Three-Arm Study of the Safety and Efficacy of Pirfenidone in Patients With Idiopathic Pulmonary Fibrosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Three-Arm Study of the Safety and Efficacy of Pirfenidone in Patients With Idiopathic Pulmonary Fibrosis (NCT00287716), a randomized phase 3 study. The primary outcome is Absolute Change in Percent Predicted Forced Vital Capacity (FVC).

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-blind, placebo-controlled, phase 3, three-arm parallel-group study of pirfenidone in people with idiopathic pulmonary fibrosis. It lists quadruple masking. The planned treatment groups were pirfenidone 2403 mg/day, pirfenidone 1197 mg/day, and placebo. The record gives enrollment as 435 and status as completed.

The primary outcome was mean change in percent predicted FVC, measured from baseline up to week 72. The posted arm summaries include 174 participants for the 2403 mg/day arm, 87 for the 1197 mg/day arm, and 174 for placebo. These are the sample sizes attached to the posted primary-outcome summaries; the record does not explain whether these numbers reflect the full randomized groups or a particular analysis population.

The registry lists seven secondary outcomes: categorical assessment of absolute change in percent predicted FVC, progression-free survival, six-minute walk distance, worst oxygen saturation during the six-minute walk test, percent predicted hemoglobin-corrected DLco, dyspnea score, and worsening of IPF. Results are posted for some, but not all, of these outcomes.

The record states that the objectives included assessing safety and efficacy at both doses and characterizing pirfenidone pharmacokinetics. The detailed protocol, treatment duration beyond the primary outcome timeframe, allocation method, concealment procedures, and original statistical design assumptions 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

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 Absolute Change in Percent Predicted Forced Vital Capacity (FVC), measured over From baseline up to 72 weeks.

The primary endpoint is the mean change in percent predicted forced vital capacity (FVC) from baseline up to week 72. The registry describes this as a continuous measure and reports the mean and standard deviation for each treatment group. A change score compares a participant’s follow-up measurement with their baseline measurement; the group mean summarizes the average change among participants included in the posted results.

FVC is the volume of air a person can forcefully exhale after taking a full breath. Percent predicted FVC expresses an observed FVC measurement relative to a predicted reference value. The endpoint is used to track change in lung function over the specified period. In this trial, the posted group means are negative, indicating that the average recorded percent predicted FVC decreased from baseline in each group. The comparison between a pirfenidone group and placebo describes the difference between those group means.

As a continuous outcome, the measure retains the size of each recorded change rather than classifying participants into categories. That can make group-level differences easier to describe in the same units as the outcome. The registry record does not report a clinically meaningful threshold for interpreting a particular difference, nor does it give a detailed explanation of how the outcome was collected or handled in the analysis.

7. Results Posted in the Registry

• Pirfenidone 2403 mg/Day: mean -8.00 versus -12.40 on control; difference 4.40 (95% CI 0.73 to 8.07), standardized effect d = 0.25; z-test p = 0.019.
• Pirfenidone 1197 mg/Day: mean -10.00 versus -12.40 on control; difference 2.40 (95% CI -2.05 to 6.85), standardized effect d = 0.13; z-test p = 0.290.

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 Six-Minute Walk Test (6MWT)Distance

• 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 deviations.
• Result:
  • Pirfenidone 2403 mg/Day: mean -60.00 versus -77.00 on control; difference 17.00 (95% CI -9.94 to 43.94), standardized effect d = 0.13; z-test p = 0.216.
  • Pirfenidone 1197 mg/Day: mean -76.00 versus -77.00 on control; difference 1.00 (95% CI -33.23 to 35.23), standardized effect d = 0.01; z-test p = 0.954.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pirfenidone 2403 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pirfenidone 1197 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.

Change in Worst Oxygen Saturation by Pulse Oximetry (SpO2) Measurement Observed During the 6-Minute Walk Test

• 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 deviations.
• Result:
  • Pirfenidone 2403 mg/Day: mean -2.00 versus -2.00 on control; difference 0.00 (95% CI -0.95 to 0.95), standardized effect d = 0.00; z-test p = 1.000.
  • Pirfenidone 1197 mg/Day: mean -1.00 versus -2.00 on control; difference 1.00 (95% CI -0.29 to 2.29), standardized effect d = 0.20; z-test p = 0.128.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pirfenidone 2403 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pirfenidone 1197 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.

