Nasal Tea Tree Oil for the Prevention of Infections in PD Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Nasal Tea Tree Oil for the Prevention of Infections in PD Patients (NCT01214395), a na phase 2 study. The primary outcome is Primary Endpoint Will be the Number of Tea Tree Oil Patients That Did Not Have a Catheter-related Infection Within 6 Months After Entry Into the Trial..

2. Clinical Question

3. Trial Design

The registry classifies this as a Phase 2, single-group study of 5% tea tree oil nasal ointment. It lists enrollment of 5 and status as completed. The recorded start is 2010-06, and primary completion is recorded as 2011-11. The sponsor is PathWest Laboratory Medicine WA.

The brief summary describes a plan to recruit a maximum of fifty subjects. It says participants would be assessed for signs of infection once per week for the first 6 weeks and then every 4 weeks until week 26. Nasal carriage of “Golden Staph” would also be assessed at enrollment. The summary says participation would end after 26 weeks infection-free or if an infection occurred during that period. These are descriptions of the planned follow-up; the registry does not report how completely follow-up was achieved.

The stated primary endpoint concerns absence of catheter-related infection within 6 months after entry. The secondary outcome listed is the number of patients who did not have a Staphylococcus aureus infection. The record identifies two outcome measures but reports no outcome analyses.

The official title describes an investigator-blinded controlled study, but the structured design fields list no masking, allocation as NA, and a single-group model. They do not identify a control arm or randomized assignment. The registry record therefore does not support interpreting the study as a randomized comparison or treating any unreported control group as part of the analysis. Further details of treatment administration, eligibility criteria, and the analysis plan are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: All enrolled patients participated in the trial.

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 Primary Endpoint Will be the Number of Tea Tree Oil Patients That Did Not Have a Catheter-related Infection Within 6 Months After Entry Into the Trial., measured over 6 months.

The primary endpoint is the number of tea tree oil patients who did not have a catheter-related infection within 6 months after trial entry. It is a participant count: each participant is classified according to whether a qualifying infection occurred during the stated period. The registry says infection status would follow standard guidelines and that both definite and probable cases would be classified as infections.

This type of endpoint is used to describe how many participants in the studied group remained free of the defined event during follow-up. It is clinically focused on catheter-related infection, rather than nasal carriage alone. The secondary outcome separately concerns the number of patients without a Staphylococcus aureus infection, so it should not be treated as interchangeable with the primary endpoint.

The record does not provide the observed primary endpoint count, a denominator for an endpoint analysis, or a measure of uncertainty around an estimate. It also does not explain how incomplete follow-up, withdrawal, or infection ascertainment would be handled. Consequently, the endpoint definition can be described, but its observed frequency and precision cannot be assessed from the registry results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a number of participants, not a time-to-event estimate or a continuous measurement. The count is intended to represent participants without catheter-related infection during the stated 6-month period. The infection definition includes definite and probable cases under standard guidelines. No method for adjudicating those categories, resolving uncertain cases, or documenting the timing of an event is reported in the registry record.

What a participant count can describe

General statistical explanation: a participant count gives the number of people in a group who meet a specified outcome definition. To interpret it fully, readers ordinarily need to know the analysis denominator and how outcomes were assigned to participants with incomplete follow-up. The registry lists actual enrollment as 5, but does not report the denominator used for the primary endpoint or an observed endpoint count. Enrollment alone cannot show how many participants remained infection-free.

A count also does not automatically describe a comparative effect. In a single-group study, the count describes experience in the enrolled group under the study’s definitions and follow-up. A causal treatment contrast ordinarily requires a suitable comparison and a stated analysis. The structured record does not identify a comparator; allocation is NA and the model is single-group. Thus, the study design as recorded does not support a randomized between-group effect estimate.

How uncertainty would be considered

General statistical explanation: an estimate based on a small group is subject to sampling uncertainty. A confidence interval is a range of values compatible with the data and the method used to construct it; its width conveys precision, not certainty that the true value lies within a particular interval. No confidence interval or other uncertainty measure for the primary outcome is reported in the registry record. Without the endpoint count and analysis denominator, one cannot reproduce or assess such an estimate.

For a binary outcome, possible analyses can summarize the number and proportion of participants meeting the definition, with an interval for the proportion. That is a general description of an analysis approach, not a claim that such an analysis was performed in this study. The record gives the outcome type as a participant count and reports zero analyses. It does not specify an inferential method, confidence-interval method, hypothesis test, or adjustment procedure.

