This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Urinary Proanthocyanidin-A2 as a Biomarker of Compliance to Intake of Cranberry Products (NCT01687114), a na na study. The primary outcome is Proanthocyanidin A2.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01687114 |
| Phase | NA |
| Condition | Urinary Tract Infection |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 5 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Tufts University |
| Results posted | Yes |
2. Clinical Question
Population
The study description concerns 5 generally healthy, pre-menopausal women aged 20-40 years, with a body mass index from 18.5 to 25 kg/m2. Participants were described as nonsmokers without major chronic cardiovascular, endocrine, gastrointestinal, or renal conditions. Eligibility also considered age, body mass index, pre-menopausal status, and whether a participant was pregnant or planning pregnancy. The recruitment area was Boston.
Intervention
Participants consumed a cranberry beverage described as 27% cranberry juice. The planned intake was 8 oz/day, following a weekly progressive dosing schedule. The record describes the intervention as cranberry juice and does not give further details about the beverage beyond its juice concentration.
Comparator
There was no concurrent comparator group. The registry classifies the study as single-group and lists no randomized allocation. Accordingly, the question is about change or pattern within participants during intake, not a contrast between cranberry juice and a control beverage or usual intake.
Primary question
The primary question was whether urinary proanthocyanidin A2, also called PAC-A2, could serve as a marker of compliance with cranberry intake. The study hypothesis was that progressive cranberry beverage intake would increase urinary PAC-A2 excretion. Urinary concentrations were to be measured in 24-hour urine and morning spot urine. The endpoint is a biomarker measure, not a measure of urinary tract infection occurrence or prevention.
3. Trial Design
This was a completed pilot study at Tufts University, registered as NCT01687114. Its record lists a single-group model, no masking, and no randomized allocation. The registry lists 5 participants enrolled. The recorded start was 2012-09 and primary completion was 2013-03. Phase is listed as not applicable.
The study was designed to examine urinary PAC-A2 as a potential biomarker of compliance with cranberry product intake. Participants were asked to consume 8 oz/day of a 27% cranberry juice beverage according to a weekly progressive dosing schedule. The registry description says that relevant clinical information and eleven 24-hour and morning spot urine samples each would be collected during the study. It does not provide a more detailed schedule for the dose progression or specimen collection.
The primary measure was urinary proanthocyanidin A2 concentration, expressed in ng/mg creatinine and summarized as a mean with standard deviation. The stated measurement timeframe was 24-hour urine and morning spot urine. The record says concentration would be determined using an LC-MS/MS method. It does not report the numerical PAC-A2 results, the values at individual time points, or an estimate of change over intake.
Because there was no concurrent control group, the design can describe biomarker patterns during the intake schedule but cannot directly compare those patterns with a control condition. The registry record does not report the protocol details, sample-size justification, analysis plan, or any interim analyses. The stated enrollment of 5 describes the small scale of the study, but the record does not explain how that enrollment target was chosen.
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
| Stage | Cranberry Juice |
|---|---|
| STARTED | 5 |
| COMPLETED | 5 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The subjects included 5 generally healthy premenopausal women, age 20-40 y, with a body mass index (BMI) ranging from 18.5 to 25 kg/m2. The specific operational criteria used to assess eligibility included: age, BMI, premenopausal status, not pregnant or planning to become pregnant.
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.
| Characteristic | Unit | Cranberry Juice |
|---|---|---|
| Participants analysed | 5 | |
| Age, Continuous | years | 27.6 (SD 3.4) |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 5 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 5 |
| Sex: Female, Male: Male | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 5 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 5 |
6. Primary Endpoint
The registry lists the primary outcome as Proanthocyanidin A2, measured over 24-hour urine and morning spot urine.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ng/mg creatinine |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is urinary proanthocyanidin A2 concentration, a measure of PAC-A2 in urine. Its unit is ng/mg creatinine, and the registry describes the summary measure as a mean with standard deviation. The stated timeframe includes both 24-hour urine and morning spot urine. The concentration was to be determined using an LC-MS/MS method.