Change in Percent Predicted Hemoglobin (Hb)-Corrected Carbon Monoxide Diffusing Capacity (DLco) of the Lungs

• 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 deviations.
• Result:
  • Pirfenidone 2403 mg/Day: mean -8.00 versus -10.00 on control; difference 2.00 (95% CI -0.32 to 4.32), standardized effect d = 0.18; z-test p = 0.091.
  • Pirfenidone 1197 mg/Day: mean -9.00 versus -10.00 on control; difference 1.00 (95% CI -1.92 to 3.92), standardized effect d = 0.09; z-test p = 0.502.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pirfenidone 2403 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Pirfenidone 1197 mg/Day and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the assessment beyond the primary FVC measure. They cover walking distance, oxygen saturation during the six-minute walk test, DLco, categorical FVC change, progression-free survival, dyspnea, and worsening of IPF. The posted numerical summaries include changes in six-minute walk distance, worst oxygen saturation, and percent predicted DLco. Results for the other listed secondary outcomes are not reported in the registry record.

Across the posted continuous secondary summaries, the group means and treatment-versus-placebo estimates vary by outcome and dose. Their confidence intervals include zero in the comparisons for which intervals are posted. This means the summaries do not show a clearly separated treatment-versus-placebo estimate for those secondary measures under their unadjusted interval calculations. They do not negate or independently confirm the primary comparison: each outcome measures a different aspect of health or function, with its own variability and precision.

Secondary results generally carry less weight than a prespecified primary result when many outcomes or comparisons are examined. Each additional test creates more opportunity for a nominally notable result to arise by chance. The registry record does not report a multiplicity procedure or a hierarchy for interpreting the secondary outcomes. The listed p-values are unadjusted, so they should not be treated as if they accounted for the full set of tests.

Some secondary outcomes are continuous and summarized using means and standard deviations, while others are categorical or time-to-event outcomes. They require different interpretations and may use different analysis methods. The record does not provide the full analytic detail for the unreported secondary outcomes. Taken together, the secondary information describes a wider set of measurements, but it does not provide a complete or multiplicity-adjusted account of the trial’s secondary evidence.

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

• Categorical Assessment of Absolute Change in Percent Predicted Forced Vital Capacity (FVC)
• Progression-free Survival (PFS)
• Change in Six-Minute Walk Test (6MWT)Distance
• Change in Worst Oxygen Saturation by Pulse Oximetry (SpO2) Measurement Observed During the 6-Minute Walk Test
• Change in Percent Predicted Hemoglobin (Hb)-Corrected Carbon Monoxide Diffusing Capacity (DLco) of the Lungs
• Change in Dyspnea Score
• Worsening of Idiopathic Pulmonary Fibrosis (IPF)

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous, and the registry reports group means and standard deviations. A mean is the arithmetic average of observations in a group. A standard deviation describes how spread out individual observations are around that average; it is not a measure of how precisely the mean has been estimated. Here the posted standard deviations are 16.47, 16.68, and 18.45 for the 2403 mg/day, 1197 mg/day, and placebo groups, respectively.

What does a mean difference represent?

A mean difference compares the average outcome in one group with the average in another. In the posted primary comparisons, placebo is the reference group and each dose is compared with it. A positive difference means the treatment-group mean change is higher than the placebo mean change on the reported scale. Since all three primary group means are negative, a higher value in this comparison represents a less negative average change. This is a description of the numerical direction, not a judgment about clinical importance.

The posted comparison estimates and confidence intervals are unadjusted calculations based on the group summaries. The record does not describe an adjusted model or provide enough detail to establish whether its primary analysis used these same summary-statistic calculations. The registry record does not report a prespecified covariate adjustment, a repeated-measures model, or the precise method used for the sponsor’s primary analysis.

How should the p-values be read?

