Effect of Albendazole Dose on Treatment of Lymphatic Filariasis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Albendazole Dose on Treatment of Lymphatic Filariasis (NCT00511004), a randomized phase 2 study. The primary outcome is Microfilarial Counts at 1 Year.

2. Clinical Question

3. Trial Design

This was a phase 2 randomized, open-label, parallel-group study of albendazole dose and treatment interval for lymphatic filariasis. It was conducted in Kerala, India, and the official title identifies Brugia malayi microfilarial clearance as its focus. The registry lists enrollment as 40 and the study status as completed. The recorded start was 2007-07, and primary completion was 2014-02.

Participants were assigned to one of three regimens. Standard therapy combined albendazole 400 mg with DEC 300 mg yearly for 2 years. The higher-dose annual regimen combined albendazole 800 mg with DEC 300 mg yearly for 2 years. The higher-dose semiannual regimen used albendazole 800 mg with DEC 300 mg twice yearly, every 6 months, for 2 years. Randomization is reported, but the method used to generate the allocation sequence and whether allocation was concealed are not reported in the registry record.

The study was unmasked: participants and study personnel were not blinded according to the registry’s masking classification. This is relevant to procedures, symptom reporting and clinical management, although the primary endpoint was a laboratory count. The registry does not describe steps taken to keep laboratory assessment masked.

The primary endpoint was night-time microfilarial counts at one year from enrollment, measured in MF/ML. The registry lists additional outcomes concerning adult worm burdens at 2 years, microfilarial levels at 2 years and Brugia-specific IgG4 antibodies. The record does not provide enough detail to establish the full assessment schedule or analysis population for each outcome. A sample-size justification, prespecified interim analyses and a full statistical 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.

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 Microfilarial Counts at 1 Year, measured over 1 year from time enrolled.

The primary endpoint is the night-time microfilarial count at one year from enrollment, expressed in MF/ML. Microfilariae are the circulating larval forms of filarial worms; a blood count therefore provides a measure of their presence in the bloodstream at the specified assessment time. In this trial, the endpoint was used to compare the observed counts under the standard and higher-dose regimens.

The registry specifies the summary measure as a median and the spread as the full range. A median describes the middle of the ordered observations, while the full range gives the lowest and highest reported values. This presentation can be useful when counts are skewed or when some observations are far from the center, because the median is less influenced by extreme values than the arithmetic mean. That is a general statistical property, not a claim about the observed distribution in this trial.

All three reported group medians were 0 MF/ML. The full ranges were 0 to 20 for standard therapy, 0 to 12 for the higher-dose annual regimen, and 0 to 9 for the higher-dose semiannual regimen. The registry does not report a confidence interval for these medians, individual participant values, or a numerical estimate of the difference between regimens. Identical medians do not establish that every participant had the same count, nor do they describe how observations were distributed within each range.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary summaries use medians and full ranges rather than means and standard deviations. A median is the central observation after measurements are ordered. The full range reports the smallest and largest values. These are descriptive statistics: they summarize the observed endpoint values but do not, by themselves, estimate a treatment contrast or show the uncertainty around one. As a general matter, medians and ranges can be informative for skewed data, but the registry does not report the distribution of the individual microfilarial counts.

What does the reported p-value test?

The registry lists a Fisher exact test across the three treatment groups and reports p < 0.2. In general, Fisher’s exact test evaluates the evidence against independence in a categorical table, calculating a probability without relying on a large-sample approximation. The record does not describe the table used for this test, the categories formed from the endpoint, or the exact null hypothesis. Because the primary outcome is described as a count and summarized by medians and ranges, the missing detail matters: the test’s input cannot be reconstructed from those summaries alone.

The reported p-value is an inequality rather than an exact value. It indicates only that the p-value was below 0.2. It does not locate the value more precisely, and it cannot establish whether it is below a particular decision threshold such as 0.05. A p-value is not the probability that the null hypothesis is true, nor is it a measure of the size or clinical importance of a difference. It describes how compatible the observed data are with a specified null model, conditional on the test’s assumptions.

