Effect of Oseltamivir on Cognitive Function in Subjects With Influenza: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Oseltamivir on Cognitive Function in Subjects With Influenza (NCT01249833), a randomized phase 4 study. The primary outcome is Change in Attention Assessment.

2. Clinical Question

3. Trial Design

This completed Phase IV study evaluated oseltamivir as an addition to standard care for influenza. Its official title describes a randomized, open-label, multicentre study in subjects with confirmed influenza virus infection. The registry lists a parallel-group model and no masking. Participants were assigned to oseltamivir added to standard care or to standard care alone. The registry lists enrollment of 122 and identifies Trial Management Group Inc. as the sponsor.

The recorded start was 2010-11 and the primary completion was 2012-04. These dates describe the registry timeline; they do not, by themselves, establish how long individual participants were followed. The stated primary assessment was change from baseline at Day 4. The registry lists working memory and processing speed as secondary outcomes, also assessed as change from baseline at Day 4.

For the primary result, the posted arm summaries include 53 analyzed participants in the oseltamivir group and 55 in the standard-care-alone group. The analysis population description says that baseline and Day 4 data were required. It reports baseline data for 58 of 59 randomized participants in the oseltamivir group and Day 4 data for 53; for the standard-care-alone group it reports baseline data for 61 of 63 randomized participants. The Day 4 availability detail for that group is not reported in the registry record, although 55 participants are listed in the primary result.

The registry record does not report the original design assumptions behind enrollment, the full allocation procedure, or additional details about conduct at the study centres. The fact that the study is described as open-label means masking was not used; the record does not describe whether any specific steps were taken to reduce possible influence of this design on assessments or analysis.

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: All randomised subjects for whom data was collected at both baseline and Day 4. Oseltamivir group: baseline data available for 58 of 59 randomised subjects and Day 4 data for 53 subjects (53 subjects analysed). Standard of Care Alone group: baseline data available for 61 of 63 subjects and Day 4 data for 55 subjects (55 subjects analysed).

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 in Attention Assessment, measured over Change from baseline at Day 4.

The primary endpoint is change from baseline at Day 4 in the Attention Assessment, expressed in milliseconds. The assessment uses simple reaction time, calculated as the mean of a Reaction Time Subtest and a Cued Reaction Time Subtest. The registry states that lower values indicate better attention. The endpoint therefore captures performance on a defined attention task, rather than a broad measure of all aspects of cognition or day-to-day functioning.

Reaction time is a continuous measure: each participant's performance can take a range of values, and the group result can be expressed as a mean change. The posted arm results are least-squares means, with standard errors reported as the measure of dispersion. The reported comparison is the least-squares means difference from an ANCOVA analysis. These adjusted summaries are intended to compare average change between groups while accounting for the model's included terms; which covariates and model details were used is not reported in the registry record.

Using change from baseline focuses the endpoint on how the measured score shifted during the study period, rather than only comparing scores at Day 4. A continuous task measure can detect gradations in performance, but its meaning remains specific to the task and the assessment conditions. The record does not provide information on how the measured changes relate to daily functioning or how a clinically important difference was defined. The endpoint is a statistical measure of attention-task performance, and should be interpreted in that scope.

7. Results Posted in the Registry

• Oseltamivir: mean -70.00 versus -39.70 on control; difference -30.30 (95% CI -60.51 to -0.09), standardized effect d = -0.38; z-test p = 0.049.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change in Working Memory Assessment

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Oseltamivir: mean 8.20 versus 4.40 on control; difference 3.80 (95% CI 1.18 to 6.42), standardized effect d = 0.54; z-test p = 0.004.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Oseltamivir than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change in Processing Speed Assessment

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Oseltamivir: mean -551.90 versus -555.80 on control; difference 3.90 (95% CI -212.03 to 219.83), standardized effect d = 0.01; z-test p = 0.972.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Oseltamivir and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcome pattern is mixed rather than uniform across cognitive domains. The registry reports a working-memory result that differs between groups and a processing-speed result whose estimated difference is near zero relative to its uncertainty. These secondary endpoints complement the primary attention measure by assessing other task-based aspects of cognitive performance, but they do not measure the same construct as attention.