A p-value describes how incompatible the observed data are with a specified null hypothesis under the assumptions of the statistical test. For a mean-difference comparison, the usual null is that the population means do not differ. A smaller p-value indicates greater incompatibility with that null under the test assumptions; it is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. The posted p-values for the primary comparisons are unadjusted, so they do not account for a possible multiplicity adjustment.

Why use confidence intervals?

A confidence interval gives a range of values compatible with the data under the method used to construct it. Its width reflects precision: narrower intervals indicate more precise estimates, while wider intervals indicate greater uncertainty. An interval that includes zero does not rule out a difference in either direction. An interval entirely on one side of zero indicates that values on the other side are not included under that interval procedure, but it does not resolve questions about bias, missing data, multiplicity, or clinical importance.

What does standardization add?

A standardized effect expresses a mean difference in relation to the pooled standard deviation, allowing a difference to be described on a scale that is less dependent on the original measurement units. The posted standardized effects are 0.252 for the 2403 mg/day comparison and 0.134 for the 1197 mg/day comparison. Such values summarize magnitude relative to observed variability. They do not determine whether the difference matters to patients, and they do not replace interpretation in the original outcome units.

What is not known about the analysis?

The registry record does not report the planned analysis model, the definition of the analysis population, the method for handling missing measurements, or whether any interim analyses were planned or conducted. It also does not report the trial’s original sample-size justification or the original design assumptions. Randomization supports comparison of groups in principle, but the available summary does not document the allocation sequence, concealment, or the balance of baseline characteristics. Those absences limit what can be concluded about how the posted estimates were produced.

General statistical interpretation also depends on assumptions. For instance, methods based on a normal approximation can be less reliable when outcomes are highly skewed or when observations do not meet model assumptions. The registry record does not provide distributional diagnostics. The estimates and intervals should therefore be understood as the posted summary-statistic comparisons, not as a complete account of every feature of the trial’s analysis.

11. Confidence Intervals and Precision

The primary confidence interval for the 2403 mg/day comparison runs from 0.725 to 8.075 around a mean difference of 4.4. It is entirely above zero, while still allowing a range of possible positive differences rather than identifying a single exact value. The primary confidence interval for the 1197 mg/day comparison runs from -2.05 to 6.85 around a mean difference of 2.4. It includes zero and permits both negative and positive differences, so the direction is less precisely established by this estimate.

Confidence intervals are useful because they display the uncertainty around an estimate in the outcome’s units. A point estimate alone can appear more definite than the data warrant. The interval reflects sampling uncertainty under the calculation method; it does not incorporate every possible source of uncertainty, such as bias, missing data, outcome measurement issues, or unreported analysis choices.

The lower-dose interval is wider than the higher-dose interval. The posted lower-dose group has 87 participants, whereas the higher-dose and placebo primary summaries each include 174 participants. Differences in sample size and variability can affect precision. The posted standard deviations also describe substantial variation in individual measurements, which is distinct from uncertainty about the group mean.

The record does not report whether the posted intervals are adjusted for the multiple treatment comparisons or the multiple outcomes. They should therefore be read as unadjusted intervals. Their stated precision does not by itself establish clinical relevance, and the registry does not give a threshold for interpreting the size of a meaningful FVC change.

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 for the continuous-outcome comparisons, not total participants across both arms. The planning illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It considers detecting the stated fraction of the observed effect. The trial’s own original design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the illustrative number of participants per arm for a design with an 80% chance of detecting the specified effect under the listed assumptions, if that effect is present. The 90% power column gives the corresponding illustrative number per arm for a design with a 90% chance. Power is a property of a planned design under assumptions; it is not a measure of whether the observed trial result is true.

The rows for 100%, 75%, and 50% of the observed effect consider progressively smaller effects relative to the observed estimate. Smaller effects need more participants to detect with the same target power, which is why the illustrative requirements increase as the assumed fraction decreases. Very small observed estimates can yield especially large planning figures. These calculations are not observed power; they are planning illustrations based on the observed effects, not the trial’s original design.

The figures are conditional on the stated assumptions and do not account for any trial-specific design features that are not reported in the registry record. They should be read as illustrations of how sample-size requirements respond to effect size, rather than as a retrospective verdict on the adequacy of the completed trial.