Why is a confidence interval useful?

In general, a confidence interval gives a range of effect estimates compatible with the data under a stated procedure. It communicates precision as well as direction and magnitude. The registry does not report a confidence interval or a numerical effect estimate for a pairwise comparison. Consequently, readers cannot use the posted analysis to assess how large a contrast might be, or how uncertain that contrast is. The arm medians are not a substitute for an interval around a treatment effect.

What can be learned from the group summaries?

The median is 0 MF/ML in each group. The full ranges are 0 to 20, 0 to 12 and 0 to 9 for standard, higher-dose annual and higher-dose semiannual therapy, respectively. A shared median does not imply matching distributions: groups can have the same median while differing in other parts of their distributions. Conversely, differing range endpoints do not establish a systematic group difference, because a range depends on only the smallest and largest observations and is sensitive to extreme values. Individual values or richer distribution summaries would be needed to examine these features.

Over-dispersion is a general issue when count data vary more than a chosen statistical model expects. If present, it can make standard errors and tests based on a restrictive count model unreliable unless the extra variability is addressed. The registry does not report a count-model analysis, a dispersion assessment or enough detail to determine whether over-dispersion was examined. No conclusion about its presence or effect on the analysis can be drawn from the reported medians and ranges.

How should the three-arm comparison be read?

The registry presents a test involving all three groups, not a reported set of pairwise effect estimates. An overall test, in general, addresses whether the groups show evidence of variation under its specified null hypothesis; it does not identify which particular pair differs or the size of any pairwise contrast. No pairwise confidence intervals or adjusted pairwise p-values are reported. The record also does not report the test’s exact inputs, degrees of freedom or test statistic, so the result cannot be independently reconstructed from the posted endpoint summaries.

The endpoint entries list 13 participants in each group. Those entries provide context for the descriptive summaries, but do not explain whether these are all randomized participants, all participants with an observed one-year count, or another analysis set. The registry does not report how missing endpoint values were handled. No assumptions about imputation, exclusion or the analysis population should therefore be made.

Any sample-size figures presented as planning illustrations should be interpreted as hypothetical planning calculations based on an observed effect, not as observed power or as evidence that the trial was designed to detect a particular effect. A design justification, target effect and sample-size calculation from the trial’s own protocol are not reported in the registry record. The posted endpoint result also does not provide a suitable numerical pairwise effect for an independent recalculation from summary statistics.

10. Analyses Reported by the Sponsor

The registry’s reported analysis is a Fisher exact test across the three groups, with p < 0.2. It does not include a test statistic, exact p-value, confidence interval or numerical estimate of a treatment contrast. The endpoint summaries give a median and full range for each group, but those statistics are not enough to reconstruct a pairwise comparison from the posted results.

No recalculated two-arm comparison is available from the posted summary statistics. The record indicates that values were missing or not estimable for such a comparison. This means there is no independent numerical recalculation to set alongside the registry’s analysis. The registry result should be read as the reported analysis, while recognizing that its broad p-value bound and absent effect estimate limit interpretation.

The record does not provide further details of the test’s input or explain how the Fisher exact test relates to the count endpoint. It is therefore not possible to verify the analysis from the medians and ranges alone. The registry’s own analysis and the descriptive endpoint summaries answer different questions: the summaries describe the group results, while the reported test supplies a limited omnibus inference. Neither gives a quantified pairwise treatment effect or its precision.

11. Multiplicity, Missing Data and Analysis Populations

The study lists a primary outcome of microfilarial counts at one year and secondary outcomes of adult worm burdens at 2 years, microfilarial levels at 2 years and Brugia-specific IgG4 antibodies. The record also indicates four outcome measures and two analyses, but does not fully specify the relation between those entries and the named outcomes. The analysis reported for the primary endpoint involves three groups. It is not clear whether additional pairwise tests, subgroup analyses or other outcome analyses were planned or conducted.

