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 Evaluation of the Efficacy and Safety of Indigo Naturalis Oil Extract on Psoriatic Nails (NCT00999687), a randomized phase 2, phase 3 study. The primary outcome is Change From Baseline in Single-Hand Nail Psoriasis Severity Index (NAPSI)and in the Modified Target NAPSI for the Single Most Severely Affected Nail of Each Hand at Week 12..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00999687 |
| Phase | Phase 2, Phase 3 |
| Condition | Nail Psoriasis |
| Allocation | Randomized |
| Design model | Single Group |
| Masking | Single |
| Enrollment | 31 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Chang Gung Memorial Hospital |
| Results posted | Yes |
2. Clinical Question
Population
Participants with nail psoriasis were enrolled. The registry record reports an enrollment of 31. It describes scoring the fingernails of both hands, with each hand assessed separately during the initial comparison period.
Intervention
Indigo naturalis extract in oil (INEO) was applied to the fingernails of one hand twice daily for the first 12 weeks. For another 12 weeks, INEO was applied twice daily to all affected nails on both hands.
Comparator
Olive oil was applied twice daily to the fingernails of the other hand for the first 12 weeks. For another 12 weeks, INEO was applied to all affected nails on both hands, so the initial hand-to-hand comparison does not continue in the same form during that later period.
Primary question
The stated primary outcome concerns change from baseline to Week 12 in single-hand NAPSI and modified target NAPSI for the most severely affected nail of each hand. Higher scores indicate worse nail involvement. Numerical changes and confidence intervals are not reported in the registry record.
3. Trial Design
The registry record describes a randomized, single-masked study, lists Phase 2 and Phase 3, and reports enrollment of 31. Its design model is recorded as single group, while the arm descriptions specify a side-to-side comparison: one hand received indigo naturalis extract in oil (INEO) and the other received olive oil during the first 12 weeks. These features describe different aspects of the record; the registry does not report further detail that resolves how randomization and masking were implemented.
During the first 12 weeks, INEO was applied twice daily to the fingernails of one hand and olive oil was applied twice daily to the fingernails of the contralateral hand. The description then states that INEO was applied twice daily to all affected nails on both hands for another 12 weeks. Thus the initial period provides the stated side-to-side contrast, while the later period has both hands receiving INEO and does not preserve that same hand-to-hand treatment contrast.
The study began in 2009-09, had primary completion in 2010-09, and is listed as completed. Chang Gung Memorial Hospital is named as the sponsor. The registry describes two interventions and two outcome measures. It does not report the allocation sequence, concealment procedures, who was masked, or additional operational detail about the change in application after Week 12.
The primary outcome is described as change from baseline at Week 12 in two scores: single-hand Nail Psoriasis Severity Index (NAPSI) and modified target NAPSI for the most severely affected nail of each hand. The registry record does not report numerical results for either measure. It also does not report an analysis population, a statistical analysis plan, or the numerical confidence intervals associated with the outcome.
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: 35 participants recruited and screened, 4 excluded (3 did not meet the eligibility criteria and 1 refused participation).
First Intervention
| Stage | All Participants (Indigo Naturalis Oil Extract /Olive Oil) |
|---|---|
| STARTED | 31 |
| COMPLETED | 30 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | All Participants (Indigo Naturalis Oil Extract /Olive Oil) |
|---|---|
| Withdrawal by Subject | 1 |
Second Intervention
| Stage | All Participants (Indigo Naturalis Oil Extract /Olive Oil) |
|---|---|
| STARTED | 30 |
| COMPLETED | 27 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | All Participants (Indigo Naturalis Oil Extract /Olive Oil) |
|---|---|
| Withdrawal by Subject | 2 |
| Lack of Efficacy | 1 |
Analysis population for the primary outcome, as defined in the registry: Higher values represent a worse outcome. For example, a higher score at baseline and a lower score after treatment represent an improvement.
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.
| Characteristic | Unit | All Participants (Indigo Naturalis Oil Extract /Olive Oil) |
|---|---|---|
| Participants analysed | 31 | |
| Age, Continuous | years | 40.7 (SD 12.6) |
| Sex: Female, Male: Female | Participants | 7 |
| Sex: Female, Male: Male | Participants | 24 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in Single-Hand Nail Psoriasis Severity Index (NAPSI)and in the Modified Target NAPSI for the Single Most Severely Affected Nail of Each Hand at Week 12., measured over Baseline and Week 12.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary outcome concerns change from baseline to Week 12 in single-hand NAPSI and modified target NAPSI for the most severely affected nail of each hand. These scores quantify signs of nail psoriasis. For single-hand NAPSI, the description considers nail-bed features, including onycholysis, splinter hemorrhages, discoloration, and subungual hyperkeratosis, and nail-matrix features, including pitting, leukonychia, red spots in the lunula, and nail-plate crumbling. The five fingers in a hand are scored together. The described hand-level score ranges from 0 to 40.