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 = 4.400; pooled standard deviation σ = 17.488.
2. n = 2 × (1.96 + 0.842)² × 17.488² / 4.400² = 248.0, rounded up to 248 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 <- 4.4                      # observed difference in means
sigma <- 17.4880444875921                     # 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(287716)
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 = 248 (80% power), 332 (90% power)
 75% of observed effect: n per arm = 441 (80% power), 591 (90% power)
 50% of observed effect: n per arm = 992 (80% power), 1,328 (90% power)
power.t.test: 248.9 
Simulated power at n = 248 per arm: 0.802 (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. Multiplicity, Missing Data and Analysis Populations

The registry record lists two dose-versus-placebo comparisons for the primary outcome and several secondary outcomes. Testing multiple hypotheses raises the possibility of false-positive findings across the collection of tests. The primary comparison p-values and the posted comparison intervals are unadjusted. Whether the trial’s prespecified analysis controlled the family-wise error rate or used another multiplicity strategy is not reported in the registry record.

The registry describes the primary outcome timeframe as baseline up to week 72, but does not give the timing or rules for selecting the primary analysis time point beyond that description. It does not report whether interim analyses were planned or conducted, whether stopping boundaries were used, or how the primary and secondary outcomes were ordered for formal inference. These details matter when interpreting nominal p-values in a multi-arm, multi-outcome study.

The record also does not report the analysis population, the number of participants with an observed primary endpoint, or the amount and pattern of missing data. It is not possible from the posted summaries to determine whether all randomized participants were analyzed, whether an intention-to-treat population was used, or how missing measurements were handled. The reasons for missingness and any sensitivity analyses are not reported in the registry record.

These omissions do not establish that the trial lacked a multiplicity plan or missing-data procedures; they mean those procedures cannot be assessed from the registry record. Likewise, the available summaries do not explain whether the posted group sizes differ from the number randomized or whether exclusions occurred. These are important considerations when evaluating the reliability and scope of the estimates.

15. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: idiopathic pulmonary fibrosis (8.0%), atrial fibrillation (3.4%), coronary artery disease (3.4%), chest pain (3.4%), pneumonia (3.4%).

The serious adverse event summaries list 60 affected participants among 174 at risk in the pirfenidone 2403 mg/day group, 28 among 87 at risk in the 1197 mg/day group, and 58 among 174 at risk in the placebo group. These are counts of participants with serious adverse events as recorded in the registry, not counts of all event episodes. A participant may have had more than one event; the record does not clarify the counting convention beyond the affected-participant summary.

The registry also lists other adverse events affecting 171 of 174 participants in the higher-dose group, 86 of 87 in the lower-dose group, and 169 of 174 in the placebo group. These are separate posted summaries and should not be treated as serious-event counts. Deaths are not reported in the registry record.

The listed serious-event terms include idiopathic pulmonary fibrosis at 8.0%, and atrial fibrillation, coronary artery disease, chest pain, pneumonia, and pulmonary embolism at 3.4% each. The registry record does not specify in this summary the denominators or whether these term percentages apply across treatment groups or to a particular group. These figures describe reported events and do not by themselves establish causation or comparative safety.

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

The posted primary results compare mean FVC change between each pirfenidone dose and placebo over the stated timeframe. The higher-dose comparison has a positive unadjusted mean difference with a confidence interval above zero. The lower-dose comparison also has a positive point estimate, but its interval includes zero. Those are statements about the estimates and their statistical uncertainty, not conclusions about individual outcomes or treatment decisions.

A group mean is not a prediction for a particular participant. Participants within a group can have different measurements and trajectories, and the mean does not show that distribution in full. The registry record does not provide participant-level results or a threshold for deciding whether a given change is clinically meaningful. It also does not provide the details needed to assess whether missing data, exclusions, or other analysis choices affected the estimates.

The findings should be understood alongside the trial’s randomized, blinded design and the limitations of the registry summaries. Randomization is intended to support fair comparisons between groups, while masking is intended to reduce the influence of knowledge of treatment assignment. The record does not describe the implementation details or report baseline balance, so the summaries alone cannot confirm how well those protections operated.

