Residual Gastric Volume Measured by Ultrasound in Diabetic Surgical Population Versus Non-diabetic Surgical Population.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Residual Gastric Volume Measured by Ultrasound in Diabetic Surgical Population Versus Non-diabetic Surgical Population. (NCT05435157), a registered phase not stated study. The primary outcome is Residual Gastric Volume.

2. Clinical Question

The clinical question concerns a measured preoperative characteristic, not the effect of an assigned treatment. Both groups are described as undergoing scheduled surgery, and the primary outcome is residual gastric volume measured by ultrasound before surgery. The record also lists antral cross-sectional area as a secondary outcome, but does not report its results.

Because this is an observational comparison, any difference in the measured endpoint could reflect differences between the groups other than diabetic status. The registry record does not specify how those differences were handled analytically. It also does not give the primary endpoint population, so the relationship between the overall enrollment and the number included in the endpoint analysis cannot be established. The primary question is therefore identifiable, but its answer and the precision of that answer are not reported.

3. Trial Design

NCT05435157 is a completed observational study titled “Residual Gastric Volume Measured by Ultrasound in Diabetic Surgical Population Versus Non-diabetic Surgical Population.” The official title describes a comparative observational study of residual gastric volume measured by ultrasound after preoperative fasting. The listed condition is Diabetes Mellitus, and the sponsor is Fundación Instituto de Estudios de Ciencias de la Salud de Castilla y León.

The registry reports enrollment of 592. The study began on 2022-03-09, and the primary completion date is 2024-12-31. The status is COMPLETED. These record details describe the study’s administrative timeline and enrollment; they do not establish how many participants contributed usable data to the primary endpoint analysis.

The two described study groups are diabetic patients undergoing scheduled surgery and non-diabetic patients undergoing scheduled surgery. Allocation is not stated. The registry explicitly identifies this as not a randomized comparison and says the arms are not a like-for-like control comparison. The record does not describe matching, recruitment procedures, a common eligibility framework, or adjustment for differences between groups.

The primary outcome is residual gastric volume in mL, measured in the preoperative timeframe and summarized using the median and interquartile range. The outcome description gives an ultrasound-based formula involving CSARLD and age. Antral cross-sectional area is listed as a secondary outcome. The registry record does not report outcome values, confidence intervals, p-values, or the estimates for the four listed analyses.

Additional design details that would help assess comparability and data quality—including the planned sample-size justification, missing-data approach, analysis populations, and statistical adjustment strategy—are not reported in the registry record. A description of these design elements should not be inferred from the study’s completed status or its enrollment count.

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 Residual Gastric Volume, measured over Preoperative.

The primary endpoint is residual gastric volume, measured in mL by ultrasound in the preoperative timeframe. The registry specifies that the endpoint is summarized with a median and interquartile range. The median describes the central position of the observed values, while the interquartile range describes the spread of the middle half of those values. These summaries can be useful when measurements are skewed or include unusually high or low values, because they do not rely on the mean and standard deviation to describe the distribution.

The registry’s measurement description gives the formula: Volume (mL) = 27.0 + 14.6 × CSARLD (cm²) - 1.28 × age (years). The record does not expand the abbreviation CSARLD or provide details about the ultrasound acquisition procedure, operator training, measurement reliability, or validation of the formula for this study population.

In general, a preoperative residual-volume measure can describe the amount of gastric content estimated to remain after fasting. That makes it a physiologic measurement relevant to the study’s comparison of surgical populations. This general rationale does not establish what the measured values were in this study or what clinical implications any difference might have. The registry record does not report the group medians, interquartile ranges, or a direct comparison for the primary endpoint.

Antral cross-sectional area is listed as a secondary outcome, but its measurement details and results are not reported in the registry record. Consequently, the primary endpoint definition is available, while its observed distribution and comparative precision are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the median and interquartile range describe?

General statistical explanation: The median is the middle of an ordered set of measurements. The interquartile range describes the span from the lower to the upper quartile, covering the middle half of the observations. These summaries focus on the distribution’s center and spread without assuming that measurements follow a symmetric, bell-shaped pattern. They are often useful for measurements that are skewed. The registry specifies these summaries for residual gastric volume, but does not report the resulting values.

A median and interquartile range do not, by themselves, quantify the uncertainty in a group comparison. A comparison might also be reported with an estimated difference and a confidence interval, or with another appropriate inferential method. The registry record does not state which inferential method was used, nor does it report a confidence interval or comparative estimate. Readers therefore cannot recover the precision of the group comparison from the endpoint summary specification alone.

How should the ultrasound-based formula be read?

The registry describes residual gastric volume as calculated using Volume (mL) = 27.0 + 14.6 × CSARLD (cm²) - 1.28 × age (years). The expression combines a constant with terms involving CSARLD and age. The registry does not expand CSARLD, so its meaning should not be assumed. It also does not report the measurement protocol, whether measurements were repeated, or how measurement variability was assessed.

General statistical explanation: When an outcome is calculated from measured inputs, uncertainty can enter through both the input measurements and the relationship used in the formula. A formula can standardize how an outcome is derived, but it does not remove measurement error or establish that the formula performs equally in all groups. The record does not report validation or group-specific performance information for this calculation.