The working-memory pattern is directionally consistent with a more favorable change in the oseltamivir group, while the processing-speed estimate does not provide a clear separation between groups. Taken together, the posted results do not establish a consistent difference across all measured cognitive outcomes. They also do not overturn the primary result: each endpoint has its own measurement, uncertainty, and analysis, and the trial's primary question concerned attention.

The secondary p-values are unadjusted. When multiple outcomes are examined, the chance of obtaining at least one apparently unusual result can increase, even if none of the outcomes truly differs between groups. A multiplicity adjustment or a prespecified hierarchy can help control how results across several tests are interpreted. The registry record does not report such an adjustment or hierarchy, so the secondary findings should be treated as exploratory or supportive rather than as independent confirmatory evidence.

The registry lists two secondary outcomes, but does not provide a complete account of all analyses considered or explain how the secondary endpoints were selected and prioritized. The posted results therefore support a cautious description of the overall pattern, not a claim that all cognitive domains changed in the same way or that secondary findings independently establish the primary conclusion.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change in Working Memory Assessment
• Change in Processing Speed Assessment

9. Statistical Interpretation

10. Statistical Methods Explained

What does the ANCOVA result represent?

The sponsor's reported primary comparison uses ANCOVA and is expressed as a difference between least-squares means. In general, analysis of covariance compares group outcomes while adjusting for other terms included in the model. The resulting least-squares means are model-based group estimates, and the difference is the estimated contrast between them. This can differ from a simple subtraction of raw group summaries when model adjustment is used. The registry record does not report which covariates were included, the exact model specification, or diagnostic checks.

For this endpoint, the reported difference is -30.4 milliseconds, with a 95% confidence interval of -60.7 to -0.1 and p = .0492. As lower reaction times indicate better attention, a negative contrast is in the direction of a lower mean change for the oseltamivir group relative to standard care alone. The interpretation is tied to the endpoint's sign convention and to the stated comparison; a negative value should not be called better without checking the endpoint definition.

How should least-squares means and standard errors be read?

A least-squares mean is a model-derived estimate of a group average, rather than necessarily the unadjusted arithmetic average of individual observations. Its value depends on the fitted model. The registry reports standard errors for the arm summaries. In general, a standard error describes the sampling uncertainty of an estimate: smaller standard errors indicate greater precision under the statistical model. It is not the same thing as the spread of individual participant measurements. The registry does not post individual-level results or the standard deviation of the primary outcome.

The unadjusted recalculation uses the posted arm means, standard errors, and group sizes to estimate a difference and uncertainty. The pooled standard deviation used in the standardized effect-size calculation is approximate, as indicated in the posted analysis details. Such a recalculation can help readers understand the scale of the contrast, but it does not reproduce the sponsor's ANCOVA. It does not account for unreported covariates, model choices, or data-handling procedures. The sponsor's reported analysis remains the primary account of the trial's analysis.

What do confidence intervals and p-values contribute?

A confidence interval conveys the range of effect estimates reasonably compatible with the observed data under the analysis procedure. Its width reflects precision: a wider interval indicates more uncertainty about the effect's magnitude. A 95% confidence interval is generated by a method that, over repeated applications under its assumptions, would cover the target parameter in 95% of such intervals. It does not mean there is a 95% probability that this particular interval contains the true effect.

A p-value measures how unusual the data, or data more extreme, would be under a null hypothesis and the model assumptions. It does not measure the probability that the result occurred by chance in an ordinary-language sense, and it does not quantify clinical relevance. Interpretation should consider the point estimate, the interval, the outcome's scale and direction, and the analysis context together. A result near a conventional threshold is not a distinct kind of evidence from one just across that threshold.

Why can over-dispersion matter?

Over-dispersion arises when the observed variability is greater than a model expects. In general, if a model understates variability, standard errors can be too small and confidence intervals too narrow, which can make statistical evidence appear stronger than it is. The primary outcome is continuous and is reported with standard errors; the registry record does not report a specific over-dispersion assessment or identify an over-dispersion model. This general issue is therefore a consideration in statistical modeling, not a reported feature of this trial.

How should the design and analysis populations be considered?

Randomization is intended to support fair group comparisons by assigning participants to treatment groups through a chance-based procedure. The registry labels the study randomized, but does not describe the sequence-generation or concealment procedures. Open-label status means the trial was not masked. In general, lack of masking can influence participant or investigator behavior and can affect outcome assessment; the primary endpoint is an objective reaction-time task, though that fact does not remove every possible influence of an open-label design.

