Retrospective Study on Referral Patterns for High Risk Patients Post Nephrectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Retrospective Study on Referral Patterns for High Risk Patients Post Nephrectomy (NCT04309617), a registered phase not stated study. The primary outcome is Follow-up Duration.

2. Clinical Question

The clinical question is descriptive rather than a comparison of assigned treatments. The registry describes a population with locoregional renal cell carcinoma after nephrectomy and sets out goals concerning recurrence risk, referrals, and subsequent treatment. It also identifies outcomes intended to characterize recurrence and disease-free interval, including in a subgroup receiving adjuvant systemic therapy with sunitinib.

These aims should be distinguished from results. The registry record reports the primary outcome definition but does not report its numerical median or full range. It also does not provide numerical findings for recurrence, disease-free interval, referral patterns, or treatment. The entry therefore establishes what the investigators intended to characterize, but does not establish the observed values or support a comparison between treatment strategies.

3. Trial Design

This is a retrospective study of medical-record data, registered as NCT04309617 and sponsored by Pfizer. Its title concerns provider referral patterns following nephrectomy in high-risk locoregional renal cell carcinoma. The registry describes the study population as patients diagnosed with renal cell carcinoma who received nephrectomy between 01Apr2014 and 31Mar2019. Enrollment is recorded as 618.

The study period recorded in the registry begins 2019-07-31, with primary completion on 2020-04-28, and the status is COMPLETED. The brief description says that the study aimed to estimate the proportion of patients at high risk for recurrence following nephrectomy, describe referral patterns, characterize treatment, and report recurrence and disease-free interval. It also specifies an intended subgroup assessment among patients receiving adjuvant systemic therapy with sunitinib. These are stated objectives; numerical findings for them are not reported in the registry record.

Nephrectomy is the listed intervention and is classified as a procedure. Because the study looks back at people whose care had already occurred, that listing does not mean the procedure was assigned by the study. The registry does not describe a randomized allocation or a control arm suitable for a like-for-like treatment comparison. Its allocation field is not stated, and the arm description identifies patients who received nephrectomy rather than distinct assigned strategies.

The primary outcome is follow-up duration, described as a median with a full range. The analysis population is defined as all eligible participants whose data were retrieved from medical records and studied. Although the registry records 20 outcome measures, it lists 0 analyses. The registry record does not report a protocol-level statistical plan, sample-size justification, or details of how referral and treatment patterns were analyzed.

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: Data collected were observed and evaluated in this study's duration of approximately 9 months.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Analysis population included all eligible participants whose data were retrieved from medical records and studied.

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: Analysis population included all eligible participants whose data were retrieved from medical records and studied.

6. Primary Endpoint

The registry lists the primary outcome as Follow-up Duration, measured over From index date to the last entry in the medical record, death, or disease recurrence, approximately during 5 years (data observed during 9 months of retrospective study).

The primary endpoint is follow-up duration in years, summarized by the median and full range. It is defined as the time from the date of nephrectomy, designated the index date, to the last entry in the medical record, death, or disease recurrence. The stated timeframe refers to approximately 5 years, with data observed during 9 months of retrospective study.

Follow-up duration describes how long outcome information was available in the records. It helps readers understand the period over which recurrence or other clinical events could be documented, and whether follow-up was brief or extended across the study population. The median is a measure of the middle of the ordered follow-up times and is less influenced by unusually long or short observations than the arithmetic mean. The full range describes the minimum and maximum recorded durations, but it does not show how observations are distributed between those extremes.

This measure is not itself a recurrence rate or disease-free interval. Its definition includes several possible endpoints for the observation period, including the last record entry, death, and recurrence. The registry record does not provide the numerical median or full range, so the magnitude and spread of follow-up cannot be interpreted from the registered outcome definition alone. It also does not report a numerical result for the recurrence or disease-free-interval objectives.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry defines the primary measure as median follow-up duration and specifies the full range as its dispersion. This is a descriptive summary, not a treatment-effect estimate. The time origin is the date of nephrectomy, called the index date. The endpoint of the follow-up interval is the last medical-record entry, death, or disease recurrence, according to the outcome definition. The stated timeframe is approximately 5 years, while the record also says data were observed during 9 months of retrospective study.

What does the median describe?

In general, the median is the middle value after observations are ordered. It communicates a typical central position without requiring unusually long observations to have as much influence as they would on a mean. The median does not describe the full shape of the distribution. Two datasets can have the same median while differing in their spread, clustering, or tails. The full range supplies only the endpoints of that spread; it does not reveal how many observations lie near either endpoint or whether most observations are concentrated in a narrow interval.

