Curcumin and Function in Older Adults: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Curcumin and Function in Older Adults (NCT03085680), a randomized phase 2, phase 3 study. The primary outcome is Curcumin and Physical Function -Walking.

2. Clinical Question

In practical statistical terms, the study asks whether the average change in walking speed differs between participants assigned curcumin and those assigned placebo. The posted arm-level means describe change from baseline to 3 months, but an arm-level mean alone does not establish the size or precision of a between-group contrast. The registry record does not report an inferential comparison for this outcome, so it does not establish whether the observed arm-level results are compatible with a difference or with no difference.

3. Trial Design

The registry identifies NCT03085680 as a completed randomized trial with a parallel-group model and double masking. It lists PHASE2 and PHASE3. The sponsor is the University of Florida. The recorded start date is 2017-08-11, and the primary completion date is 2019-10-18. Enrollment is listed as 17.

The two assigned groups were curcumin and placebo. The curcumin group was instructed to take 1000 mg/day in identical capsules; the placebo capsules contained microcrystalline cellulose. The capsule instructions specified taking two capsules before breakfast each morning with a glass of water. The stated treatment period was three months. The registry record does not describe allocation concealment, the randomization sequence, or whether participants, caregivers, and outcome assessors were all masked.

The primary outcome was titled “Curcumin and Physical Function -Walking.” It concerns change in walking speed, measured in meters/second, from baseline to 3 months, using a 400-meter walk test. The registry lists three secondary outcomes: attention and memory, pain, and interleukin-6 as an inflammation measure. Five outcome measures are listed in total, but further outcome details and results are not reported in the registry record.

The posted primary outcome data include 9 participants in the curcumin group and 8 in the placebo group. These are the group sizes attached to the outcome results, not a description of every stage of trial participation. Recruitment flow, exclusions from the outcome analysis, and the number assessed at each time point are not reported in the registry record. The record does not report a detailed statistical analysis plan, a sample-size justification, interim analyses, or a protocol-level explanation for the enrollment target.

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 Curcumin and Physical Function -Walking, measured over Change in walking speed (meters/second) from Baseline and 3 months.

The primary endpoint is change in walking speed, measured in meters/second, from baseline to 3 months. The registry describes measurement with a 400-meter walk test. Walking speed is a continuous measure: it can take values across a scale rather than being limited to categories such as improved or not improved. The posted outcome is characterized as a mean, with standard deviation as its measure of spread.

Walking speed is used in this trial as a measure of physical function. In a study focused on older adults at increased risk of disability, a performance measure can provide a standardized way to describe functional capacity and to compare average changes between assigned groups. The registry frames the goal as examining whether dietary curcumin maintains or improves physical function, but the statistical endpoint is specifically walking speed; it should not be treated as a direct measure of every aspect of daily function.

A change score compares the recorded value at follow-up with the value at baseline. Its interpretation depends on the registry's scoring convention, including which direction represents a faster walk and how change is calculated. Those details are not fully reported in the registry record. The arm-level values are therefore best read as the posted mean changes, rather than as a complete account of each participant's trajectory or an adjusted treatment effect.

The endpoint's usefulness for comparing groups also depends on how consistently the walk test was administered, the completeness of baseline and follow-up measurements, and the analysis used. These details are not reported in the registry record. The endpoint provides a focused measure of walking performance, but it does not by itself summarize the trial's secondary questions about attention, memory, pain, or inflammation.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous and summarized with a mean and standard deviation. These statistics answer different questions. The mean gives the average observed change within a group. The standard deviation describes how dispersed the participant-level changes are around that group mean. Neither statistic alone is a comparison of the randomized groups.

What would a between-group estimate describe?

A between-group estimate would express the contrast in average change between the curcumin and placebo groups. It would directly address the randomized comparison more clearly than reading the two means separately. The registry record reports the two arm-level means, but does not report a between-group estimate for the primary outcome. A new contrast should not be calculated from the posted summaries as though it were the sponsor's analysis.

What does a confidence interval add?

In general, a confidence interval describes the uncertainty around an estimated quantity, such as a mean or a between-group contrast. Its width reflects both the variability in the data and the amount of information available under the analysis. A narrow interval indicates greater precision than a wide interval, while an interval that includes values consistent with no contrast does not establish that the groups are equivalent. The registry record does not report a confidence interval for the primary comparison, so its precision cannot be assessed from an interval.

What does a p-value answer?

In general, a p-value is calculated under a statistical model and a null hypothesis, and describes how compatible the observed data are with that model's assumptions. It is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of an effect. No primary-outcome p-value is reported in the registry record. Statistical significance therefore cannot be assessed from the posted arm-level means and standard deviations alone.

Why does the analysis population matter?

