to follow-up by 12 months. The registry record does not report the missing-data approach or participant flow in sufficient detail to assess how that loss may have affected the comparison. The outcome denominators cover fewer participants than the enrollment.

The result also does not establish equivalence or prove that there is no difference. The confidence interval crosses zero, but that is not the same as demonstrating that any difference is small enough to be unimportant. An equivalence or noninferiority margin and a corresponding analysis are not reported in the registry record.

The endpoint is limited to cumulative diagnosis by 12 months. It does not summarize severity, duration, quality of life, or the timing of onset. The record lists other outcomes related to eczema onset, emollient use, skin barrier function, hydration, pH, and mutation status, but results for those outcomes are not reported in the registry record. The primary finding cannot answer those separate questions.

The planning illustrations based on the observed effect are not evidence of the trial's original design or of the probability that its result is correct. The registry record does not report the original sample-size justification or full analysis plan. The most defensible interpretation is therefore descriptive: the percentages differed in the observed outcome data, but uncertainty, loss to follow-up, and incomplete reporting constrain what can be concluded from that contrast.

16. Why This Trial Matters Statistically

This trial is statistically instructive because its arm percentages point in one direction while the confidence interval remains compatible with differences in either direction. A point estimate is not the whole result. Reading the interval alongside the estimate makes clear that the observed contrast is imprecise rather than a settled estimate of what would happen in another group of infants.

The endpoint is a binary diagnosis assessed at a fixed follow-up time. That makes the result readily expressible as percentages, but it does not capture when diagnosis occurred or the range of skin-related outcomes listed elsewhere in the registry. The trial also illustrates why the denominator matters: the primary result is based on 38 and 32 participants, while the record reports 100 enrolled and notes around 28% lost to follow-up by 12 months.

Random allocation and blinded investigator assessment are relevant strengths in the stated design. At the same time, the registry does not describe the missing-data method, analysis population, original sample-size rationale, or full analysis plan. Statistical interpretation must distinguish the design features that are reported from procedures that are not. A randomized label alone cannot resolve unanswered questions about incomplete outcome data.

The planning illustrations also demonstrate how sample-size requirements depend on the effect chosen for planning: the smaller the target effect, the more participants are listed per arm. Because the calculations use the observed effect, they are not a substitute for the trial's unreported original rationale and do not measure the study's observed power. Together, these features make the record useful for understanding how estimates, uncertainty, follow-up, and planning assumptions should be considered separately.

17. 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.
• Participant counts were reconstructed from posted percentages and arm sizes, so small rounding differences are possible.

The registry record identifies the study as a pilot and reports enrollment of 100, but does not report the original sample-size justification. The posted primary outcome has denominators of 38 and 32, and the record states that around 28% of subjects enrolled were lost to follow-up by 12 months. The full participant flow, reasons for loss, and methods for addressing missing outcomes are not reported. This limits assessment of whether the posted percentages represent the randomized groups without bias.

The single-masking designation is not accompanied by details about who was masked beyond the description of a blinded investigator for the primary diagnosis. The record does not state how adherence to either regimen was assessed, whether care outside the assigned routine was permitted, or whether group assignment was maintained throughout follow-up. Such details should not be assumed.

The record does not report the original statistical analysis plan, the analysis population, interim analyses, or adjustment for multiplicity. It lists secondary outcomes but does not report their results. The primary result is therefore not accompanied by a complete account of all planned analyses or outcome findings. The registry also does not provide confidence intervals for the individual arm percentages.

The two care routines differ in both product and moisturizer-use instructions: Cetaphil moisturizer was specified once daily, while standard-care moisturizer could be used as often as desired. The observed comparison thus concerns the assigned regimens as a whole. It cannot isolate the contribution of an individual product or instruction. The record's description of the primary outcome is specific to diagnosis by 12 months and does not answer questions about severity, timing, or other skin measures.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Comparing Cetaphil Restoraderm System Versus Standard Skin Care in Infants — NCT01375205.
• Registry record last updated 2020-02-12; status last verified 2020-01.
• Results first posted 2019-04-12.
• 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.

21. Record Summary

NCT01375205 is a completed randomized, single-masked, parallel pilot trial comparing Cetaphil Restoraderm skin care with standard skin care in infants at risk for atopic dermatitis. Oregon Health and Science University is listed as the sponsor. Enrollment was 100; the recorded study start is 2011-06 and primary completion is 2014-10.

The primary endpoint was the percentage of participants with cumulative atopic dermatitis diagnosed by a blinded investigator at 12 months. The posted values were 13.2% for Cetaphil Restoraderm and 25.0% for standard care. The unadjusted risk-difference interval includes zero, and the unadjusted p-value is 0.204. Around 28% of subjects enrolled were lost to follow-up by 12 months.

The registry lists secondary outcomes but does not report their results. It also does not report the original sample-size justification, missing-data methods, analysis population, or full statistical analysis plan. The posted primary comparison is descriptive and should be interpreted in light of its uncertainty and incomplete follow-up information.