What does the observational comparison allow?

The study compares existing groups defined by diabetic status; it does not assign participants to those groups at random. The registry says allocation is not stated and that the arms are not a like-for-like control comparison. General statistical explanation: Random allocation, when used, helps balance measured and unmeasured characteristics on average. In an observational comparison, group characteristics may differ for reasons related to both group membership and the outcome. Statistical adjustment can sometimes address measured differences, but cannot automatically account for unmeasured factors.

The registry record does not report whether any adjustment was undertaken, which variables were considered, or whether the analysis was stratified or matched. It is therefore not possible to determine how the analysis handled group differences. The reported design supports a comparison of observed populations, but a causal interpretation would require stronger assumptions and information than the record provides.

What can be inferred from the listed analyses?

The record lists two outcome measures and four analyses. It does not describe the analysis methods, identify the four analyses in sufficient detail, or state how they relate to the two outcome measures. The primary endpoint is identified as residual gastric volume; antral cross-sectional area is listed as a secondary outcome. The results for both are not reported in the registry record.

General statistical explanation: If researchers examine multiple outcomes, subgroups, or alternative models, the chance of encountering an apparently notable result can increase. Multiplicity procedures can control or otherwise address this issue, depending on the purpose and structure of the analyses. The registry record does not report whether a multiplicity strategy was planned or applied. No conclusion about that strategy should be inferred from the number of listed analyses alone.

What do the sample-size assumptions mean?

The registry describes planning illustrations computed from the observed effect, not the study’s own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event tables, the description says the quantity is a total number of events, while other tables give participants per arm. The primary outcome described in this record is not presented as a time-to-event outcome.

General statistical explanation: A sample-size planning illustration asks how much information might be needed under specified assumptions to detect a target effect with a chosen error rate and power. Such an illustration is not evidence that a study was designed with those assumptions, and it is not a measure of observed power. The registry record does not report a trial-specific sample-size justification or the numerical planning outputs. The illustrations also depend on the effect used as their starting point, so they should not be read as independent evidence that the observed comparison is precise.

For any planning quantity, the distinction between an assumed target and an observed result is essential. Participants per arm for 80% power, for example, would be a planning quantity rather than a count of participants who experienced an outcome. The registry record does not report numerical values for such quantities in the registry record for this analysis.

Overall, the statistical methods that can be described are limited to the stated endpoint summary and the listed planning assumptions. The inferential model, adjustment strategy, uncertainty estimates, and treatment of missing measurements are not reported in the registry record. Those omissions prevent a more complete assessment of the analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: residual gastric volume as the primary outcome and antral cross-sectional area as a secondary outcome. It also lists four analyses. The record does not explain what each analysis estimates, whether they include subgroup or sensitivity analyses, or which results were designated as confirmatory. It does not report a procedure for handling multiplicity.

General statistical explanation: When several outcomes or comparisons are examined, interpreting each result as if it were the only planned test can overstate how much evidence an individual result provides. A multiplicity approach may define a hierarchy of outcomes, adjust inference, or treat some analyses as exploratory. Which approach is appropriate depends on the design and aims. No particular approach can be attributed to this study because it is not reported in the registry record.

The record does not report the number of participants with available primary endpoint measurements, how missing measurements were handled, or whether any values were excluded. It does not state whether analyses used all enrolled participants, an endpoint-complete population, or another analysis population. Enrollment of 592 is not a substitute for an analysis denominator.

General statistical explanation: Missing measurements can affect both the amount of information available and the comparability of groups. If missingness is related to participant characteristics or measurement values, analyzing only observed data may yield a result that differs from the result for the intended population. Evaluating that possibility typically requires information about the amount and reasons for missingness and the analytical approach. These details are not reported in the registry record, so the direction or importance of any missing-data concern cannot be determined.

11. 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 lists safety counts for Diabetic Patients, Non-diabetic Patients, and Diabetic Patients With Dysautonomia. For these groups, the reported numbers at risk are 216, 144, and 221, respectively. Each group has zero serious events, zero other events, and zero deaths in the registry’s safety figures. No serious adverse-event terms are listed.

These figures should be read as the safety counts recorded for the named groups, not as a complete account of the study’s safety monitoring. The registry record does not describe the adverse-event collection period, event definitions, severity grading, relatedness assessment, or completeness of reporting. It also does not explain how the safety groups relate to the two main comparison groups or to the primary endpoint analysis population. In particular, the dysautonomia group is separately listed in the safety information, and the record does not establish that it is a third primary comparison arm.

General statistical explanation: A recorded count of zero means that no events of that category are entered for the listed group in the record. It does not, by itself, establish that no events occurred outside the recorded collection or that the event risk is zero. The zero counts should therefore be interpreted alongside the available information about monitoring and reporting, which is limited in the registry record.

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

The registry record establishes that the study was a completed observational comparison of diabetic and non-diabetic surgical populations, with preoperative ultrasound-measured residual gastric volume as the primary endpoint. It specifies the measurement unit, timeframe, summary approach, and formula. These features define the question and measurement strategy, but they do not provide the answer to the comparison.