The endpoint was selected to test a biomarker question: whether urinary PAC-A2 could indicate compliance with cranberry intake. In general, a biomarker is a measurable biological feature used to represent an exposure or biological process. For this study, the proposed logic was that cranberry intake would be followed by increased PAC-A2 excretion in urine. The planned progressive dosing schedule was intended to examine the marker in relation to intake, but numerical endpoint results are not reported in the registry record.
The measure should not be read as a urinary tract infection outcome. Although urinary tract infection is listed as a condition, the primary endpoint is a laboratory concentration, not infection occurrence, symptoms, or prevention. The registry does not report whether the endpoint was analyzed separately by specimen type, dose period, or collection time. Those analysis details are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry supports a clear description of the study question and design, but not an assessment of the observed biomarker response. It identifies urinary PAC-A2 concentration as the primary measure and describes a progressive cranberry beverage intake schedule. It does not report the mean PAC-A2 concentration, its standard deviation, individual participant values, or any estimate comparing measurements across the schedule. Therefore, the direction and size of any observed change cannot be established from the registry record.
The distinction between a stated hypothesis and a reported result is important. The study hypothesized that cranberry intake would increase urinary PAC-A2 excretion. A hypothesis describes what investigators expected to investigate; it is not evidence that the expected pattern occurred. Without outcome values and an analysis, the registry cannot show whether PAC-A2 rose, stayed similar, or varied inconsistently across participants or specimen types.
The design is also limited for causal comparisons. All participants received the cranberry beverage, and the registry lists no comparator group. Any pattern over time would consequently be a within-group observation. General changes over the study period, differences in urine collection, or other factors could not be separated from beverage intake using a concurrent randomized comparison. This does not make a pilot biomarker study uninformative, but it narrows the conclusions the design can support.
The enrollment was 5, so any participant-level pattern would also need to be read as preliminary. Small studies can help establish whether measurements can be collected and can motivate further work, but estimates are often imprecise and sensitive to the observations of individual participants. The registry does not report uncertainty intervals or inferential statistics, so the precision of any biomarker estimate cannot be evaluated.
The record lists one primary outcome measure and no statistical analyses. It does not report the analysis population, the handling of missing or unusable urine samples, or methods for accounting for repeated measurements within a participant. These omissions prevent evaluation of how the intended data were reduced to a final estimate. The completed status means the study is recorded as completed; it does not mean that outcome results are available in the registry.
9. Statistical Methods Explained
The registry identifies a continuous outcome summarized by a mean and standard deviation. In general, a mean describes the average measured concentration across observations included in an analysis. A standard deviation describes how dispersed those measurements are around their mean. The mean gives a central summary, while the standard deviation gives information about variation among the measurements. Neither statistic is reported numerically for urinary PAC-A2 in the registry record, so the level and variability of the measured concentration cannot be assessed.
The endpoint is expressed relative to creatinine, in ng/mg creatinine. In general, expressing a urinary analyte relative to creatinine is a way to account for differences in urine concentration. The resulting measure remains a biomarker concentration; it does not itself establish whether participants followed the intake schedule or whether a clinical outcome changed. The registry’s intended validation question is whether urinary PAC-A2 can act as an indicator of cranberry intake.
Repeated urine collections from the same participant are not independent observations. In general, measurements from one person can be more alike than measurements from different people because they share individual characteristics. An analysis of repeated measurements should account for this within-person relationship; treating every specimen as independent can make the apparent amount of information too large and uncertainty too small. The registry describes 24-hour and morning spot urine collections but does not report the statistical approach used to model repeated measurements, summarize different collection types, or compare time points.
Two specimen types can also represent different sampling contexts. In general, a 24-hour collection summarizes excretion across a collection interval, whereas a morning spot specimen is a sample collected at a particular time. Their values need not be interchangeable. A clear analysis would need to define how each type contributes to the endpoint and how measurements are aligned with the progressive dosing schedule. Those details are not reported in the registry record.
A confidence interval, in general, expresses uncertainty around an estimated quantity under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, while neither interval width nor statistical significance alone establishes the practical meaning of a biomarker. The registry does not report confidence intervals or any other uncertainty estimates for PAC-A2. It is therefore not possible to judge the precision of the observed response from this record.
