Comparison of Refined and Crude Indigo Naturalis Ointment in Treating Psoriasis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Refined and Crude Indigo Naturalis Ointment in Treating Psoriasis (NCT01022502), a randomized phase 2 study. The primary outcome is Change From Baseline in Psoriasis Severity Idex(PSI) at Week 8..

2. Clinical Question

The within-patient arrangement is important: each patient received both ointments, one on each lesion. The intended comparison is therefore between paired lesions, rather than between separate groups of people assigned to one ointment each. The record also lists patient ratings of overall improvement at Week 8 and patient preference for ointment type as secondary outcomes. Their results are not reported in the registry record.

3. Trial Design

This completed Phase 2 trial is recorded as randomized and single-masked. It enrolled 38 participants with psoriasis vulgaris. Each participant had 2 bilaterally symmetrical psoriatic plaque lesions of the same patient treated in parallel: refined indigo naturalis ointment was applied to one lesion and crude indigo naturalis ointment to the other. Both topical treatments were used for 8 weeks, starting on the date of enrollment.

This paired-lesion design makes the patient the shared context for the comparison. Characteristics that are the same for both lesions within a patient, such as the person’s general health and background, are not separated into treatment groups. The randomized allocation applies to which lesion received which ointment, although the method for generating the allocation sequence and the procedure for assigning treatment to a lesion are not reported in the registry record.

The registry record labels the model as single group while also describing a randomized comparison of two ointments on paired lesions. The treatment descriptions clarify that both ointments were used within each patient; the single-group label should not be read as meaning that only one ointment was evaluated. The record says the trial was single-masked but does not report who was masked or how masking was maintained. Details about treatment adherence, co-interventions, and the handling of participants who did not complete treatment are not reported in the registry record.

The primary outcome is change from baseline in PSI at Week 8. The registry describes the analysis population as participants completing the 8 week intervention period and states that a paired t-test was used to compare PSI scores between lesions and before and after treatment. The number completing the period and the numerical outcome results 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: 41 participants recruited and screened,3 exclude ( 2 did not meet the eligibility criteria and 1 refuesed to participate).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Total number of participants completing the 8 week period with study intervention. The paired t-test was used to compared PSI scores between the two lesions and before treatment with those after treatment.

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 Change From Baseline in Psoriasis Severity Idex(PSI) at Week 8., measured over Baseline and Week 8.

The primary endpoint is change from baseline in the Psoriasis Severity Index (PSI) at Week 8. PSI combines scores for scaling, erythema, and induration. Each component is graded on a 5-point scale from 0, absent, to 4, very severe; their sum ranges from 0 to 12. Higher PSI values indicate worse severity, so a lower score after treatment than at baseline represents improvement according to the registry’s description.

Using change from baseline focuses the comparison on how severity shifted during the treatment period, rather than only comparing scores at Week 8. In this trial, the relevant contrast is paired: each patient had one lesion treated with each ointment. The registry describes the endpoint as a mean and specifies a 95% confidence interval as the measure of dispersion. It also states that a paired t-test was used for comparisons between the two lesions and between measurements before and after treatment.

The registry record does not report the mean changes, confidence intervals, or test results. Thus, the scale and direction of the endpoint are defined, but the size and precision of the observed treatment comparison cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Why use a paired comparison?

In a paired design, each patient contributes observations under both treatments. Here, one of 2 symmetrical lesions received refined ointment and the other received crude ointment. The analysis can compare the two lesions within the same patient, rather than treating every lesion as if it came from a different person. This approach can reduce the influence of patient-level differences that affect both lesions, because those shared features are held constant within the pair.

The benefit depends on the lesions being meaningfully comparable and on the paired data being handled correctly. Symmetry is part of the trial description, but it does not establish that paired lesions had identical baseline severity or would have followed the same course without treatment. The registry record does not report baseline lesion scores, the randomization procedure for assigning ointments to lesions, or further details about the paired analysis.

What does the paired t-test do?

The registry record states that a paired t-test was used to compare PSI scores between lesions and between measurements before and after treatment. In general, a paired t-test first forms a difference for each matched pair and then assesses the average of those differences. For the lesion comparison, the pair is the two lesions in one patient. For a before-and-after comparison, the pair is the same lesion measured at baseline and Week 8. The test therefore uses the relationship between measurements instead of assuming that paired observations are independent.

As a general statistical matter, the paired t-test is a method for comparing an average paired difference. Its inference relies on the paired differences being suitable for a mean-based analysis, including an adequate approximation to the model’s distributional assumptions. The registry record does not report diagnostic checks, alternative analyses, or details about whether separate tests were performed for each comparison. No test statistic or p-value is reported, so the conduct and result of the stated test cannot be independently assessed from the record.

How should the mean and confidence interval be read?