The primary analysis population was described as randomized subjects with baseline and Day 4 data. The record gives analyzed group sizes and some baseline availability, but does not report a full participant flow, the reasons for missing measurements, or the method used to handle missing data. In general, analyzing only participants with complete measurements can lead to bias if data availability is related to treatment or outcome. Whether that issue affected this result cannot be determined from the registry record.

The registry reports an ANCOVA analysis for the primary and secondary outcomes, but does not report the full statistical analysis plan, model covariates, assumption checks, or a multiplicity strategy. These omissions limit independent assessment of whether the analysis followed a prespecified plan and how well its assumptions fit the data. They do not change the values reported, but they matter when deciding how much weight to place on the estimates.

11. Confidence Intervals and Precision

The primary sponsor-reported estimate is -30.4 milliseconds, with a 95% confidence interval from -60.7 to -0.1. The interval expresses uncertainty about the size of the difference in mean change. It includes values close to no group difference as well as more substantial negative differences. Thus, the estimated direction favors a lower reaction-time change in the oseltamivir group, but the precise magnitude is uncertain. The interval's upper limit is near zero, which is consistent with the reported p-value of .0492 being close to a conventional statistical threshold.

Confidence intervals are more informative than a point estimate alone because they show the range of effect sizes compatible with the data and analysis. A narrow interval would imply more precise estimation; a broad interval would leave more uncertainty about magnitude. The primary interval should be read in milliseconds and with the endpoint's direction in mind: lower simple reaction time values indicate better attention. It should not be translated into a clinical benefit without a meaningful-difference threshold, which is not reported in the registry record.

The recalculated unadjusted interval is -60.51 to -0.087, while the sponsor's ANCOVA interval is -60.7 to -0.1. Their similarity is consistent with the close estimates, but the methods differ. The recalculated interval is based on summary information and does not include any model adjustment that may have been used in the sponsor analysis. The sponsor result is the reported trial analysis; the recalculation is a supplementary, unadjusted estimate.

Precision also depends on the available observations and on assumptions about the analysis. The primary result lists 53 participants in the oseltamivir arm and 55 in the standard-care-alone arm. Missing-data handling and the covariates in the ANCOVA are not reported in the registry record, so the interval cannot be independently reconstructed from the record alone. The confidence interval quantifies sampling uncertainty under the analysis; it does not account for every uncertainty about design, missingness, or generalizability.

12. 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 planning figures are participants per arm, not total events. They are illustrations based on the observed effect, rather than the trial's original design calculation. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each row considers an effect to detect equal to the stated fraction of the observed effect. The original trial's own sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the planned participants per arm for a hypothetical study with an 80% chance of detecting the specified effect under the listed assumptions, if that effect and the model assumptions are correct. The 90% column uses a higher target chance of detection and therefore generally requires more participants for the same assumed effect. These are design-planning quantities, not estimates of what happened in this completed trial.

The rows considering 100%, 75%, and 50% of the observed effect illustrate how the assumed effect size changes the required enrollment. Smaller effects are harder to distinguish from random variation, so planning to detect a smaller effect requires more participants. This is especially consequential when the observed estimate is modest or imprecise: using the observed effect as the planning target may not be a stable basis for a future design.

These figures are planning illustrations, not observed power. Observed power is not a useful substitute for interpreting the estimated effect and its confidence interval after a trial has been completed. The confidence interval and the study's design and analysis limitations are more relevant to understanding what the results can establish.

13. 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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -30.300; pooled standard deviation σ = 80.112.
2. n = 2 × (1.96 + 0.842)² × 80.112² / -30.300² = 109.7, rounded up to 110 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
delta <- -30.3                      # observed difference in means
sigma <- 80.1123067831229                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1249833)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 110 (80% power), 147 (90% power)
 75% of observed effect: n per arm = 196 (80% power), 262 (90% power)
 50% of observed effect: n per arm = 439 (80% power), 588 (90% power)
power.t.test: 110.7 
Simulated power at n = 110 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-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.

14. Analyses Reported by the Sponsor

The sponsor's primary analysis is an ANCOVA comparing least-squares means. It reports a difference of -30.4 milliseconds, a 95% confidence interval from -60.7 to -0.1, and p = .0492. The unadjusted recalculation from the posted summary statistics gives a difference of -30.3 milliseconds, an interval from -60.51 to -0.087, and p = 0.049. The estimates are close, and both intervals end just below zero.

