Supplemental Oxygen in Pulmonary Fibrosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Supplemental Oxygen in Pulmonary Fibrosis (NCT01961362), a registered phase not stated study. The primary outcome is Change in University of California San Diego Shortness of Breath Questionnaire From Immediately Prior to One Month After Starting Daily-use Supplemental Oxygen.

2. Clinical Question

This is a within-patient, before-and-after question rather than a comparison of outcomes between a treatment group and a control group. It asks about change in reported breathlessness after oxygen was prescribed; it does not, by itself, determine what would have happened over the same period without the prescription.

The study also sought to understand how patients perceived supplemental oxygen and how perceptions and patient-centered measures changed over time. Listed secondary outcomes are the Physical Component Summary (PCS) Score from the Medical Outcomes Study Short-Form, 36-item Questionnaire (SF-36) and the Fatigue Severity Scale. Numeric results for these outcomes are not reported in the registry record.

3. Trial Design

The registry describes a completed study sponsored by National Jewish Health. The listed condition is pulmonary fibrosis, and the enrollment is 19. The study began in 2013-10 and its primary completion was 2016-12. The registry record does not report a randomized allocation scheme; it explicitly notes that this is not a randomized comparison and that the arms are not a like-for-like control comparison.

The population description includes patients with pulmonary fibrosis of any cause, naming idiopathic disease, connective tissue disease, and chronic hypersensitivity pneumonitis. The described study question centers on daily-use supplemental oxygen and patient perceptions and outcomes before and after oxygen was prescribed. The primary outcome is a change in the UCSD Shortness of Breath Questionnaire score from immediately before prescription to one month after starting oxygen.

Two secondary outcomes are listed: the SF-36 Physical Component Summary score and the Fatigue Severity Scale. The record lists 3 outcome measures and 3 analyses, but does not provide the numeric results or explain the methods used for each analysis. The registry record does not report a sample-size justification, a detailed protocol, or an allocation method.

Because no comparable control group is described, the before-and-after design can describe the course of measurements in the enrolled group, but it cannot distinguish a change associated with the timing of oxygen prescription from changes that might also occur over time for other reasons. No conclusion about a treatment effect should be drawn from a within-group change alone.

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: We enrolled 19 subjects.

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.

Population: We enrolled patients with PF not using supplemental O2 and then followed them forward until they were prescribed supplemental O2 by their treating practitioner, and then we followed them for an additional 12 months after being prescribed O2.

6. Primary Endpoint

The registry lists the primary outcome as Change in University of California San Diego Shortness of Breath Questionnaire From Immediately Prior to One Month After Starting Daily-use Supplemental Oxygen, measured over UCSD SOB score at one month after being prescribed supplemental O2.

The primary endpoint is change in the University of California San Diego Shortness of Breath Questionnaire (UCSD SOB) score from immediately before starting daily-use supplemental oxygen to one month after it was prescribed. The questionnaire has 24 items, each with response options from 0 to 5, corresponding to “None at all” and “Maximally or unable to do because of breathlessness.” Total scores range from 0 to 120, with higher scores indicating greater shortness of breath.

This is a patient-reported measure: it captures participants’ own reports of breathlessness rather than an observer’s rating alone. A change score is intended to describe how the measure differs between the prespecified time points for the patients assessed. The registry identifies the outcome as a mean with standard deviation, which would describe the group’s average change and the spread of individual changes if those results were reported.

The timeframe makes the endpoint specific to the first month after oxygen was prescribed. It does not represent longer-term change. The numeric mean change, its standard deviation, the number of participants contributing data, and any interval estimate are not reported in the registry record. Therefore, the direction, magnitude, and precision of the primary outcome cannot be evaluated from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure analyzed as a mean with standard deviation. A continuous measure can take values across a numerical scale rather than falling into categories such as event or no event. For a change endpoint, each participant’s follow-up score is considered in relation to that participant’s score before oxygen was prescribed, and a group summary can describe the average change.

What does a mean describe?

In general, a mean is a way to summarize the center of a set of measurements. For this endpoint, a mean change would describe the average difference in UCSD SOB scores over the stated interval among participants included in the analysis. It does not indicate that every participant experienced the same change, and it can conceal variation in individual experiences.

Why report a standard deviation?