In a randomized trial, the analysis population determines which participants contribute to the estimate and how assignment is handled when follow-up information is incomplete or treatment is not taken as instructed. An analysis based on assignment can preserve the original randomized comparison under its assumptions; an analysis based on treatment received or complete outcomes answers a different question and may be more vulnerable to bias. The registry record does not report the analysis population or how incomplete measurements were handled.

How should the planning illustrations be read?

In general, a sample-size calculation estimates how much information a future study would need under chosen assumptions. The stated planning assumptions use a two-sided significance level of 0.05, equal allocation, and a normal approximation. The target effect is described as a stated fraction of the observed effect. These are planning assumptions, not a reconstruction of the trial's design rationale. The registry record does not report the trial's own sample-size justification.

Planning calculations based on an observed effect are sensitive to the estimate used, especially when the observed groups are small. Such calculations illustrate a hypothetical design under their assumptions; they are not observed power and do not show that the current trial had adequate power. The planning illustration should be interpreted separately from the outcome results. No planning values need to be mistaken for participants actually enrolled or analyzed.

What does the standard deviation not tell us?

A standard deviation measures spread in participant outcomes, whereas a standard error is associated with the precision of an estimated mean. A confidence interval for a treatment contrast would require an estimate and an analysis that accounts for the study design and available data. The posted standard deviations do not supply all of that information. A reader should not use them as if they were uncertainty intervals for the treatment comparison.

In general, the method used for a change score can affect interpretation. Comparing mean changes is one approach; modeling follow-up values while accounting for baseline is another. The registry record does not report whether the primary analysis used a change-score comparison, baseline adjustment, or another model. It also does not report whether assumptions were checked or how influential observations were handled. Consequently, the posted descriptive summaries cannot identify the sponsor's analytic method.

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("Curcumin", "Placebo")
n   <- c(9, 8)
m   <- c(0.014, 0.103)
sp  <- c(0.09, 0.1)
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  Curcumin  9  0.014  0.090  -0.055  0.083
CARM  Placebo  8  0.103  0.100  0.019  0.187

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three secondary outcomes: attention and memory, pain, and interleukin-6. It also lists five outcome measures in total. The record does not report results for these secondary outcomes in the posted results, nor does it report how many statistical tests were conducted. No multiplicity adjustment or hierarchy for interpreting primary and secondary outcomes is reported in the registry record.

Multiplicity arises when several outcomes or comparisons are tested. In general, the more tests considered, the greater the chance that at least one result may appear notable by chance if each test is interpreted independently. A prespecified testing strategy or adjustment can help explain how to interpret a family of results. Because the registry record does not describe such a strategy, the handling of multiplicity cannot be assessed.

Missing-data procedures are also not reported. The posted outcome group sizes are 9 for curcumin and 8 for placebo, but the record does not provide a participant flow, the amount or pattern of missing walking-speed data, or reasons for missingness. It does not say whether the posted means include all randomized participants, only participants with follow-up measurements, or another analysis population. The handling of missing baseline or follow-up observations is not reported in the registry record.

The registry record also does not report an intention-to-treat definition, a per-protocol analysis, imputation, sensitivity analyses, or a method for accounting for any deviations from assigned treatment. These omissions limit assessment of whether the outcome summaries preserve the original randomized comparison and how robust they are to incomplete data. The record lists no posted analyses for the outcome results described, so the analysis population and missing-data approach remain unclear.

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 posted adverse-event figures list 9 participants at risk in the curcumin group and 8 in the placebo group. The record reports 0 serious adverse events in each group, 0 other adverse events in each group, and 0 deaths in each group. These are the counts recorded in the registry for the listed groups.

Zero events in a group means that no event of that category was recorded in the posted results for that group. It does not establish that the intervention has no risk, and it does not show that the groups have equivalent safety. With these group sizes, the absence of recorded events provides limited information about uncommon outcomes. The registry record does not report event definitions, follow-up completeness for safety, or details of how events were collected and reviewed.

The serious-event summary should be read separately from the primary walking-speed outcome. It does not provide evidence about the effect on physical function, and the physical-function summaries do not establish safety. The record lists no top serious-event terms. Further detail about other event types, severity, timing, or attribution is not reported in the registry record. These figures describe the registry's posted counts only; they should not be interpreted as a comprehensive safety assessment.

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

The registry record supports a limited descriptive statement: it reports mean changes in walking speed for participants assigned to curcumin and placebo, along with a standard deviation for each group. It does not report a statistical estimate comparing the groups, a confidence interval, or a p-value for the primary outcome. The posted information therefore does not quantify the magnitude or precision of the randomized treatment contrast.

The figures do not establish that curcumin maintained or improved walking speed, nor do they establish that it did not. Those conclusions require an interpretable comparison and uncertainty assessment, together with an understanding of the analysis population and missing data. The record's description of the trial objective is not itself evidence that the objective was achieved.