Here, neither the numerical median nor the full range is reported in the registry record. As a result, the registered method can be explained but not used to describe the observed follow-up distribution. The measure also depends on information captured in medical records. A last record entry marks the end of documented observation, which is not necessarily the same as a biological event. The registry does not provide more detail about record coverage or follow-up procedures.

How is follow-up different from an event outcome?

In general, follow-up duration describes the observation period, whereas an event outcome describes whether and when a particular event occurs. The study separately names recurrence and disease-free interval as outcomes it intends to report. Those outcomes should not be conflated with the primary follow-up measure: the endpoint definition allows the follow-up interval to end at the last record entry, death, or recurrence. The registry does not give numerical event results or explain the analysis methods used for recurrence or disease-free interval.

Time-to-event methods can account for differences in observation length when the event time and censoring information are appropriately recorded. In general, censoring means that an event time is not observed during a participant’s available follow-up, so the information contributes up to the last known observation without establishing a later event time. The registry does not report whether a particular time-to-event estimator was used for the listed outcome measures. It is therefore not appropriate to attribute a survival curve, hazard model, or censoring procedure to this study.

What can a confidence interval add?

In general, a confidence interval expresses the uncertainty around an estimate under the assumptions of the analysis. A narrow interval indicates greater statistical precision than a wide interval, while the interval’s location indicates which values remain compatible with the data and method. A confidence interval does not eliminate bias from selective record availability, outcome misclassification, or confounding. No confidence interval for the primary endpoint is reported in the registry record, and no numerical estimate is available to interpret.

For counts, proportions, and event rates, the denominator and the definition of each outcome are essential. A proportion of patients with high-risk disease, for example, requires a clear population and a documented high-risk definition. The brief description states the objective of estimating that proportion, but the registry record does not report the criteria or a numerical estimate. It also does not give outcome-specific denominators. Enrollment of 618 cannot be assumed to equal the number with complete information for any particular outcome.

What do the planning assumptions mean?

In general, a sample-size illustration based on an observed effect describes the size of a future study that might be needed to detect a specified fraction of that effect under stated assumptions. Such an illustration is not the original study’s sample-size justification and is not observed power. The listed planning convention specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it says time-to-event illustrations use total events, while other illustrations use participants per arm. These are planning assumptions, not evidence that the retrospective study used equal allocation or conducted a randomized comparison. No effect estimate or sponsor-reported hazard ratio is reported in the registry record for interpreting such an illustration. For time-to-event planning, the stated convention is to use sponsor-reported hazard ratios only.

More generally, over-dispersion occurs when count variability exceeds what a simple statistical model expects. Accounting for it can prevent uncertainty from being understated when the model is too restrictive. The registry record does not identify an over-dispersion analysis or a model for count outcomes, so this is a general statistical consideration rather than a description of the study’s methods.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 20 outcome measures and 0 analyses. The outcome count indicates that multiple measures were registered, but the record does not provide analysis results with which to evaluate them. It does not report whether a primary analysis was selected for each outcome, how secondary outcomes were prioritized, or whether any adjustment for multiple testing was planned. When many outcomes are examined, the chance of at least one apparently notable result can increase; in general, a prespecified analysis plan and transparent reporting help readers distinguish confirmatory analyses from exploratory ones. No such details are reported in the registry record.

Missing-data handling is also not described. The primary analysis population is defined as eligible participants whose data were retrieved from medical records and studied, but there is no account of how many records were unavailable, which variables were incomplete, or how incomplete observations were handled. The registry record does not report imputation, sensitivity analyses, or an assessment of missingness. These details matter because the availability of records can affect which patients contribute to a descriptive estimate and can limit how representative that estimate is.

Enrollment is recorded as 618, but the registry does not provide outcome-specific denominators or a participant flow for each analysis. It is therefore not possible to infer that every enrolled participant contributed to every outcome, or to judge the amount of missing outcome information. The record also does not report subgroup sizes for patients receiving adjuvant sunitinib. Without those details, precision and comparability across the planned descriptions cannot be assessed.

The study’s retrospective medical-record basis makes completeness and consistency of documentation important considerations. The registry does not describe procedures used to verify records or classify outcomes. These are limitations in the information available for interpretation, not proof that any specific data problem occurred.

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

The record establishes that a retrospective study was completed to characterize patients with renal cell carcinoma after nephrectomy, with an emphasis on high-risk locoregional disease, referral patterns, and subsequent treatment. It defines follow-up duration from nephrectomy to the last medical-record entry, death, or recurrence, and identifies the median and full range as the intended summaries. These definitions clarify what the study set out to measure.

The numerical primary result is not reported in the registry record. Thus, the record does not establish the median follow-up duration, the observed range, or the precision of either summary. It also does not provide numerical results for the stated aims concerning high-risk disease, referral patterns, recurrence, disease-free interval, or treatment. The study’s COMPLETED status does not fill this reporting gap.