In general, a standard deviation describes how dispersed the individual measurements are around their mean. A relatively broad spread indicates that individual changes vary substantially; a narrower spread indicates more clustering around the average. The standard deviation is not itself an uncertainty interval for the mean. It describes variation among observations, whereas an interval estimate for a mean addresses uncertainty about the estimated group average.

The registry record specifies mean and standard deviation for the primary measure but does not report their numerical values. It also does not report an interval estimate or a hypothesis-test result. Consequently, the record does not allow readers to assess the estimated change’s precision or evaluate a statistical test of the primary outcome.

What would an interval estimate add?

In general, a confidence interval gives a range of values compatible with the data and the statistical procedure used, while conveying uncertainty in an estimate. A narrow interval indicates greater precision than a broad interval, all else equal. An interval does not correct for design limitations, missing data, or measurement bias. No confidence interval for the primary result is reported in the registry record.

What does the before-and-after design estimate?

In general, repeated measurements in one group can describe how outcomes change over time. A comparison with a concurrent, comparable control group is a different design feature: it helps separate changes associated with the intervention from background changes and other influences. Here, the record says the study is not a randomized comparison and that the arms are not a like-for-like control comparison. The design therefore does not provide a randomized between-group estimate of the effect of oxygen.

The primary timeframe is one month after daily-use oxygen was prescribed. This anchors the intended follow-up measurement but does not establish that all participants completed it. The registry record does not report how missing measurements were handled, whether any imputation was used, or which participants were included in each analysis.

How should the planning assumptions be understood?

General sample-size calculations can illustrate how many participants per arm might be needed to detect a specified effect under stated assumptions. The registry’s planning description uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it defines the effect to detect as a stated fraction of the observed effect. These are planning assumptions, not observed trial results. The registry record does not report the numeric observed effect needed to interpret those illustrations, and the study is not described as a randomized two-arm comparison.

A planning calculation is not observed power. Observed power is not a substitute for reporting the estimate and its uncertainty: once results are available, the effect estimate, variability, and an appropriate interval are more informative. Here, numeric outcome estimates are not reported in the registry record, so the planning assumptions cannot establish what the study observed or how precise its findings were.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Pulmonary Fibrosis Patients")
n   <- c(19)
m   <- c(0.9)
sp  <- c(8.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Pulmonary Fibrosis Patients  19  0.900  8.700  -3.293  5.093

11. Multiplicity, Missing Data and Analysis Populations

The record lists a primary UCSD SOB change outcome and two secondary outcomes: the SF-36 Physical Component Summary score and the Fatigue Severity Scale. It also lists 3 outcome measures and 3 analyses. Examining multiple outcomes raises a general multiplicity issue: the more statistical questions considered, the greater the chance that at least one result may appear notable by chance if all are treated as confirmatory. The registry record does not report a multiplicity adjustment, a hierarchy for testing outcomes, or which analyses were intended to be confirmatory.

The numeric results for the primary and secondary outcomes are not reported in the registry record. The record also does not report whether all planned measures were collected at each time point, how missing observations were handled, or whether any participants were excluded from an analysis. These omissions prevent assessment of the available-data pattern and how it may have influenced the reported estimates.

The analysis population is not reported in the registry record. Enrollment is listed as 19, but the record does not say how many participants contributed to each outcome analysis. It does not describe an intention-to-treat population, a complete-case population, imputation, or other missing-data methods. These are important distinctions for interpreting the representativeness and uncertainty of a change estimate.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry’s adverse-event figures list 19 patients at risk for serious adverse events and 0 affected; it also lists 19 at risk for other adverse events and 0 affected. The recorded number of deaths is 0. No serious adverse-event terms are listed.

These figures describe what was recorded for this group in the registry. They should not be read as proof that no adverse events can occur, or that the intervention is free of risk. The enrollment is 19, and the record does not provide further detail about safety monitoring, event collection methods, or the period of observation for these figures. It also does not report whether all participants had the same duration of follow-up for safety assessment.

Zero recorded events in a study group do not establish that the underlying event risk is zero. With no event terms or additional follow-up information, the safety figures are limited to the counts posted in the registry and do not support broader conclusions.

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

This registry record describes a completed study of supplemental oxygen in patients with pulmonary fibrosis, with a primary focus on change in self-reported shortness of breath from before oxygen was prescribed to one month afterward. It also identifies patient perceptions, physical component health status, and fatigue as areas of interest. These are relevant patient-centered outcomes, but the registry record does not report numeric findings for them.