The primary measure is a mean on a continuous severity scale. A mean summarizes the average score or change across the analysis population, but it does not show how variable individual lesion responses were. A 95% confidence interval is an uncertainty interval for the mean estimate under the statistical method used. A narrower interval indicates greater precision than a wider interval, while the interval’s location indicates the range of changes compatible with the data and assumptions.

These are general interpretations; the registry record gives no numerical mean or confidence interval for the primary outcome. It is consequently not possible to judge how large the average change was, whether the estimate was precise, or whether a difference between ointments was consistent with a range of clinically relevant values. A confidence interval is not a display of every patient’s result, and it does not show the full distribution of responses.

What does randomization contribute?

Random assignment of the ointments to lesions can help reduce systematic allocation of one treatment to lesions with a particular feature. In a paired-lesion trial, the key assignment concerns which of the two lesions receives each ointment. The record identifies the trial as randomized but does not report how the random sequence was generated, whether allocation was concealed, or how the assignment was implemented. These missing details prevent a fuller assessment of the protection randomization offered against allocation bias.

The trial is also listed as single-masked. Masking can reduce the influence of treatment knowledge on aspects of trial conduct or assessment, depending on who is masked. The registry record does not identify the masked party or explain whether participants, clinicians, outcome assessors, or analysts were unaware of treatment assignment. It is not possible to infer the practical effectiveness of masking from the label alone.

What role does the analysis population play?

The primary outcome population is described as participants completing the 8 week period with study intervention. That description suggests the primary analysis was tied to completion, but the record does not report the number of completers, the number with evaluable PSI measurements, or the reasons for any missing data. It also does not state whether participants were analyzed according to their original randomized lesion assignments or whether another analysis population was used.

As a general principle, analyses limited to people with complete follow-up can be vulnerable to bias if completion is related to treatment response or tolerability. Handling missing data requires information about the amount and pattern of missingness, as well as the assumptions used in any statistical method. Those details are not reported in the registry record, so the impact of missing observations on the PSI comparison cannot be judged.

What cannot be inferred from the available analysis record?

The registry reports 0 analysis entries and does not post the numerical primary outcome results. That absence should not be interpreted as proof that no analyses were conducted; it means the registry record does not present them in a form that can be examined. The record does not report a statistical analysis plan, adjustment for multiple outcomes, interim analyses, or a sample-size justification. These items are not reported in the registry record.

Planning calculations based on an observed effect, when presented, are illustrations rather than observed power. They do not establish that a trial had a particular probability of detecting an effect after the results are known. No numerical planning result is reported in the registry record for interpretation. General statistical concepts can clarify what the stated methods mean, but they cannot replace missing estimates or missing details about how the methods were applied.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists the PSI change as the primary outcome and also names patient rating of overall improvement at Week 8 and patient preference for ointment type as secondary outcomes. It reports 5 outcome measures in total, but does not provide results for these outcomes or an analysis plan explaining which comparisons were primary, how they were defined, or whether any adjustment for multiple testing was planned. A multiplicity procedure is not reported in the registry record.

When researchers assess multiple outcomes or make multiple comparisons, the chance of obtaining at least one apparently notable result can increase. This is a general statistical issue, not a claim that any particular result in this trial is spurious. Without a reported analysis plan and results, readers cannot determine how outcome selection or multiplicity was handled. The registry also notes that the primary outcome has several categories or time points and is not reduced to one comparison; the record does not provide a single numerical comparison to interpret.

The primary population is described as participants completing the 8 week study intervention. Enrollment is reported as 38, but the number completing follow-up and the number with usable PSI measurements are not reported in the registry record. Reasons for missing data, the handling of missing measurements, and whether the analysis followed randomized lesion assignment are also not reported. These omissions limit assessment of the analysis population and the possibility that incomplete follow-up affected the estimated comparison.

11. 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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry record lists serious adverse event counts of 0 for crude indigo naturalis ointment and 0 for refined indigo naturalis ointment. It gives 38 as at risk in each ointment group. These are the posted serious-event figures; they do not establish that the risk of serious harm is absent, particularly because the record does not provide an uncertainty interval or further details about event surveillance.

For other adverse events, the record lists 3 for crude ointment and 1 for refined ointment, with 38 at risk in each group. These are reported counts, not calculated rates or a statistical comparison. The record does not describe the events or state their severity, timing, or relationship to treatment. Deaths are not reported in the registry record.

Because both treatments were applied to lesions in the same patients, these group-level safety entries should not automatically be treated as results from independent participant groups. The record does not explain how adverse events affecting a participant were assigned or counted by ointment. The figures offer limited descriptive information and should not be used alone to characterize comparative safety.