The recalculation is a simple, unadjusted analysis of the posted group summaries. It is not a reconstruction of ANCOVA and cannot incorporate covariates or other modeling details that are not reported. The registry does not provide the ANCOVA's full specification, so the adjusted result cannot be independently reproduced from the record. The sponsor's reported value should therefore be read as the trial's own analysis; the recalculation is a supplementary check on the summaries, not a replacement for that analysis.

The close estimates do not eliminate uncertainty about precision, missing data, model assumptions, or the practical importance of the difference. Nor does agreement between the two calculations establish that all analysis choices were appropriate. It does show that the primary contrast calculated from the posted summaries is similar in magnitude and direction to the reported ANCOVA contrast.

15. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and secondary outcomes, but does not report a multiplicity adjustment, a testing hierarchy, or a statistical analysis plan. Multiplicity matters when several outcomes or comparisons are tested: without an adjustment or a prespecified strategy, the chance of at least one apparently statistically notable result can be higher than for a single test. The reported secondary p-values are unadjusted, so they should not be interpreted as if they were the sole planned test.

The primary analysis is reported as an ANCOVA, but the record does not identify the covariates, model specification, assumption checks, or whether the analysis plan was finalized before outcome data were examined. These details would help assess how the reported estimates were produced and whether the model was suitable for the data. Their absence from the registry record does not establish that the procedures were not conducted; it means they cannot be assessed from this record.

The primary analysis population is described as randomized participants for whom baseline and Day 4 data were collected. The record lists 53 analyzed participants in the oseltamivir group and 55 in the standard-care-alone group. It reports baseline availability of 58 of 59 randomized participants in the oseltamivir group and 61 of 63 in the standard-care-alone group, but does not report the latter group's Day 4 availability in the population description. Reasons for missing assessments and the method used to handle missing data are not reported in the registry record.

For secondary outcomes, the posted analyzed group sizes differ from those for the primary endpoint. The registry record does not explain why measurement availability varied or whether any imputation or sensitivity analyses were performed. In general, complete-case comparisons can be biased if the likelihood of having a measurement is associated with the outcome or treatment. Whether that concern applies cannot be determined without further information.

The record also does not report whether all randomized participants were included in an intention-to-treat analysis, whether protocol deviations occurred, or how those deviations were handled. These details matter for judging the protection offered by randomization and the robustness of the result. They should be regarded as unreported information, not assumed evidence of a particular flaw.

16. 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 registry reports serious adverse events in 0 participants in the oseltamivir group, among 59 at risk, and 0 participants in the standard-care-alone group, among 63 at risk. No serious adverse-event terms are listed. The record also reports other adverse events in 8 participants in each group, with 59 and 63 at risk respectively. These counts describe what was recorded in the registry; they do not, by themselves, establish whether an event was caused by treatment.

The deaths field is not reported in the registry record. The record does not provide event descriptions for the other adverse events, their severity, timing, or relationship to treatment. A count of zero recorded serious adverse events is not evidence that no adverse events of any kind occurred, and the other adverse-event counts should not be interpreted without details on collection and classification.

These safety figures are descriptive and should be read alongside the available at-risk counts and the limited event detail. They do not support a broader safety conclusion beyond the reported counts.

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

The primary result describes an estimated difference in change in an attention task between the trial groups at Day 4. The sponsor-reported ANCOVA estimate is -30.4 milliseconds, with a 95% confidence interval from -60.7 to -0.1. Since lower simple reaction-time values indicate better attention, the estimate is in the direction of a larger reduction for the oseltamivir group. The interval indicates uncertainty about the size of that difference and reaches close to no difference.

This is evidence about performance on the reaction-time assessment under the trial's conditions. It does not by itself establish an effect on every aspect of cognition, everyday functioning, or outcomes beyond the measured Day 4 endpoint. The registry does not report a threshold for a clinically important difference, so the practical importance of the estimate cannot be determined from statistical significance alone.

The secondary findings are not consistent across all cognitive measures, and their p-values are unadjusted. They provide context about working memory and processing speed but should not be treated as independent confirmation of the primary result. The trial's open-label design and incomplete reporting of missing-data handling and analysis details also limit how confidently the result can be generalized or independently evaluated.