The record therefore does not show the direction or size of the average change in UCSD SOB score, how variable individual changes were, or how precise an estimate might be. It also does not support a conclusion about changes in the listed secondary measures. The score’s range and interpretation are described, but the absence of outcome values means those definitions cannot be used to infer what participants experienced.

The study design is also important. It is not a randomized comparison, and the registry says the arms are not a like-for-like control comparison. A before-and-after observation can describe what happened to measurements in the enrolled group over time, but it cannot by itself determine how much of any change was caused by oxygen. Other changes over time could also contribute.

The posted safety counts are limited to the recorded figures: no serious or other adverse events and no deaths are listed for the described group. These counts do not demonstrate an absence of possible risk. The record does not provide enough information about event collection or follow-up to support broader safety conclusions.

Overall, the registry record documents the study question, population, outcome definitions, and selected design features. It does not provide the outcome estimates needed to judge the observed changes or their precision. The record should not be interpreted as evidence that supplemental oxygen did or did not produce a particular clinical effect.

14. Why This Trial Matters Statistically

This study is statistically notable for the contrast between a clearly stated patient-centered question and the limited information available to evaluate its results. The primary outcome is defined as a change in a validated questionnaire score over a specified interval, and the record explains how to interpret the score’s direction. Yet the numeric result, variability, and uncertainty are not reported in the registry record. Without those quantities, neither the magnitude nor the precision of the change can be assessed.

The design also illustrates why the target comparison matters. A pre-prescription and post-prescription measurement can describe change over time, but without a like-for-like control comparison it cannot isolate the effect of the intervention. This is a different inferential question from whether the group’s score changed. Clear language about that distinction helps prevent a within-group observation from being mistaken for a causal estimate.

The registry lists additional patient-centered outcomes, which broadens the clinical questions under study but also makes prespecification and multiplicity methods relevant. The record does not describe how multiple outcomes were handled statistically. It likewise does not report the analysis populations or missing-data methods, which are essential context for interpreting repeated-measure results.

The study’s small listed enrollment and the absence of numeric outcome results make precision especially important to assess, but no outcome estimate or interval is reported. Planning illustrations cannot replace observed results, and their two-arm assumptions do not describe a randomized comparison in this record. Transparent reporting of estimates, variability, uncertainty, analyzed participants, and missingness would be needed for a fuller statistical appraisal.

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 most direct limitation of the registry record is that it does not report numeric results for the primary UCSD SOB outcome or the listed secondary outcomes. The record therefore does not allow assessment of the observed direction or size of change, variability, or precision.

The study is not described as a randomized comparison, and the registry explicitly says the arms are not a like-for-like control comparison. This limits causal interpretation of any before-and-after change: a change over time cannot be separated from other influences using a comparable control contrast in the described design.

The registry lists enrollment of 19 but does not report how many participants contributed data to each outcome analysis. Missing-data methods, analysis populations, and reasons for any unavailable measurements are not reported in the registry record. The record also does not report a sample-size justification or the statistical plan for handling multiple outcomes.

The primary endpoint is measured at one month after oxygen was prescribed, so the stated outcome timeframe does not address longer-term change. The safety counts are limited to the posted figures; details about event ascertainment and follow-up are not reported in the registry record. These limitations mean the record gives useful context about the study question and measurement, but insufficient detail to evaluate the outcome evidence or its generalizability.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Supplemental Oxygen in Pulmonary Fibrosis — NCT01961362.
• Registry record last updated 2020-02-25; status last verified 2020-02.
• Results first posted 2020-02-25.
• 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

NCT01961362, titled “Supplemental Oxygen in Pulmonary Fibrosis,” is a completed study sponsored by National Jewish Health. The record lists pulmonary fibrosis, enrollment of 19, a start date of 2013-10, and primary completion in 2016-12.

The primary outcome is change in UCSD SOB score from immediately before to one month after starting daily-use supplemental oxygen. Listed secondary outcomes are the SF-36 Physical Component Summary score and the Fatigue Severity Scale. The registry identifies the study as not a randomized comparison and says the arms are not a like-for-like control comparison.

Numeric outcome findings, analysis populations, and missing-data methods are not reported in the registry record. The listed adverse-event figures are 0 serious events, 0 other events, and 0 deaths.