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

This trial addresses a focused question: whether PSI changed differently for paired psoriatic plaques treated with refined versus crude indigo naturalis ointment over 8 weeks. The record provides useful design details, including topical application to symmetrical lesions in the same patient, the PSI scale and its direction, and the stated use of a paired t-test. Those details explain how the primary comparison was intended to be framed.

The record does not report the primary mean changes, confidence intervals, or test results. It therefore cannot establish from the posted results how the two ointments compared on PSI, how large any difference was, or how precisely it was estimated. No conclusion about whether either treatment improved severity relative to the other can be drawn from the design information alone. This is a limitation of the results available in the registry record, not evidence that the treatments had equal effects.

The secondary outcomes, patient rating of overall improvement and preferred ointment type, are also named without reported results. Their absence means the record does not allow comparison of patient-reported impressions with the clinician-scored severity measure. Likewise, the limited adverse event counts cannot substitute for detailed safety results or settle a comparison of harms.

More broadly, the record leaves important aspects of interpretation unresolved: the number completing follow-up, missing-data handling, the details of randomization and masking, and the statistical plan are not reported. These omissions affect confidence in how fully the design and analysis can be evaluated. A reader can identify the trial’s question and its paired structure, but cannot determine the trial’s numerical answer from the registry results recorded.

13. Why This Trial Matters Statistically

The design is statistically notable because it compares treatments within the same patient rather than assigning separate sets of patients to each ointment. Each patient serves as a block for the lesion comparison: shared patient characteristics are common to both treatment observations. This illustrates why paired analysis can be appropriate when observations naturally occur in matched sets.

The registry’s description also makes clear why the unit of analysis matters. Although the treatments are described as ointment groups, each patient contributes a lesion treated with each product. Treating the lesion observations as independent would fail to reflect their within-patient relationship. The stated paired t-test recognizes that relationship in its basic form, although the registry does not report the detailed analysis or its results.

The record is also a reminder that an identifiable study question and a clear outcome scale do not guarantee that the evidence can be interpreted fully. The PSI has a defined range and direction, and the record names a confidence interval and paired comparison method. Yet without numerical estimates, uncertainty intervals, and follow-up details, the central treatment contrast remains unquantified for readers.

Finally, the distinction between an outcome definition and an outcome result is essential. A registry can describe what was measured and how it was intended to be analyzed, while leaving the findings unavailable. Statistical interpretation depends on estimates and their uncertainty, not on design labels alone. This record therefore illustrates both the strengths of within-person comparison and the limits created when results and analysis details are not reported.

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.

Several trial-specific limitations affect how the registry record can be assessed. Although randomization is reported, the method used to assign ointments to lesions, allocation concealment, and sequence generation are not reported. The record also calls the trial single-masked without identifying who was masked or describing how masking was maintained. These details matter for judging potential sources of bias in treatment assignment and outcome assessment.

The primary outcome population is defined by completion of the 8 week intervention period, but the number completing follow-up is not reported. The registry does not describe missing PSI measurements, reasons for non-completion, or the methods used to handle incomplete data. It also does not provide baseline PSI values for the paired lesions or show the distribution of individual changes. The impact of baseline lesion differences, missing observations, and variability therefore cannot be evaluated.

The record states that a paired t-test was used but provides no test results, estimates, confidence intervals, or analysis diagnostics. The statistical analysis plan and any approach to multiple outcomes are not reported. The results of the named secondary outcomes are also absent. Consequently, it is not possible to examine whether the reported analytical approach matched the intended comparisons or to compare clinician-scored and patient-reported outcomes.

The registry’s single-group model label sits alongside a description of a randomized paired-lesion comparison. The arm descriptions clarify that both ointments were applied within each patient, but the record does not provide further details about the structure of the analysis. Finally, the safety entries are sparse: event descriptions and deaths are not reported. Taken together, these gaps limit evaluation of efficacy, safety, and the robustness of the comparison.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of Refined and Crude Indigo Naturalis Ointment in Treating Psoriasis — NCT01022502.
• Registry record last updated 2012-10-16; status last verified 2012-09.
• Results first posted 2012-10-16.
• 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.

18. Record Summary

The completed Phase 2 trial enrolled 38 participants with psoriasis vulgaris and was recorded as randomized and single-masked. Each patient had one of 2 symmetrical plaque lesions treated with refined indigo naturalis ointment and the other treated with crude ointment for 8 weeks.

The primary outcome was change from baseline in PSI at Week 8, a severity scale ranging from 0 to 12 in which higher scores indicate worse severity. The registry states that a paired t-test was used and identifies the primary population as participants completing the intervention period. The number completing and the numerical PSI results are not reported in the registry record.

Patient-rated improvement and ointment preference were listed as secondary outcomes, with results not reported in the registry record. Serious adverse event counts were 0 for each ointment; other adverse event counts were 3 for crude and 1 for refined ointment. The record does not report event descriptions or deaths.