A p-value near a conventional threshold does not answer whether an effect is large, durable, or important to participants. The confidence interval, outcome definition, and analysis population all matter. This trial supplies a bounded estimate for one task-based endpoint in a defined study setting; it does not settle broader clinical questions or establish outcomes that were not measured.

No treatment recommendation follows from these statistics. The registry results describe group-level estimates and recorded adverse-event counts. They do not predict an individual participant's response, and they do not provide a full account of benefits and harms beyond the reported outcomes.

18. Why This Trial Matters Statistically

This trial illustrates why a treatment comparison should be read through its endpoint definition, estimate, and uncertainty rather than through a p-value alone. The primary endpoint is a continuous reaction-time measure with a stated direction: lower values indicate better attention. That direction makes it possible to interpret the negative group contrast, but the scale remains a task-specific measure rather than a broad substitute for cognition or functioning.

It also illustrates the distinction between a model-based sponsor analysis and an unadjusted recalculation from summary statistics. Their estimates are close, but they answer slightly different statistical questions because ANCOVA may adjust for model terms that are not reported in the registry. Independent calculations are useful for orientation, but cannot replace the reported model when its full specification is unavailable.

The confidence interval is especially important in a result near a conventional significance boundary. It shows that the estimated difference is compatible with values close to no difference as well as larger differences in the observed direction. This is a reminder that statistical evidence and estimation precision are related but not identical, and neither determines clinical importance without an appropriate contextual threshold.

Finally, the different patterns across attention, working memory, and processing speed illustrate why multiple endpoints require a clear interpretation plan. Unadjusted secondary results can be informative, but they carry less confirmatory weight when a multiplicity strategy is not reported. Together, these features make the trial useful for learning how endpoint-specific meaning, model adjustment, uncertainty, and multiple testing shape interpretation of a clinical study.

19. 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 does not report the full ANCOVA specification, including covariates, model checks, or the statistical analysis plan. That limits independent reproduction of the sponsor's analysis and assessment of whether the model assumptions were appropriate. The unadjusted recalculation uses summary statistics and cannot resolve those questions.

The trial was open-label, with no masking. The primary outcome is an objective reaction-time task, but the record does not describe safeguards against possible behavioral or assessment influences associated with unmasked treatment assignment. The trial's method for generating and concealing the randomization sequence is also not reported in the registry record.

The primary analysis population required baseline and Day 4 data. The registry provides analyzed group sizes and some baseline availability, but not a complete flow of participants, reasons for missing assessments, or the missing-data method. It also does not report sensitivity analyses addressing missingness. These omissions make it difficult to assess whether the analyzed participants represent all randomized participants.

The primary endpoint is a task-based attention measure assessed at Day 4. The registry does not report a clinically important difference threshold or evidence connecting the measured change to everyday function. The secondary results concern additional cognitive tasks, but their p-values are unadjusted and no testing hierarchy is reported. They therefore require cautious interpretation.

Safety information is limited to event counts and at-risk numbers; event descriptions, timing, attribution, and the deaths field are not reported. More broadly, the registry does not provide enough detail to judge longer-term outcomes, centre-level differences, or the representativeness of the enrolled population. These are limits on interpretation of the available record, not evidence that unreported procedures or outcomes were absent.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Effect of Oseltamivir on Cognitive Function in Subjects With Influenza — NCT01249833.
• Registry record last updated 2017-03-09; status last verified 2017-01.
• Results first posted 2017-03-09.
• 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.

23. Record Summary

The registry describes a completed, randomized, open-label, parallel-group Phase IV study of oseltamivir added to standard care for influenza compared with standard care alone. The primary outcome was change from baseline at Day 4 in an attention assessment based on simple reaction time. The sponsor-reported ANCOVA estimated a -30.4 millisecond least-squares means difference, with a 95% confidence interval from -60.7 to -0.1 and p = .0492.

The posted results also include working-memory and processing-speed outcomes. Their pattern is mixed, and secondary p-values are unadjusted. The record reports no serious adverse events in either group and 8 other adverse events in each group; event details and the deaths field are not reported. Missing-data methods, full model details, multiplicity procedures, and the original sample-size justification are not reported in the registry record.