The record includes a planning illustration based on an observed effect and describes assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also specifies that the illustration’s target effect is a stated fraction of the observed effect. These are planning assumptions, not evidence of the study’s original design. The actual study is single-group, with no two-arm randomized comparison, so an equal-allocation two-arm calculation does not describe the trial design. The registry does not report a sample-size justification for the pilot itself. Any values used for future planning should be treated as illustrations rather than as observed power or proof that the study could detect a particular effect.
In general, power calculations concern the probability of detecting a specified effect under stated assumptions if a study is conducted and analyzed as planned. They do not measure whether a completed study’s result is valid, and they do not replace estimates with uncertainty intervals. A calculation based on an observed effect is especially dependent on that estimate; small pilot studies can produce unstable estimates. The registry does not provide a numerical PAC-A2 effect estimate, so the effect underlying the planning illustration cannot be evaluated from the record.
The registry lists no statistical analyses. It does not describe a statistical model, a hypothesis test, a method for handling repeated observations, or adjustments for multiple comparisons. It also does not give an analysis population or missing-data procedure. These are not details that can be inferred from the mean-and-standard-deviation description. They are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure: urinary proanthocyanidin A2 concentration. That does not by itself establish how many statistical comparisons were planned. Measurements were described for 24-hour urine and morning spot urine over a progressive dosing schedule, so there could be multiple observations or possible comparisons, but the registry does not state which comparisons were prespecified or whether any multiplicity adjustment was planned. The analysis plan and any adjustment for multiple testing are not reported in the registry record.
The record does not report missing-data methods, rules for incomplete urine collections, or how unusable specimens would be handled. It also does not define an intention-to-treat, per-protocol, or other analysis population, nor does it state how participants with incomplete intake or specimen data would be treated. These details matter because the analyzed measurements may differ from all measurements originally intended for collection.
The registry lists no statistical analyses and gives no numerical endpoint results. It is therefore not possible to determine how many participants or samples contributed to an analysis, whether all planned collections were obtained, or how missing observations affected the reported estimate. Missingness and analysis-population details are not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Cranberry Juice | 0 | 5 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Cranberry Juice | 0 of 5 |
The adverse-event figures list 5 participants at risk for serious adverse events and 0 affected. For other adverse events, the figures also list 5 at risk and 0 affected. No serious adverse event terms are listed. These are the registry’s reported counts; they should be read as counts recorded for this small study, not as evidence that an event was impossible.
The death field is not populated with a numerical value, so the number of deaths is not reported in the registry record. A blank or unavailable death figure should not be interpreted as a reported count of zero. The record also does not provide event descriptions, timing, severity beyond the serious-versus-other grouping, or a narrative explaining how events were collected and assessed.
With only 5 participants at risk, the event counts are descriptive and offer limited information about uncommon harms. The registry’s counts do not establish comparative safety because there was no concurrent control group, and they do not support broad conclusions beyond the recorded participants and study period.
12. What the Result Does, and Does Not, Mean
The study addresses a focused measurement question: whether urinary PAC-A2 can serve as a marker of cranberry intake. It records a progressive intake schedule, a cranberry beverage, and planned collection of 24-hour and morning spot urine. These design details explain what the investigators intended to examine. They do not establish that PAC-A2 tracked intake, because the registry does not report the measured concentrations or a statistical analysis.
A positive biomarker finding would require evidence in the actual measurements, along with a clear account of how repeated specimens and participant-level variation were handled. That evidence is not reported in the registry record. The stated hypothesis that intake would increase urinary PAC-A2 should therefore remain a hypothesis when interpreting this record.
Even if a biomarker pattern were reported, it would answer a different question from whether cranberry products prevent or treat urinary tract infection. The recorded primary endpoint is PAC-A2 concentration, not infection incidence or a clinical symptom. The study population is described as generally healthy women, and the registry gives no clinical urinary tract infection result. The record cannot establish a clinical effect.