The modified target NAPSI focuses on the most severely affected nail. It scores nail-matrix and nail-bed psoriasis in each nail quadrant from 0 (no sign) to 3 (severe involvement); the described total ranges from 0 to 96. The registry also explains the broader NAPSI scale across all 10 fingernails, which ranges from 0 to 80, but the stated single-hand outcome uses the hand-level scoring approach.
These measures are used to represent the extent and severity of visible nail-disease signs. Higher values indicate worse outcomes, so a lower score after treatment than at baseline would represent improvement as defined by the record. The registry does not report the numerical changes, confidence intervals, or a comparison estimate for the primary outcome, so the magnitude and precision of any observed change cannot be assessed from the recorded results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary outcome and its assessment time, but it does not report numerical results for that outcome. In particular, it gives no mean change from baseline, between-hand contrast, confidence interval, or statistical test result for single-hand NAPSI or modified target NAPSI at Week 12. Therefore, the size, direction, and statistical precision of the primary comparison cannot be described from the record.
The design description indicates an initial within-participant, side-to-side comparison: INEO was used on one hand and olive oil on the other for the first 12 weeks. In general, measurements from two hands belonging to one participant are related rather than independent. A statistical comparison that accounts for that pairing can use the fact that the hands belong to the same person, while a method that treats them as unrelated may misrepresent uncertainty. The registry record does not report the analysis method, so it is not possible to establish how the relationship between hands was handled.
The stated outcome is change from baseline, with results intended to be expressed as a mean and a 95% confidence interval. In general, a confidence interval describes uncertainty around an estimate under the assumptions of the analysis. Its width depends on the variability and amount of information in the data, among other factors. Because no interval values or underlying summary statistics are reported, the precision of the estimated changes is not available. No conclusion about statistical significance can be drawn from an outcome description alone.
The later treatment period also matters when interpreting the design. After the first 12 weeks, the description says INEO was applied to affected nails on both hands for another 12 weeks. This means the initial olive-oil comparison is not maintained in the same way for the full stated treatment period. The primary outcome is specified at Week 12, but numerical Week 12 results are absent, and the registry does not state a later comparative primary outcome.
The completed status and enrollment figure describe study conduct, not the result of the comparison. Likewise, the absence of a result in the registry record is not evidence that scores were unchanged, that treatments were equivalent, or that a particular difference was present. The posted information permits a description of the question, scoring measures, and treatment sequence, but not an estimate of efficacy or an assessment of the observed effect's precision.
9. Statistical Methods Explained
What does a mean change represent?
The outcome is described as a mean, a summary of the average change in a continuous score. A change score compares a participant's measurement at a follow-up time with that participant's baseline measurement. For these outcomes, a lower score after treatment than at baseline is described as improvement because higher values represent worse nail involvement. This interpretation identifies the direction of the scale; it does not establish that a change occurred in this study. Numerical mean changes are not reported in the registry record.
There are two named outcomes within the primary-outcome description: single-hand NAPSI and modified target NAPSI. They measure related but distinct features and units of assessment. Single-hand NAPSI combines scores across five fingers of a hand; modified target NAPSI scores the most severely affected nail. A result for one measure would not automatically supply the result for the other. The registry does not report a numerical estimate for either one.
How should a confidence interval be read?
In general, a 95% confidence interval expresses the uncertainty around an estimated mean or contrast under the statistical method's assumptions. A narrower interval indicates greater precision for that estimate, while a wider interval indicates greater uncertainty. It is not a guarantee that the true value lies within a particular interval, and it does not by itself establish clinical importance. The registry describes 95% confidence intervals as the dispersion measure but does not report their endpoints, so precision cannot be judged.
Why does the side-to-side setup matter?
The first 12 weeks are described as an intra-participant, side-to-side comparison. Each participant has one hand assigned to INEO and the other to olive oil during this period. In general, measurements from two hands in the same person may be correlated because they share participant-level characteristics. A paired analysis compares the two hands within each participant and accounts for this dependence. An analysis treating both hands as independent observations would ignore the pairing. The specific analysis used is not reported in the registry record.