When a study examines several outcomes or multiple contrasts, the chance of observing at least one apparently unusual result can increase. Statistical methods can address multiplicity, for example by adjusting inference or by defining a prespecified hierarchy of outcomes and comparisons. This is a general principle. The registry record does not report a multiplicity strategy, a hierarchy of hypotheses, or whether the reported p-value is adjusted. It should not be described as adjusted or unadjusted without that information.

The registry does not report a full statistical analysis plan, the handling of missing endpoint values, imputation procedures, or sensitivity analyses. It also does not identify the primary analysis population or explain whether the endpoint entries include all randomized participants with available measurements. The endpoint group sizes are recorded as 13 in each arm, but the record does not explain the relationship of those counts to the listed enrollment of 40. No conclusions about attrition, exclusions or reasons for missing measurements can be drawn from that difference.

Random assignment is reported, but the record does not state whether analyses followed intention-to-treat principles, a per-protocol definition or another approach. It also does not report whether outcome assessors were masked or whether the analysis accounted for baseline values. These omissions leave uncertainty about the analysis population and the handling of potential sources of bias. They do not demonstrate that a particular method was or was not used; those details are simply not reported in the registry record.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event entries report no serious adverse events in any of the listed groups. The recorded serious-event denominators are 13 for standard therapy, 13 for higher-dose annual therapy and 14 for higher-dose semiannual therapy. The registry does not list serious adverse-event terms. Death counts are null, so deaths are not reported in the registry record; a null entry should not be read as a confirmed count of zero.

Other adverse events are reported for 9 participants in the standard group, 8 in the higher-dose annual group and 11 in the higher-dose semiannual group. The corresponding denominators are 13, 13 and 14. These entries are counts, not estimates of a causal treatment effect. The record does not describe event severity beyond the serious-event classification, timing, duration, recurrence, or how events were attributed to treatment.

Safety comparisons require attention to follow-up duration, event definitions, the population at risk and the completeness of reporting. The different recorded denominators across the primary endpoint and safety entries are not reconciled in the registry record. The absence of reported serious events does not prove that serious events could not occur; it describes what the registry reports for the listed groups. These figures alone do not support a broader safety conclusion.

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

The posted findings are descriptive: the median one-year night-time microfilarial count was 0 MF/ML in each regimen group, and the full ranges extended to 20, 12 and 9, respectively. The registry also reports a Fisher exact test with p < 0.2 across the groups. Taken together, these registry entries describe the endpoint summaries and an imprecisely bounded test result; they do not quantify the size of a treatment effect.

The common median should not be interpreted as showing that the regimens had identical effects. Group medians can match even when the distributions differ, and the registry does not provide the individual observations or a distributional comparison. The different maximum values likewise do not establish that one regimen is better. Extreme observations can affect ranges, and the record does not report a confidence interval or an interpretable pairwise contrast.

The reported p-value does not establish a statistically significant difference at a specified threshold because the record gives only the bound p < 0.2. It also does not establish equivalence or absence of a difference. Such conclusions would require an appropriate estimate and uncertainty interval, and for equivalence, a prespecified margin and a suitable analysis. Those details are not reported in the registry record.

These results concern the registered one-year endpoint and the described treatment groups. The additional listed outcomes include adult worm burdens and microfilarial measures at 2 years and Brugia-specific IgG4 antibodies, but their numerical results are not included in the registry record for this analysis. The one-year endpoint therefore cannot be treated as a complete account of all outcomes or longer-term observations.

The trial record supports a narrow conclusion: it reports the same median count in the three groups, different full ranges, and a broad p-value bound from a three-group test. It does not establish that a particular dose or interval clears microfilariae more quickly, nor does it establish that the regimens are interchangeable. Statistical interpretation must remain limited to the posted results and their reported precision.