The study does not establish a causal effect of nephrectomy or sunitinib. The record describes patients who received nephrectomy and an intended subgroup receiving adjuvant systemic therapy, but it does not describe randomized assignment or a like-for-like control comparison. In general, treatment received in routine care may be related to patient characteristics and clinical decisions. Without a suitable comparison and adjustment details, observed group differences cannot by themselves be interpreted as treatment effects.

Enrollment of 618 describes the registered study size, not necessarily the number contributing to every outcome. The registry does not report outcome-specific denominators or missing-data handling. Consequently, the precision and representativeness of any outcome estimates cannot be evaluated from this record. The appropriate conclusion is limited: the registry documents the study question and outcome definitions, but does not provide the numerical results needed to characterize what was observed.

12. Why This Trial Matters Statistically

Retrospective studies of medical records can address questions about how care was delivered and how patients were followed in a defined clinical setting. This study’s stated objectives connect follow-up after nephrectomy with provider referral patterns, treatment characterization, recurrence, and disease-free interval. Those are distinct descriptive questions, and each depends on clear outcome definitions and an account of which records contribute.

Statistically, the primary endpoint highlights the importance of distinguishing observation time from an event. A median follow-up duration describes the length of available documentation, while recurrence and disease-free interval concern clinical outcomes. Reporting both the estimate and its spread would help readers understand the observation window behind outcome descriptions. The registry defines the measure but does not report its numerical median or full range, leaving that interpretation unavailable.

The study also illustrates why an enrollment figure alone is not enough to judge a retrospective analysis. Outcome-specific denominators, record completeness, missing-data methods, and subgroup sizes are needed to assess precision and potential selection. The record does not report these details. Similarly, intended comparisons involving patients who did and did not receive adjuvant therapy would require careful interpretation because the registry does not describe random allocation or an analysis plan that addresses group differences.

Finally, a completed status and a detailed set of objectives are not substitutes for posted estimates. With 20 outcome measures listed and 0 analyses, readers can identify the scope of the investigation but cannot evaluate the numerical findings or their uncertainty from the registry record. This distinction between planned questions and publicly reported evidence is central to sound statistical interpretation.

13. 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 primary limitation for interpreting this trial record is the absence of numerical results for its primary endpoint. Although median follow-up and the full range are specified, neither value is reported in the registry record. The stated timeframe of approximately 5 years and observation during 9 months of retrospective study do not provide the actual follow-up distribution.

The registry describes several additional objectives but does not report numerical findings for the proportion considered high risk, referral patterns, treatment, recurrence, or disease-free interval. It does not define the criteria for high-risk status or give outcome-specific denominators. The intended subgroup receiving adjuvant systemic therapy with sunitinib is mentioned, but the record does not report its size or results.

The retrospective design relies on medical-record data, yet the registry does not describe the completeness of records, outcome ascertainment, or steps taken to address missing information. It also does not report a participant flow or clarify how many eligible records contributed to each measure. These omissions prevent assessment of precision and leave open the possibility that recorded participants differ from those whose information was unavailable; the record does not establish whether or to what extent that occurred.

No randomized allocation or like-for-like control comparison is described. The allocation method is not stated, and the listed arm description is a population that received nephrectomy. The registry record also does not report an analysis plan, sample-size justification, interim analyses, or multiplicity handling. These are limitations in what can be evaluated from the registry entry, rather than evidence that particular methods were or were not used outside the record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Retrospective Study on Referral Patterns for High Risk Patients Post Nephrectomy — NCT04309617.
• Registry record last updated 2021-05-19; status last verified 2021-04.
• Results first posted 2021-05-19.
• 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.

17. Record Summary

NCT04309617 is a completed retrospective study sponsored by Pfizer, titled “Retrospective Study on Referral Patterns for High Risk Patients Post Nephrectomy.” The official title is “Provider Referral Patterns Following Nephrectomy in High-Risk Locoregional Renal Cell Carcinoma.” Enrollment is recorded as 618. The registry lists a study start of 2019-07-31 and primary completion of 2020-04-28.

The population description covers patients diagnosed with renal cell carcinoma who received nephrectomy between 01Apr2014 and 31Mar2019. Nephrectomy is the listed procedure. The primary outcome is median follow-up duration in years, with full range, measured from the nephrectomy date to the last medical-record entry, death, or recurrence. The study also aims to describe referral and treatment patterns and report recurrence and disease-free interval.

The registry lists 20 outcome measures and 0 analyses. It does not report the primary endpoint’s numerical result, outcome-specific denominators, or numerical findings for the other stated objectives.