Design and interpretation

General statistical explanation: masking can reduce the influence of knowledge of treatment assignment on some aspects of care or assessment, while a control group can provide a basis for comparison. These design features address different sources of bias and do not replace one another. Here, the official title describes investigator blinding and a controlled study, but the structured fields record masking as none and the model as single-group. A comparator and the practical details of any blinding are not reported in the registry record. The discrepancy in wording should not be resolved by assuming details that the structured record does not provide.

The brief summary describes repeated infection assessments during follow-up, first once per week for the first 6 weeks and then every 4 weeks until week 26. Repeated assessment can help identify events over time, but the registry’s primary endpoint is framed as a count without catheter-related infection within 6 months. It does not report a time-to-event analysis or explain how the follow-up schedule maps to the endpoint’s 6-month window. The summary’s stopping description—26 weeks infection-free or an infection during that period—does not establish the analysis method.

Planning illustrations are not trial findings

The sample-size assumptions describe planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is framed as a stated fraction of the observed effect. The assumptions also distinguish total events for time-to-event illustrations from participants per arm for other designs. These are general planning conventions, not evidence that this single-group study used a two-arm design or that it conducted a randomized comparison. The registry record does not report the trial’s own sample-size justification, and calculated planning illustrations are not observed power.

General statistical explanation: over-dispersion matters when the variability in observed data exceeds what a statistical model assumes. It can make standard errors too small if ignored. The registry does not report an over-dispersion assessment, and the listed participant-count endpoint does not establish that such a model was used. More broadly, there is no reported statistical analysis plan from which to infer model selection, assumptions, or sensitivity analyses.

The appropriate reading is therefore narrow: the record specifies a planned endpoint and describes a study group, but does not provide analyzed outcome estimates. General concepts about binary outcomes, uncertainty, and planning explain what such analyses might mean; they do not fill in the missing results or establish which methods were actually used.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Tea Tree Oil")
n      <- c(5)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Tea Tree Oil  5  0  0.0  0.0  52.2  0.0  43.4  0.4  45.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: the primary count of tea tree oil patients without catheter-related infection within 6 months, and the secondary count of patients without a Staphylococcus aureus infection. It reports zero analyses. No outcome results, p-values, confidence intervals, or analysis populations are reported in the registry record.

Multiplicity concerns arise when several outcomes or hypotheses are tested. General statistical explanation: examining multiple outcomes can increase the chance of at least one apparently notable result, depending on how the analyses are planned and interpreted. A prespecified hierarchy or adjustment approach can address some multiplicity concerns. The registry record does not report such a strategy, or whether any outcomes beyond those listed were assessed. No adjustment should be assumed.

The record does not specify how missing outcome data were handled, whether participants who stopped follow-up were included in an endpoint denominator, or how an infection occurring before the planned end of follow-up was treated analytically. Although the brief summary says participation would end after an infection or after 26 weeks infection-free, that description does not state a missing-data method. The amount and pattern of missing data are not reported in the registry record.

An analysis population, such as all enrolled participants or a defined subset, is not reported. Nor are inclusion rules for the primary analysis, exclusions, protocol deviations, or handling of participants with incomplete infection assessments. These omissions prevent a clear assessment of which participants would contribute to an outcome estimate. The planned recruitment maximum and actual enrollment do not by themselves define an analysis population.

12. 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 2% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: peritonitis (40.0%).

The safety record lists 5 participants at risk in the Tea Tree Oil Application group, with 2 serious adverse events and 0 other adverse events in the displayed categories. Peritonitis is listed among the serious adverse event terms at 40.0%. The registry record does not report a death count; that value is not reported in the registry record.

These entries should be read as safety reporting, not as a measure of the primary endpoint. The primary outcome concerns absence of catheter-related infection within 6 months, while the safety data are presented as adverse event categories. The record does not explain whether the serious event count represents distinct participants or event occurrences, how terms were coded, or whether events were judged related to the ointment.

The percentage attached to peritonitis is a registry-listed term-level figure. The available information does not describe its denominator or relationship to the 2 serious adverse events, so further interpretation would require details not reported in the registry record. No conclusion about comparative risk is possible because a control group is not identified in the structured design fields.

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

The record establishes that a Phase 2 study of 5% tea tree oil nasal ointment was completed, with enrollment of 5 and a stated primary endpoint concerning catheter-related infection within 6 months. It also records a secondary outcome concerning Staphylococcus aureus infection and provides limited serious adverse event information. These are descriptions of the trial and its registry entries, not evidence of an estimated treatment effect.