The study’s single-group structure also means that it does not provide a controlled comparison of cranberry intake with another condition. Any change during the dosing schedule would be observed within participants, without a concurrent group to help distinguish the intake pattern from other changes over time. The small enrollment further limits the scope and precision of any conclusions that could be drawn from the study.
Accordingly, the registry establishes that a completed pilot study was intended to evaluate urinary PAC-A2 as a compliance biomarker, and it describes the population, intake, specimen types, and endpoint. It does not establish the size, direction, consistency, or precision of a PAC-A2 response. It also does not establish clinical benefit or harm. Those conclusions require outcome information and analyses that are not reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically interesting because it separates an exposure-monitoring question from a clinical-outcome question. A biomarker may help researchers assess whether an intended intake occurred, but that role requires evidence that the marker responds in a predictable way to the exposure and can be measured reliably. The registry describes that intended validation question using urinary PAC-A2, but it does not report endpoint values with which to assess the proposed relationship.
The repeated urine collections also raise a common design issue: measurements from the same participant are related. The number of specimens is not equivalent to the number of independent participants. Statistical analysis must preserve the participant as the unit that contributes repeated observations, or otherwise account for within-person dependence. The registry does not report how this issue was handled, making the analysis method important for any interpretation of future results.
The contrast between the actual single-group design and the two-arm assumptions described for planning is another useful statistical lesson. A planning illustration can be useful for exploring what a later study might require, but its assumptions need to match the intended design. A two-arm calculation is not a description of a single-group pilot and should not be mistaken for the pilot’s original sample-size rationale or for observed power.
Finally, a completed registry entry is not necessarily a complete results report. This record identifies an outcome but lists no statistical analyses and gives no numerical endpoint results. That distinction matters when readers assess the evidence: trial registration can clarify what question was intended, while conclusions about magnitude and uncertainty require reported data and analysis.
14. 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 for interpretation is that the registry does not report numerical PAC-A2 results. Without means, standard deviations, participant-level measurements, or estimates across the intake schedule, the proposed biomarker response cannot be evaluated. The record also lists no statistical analyses, so there is no reported estimate of change or uncertainty.
The study enrolled 5 participants and had a single group. The small enrollment limits the breadth and precision of conclusions, while the lack of a comparator limits separation of intake-related patterns from other changes over time. The participant description is narrow: generally healthy, nonsmoking, pre-menopausal women aged 20-40 years, with a body mass index from 18.5 to 25 kg/m2. Findings, if available, would not automatically apply to populations outside those characteristics.
The registry describes two urine collection types and repeated sampling but does not report detailed collection timing, the number of usable samples, adherence assessment, or how specimens were analyzed in relation to dose periods. It does not describe handling of missing data, incomplete collections, or repeated-measure dependence. Those omissions limit assessment of measurement quality and analytic validity.
The registry record also does not report the study’s sample-size justification, detailed statistical plan, or any interim analyses. It is not possible to determine whether the listed planning illustration was intended for a later study or how its assumptions relate to the pilot beyond the stated two-arm framework. Finally, the endpoint is a biomarker rather than a urinary tract infection outcome, so it cannot by itself establish a clinical effect.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Urinary Proanthocyanidin-A2 as a Biomarker of Compliance to Intake of Cranberry Products — NCT01687114.
- Registry record last updated 2014-12-15; status last verified 2014-12.
- Results first posted 2014-12-15.
- 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.
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18. Record Summary
NCT01687114 is a completed, single-group pilot study sponsored by Tufts University. It enrolled 5 generally healthy pre-menopausal women and examined urinary PAC-A2 as a potential marker of cranberry intake. Participants were asked to consume 8 oz/day of a beverage described as 27% cranberry juice on a weekly progressive dosing schedule.
The primary measure was urinary proanthocyanidin A2 concentration in ng/mg creatinine, summarized as a mean with standard deviation. The timeframe included 24-hour urine and morning spot urine, and the concentration was to be measured using an LC-MS/MS method. The registry does not report numerical endpoint results or statistical analyses.
Adverse-event counts list 0 serious and 0 other events among 5 participants at risk in each category. The death count is not reported in the registry record. The study’s biomarker question is distinct from a clinical urinary tract infection outcome.