The result does not establish a direct difference between the two pirfenidone doses, since the posted primary comparisons are each against placebo. Nor does it answer every question addressed by the listed secondary outcomes or characterize all safety outcomes. Multiplicity handling, the original analysis plan, and missing-data methods are not reported in the registry record. The most defensible reading is therefore bounded: the posted summary-statistic comparison for one dose is more clearly separated from zero than the other, while the size, clinical importance, and robustness of the estimates require information not contained in the registry summaries.

17. Why This Trial Matters Statistically

This trial is statistically informative because it has three randomized arms and reports a continuous primary outcome at a specified follow-up timeframe. The two dose groups allow separate comparisons with placebo, while the primary outcome is reported on a common measurement scale. The arm summaries and comparison estimates make it possible to distinguish the size of each estimated difference from its uncertainty.

The results also illustrate why a point estimate should not be read alone. The higher-dose and lower-dose comparisons have different interval widths and different degrees of compatibility with a zero difference. Looking at the interval alongside the estimate gives a more complete account of precision than relying only on a p-value. The lower-dose arm’s smaller posted sample size is also relevant to how precisely its mean is estimated.

At the same time, the registry record illustrates the limits of summary-level reporting. It does not report the analysis population, missing-data approach, multiplicity procedure, or original sample-size justification. These details affect how confidently readers can connect the posted comparisons to the trial’s planned inference. The listed secondary outcomes add breadth but also raise questions about how multiple results were to be interpreted.

For biostatistical interpretation, the key distinction is between the observed summary, the uncertainty around it, and the wider evidentiary context. The numerical estimates describe group averages; confidence intervals describe sampling uncertainty under the calculation method; neither alone determines clinical importance or resolves potential bias. The record supports a careful comparison of the posted estimates, while leaving several design and analysis details unreported.

18. 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 offers arm-level means and standard deviations for the primary outcome, but it does not report participant-level data or the number with observed outcomes at each time point. The posted arm sample sizes therefore cannot be assumed to describe the complete analysis population. The handling and reasons for missing measurements are not reported in the registry record.

The record does not provide the detailed primary analysis plan, including any model-based adjustment, the approach to repeated observations, or the method used for the sponsor’s primary inference. The posted unadjusted comparisons are useful summaries, but they may not reproduce an analysis that accounts for trial-specific design features. Baseline characteristics and balance between arms are also not reported in the information summarized by the registry record.

Multiple comparisons are a further limitation. The trial has two dose comparisons and multiple secondary outcomes, but the registry record does not report a multiplicity strategy or clarify the inferential status of each outcome. This makes unadjusted p-values and intervals less conclusive when considered across the full set of tests.

Several secondary outcomes are listed without posted results, including categorical FVC change, progression-free survival, dyspnea score, and worsening of IPF. The record also does not report deaths, detailed adverse-event definitions, or the denominators and grouping basis for the listed serious-event terms. Finally, the registry does not report the original sample-size justification, interim-analysis plans, or detailed allocation and masking procedures. These are limits of the available record and do not establish that the trial did not use such procedures.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Three-Arm Study of the Safety and Efficacy of Pirfenidone in Patients With Idiopathic Pulmonary Fibrosis — NCT00287716.
• Registry record last updated 2017-05-22; status last verified 2017-04.
• Results first posted 2011-06-13.
• 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.

22. Record Summary

NCT00287716 is a completed, randomized, double-blind, quadruple-masked, parallel-group phase 3 study of pirfenidone in idiopathic pulmonary fibrosis. The registry lists enrollment of 435 and three arms: pirfenidone 2403 mg/day, pirfenidone 1197 mg/day, and placebo.

The primary outcome was mean change in percent predicted FVC from baseline up to week 72. The posted unadjusted mean differences versus placebo were 4.4 for the 2403 mg/day arm and 2.4 for the 1197 mg/day arm. Their 95% confidence intervals were 0.725 to 8.075 and -2.05 to 6.85, respectively.

Several secondary continuous outcomes have posted summaries, while results for other listed secondary outcomes are not reported in the registry record. The record also does not report the trial’s original sample-size justification, multiplicity handling, analysis population, or missing-data methods.