Randomization is listed, but the record does not describe the unit or procedure of randomization in sufficient detail to establish the exact allocation process. It also lists the design model as single group while describing two hand-level treatment conditions. The registry does not provide further statistical detail that explains this combination. It is therefore appropriate to describe the treatment sequence as recorded without assuming a particular allocation or analysis procedure.
What does a mean-based analysis assume?
In general, analyses of means rely on assumptions appropriate to the data and design. These may concern how observations are related, how variability is represented, and whether the chosen summary adequately describes the distribution. A score with a bounded range can have features that matter for modeling, such as clustering near a scale limit. Whether those features affected this study cannot be assessed without the observed data and analysis details.
Over-dispersion is a general concern when observed variability exceeds what a statistical model expects. If a model underestimates variability, its uncertainty estimates may be too small. This is a general statistical consideration, not a finding about this trial: the registry record does not report a model, dispersion assessment, or raw outcome data.
What can be concluded from the stated analysis description?
The record names a mean outcome and 95% confidence interval, but it does not describe the statistical test, model, adjustment variables, handling of repeated measurements, or approach to missing observations. No analysis results are listed. It is therefore not possible to verify how the estimates were produced, whether the hand pairing was accounted for, or whether any adjustment was made. The methodological description supports an explanation of how the scores are intended to be interpreted, but not a reconstruction of the trial's statistical analysis.
The registry also contains no reported analyses in its analysis count. That does not establish that no analysis was performed; it means analysis details and numerical results are not reported in the registry record. Any interpretation must remain limited to the design and outcome descriptions that are recorded.
10. Multiplicity, Missing Data and Analysis Populations
The primary-outcome description includes two measures: single-hand NAPSI and modified target NAPSI for the most severely affected nail of each hand. Considering more than one measure can raise a multiplicity question: when several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase. In general, a prespecified hierarchy or an adjustment method can address this issue. The registry record does not report whether either approach was planned or used, and numerical results for the measures are not reported.
The record lists two outcome measures and notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not report how those categories or time points were handled analytically, whether a single contrast was designated as decisive, or how any multiplicity was addressed. No statistical plan is reported in the registry record.
Missing-data handling is also not reported in the registry record. There is no information about the number of participants with Week 12 measurements, incomplete assessments, exclusions, imputation, or sensitivity analyses. Enrollment of 31 does not establish how many participants contributed to each outcome analysis.
The analysis population is not reported in the registry record. The available description does not state whether results were intended for all randomized participants, participants who completed treatment, participants with available measurements, or another population. Without those details and the outcome values, it is not possible to assess attrition or determine how missing observations may affect the estimates.
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 |
|---|---|---|---|
| All Participants (Indigo Naturalis Oil Extreact/Olive Oil) | 0 | 31 | 0.0% |
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 |
|---|---|
| All Participants (Indigo Naturalis Oil Extreact/Olive Oil) | 0 of 31 |
The serious and other adverse-event group is titled “All Participants (Indigo Naturalis Oil Extreact/Olive Oil)” and reports 31 at risk for each category. The registry lists 0 serious adverse events and 0 other adverse events. No serious adverse-event terms are listed. These figures describe what is recorded in the adverse-event fields for this group; they do not provide event-level detail or a breakdown by hand or treatment period.
The deaths field is null. A null entry is not a count of zero; deaths are not reported in the registry record. The record also does not give information about how adverse events were collected, how long participants were monitored for safety, or whether the displayed group corresponds to a particular treatment exposure period.
Counts should be interpreted alongside their denominators and reporting context. The listed at-risk count is 31, but the record does not specify further safety-analysis details. A zero count in a registry field means no events are listed there; on its own, it does not establish that no adverse effects occurred or that a treatment is safe. The available figures support only a description of the recorded counts, not a broader safety conclusion.
12. What the Result Does, and Does Not, Mean
The registry record establishes that this completed randomized, single-masked study enrolled 31 participants with nail psoriasis and compared INEO on one hand with olive oil on the other during the first 12 weeks. It identifies Week 12 change in single-hand NAPSI and modified target NAPSI as the primary outcome. These scores represent nail-disease signs, and higher values are defined as worse outcomes.
However, numerical primary-outcome results are not reported in the registry record. There is no mean change, treatment contrast, confidence interval, or test result with which to describe the observed effect or its precision. Consequently, the record does not support a conclusion about whether scores changed, how large any change was, or how the hand-level outcomes compared. Missing numerical results should not be interpreted as evidence of no effect or as evidence of equivalence.