The endpoint captures walking speed measured by a 400-meter walk test from baseline to 3 months. It does not encompass all physical function, cognitive function, pain, or inflammatory activity. Although the registry lists secondary outcomes in those areas, their results are not reported in the registry record. The primary outcome cannot be used as a substitute for those unreported results.

The completed status and randomized, double-masked design provide context for the trial, but do not resolve the limitations of the posted analysis. The record does not explain the randomization procedures, adherence, handling of incomplete data, or analysis population. The posted safety counts record no serious or other adverse events and no deaths in either group, but those counts alone cannot establish the absence of risk.

Planning illustrations answer a different question from trial results: they describe hypothetical sample sizes under stated assumptions. They are not observed evidence of effect and are not a measure of the trial's power. The most defensible reading is that the registry contains descriptive primary-outcome summaries and adverse-event counts, while the inferential comparison needed to judge the treatment contrast is not reported.

14. Why This Trial Matters Statistically

This trial is statistically notable because it asks a randomized question about a continuous functional outcome in older adults at increased risk of disability. The primary endpoint, walking-speed change, is directly interpretable as a measured performance value, while the secondary outcomes broaden the scientific questions to attention and memory, pain, and inflammation. Keeping those outcomes distinct matters: evidence about walking speed would not automatically answer the questions about cognition, pain, or interleukin-6.

The record also illustrates the difference between descriptive summaries and comparative inference. Means and standard deviations help describe each assigned group, but the central randomized question concerns the contrast between groups. Without a reported contrast and its uncertainty, readers cannot assess how precisely the trial estimates that comparison. This distinction is especially important when the posted outcome groups are small, because descriptive values may be sensitive to individual observations.

Registry reporting matters for reproducibility and interpretation. Information about the analysis population, missing measurements, outcome timing, and statistical model helps readers understand what the reported estimate represents. Such details are not reported for this primary analysis. The absence of those details does not show that a particular method was or was not used; it limits what can be concluded from the registry record.

The planning illustrations also demonstrate why design calculations should not be confused with results. A hypothetical sample size depends on assumptions about the target effect and statistical approach. It cannot supply an unreported effect estimate or convert descriptive outcomes into evidence of a treatment difference. Clear separation of planning assumptions, observed summaries, and inferential analyses is essential when interpreting small clinical trials.

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 main trial-specific limitation for interpreting the primary result is that the registry reports arm-level means and standard deviations but no inferential comparison. There is no posted treatment-effect estimate, confidence interval, or p-value for the walking-speed outcome. Readers therefore cannot assess the reported contrast's precision or determine how the analysis addressed uncertainty.

The posted outcome groups comprise 9 participants assigned to curcumin and 8 assigned to placebo. The registry does not provide participant flow, reasons for any exclusions, or a clear analysis population. It is not possible to tell from the record whether all randomized participants contributed to the reported outcome summaries or how missing measurements were handled.

The registry record does not report adherence, treatment discontinuation, allocation concealment, the complete masking procedures, or the statistical model used for the primary outcome. It also does not report the trial's sample-size justification, interim analyses, or a detailed prespecified analysis plan. These gaps prevent evaluation of several design and analysis choices that could influence interpretation.

Although secondary outcomes are listed, their results are not reported in the registry record. The number of outcome measures and the lack of reported multiplicity procedures leave uncertainty about how multiple outcomes were intended to be interpreted. Safety counts show no posted serious or other adverse events and no deaths in either group, but the record provides limited detail about ascertainment and follow-up. Together, these limitations mean the registry offers a narrow descriptive record rather than a complete account of the trial's results and methods.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Curcumin and Function in Older Adults — NCT03085680.
• Registry record last updated 2022-07-26; status last verified 2022-07.
• Results first posted 2022-02-02.
• 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

NCT03085680, “Curcumin and Function in Older Adults,” is listed as a completed randomized, double-masked, parallel trial sponsored by the University of Florida. The registry lists PHASE2 and PHASE3, enrollment of 17, a start date of 2017-08-11, and a primary completion date of 2019-10-18.

The comparison was curcumin versus placebo containing microcrystalline cellulose, with a stated three-month treatment period. The primary outcome was change in walking speed from baseline to 3 months, measured in meters/second using a 400-meter walk test. The posted mean changes were 0.014 with standard deviation 0.09 in the curcumin group and 0.103 with standard deviation 0.1 in the placebo group.

The registry record does not report an inferential comparison for the primary outcome. It lists secondary outcomes concerning attention and memory, pain, and interleukin-6, without posted results for those outcomes in the record described. The adverse-event summary lists no serious events, other adverse events, or deaths in either group.