The primary outcome result is not reported in the registry record. Consequently, the posted information does not show how many enrolled participants met the infection-free endpoint, how precisely that count could be estimated, or how the result compares with an alternative intervention or usual care. The single-group classification and absence of an identified comparator further limit any causal interpretation. A finding within the treated group, even if one were available, would not alone establish what would have occurred without the intervention.

The registry’s intended follow-up schedule and infection definitions help explain what researchers planned to measure. They do not establish that every participant completed follow-up or that outcome ascertainment was complete. Details about missing observations, analysis populations, and statistical methods are not reported. The safety entries likewise lack comparative context and do not establish causation.

For these reasons, the record is useful for understanding the study question, design classification, planned endpoint, and extent of registry reporting. It does not support a conclusion that the intervention does or does not prevent infection. Such a conclusion would require outcome data and an analysis with enough detail to assess the estimate, uncertainty, and design limitations.

14. Why This Trial Matters Statistically

This study illustrates why a clearly stated endpoint and a reported endpoint result are different things. The registry defines a participant count for absence of catheter-related infection within 6 months, but does not give the observed count or an analysis denominator. Without those values, the endpoint cannot be translated into an estimate of the group’s infection experience.

It also highlights the importance of consistent design descriptions. The official title calls the study controlled and investigator blinded, while the structured fields identify a single group, no masking, and allocation as NA. Those differences matter because a comparative interpretation depends on knowing whether a valid comparator existed and how assignment and assessment were handled. The record does not resolve the discrepancy.

The difference between the stated maximum recruitment of fifty and actual enrollment of 5 is also relevant to precision and interpretation, but the reason for that difference is not reported. A planning target is not a substitute for the number analyzed, and enrollment does not reveal the number with complete outcome data. The registry’s zero analyses makes that distinction especially important.

Finally, planning calculations and observed trial results answer different questions. Planning illustrations can show how design assumptions relate to sample-size requirements, but they cannot supply missing outcome evidence or establish observed power. The statistical lesson is that transparent reporting of participants, endpoint counts, analysis rules, uncertainty, and comparator structure is necessary to interpret a clinical study responsibly.

15. 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 interpretation is that the registry record reports no primary or secondary outcome analysis. It identifies actual enrollment as 5 but does not report how many participants were free of catheter-related infection, how many developed infection, or how many contributed to endpoint analysis. No estimate of outcome frequency or precision can therefore be assessed.

The structured design fields identify a single-group study, allocation as NA, and masking as none, while the official title describes a controlled, investigator-blinded study. The registry does not identify a comparator or explain this difference. The study should not be treated as a like-for-like controlled comparison based on the title alone.

The brief summary describes infection monitoring through week 26 and an endpoint window of 6 months. How those time frames correspond analytically is not reported. The record also does not state how infection status was adjudicated beyond the general reference to standard guidelines and classification of definite and probable cases. Rules for incomplete follow-up, withdrawals, and missing assessments are not reported.

The planned maximum of fifty participants contrasts with enrollment of 5, but the reason is not given. The registry does not report the trial’s sample-size justification, detailed eligibility criteria, intervention schedule, statistical analysis plan, or analysis population. Safety reporting is also limited: event timing, attribution, coding, and the meaning of the term-level percentage are not explained. These gaps constrain both efficacy and safety interpretation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Nasal Tea Tree Oil for the Prevention of Infections in PD Patients — NCT01214395.
• Registry record last updated 2012-08-03; status last verified 2012-06.
• Results first posted 2012-08-03.
• 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.

19. Record Summary

The registry describes a completed Phase 2 study of 5% tea tree oil nasal ointment in patients with end stage renal failure on dialysis. It records enrollment of 5, a single-group model, allocation as NA, and masking as none. The sponsor is PathWest Laboratory Medicine WA; the recorded start is 2010-06 and primary completion is 2011-11.

The primary endpoint is the number of tea tree oil patients without catheter-related infection within 6 months. The secondary outcome concerns patients without Staphylococcus aureus infection. The record reports two outcome measures but zero analyses, and no observed efficacy result. Serious adverse event entries list 2 among 5 at risk, with peritonitis at 40.0%; further safety details are not reported. The available record supports description of the study and its reporting gaps, but not a comparative treatment-effect estimate.