The primary endpoint values and comparative result are not reported in the registry record. It is therefore not possible to state whether the measured distributions differed, how large any difference was, or how precisely it was estimated. The record does not provide a confidence interval or p-value for the primary comparison. The completed status should not be interpreted as evidence for a particular statistical or clinical conclusion.

The design also limits what a group difference could mean. Diabetic status was not assigned at random, and the record says the groups are not a like-for-like control comparison. General statistical explanation: An observed association between group membership and an outcome is not necessarily a causal effect. Differences in other characteristics may contribute to the observed contrast, and adjustment can address only factors that were measured and appropriately modeled. The registry does not report an adjustment strategy.

The record does not report the analysis population, endpoint completeness, missing-data handling, or the statistical model. These omissions make it difficult to evaluate whether the analyzed participants represent the enrolled population and whether the analysis accounts for relevant group differences. The stated enrollment of 592 does not establish the number contributing to the primary endpoint.

Accordingly, the statistical meaning available from the registry is primarily descriptive: it identifies a clinically framed observational question and an ultrasound-derived outcome. It does not establish the direction, magnitude, precision, or cause of a difference. Any interpretation beyond that would require results and analysis details not reported in the registry record.

13. Why This Trial Matters Statistically

This study raises a statistical question that is common in clinical research: how should a measured characteristic be compared between patient groups that arise through clinical status rather than random allocation? The endpoint is defined as preoperative residual gastric volume measured by ultrasound, and the groups are differentiated by diabetic status. The registry’s framing makes clear that this is an observational comparison, not a randomized treatment evaluation.

That distinction matters because group comparisons can be informative without being causal. Statistical interpretation depends not only on the measured outcome but also on how participants entered the groups, whether the groups differ in relevant characteristics, and how those differences are addressed. Here, allocation is not stated, the groups are explicitly not described as like-for-like controls, and adjustment methods are not reported. Readers therefore need to distinguish a comparison of observed populations from an estimate of an isolated effect of diabetic status.

The endpoint also illustrates the importance of measurement definitions. The record specifies a formula and reports that the result is summarized by median and interquartile range. Those details tell readers what quantity was intended and how its distribution was to be described. They do not substitute for reporting the observed values, uncertainty, or measurement procedures. The registry record does not provide the endpoint results or the information needed to evaluate measurement reliability.

Finally, the record shows why completion and enrollment are not sufficient for statistical assessment. Enrollment is reported as 592, but the analysis population and missing-data approach are not. Without the primary comparison and its precision, readers cannot evaluate the strength of evidence. The study’s statistical importance lies in the question and design features it makes visible, as well as in the limits imposed by missing results and methodological detail.

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 principal trial-specific limitation for statistical interpretation is that the registry record does not report the primary endpoint results. Group medians, interquartile ranges, comparative estimates, and uncertainty measures are absent. The direction and size of any difference therefore cannot be determined from the record.

The study is observational, and the registry says the arms are not a like-for-like control comparison. Allocation is not stated. The record does not report matching, adjustment, stratification, or covariates considered in analysis. This prevents assessment of whether differences between groups were addressed and limits any causal interpretation.

The registry reports enrollment of 592 but does not identify the number included in the primary endpoint analysis. It does not report exclusions, missing ultrasound measurements, analysis populations, or the handling of incomplete data. These details are needed to assess how the analyzed sample relates to the enrolled population.

The outcome description gives a formula using CSARLD and age but does not expand CSARLD or describe ultrasound acquisition, assessor training, repeatability, or formula validation. This restricts assessment of how consistently the primary endpoint was measured. Antral cross-sectional area is listed as a secondary outcome, but its results and measurement details are not reported.

The record lists four analyses without describing their methods or relationship to the outcome measures. It does not report a multiplicity strategy or trial-specific sample-size justification. Safety information includes zero recorded events across named groups, but the event collection period and definitions are not reported. These limitations concern what can be evaluated from the registry record; they do not establish that a particular procedure was or was not used.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Residual Gastric Volume Measured by Ultrasound in Diabetic Surgical Population Versus Non-diabetic Surgical Population. — NCT05435157.
• Registry record last updated 2026-08-13; status last verified 2026-07.
• Results first posted 2026-05-01.
• 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.

18. Record Summary

NCT05435157 is a completed observational study sponsored by Fundación Instituto de Estudios de Ciencias de la Salud de Castilla y León. The record reports enrollment of 592, a start date of 2022-03-09, and a primary completion date of 2024-12-31. Its stated comparison is between diabetic and non-diabetic patients undergoing scheduled surgery.

The primary outcome is preoperative residual gastric volume in mL, measured by ultrasound and summarized using the median and interquartile range. The record gives a calculation formula and lists antral cross-sectional area as a secondary outcome. It describes the comparison as non-randomized, with allocation not stated and arms that are not a like-for-like control comparison.

The primary endpoint results, comparative estimates, uncertainty measures, analysis populations, missing-data procedures, and statistical adjustment methods are not reported in the registry record. Safety counts list zero serious events, zero other events, and zero deaths for each named group; the record does not give further event-monitoring details.