The treatment sequence also defines the scope of the comparison. During the initial 12 weeks, the two hands receive different applications; afterward, the description states that INEO is applied to affected nails on both hands for another 12 weeks. The primary outcome is specified at Week 12, and the record does not report numerical results for that assessment or a later comparative primary result.
In general, a clinical trial's interpretation depends on the outcome estimates, their uncertainty, the analysis approach, and the population contributing data. Here, the registry record does not report the analysis method, analysis population, missing-data handling, or multiplicity approach. The listed adverse-event counts are also limited: 0 serious and 0 other adverse events are recorded for the group of 31, while deaths are not reported in the registry record. Those entries do not establish a complete safety profile.
The meaningful conclusion is therefore about what was studied and what remains unavailable, rather than about a treatment effect. The record describes a side-to-side Week 12 question and the scoring framework, but does not provide the numerical results required to quantify the answer.
13. Why This Trial Matters Statistically
This trial is statistically notable for its within-participant, side-to-side structure. During the first 12 weeks, each participant's hands are described as receiving different applications: INEO on one hand and olive oil on the other. In general, this design can reduce the influence of characteristics shared by the same participant when the comparison is analyzed as a paired contrast. It also makes the dependence between the two hand measurements important; treating them as unrelated observations would not reflect the described design. The registry does not report how the comparison was analyzed.
The outcome scales also show why it is important to distinguish measurement levels. Single-hand NAPSI summarizes scores across the five fingers of a hand, while modified target NAPSI focuses on the most severely affected nail. They address related signs of nail psoriasis, but they are not interchangeable summaries. Reporting both requires clarity about which result answers which question and how multiple outcomes are interpreted.
The sequence changes after Week 12: INEO is then described as being applied to affected nails on both hands for another 12 weeks. This creates an important distinction between the initial comparative period and the later treatment period. The stated primary assessment is at Week 12, but numerical results are not reported in the registry record.
Finally, the record illustrates why a design description alone cannot answer an efficacy question. An enrollment figure and outcome definitions do not substitute for estimates and uncertainty intervals. With no numerical primary results or analysis details reported, readers can identify the statistical issues raised by the design but cannot assess the magnitude or precision of the comparison.
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.
Numerical results for the stated primary outcomes are not reported in the registry record. This prevents assessment of the direction, size, and precision of the Week 12 changes. The record describes mean outcomes and 95% confidence intervals but does not report the values of either.
The design information combines a randomized allocation label and a single-group model label with descriptions of two hand-level applications. The registry does not report further detail about the randomization unit, sequence generation, allocation concealment, or masking procedures. The exact relationship among those design elements cannot be established from the recorded description.
The intervention descriptions indicate different applications during the first 12 weeks, followed by INEO on affected nails of both hands for another 12 weeks. This limits the described side-to-side contrast to the initial period. No numerical Week 12 comparison or later comparative result is reported.
Statistical analysis details are not reported in the registry record. In particular, the analysis method, treatment of paired hand measurements, adjustment strategy, analysis population, missing-data handling, and multiplicity approach are not specified. The record does not report participant counts contributing to each outcome assessment or provide raw data for independent assessment.
Safety information is also limited to recorded counts: 0 serious and 0 other adverse events among 31 at risk in the listed group. The deaths field is null, so deaths are not reported in the registry record. Further detail about safety monitoring, event collection, and treatment-period attribution is not given. These limitations restrict interpretation of both outcomes and safety to the information recorded.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Evaluation of the Efficacy and Safety of Indigo Naturalis Oil Extract on Psoriatic Nails — NCT00999687.
- Registry record last updated 2019-08-07; status last verified 2019-07.
- Results first posted 2012-09-12.
- 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.
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18. Record Summary
NCT00999687 is a completed randomized, single-masked study listed as Phase 2 and Phase 3, sponsored by Chang Gung Memorial Hospital. It enrolled 31 participants with nail psoriasis. The stated purpose was to evaluate the efficacy and safety of indigo naturalis oil extract.
For the first 12 weeks, INEO was applied twice daily to the fingernails of one hand and olive oil twice daily to the other hand. For another 12 weeks, INEO was applied twice daily to affected nails on both hands. The primary outcome concerns baseline-to-Week 12 change in single-hand NAPSI and modified target NAPSI for the most severely affected nail of each hand.
The registry record does not report numerical primary-outcome results, confidence intervals, analysis methods, or missing-data handling. It records 0 serious and 0 other adverse events among 31 at risk; deaths are not reported in the registry record.