14. Why This Trial Matters Statistically

This trial raises several important statistical issues common to clinical studies with count outcomes and multiple treatment groups. A median of zero in every group may appear simple to interpret, but medians alone can conceal meaningful variation in the rest of the distribution. Reporting full ranges adds information about extremes, yet ranges are highly dependent on the smallest and largest observations and do not show how values are concentrated between them.

The record also illustrates why a test result should be paired with a clear description of the analysis and a measure of effect. The reported Fisher exact test has only a broad p-value bound, and the registry does not explain how a count endpoint was represented for that test. Without an effect estimate and confidence interval, readers cannot assess the magnitude or precision of a contrast. A p-value, even when reported exactly, would not answer those questions on its own.

Three-arm trials also require care in distinguishing an overall comparison from pairwise questions. A test across all groups does not identify which regimens differ or quantify the difference between any particular pair. If multiple outcomes or contrasts are examined, a prespecified strategy for multiplicity can help keep interpretation aligned with the study’s objectives. The relevant statistical plan is not reported in the registry record.

Finally, the endpoint summaries and safety entries have different recorded group sizes, and the record does not explain the analysis populations or missing-data handling. This makes transparent reporting of denominators, participant flow and analysis choices especially important. The trial is statistically informative as an example of why descriptive results, inferential tests and design information need to be read together, while the missing detail limits stronger conclusions from the registry entry.

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 registry record provides limited information for evaluating the primary analysis. It reports medians, full ranges and a broad Fisher exact p-value bound, but not the exact test statistic, p-value, confidence interval or effect estimate. It does not explain how the microfilarial count data were categorized or otherwise entered into the reported test. The inferential result therefore cannot be reconstructed from the descriptive summaries.

The endpoint is presented at one year, but the record does not report the number of missing measurements, reasons for missingness, or the method used to handle missing data. It does not define the analysis population or state whether the analyses followed intention-to-treat or another approach. The endpoint group entries list 13 participants per arm, while overall enrollment is listed as 40; the registry does not reconcile these figures.

There is no reported protocol-based sample-size justification, target effect or statistical analysis plan. Allocation is described as randomized, but sequence generation and concealment are not reported. The study was open label, and masking of endpoint assessors is not reported. These omissions prevent assessment of several design and analysis safeguards from the registry record alone.

The primary endpoint summaries do not show individual counts or fuller distributional summaries. The record does not report confidence intervals for the medians, comparisons of distributions, or pairwise estimates. The additional listed outcomes are not accompanied by numerical results in the registry record, so the primary endpoint cannot stand in for the full set of study findings.

Safety information is also limited: serious adverse event counts are zero in the listed groups, but serious-event terms are not listed and death counts are null. Other adverse-event counts are reported without detail on definitions, severity, timing or attribution. These limitations constrain interpretation of both effectiveness-related outcomes and safety reporting, without implying that unreported methods or outcomes were absent from the underlying study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effect of Albendazole Dose on Treatment of Lymphatic Filariasis — NCT00511004.
• Registry record last updated 2015-08-31; status last verified 2015-07.
• Results first posted 2015-08-31.
• 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

This completed phase 2 study randomized participants in a parallel, open-label comparison of three albendazole and DEC regimens for lymphatic filariasis in Kerala, India. The registered primary endpoint was the night-time microfilarial count at one year from enrollment, expressed in MF/ML and summarized by median and full range.

The median was 0 MF/ML in each group. The ranges were 0 to 20 for standard annual therapy, 0 to 12 for higher-dose annual therapy and 0 to 9 for higher-dose semiannual therapy. The registry reports a Fisher exact test across the groups with p < 0.2, without a numerical effect estimate or confidence interval. It also lists secondary outcomes at 2 years and IgG4 antibodies, but their numerical results are not reported in the registry record. Missing-data methods, analysis populations and a full statistical plan are not reported.